CN108912943B

CN108912943B - Polymerization-inhibiting coating, method for producing the same and use thereof for preventing polymerization of styrene monomers during storage

Info

Publication number: CN108912943B
Application number: CN201710209285.3A
Authority: CN
Inventors: 菅秀君; 王申军; 贾庆龙; 朱相春; 解洪梅
Original assignee: China Petroleum and Chemical Corp
Current assignee: China Petroleum and Chemical Corp
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2020-11-17
Anticipated expiration: 2037-03-31
Also published as: CN108912943A

Abstract

The invention belongs to the technical field of hydrocarbon stabilization, and particularly relates to a polymerization-inhibiting coating, a preparation method thereof and application thereof in preventing polymerization of styrene monomers in storage. The polymerization-inhibiting coating comprises a bottom layer, a middle layer and a surface layer, wherein each layer is prepared from raw materials comprising a base material and an auxiliary material or a curing agent, the base material of the middle layer takes epoxy resin and solvent-free glass flakes as raw materials, and takes ammonium persulfate, alcohol ester 12 and a polymerization inhibitor as auxiliary agents, the base materials of the bottom layer and the surface layer do not contain the polymerization inhibitor, and the auxiliary material or the curing agent of the surface layer also contains a dispersing agent. According to the invention, the formula of the polymerization inhibitor and the formula of the coating material are changed, and the synergistic effect of the polymerization inhibitor and the dispersing agent is changed, so that the formation of low polymers on the coating can be blocked, and the polymerization inhibition effect of the coating is improved.

Description

Polymerization-inhibiting coating, method for producing the same and use thereof for preventing polymerization of styrene monomers during storage

Technical Field

The invention belongs to the technical field of hydrocarbon stabilization, and particularly relates to a polymerization-inhibiting coating, a preparation method thereof and application thereof in preventing polymerization of styrene monomers in storage.

Background

The styrene monomer is active in chemical property, is an important polymerized monomer, can be polymerized by itself or with other monomers, and is widely applied to the fields of synthetic high polymer materials, coatings, medicines and the like. Styrene can undergo a slow thermally-activated polymerization at ambient temperature. Therefore, it is necessary to add a polymerization inhibitor to ensure the product quality when the styrene monomer is transported or stored.

The common storage polymerization inhibitor is tert-butyl catechol (TBC), 2, 5-ditert amyl hydroquinone, p-hydroxyanisole and the like, and is a crystalline substance at normal temperature. During storage, at a certain temperature, part of the arene monomer in the storage tank is vaporized and condensed on the top, the side wall, the bracket, the pipe orifice and the pipeline of the tank, such as commonly called dew. The volatile steam contains almost no polymerization inhibitor, is easy to polymerize and brings great harm to production: can cause blockage of top facilities, discharge ports, nozzles, monitoring instruments in the tank and the like of the storage tank, and when the tank top polymer is serious, the tank top polymer is in a shape of stalactite; part of the gas-phase monomer is polymerized, so that the loss of the monomer in the storage tank is caused; when liquid phase monomers contact with the polymers, the polymers can be dissolved in the liquid phase to pollute products in a storage tank, so that the quality of the products is reduced or unqualified; in addition, inconvenience is brought to the overhaul of the device.

Therefore, domestic and foreign scholars research methods for preventing gas-phase monomer polymerization in styrene monomer storage tanks so as to solve the difficult problem of condensate polymerization. For example, the top of a styrene storage tank is painted to improve surface smoothness, so that condensate falls into the liquid phase as soon as possible; the number of protruding parts on the inner wall of the storage tank is reduced as much as possible, so that the number of attachment points of the styrene condensate is reduced. However, these two methods do not completely prevent the polymerization of styrene condensates without polymerization inhibitors.

CN201310256508.3 discloses a storage method of an arene monomer, which is to brush a coating on the inner wall of an arene monomer storage tank, wherein the coating contains a polymerization inhibitor, the coating consists of a bottom layer and a surface layer, the bottom layer is a coating containing the polymerization inhibitor, and the surface layer is a coating without the polymerization inhibitor. According to the storage method of the aromatic alkene monomer, the polymerization inhibitor is ground and sieved and then added into the coating material in the implementation process, and the polymerization inhibition period is 6 years by adopting a heating and mixing mode. The invention does not report the synergistic effect of the polymerization inhibitor and the dispersant in the aromatic alkene monomer condensate.

CN201410248172.0 discloses a preparation method of a polymerization-inhibiting coating for aromatic olefin monomers. The method comprises the following steps: (1) under the protection of nitrogen, EP828 type epoxy resin is used as a raw material, an ether auxiliary agent is added, and the mixture is heated and stirred to react to prepare a coating surface layer base material for later use; (2) heating, stirring and reacting according to the step (1), cooling, adding a polymerization inhibitor into the system, and carrying out heat preservation reaction to obtain a base material of the bottom layer of the coating for later use; (3) respectively adding a curing agent into the two base materials and uniformly mixing; (4) the method comprises the steps of brushing the inner wall of an aromatic olefin monomer storage tank in a layered brushing mode, firstly brushing a bottom base material to form a bottom coating, and then brushing a surface base material to form a surface coating, wherein the bottom coating is a polymerization inhibitor-containing coating, and the surface coating is a polymerization inhibitor-free coating. The compound used as the polymerization inhibitor in the step (2) can be one or a plurality of compounds selected from hydroxylamine compounds, aniline compounds, phenol compounds, quinone compounds and nitroxide free radical compounds. However, the patent does not report the synergistic effect of the dispersing agent, and the coating material formula is different from the invention, and the polymerization inhibition period is 10 years.

CN201210215514.X proposes to brush a coating on the inner wall of a vinyl monomer storage tank, wherein the coating also comprises a bottom layer, a middle layer and a surface layer, the bottom layer and the surface layer are coatings containing no polymerization inhibitor, the middle layer is a coating containing a polymerization inhibitor, and the middle layer is prepared by the following steps before being brushed: (1) adding a polymerization inhibitor into a solvent for dissolving; (2) adding the solution in the step (1) into a base material of a coating material, and stirring and mixing; (3) adding an auxiliary curing agent into the base material containing the polymerization inhibitor, stirring and mixing, and then brushing. The adhesion of the coating is improved by dissolving the polymerization inhibitor and adding the polymerization inhibitor into the base material.

CN201110199434.5 describes a styrene storage tank inner wall coating, which consists of a component A and a component B, wherein the weight ratio of the component A to the component B is 4:1, the component A comprises epoxy phenolic resin, a mixed solvent, a pigment, a filler, a polymerization inhibitor, a dispersant and an anti-settling agent, and the component B comprises an epoxy curing agent and n-butyl alcohol. The polymerization inhibitor is 2, 5-di-tert-butyl hydroquinone, and the curing agent is cardanol epoxy curing agent or aromatic amine epoxy curing agent. The coating consists of a primer, an intermediate paint and a finish paint, wherein the intermediate paint contains a polymerization inhibitor. However, the document does not disclose the preparation process conditions of the coating, does not report the adhesive force change of the coating after the polymerization inhibitor is added, and the observation period of the polymerization inhibition effect is only 3 months.

Disclosure of Invention

The invention aims to provide a polymerization inhibiting coating, a preparation method thereof and application thereof in preventing polymerization of styrene monomers in storage, wherein the formation of oligomers on the coating can be inhibited and the polymerization inhibiting effect of the coating can be improved by changing the formula of a polymerization inhibitor, the formula of a coating material and the synergistic effect of the polymerization inhibitor and a dispersing agent, so that the problem of the reduction of the polymerization inhibiting effect of the coating in the later period of the release of the polymerization inhibitor in the prior art is solved, a long-term effective polymerization inhibiting effect is sought, and the tank cleaning period of a styrene storage tank is prolonged.

The polymerization-inhibiting coating comprises a bottom layer, a middle layer and a surface layer, wherein each layer is prepared from raw materials comprising a base material and an auxiliary material or a curing agent, the base material of the middle layer takes epoxy resin and solvent-free glass flakes as raw materials, and takes ammonium persulfate, alcohol ester 12 and a polymerization inhibitor as auxiliary agents, the base materials of the bottom layer and the surface layer do not contain the polymerization inhibitor, and the auxiliary material or the curing agent of the surface layer also contains a dispersing agent.

The solvent-free glass flakes are thin-skinned or columnar, and have a fineness of 40-200 meshes, preferably 60-100 meshes.

The polymerization inhibitor is selected from one or more of ether compounds, hydroxylamine compounds, aniline compounds, phenol compounds, quinone compounds and nitroxide free radical compounds; preferably, the polymerization inhibitor is selected from one or more of ether-based compounds such as p-hydroxyanisole, hydroxylamine-based compounds such as dihydroxypropylhydroxylamine (HPHA), aniline-based compounds such as N, N' -diisobutyl-phenylenediamine, phenol-based compounds such as Hydroquinone (HQ), 2,3, 5-trimethyl-4-nitrosophenol, p-tert-butyl catechol (TBC), 2, 5-ditert amyl hydroquinone (DTBHQ), 2, 6-dibutyl-4-methylphenol, etc., quinone-based compounds such as benzoquinone, tert-butyl benzoquinone (TBBQ), benzoquinone diimide, 1, 4-naphthoquinone, and nitroxide-based compounds such as 2,2,6, 6-tetramethyl-4-hydroxy-piperidinyloxy radical (628D).

The preferable polymerization inhibitor is storage type polymerization inhibitors TBC, HQ, hydroxylamine compounds and nitrogen oxygen free radical compounds, or a compound of two of them; preferably, the TBC and dihydroxypropylhydroxylamine (HPHA) compound is prepared from TBC and HPHA in a ratio of 1: 1-9: 1.

The addition of a large amount of polymerization inhibitor leads to long polymerization inhibition duration under the same conditions, but the addition of a large amount of polymerization inhibitor also influences the adhesion and service life of the coating material. The addition amount of the polymerization inhibitor is preferably 1 to 40 wt%, and more preferably 10 to 25 wt%.

The dispersant is an organic phosphine compound, preferably, the dispersant is one or more of triphenylphosphine, diphenyl phosphorus chloride, di-tert-butylphenyl phosphine, tri-tert-butylphosphine, tert-butyldiphenylphosphine, cyclohexyl diphenylphosphine, tricyclohexylphosphine, tri (o-tolyl) phosphine, and tri (p-tolyl) phosphine, and the addition amount thereof is 0.1 to 10 wt%, preferably 1 to 6 wt%.

The bottom layer is a coating layer which does not contain a polymerization inhibitor and a dispersing agent, the middle layer is a coating layer which only contains a polymerization inhibitor, and the surface layer is a coating layer which only contains a dispersing agent. The thickness range of the coating of the bottom layer is 10-300 mu m, preferably 30-100 mu m; the thickness range of the coating of the middle layer is 10-200 μm, preferably 20-150 μm; the coating thickness of the top layer is in the range of 10 μm to 400 μm, preferably 50 μm to 300 μm, more preferably 100 μm to 250 μm.

A preparation method of a polymerization-resistant coating comprises the following steps:

(1) taking epoxy resin and solvent-free glass flakes as raw materials, taking ammonium persulfate, alcohol ester 12 and a polymerization inhibitor as auxiliaries, carrying out reaction, and directly using the obtained product as a base material of a coating interlayer;

(2) adding the dispersing agent into the auxiliary material or the curing agent, and stirring and mixing uniformly;

(3) adding auxiliary materials or curing agents into the coating base materials, stirring and mixing to respectively prepare different coating materials, wherein the base materials without polymerization inhibitor (polymerization inhibitor is not added in the stirring reaction process in the step (1)) and the auxiliary materials without dispersing agent are uniformly mixed to prepare bottom layer materials, the base materials obtained in the step (1) and the auxiliary materials without dispersing agent are mixed to obtain middle layer materials, and the base materials without polymerization inhibitor and the auxiliary materials obtained in the step (2) are mixed to prepare surface layer materials;

(4) and brushing the polymerization-inhibiting coating in a layered brushing mode.

Grinding the polymerization inhibitor or dissolving the polymerization inhibitor in a solvent, adding the polymerization inhibitor, other auxiliaries, raw material epoxy resin and solvent-free glass flakes into a reaction kettle, heating under the protection of nitrogen, raising the temperature, stirring, and uniformly mixing, wherein the heating temperature is 60-100 ℃, and the heating time is 1-5 hours.

And (3) grinding the dispersing agent in the step (2), adding the grinding agent into auxiliary materials or curing agents, and mixing for 0.5-2 h at the temperature of 20-50 ℃. After the dispersing agent is added, the styrene gas and the polymerization inhibitor can be released from the coating simultaneously along with the volatilization of the styrene gas, and the styrene gas and the polymerization inhibitor are compatible to play a synergistic effect, so that the formation of low polymers on the coating can be blocked, the polymers are prevented from being condensed on the surface of the coating, the formation of 'stalactite' -shaped high polymers is effectively avoided, and the polymerization inhibition effect of the coating is improved.

The different coating materials in the step (3) are placed for not more than 24 hours, and the painting is preferably completed within 12 hours. The preferred adjuvant or curing agent is a magma amine adduct.

Use of the polymerization inhibiting coating to prevent polymerization of styrenic monomers in storage.

The polymerization inhibitor and the dispersant are added in the process of preparing the base material and the auxiliary material of the coating material, so that the coating material is endowed with better polymerization inhibition performance, the polymerization inhibition coating adopts a layered coating mode, the adhesive force is good, the polymerization inhibition effect is durable, the release rate of the polymerization inhibitor in the coating can be effectively controlled by adjusting the adding amount of the polymerization inhibitor and the dispersant and the surface layer thickness, the formation of oligomer is blocked, the formation of stalactite-shaped high polymer is effectively avoided, the effect of long-term polymerization inhibition is achieved, and the polymerization phenomenon in the storage process of the styrene monomer is fundamentally solved.

The adhesion force of the coating after being brushed is better than 3 grades, and the smaller the adhesion force grade number is, the better the adhesion force grade number is.

After the coating is coated, once styrene monomer steam meets the wall of the vessel and is condensed, the polymerization inhibitor and the dispersant in the coating are slowly diffused into the condensate, so that the purposes of polymerization inhibition and dispersion are achieved. The release rates of the polymerization inhibitor and the dispersant in the coating can be controlled by adjusting the addition amount of the polymerization inhibitor in the coating base material, the addition amount of the dispersant in the auxiliary material and the thickness of the surface layer of the coating, and the slower the release rates of the polymerization inhibitor and the dispersant are, the longer the polymerization inhibition period is, thereby achieving the effect of inhibiting polymerization for a long time.

The rate of inhibitor release was examined in a volume of carbon steel storage tank with a concave roof. Coating a coating on the top of the tank according to a certain proportion and a coating mode, wherein the tank is filled with a certain volume of styrene monomer, and a small measuring cup is fixed close to the top of the tank and used for collecting condensate of styrene gas phase monomer. And heating the styrene in the tank to a certain temperature, collecting condensate periodically, checking the change condition of the coating of the top cover, analyzing the content of a polymerization inhibitor in the condensate, inspecting the release amount of the polymerization inhibitor from the coating, and determining the polymerization inhibition period of the polymerization inhibitor.

The polymerization inhibition effect of the dispersing agent is also examined in a carbon steel storage tank with a certain volume, different coatings are coated on a standard tin plate (50 multiplied by 100 multiplied by 0.2-0.3 mm) according to a certain proportion and a coating mode, styrene and the tin plate coated with different coatings are added into the tank, the temperature is kept constant at 80 ℃ for a certain time, and during the period, styrene polymer is deposited on the surface of the tin plate. And then cooling, taking out the tinplate, drying and weighing.

In the storage process, the formation of low polymer on the coating is blocked by the synergistic action of the polymerization inhibitor and the dispersant contained in the styrene condensate, and the polymerization-inhibiting service life of the coating is prolonged.

Changing the adding amount of the polymerization inhibitor and the thickness of the surface layer of the tank top coating, collecting the tank top condensate at the same temperature, and analyzing the content of the polymerization inhibitor in the condensate, wherein the more the adding amount of the polymerization inhibitor is increased, the thicker the surface layer is, the slower the polymerization inhibitor is released, and the longer the polymerization inhibition time is.

The monomer of the invention can be styrene, and is also suitable for p-methylstyrene, o-methylstyrene, tert-butylstyrene, diarylalkenylbenzene, chlorostyrene, bromostyrene and the like.

Compared with the prior art, the invention has the beneficial effects that:

compared with the preparation method and the process effect of the protective coating in the prior art, the preparation method and the process effect of the protective coating are different, the preparation process of the coating is simple, a new process formula is adopted in the preparation process, ammonium persulfate, alcohol ester 12 and a polymerization inhibitor are taken as auxiliary agents, a dispersing agent is added as a polymerization inhibition auxiliary agent to obtain a novel coating material with lasting polymerization inhibition performance, and the formation of low polymer on the coating can be blocked through the synergistic action of the polymerization inhibitor and the dispersing agent in the coating, so that the polymerization inhibition effect of the coating is improved. The coating has good adhesive force and long polymerization inhibition duration after use, and solves the problem of the reduction of polymerization inhibition effect in the later release stage of the coating polymerization inhibitor in the prior art. By adopting a layered brushing or spraying method, the release rates of the polymerization inhibitor and the dispersant in the coating can be effectively controlled by three effective measures of adjusting the addition of the polymerization inhibitor in the process of preparing the base material, adjusting the addition of the dispersant in the auxiliary material and adjusting the thickness of the surface layer in the brushing process of the surface layer, so that the effect of long-term polymerization inhibition is achieved, and the polymerization inhibition period can be more than 15 years.

Meanwhile, the novel polymerization-inhibiting coating obtained by the invention can effectively reduce product loss caused by monomer polymerization, ensure the product quality in the storage tank, eliminate the hidden trouble that the polymer is dissolved in the product to cause product pollution and even the whole tank product is unqualified, and prolong the tank cleaning period of maintenance.

Detailed Description

The present invention is further illustrated by the following examples, but the present invention is not limited to these examples. The spirit and scope of the present invention will be fully understood from the examples, which illustrate the features of the preparation process of the present invention.

Examples 1 to 5: preparation of the intermediate layer of the coating

Adding 300g of XH-1 type epoxy resin into a 1L reactor with a stirrer and a reflux condenser, grinding into 60g of 100-mesh solvent-free glass flakes, 10 g of ammonium persulfate and 100g of alcohol ester 12, uniformly grinding a compound of HQ and 628D, wherein the compounding ratio of HQ:628D is 6:1, heating and raising the temperature under a nitrogen environment to prepare a coating base material, adding a thick-slurry amine addition compound curing agent into the prepared base material before brushing, and stirring for 0.5h, wherein the mixing ratio of the base material to the thick-slurry amine addition compound is 6:1 (volume ratio). Then, the epoxy resin paint is coated on a standard tin plate (50 multiplied by 100 multiplied by 0.2-0.3 mm) to form a coating with the thickness of about 100 mu m. The adhesion was tested after the coating was dried out and the results of the tests for different reaction conditions are shown in table 1.

TABLE 1 preparation conditions for the intermediate layer of the coating

Examples	Reaction temperature/. degree.C	Reaction time/h	Amount of polymerization inhibitor added/%)	Adhesion of coatings
					1	60	5	40	Grade 3
2	70	3	1	2 to 3 stages
					3	80	3	10	2 to 3 stages
4	90	2	20	2 to 3 stages
					5	100	1	30	2 to 3 stages

As can be seen from Table 1, the coating materials prepared by the above-mentioned methods all meet the use requirements.

Examples 6 to 12: preparation of coating surface layer

Adding the auxiliary material of the amine addition compound into a 10L reactor with a stirrer, uniformly grinding the dispersing agent, adding into the reactor under the stirring condition, and carrying out heat preservation reaction for 0.5-2 h to obtain the coating auxiliary materials with different dispersion properties. Before brushing, the auxiliary materials are added into the base material and stirred, wherein the mixing ratio of the base material to the auxiliary materials is 8:1 (volume ratio), and the stirring time is 1 h. Then, the above materials were applied to a standard tin plate (50X 100X 0.2-0.3 mm) to form a coating of about 80 μm in thickness. The adhesion was tested after the coating dried out and the results are shown in table 2:

TABLE 2 preparation conditions of coating surface layer

As can be seen from Table 2, the coating prepared by the method of the invention has good adhesion and meets the use requirements. After the coated plate is soaked in styrene for one week, the coating is still intact, and no peeling or falling phenomenon occurs.

Examples 13 to 16: investigation of effect of inhibition of polymerization of coating

The preparation method of the epoxy resin paint comprises the following steps of coating the epoxy resin paint on the inner wall of the top of a 5L styrene storage tank:

bottom layer coating material: directly mixing the base material and the auxiliary material of the magma amine addition compound according to the volume ratio of 7:1, and stirring and mixing for 0.5 h.

Base coating material: the preparation method is as in examples 1-5, 300g of XH-1 type epoxy resin is added, the mixture is ground into 60g of 100-mesh solvent-free glass flakes, 10 g of ammonium persulfate, 100g of alcohol ester 12, the reaction temperature is 85 ℃, and the reaction time is 3 hours.

Intermediate layer coating material: and (2) adding 300g of XH-1 type epoxy resin, grinding into 60g of 100-mesh solvent-free glass flakes, 10 g of ammonium persulfate, 100g of alcohol ester 12, and compounding polymerization inhibitor TBC + HPHA, wherein the ratio of TBC to HPHA is 3:1, the addition amount accounts for 26% of the coating amount, the reaction temperature is 85 ℃, and the reaction time is 3 hours, so as to obtain the coating base material with the polymerization inhibiting performance. Before brushing, adding the auxiliary material of the magma amine addition product into the base material, and stirring, wherein the mixing ratio of the base material to the magma amine addition product is 7:1 (volume ratio), and the stirring time is 0.5 h.

Surface coating material: the coating auxiliary material is prepared by the method of the embodiment 6-12, firstly, uniformly grinding the di-tert-butyl phenyl phosphine serving as the dispersing agent, then, adding the ground di-tert-butyl phenyl phosphine into a 10L reactor with a stirrer to be mixed with the auxiliary material magma amine addition product, wherein the adding amount of the di-tert-butyl phenyl phosphine is 5% (wt) of the coating amount, and carrying out heat preservation reaction for 1h at the reaction temperature of 30 ℃ to obtain the coating auxiliary material with non-dispersing performance. Before brushing, the auxiliary materials are added into the base material and stirred, wherein the mixing ratio of the base material to the auxiliary materials is 7:1 (volume ratio), and the stirring time is 1 h.

The inner wall of the top of the 5L styrene storage tank is coated in a three-layer re-coating mode, the coating is carried out according to different thicknesses of a middle layer and a surface layer, the middle layer contains a polymerization inhibitor, the surface layer contains a dispersing agent, and the thickness of the bottom layer is 60 mu m.

After the coating was completed, the styrene condensate was periodically collected at a storage temperature of 40 ℃ and analyzed for the content of the polymerization inhibitor, as shown in Table 3.

TABLE 3 variation of inhibitor content in condensate for different primer and topcoat thicknesses

As can be seen from Table 3, by changing the thickness of the surface layer, the release rates of the polymerization inhibitor and the dispersant in the coating can be better controlled, so that the coating can maintain a longer polymerization inhibition time, and the expected effect is achieved.

If no polymerization inhibitor is added into the coating, polymers appear on the top of the tank under the same conditions, and the dispersant plays a role of an auxiliary polymerization inhibitor, so that the oligomers can be dispersed and dissolved into styrene, and a large amount of polymers are prevented from being formed and adhered to the inner wall.

The cycle time of the polymerization inhibition of the coating was examined with the tank top coating described in example 16. The amount of the inhibitor and dispersant released from the coating can be determined based on the total amount of the inhibitor and dispersant added and the amount of the collected condensate. The change in the release rate of the two adjuvants in the coating of example 21 at a storage temperature of 40 ℃ is shown in Table 4.

TABLE 4 variation in the amount of inhibitor and dispersant released in the coating

As can be seen from table 4, the amount of inhibitor released in the first month accounts for about 2.8% of the total amount added, the amount of inhibitor released in the second month accounts for about 3.3% of the total amount added, the release is significantly slowed down later, about 0.3% per month, about 4.6% after six months, and about 6.3% after one year; similarly, the first month release of dispersant was about 2.6% of the total addition, and from the third month, the release was increased by 0.3% every month, and after one year the release was about 6.0%, and the inhibition of polymerization of the coating was estimated to last more than 15 years. In the industrial application process, the storage temperature of the styrene monomer is generally below 15 ℃, the amount of the condensate on the top wall in the storage tank is less than that of the embodiment, so that the release rate of the polymerization inhibitor and the dispersant in the coating is slower and the polymerization inhibition performance lasts for a longer time under the industrial storage condition.

Comparative example 22

On the basis of the preparation method and the recoating mode of the polymerization inhibiting coating described in example 21, different coatings were applied to a standard tin plate (50 × 100 × 0.2-0.3 mm):

the bottom layer of the coating A is a coating layer which does not contain a polymerization inhibitor and a dispersing agent, the middle layer of the coating is a coating layer which only contains a polymerization inhibitor, and the surface layer of the coating layer is a coating layer which only contains a dispersing agent.

The bottom layer and the surface layer of the coating B are both coatings without polymerization inhibitor and dispersant, and the middle layer is a coating only containing polymerization inhibitor.

Styrene and two tinplate plates A and B coated with different coatings are added into a 5L carbon steel tank, and the temperature is kept constant at 80 ℃ for 24 hours, during which styrene polymer is deposited on the surfaces of the tinplate. And then cooling, taking out the tinplate, drying and weighing. As a result, the surface of the A tin plate containing the dispersant is smooth, and no obvious weight increase is seen; the surface of the galvanized iron plate B only containing the polymerization inhibitor has obvious bonding substances, and the weight of the galvanized iron plate is increased by 0.75 percent. The surface adhesion was characterized by infrared chromatography as an oligomer of styrene. Therefore, the addition of the dispersing agent in the coating has the function of dissolving and blocking the formation of the oligomer on the surface of the coating, and the polymerization inhibition efficiency of the coating is effectively improved.

Claims

1. The polymerization-inhibiting coating comprises a bottom layer, a middle layer and a surface layer, wherein each layer is prepared from raw materials comprising base materials and auxiliary materials, and the preparation method of the polymerization-inhibiting coating is characterized by comprising the following steps:

(1) taking epoxy resin and solvent-free glass flakes as raw materials, taking ammonium persulfate and alcohol ester 12 as auxiliaries, carrying out reaction, and directly using the obtained product as a base material of a coating bottom layer; taking epoxy resin and solvent-free glass flakes as raw materials, taking ammonium persulfate, alcohol ester 12 and a polymerization inhibitor as auxiliaries, carrying out reaction, and directly using the obtained product as a base material of a coating interlayer; taking epoxy resin and solvent-free glass flakes as raw materials, taking ammonium persulfate and alcohol ester 12 as auxiliaries, carrying out reaction, and directly using the obtained product as a base material of a coating surface layer;

(2) adding a dispersing agent into auxiliary materials, stirring and mixing uniformly, and mixing the base material in the surface layer in the step (1) with the auxiliary materials in the step to prepare a surface layer material, wherein a curing agent in the auxiliary materials is a magma amine addition compound; the dispersing agent is selected from one or more of triphenylphosphine, diphenyl phosphorus chloride, di-tert-butylphenyl phosphine, tri-tert-butylphosphine, tert-butyldiphenylphosphine, cyclohexyl diphenylphosphine, tricyclohexylphosphine, tri (o-tolyl) phosphine and tri (p-tolyl) phosphine, and the addition amount is 0.1-10 wt%;

(3) uniformly mixing the base material of the bottom layer in the step (1) with auxiliary materials without dispersing agents to prepare a bottom layer material; mixing the base material of the middle layer in the step (1) with auxiliary materials without dispersing agents to obtain a middle layer material;

2. The polymerization inhibiting coating of claim 1, wherein the solvent-free glass flakes are thin-skinned or columnar and have a fineness of 40-200 mesh.

3. The polymerization inhibiting coating of claim 2, wherein the solvent-free glass flakes have a fineness of 60-100 mesh.

4. The polymerization-inhibiting coating according to claim 1, wherein the polymerization inhibitor is one or more compounds selected from ether compounds, hydroxylamine compounds, aniline compounds, phenol compounds, quinone compounds, and nitroxide free radical compounds; the addition amount is 1-40 wt%.

5. The polymerization inhibiting coating of claim 4, wherein the polymerization inhibitor is selected from one or more of p-hydroxyanisole, dihydroxypropylhydroxylamine, N' -diisobutyl-phenylenediamine, hydroquinone, 2,3, 5-trimethyl-4-nitrosophenol, p-tert-butylcatechol, 2, 5-ditert-amylhydroquinone, 2, 6-dibutyl-4-methylphenol, benzoquinone, tert-butyl benzoquinone, benzoquinone diimide, 1, 4-naphthoquinone, 2,6, 6-tetramethyl-4-hydroxy-piperidinyloxy free radical; the addition amount is 10-25 wt%.

6. The polymerization inhibiting coating of claim 5, wherein the polymerization inhibitor is a compound of TBC and dihydroxypropylhydroxylamine, and the ratio of TBC to dihydroxypropylhydroxylamine is 1: 1-9: 1.

7. The polymerization inhibiting coating of claim 1, wherein the dispersant is added in an amount of 1 to 6 wt%.

8. The polymerization inhibiting coating of claim 1, wherein the coating thickness of the bottom layer ranges from 10 μ ι η to 300 μ ι η; the thickness range of the coating of the middle layer is 10-200 mu m; the coating thickness of the surface layer ranges from 10 mu m to 400 mu m.

9. The polymerization inhibiting coating of claim 8, wherein the coating thickness of the bottom layer is in the range of 30-100 μm; the thickness range of the coating of the middle layer is 20-150 mu m; the coating thickness of the surface layer ranges from 50 mu m to 300 mu m.

10. The barrier coating of claim 9, wherein the surface layer has a coating thickness in the range of 100 μm to 250 μm.

11. A method of preparing a barrier coating according to any one of claims 1 to 10 comprising the steps of:

(2) adding a dispersing agent into auxiliary materials, stirring and mixing uniformly, and mixing the base material in the surface layer in the step (1) with the auxiliary materials in the step to prepare a surface layer material, wherein a curing agent in the auxiliary materials is a magma amine addition compound;

12. The method for preparing the polymerization-inhibiting coating according to claim 11, wherein in the step (1), when preparing the interlayer base material, the polymerization inhibitor is ground or dissolved by a solvent, then the mixture is added into a reaction kettle together with other additives, raw materials of epoxy resin and solvent-free glass flakes, and then the mixture is heated and stirred under the protection of nitrogen to be uniformly mixed, wherein the heating temperature is 60-100 ℃ and the heating time is 1-5 hours.

13. The method for preparing the polymerization-inhibiting coating according to claim 11, wherein in the step (2), the dispersing agent is ground, then the dispersing agent is added into the auxiliary material, and the mixture is mixed for 0.5 to 2 hours at the temperature of 20 to 50 ℃.

14. Use of a barrier coating according to any one of claims 1 to 10 to prevent polymerisation of styrenic monomers on storage.