Carboxylic acid vinyl ester polymerization inhibitor, polymerization inhibition method and use thereof

Abstract

The present application relates to the technical field of carboxylic acid ester polymerization inhibitor, disclose a kind of carboxylic acid vinyl ester polymerization inhibitor, the polymerization inhibitor includes A component and B component, A component is 4-phenyl methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-ketone, B component is piperidine nitroxide radical compound.Effectively inhibit polymerization, and the polymerization effect is good and low toxicity.

Description

Technical Field

[0001] This invention relates to the technical field of carboxylic acid ester polymerization inhibitors, and specifically to a ethylene carboxylic acid ester polymerization inhibitor. Background Technology

[0002] Vinyl carboxylate esters are a very important class of organic chemical raw materials, among which vinyl acetate is the most representative. Vinyl acetate, also known as vinyl acetate, has the molecular formula C4H6O2. It is a colorless, flammable liquid with a sweet ether-like odor. It is mainly used in the production of polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), and ethylene copolymer emulsions, and has wide applications in slurries, coatings, synthetic fibers, and membrane materials.

[0003] However, vinyl carboxylate is prone to self-polymerization during production, storage, and transportation. This self-polymerization can significantly impact the safety of production and storage facilities. Therefore, polymerization inhibitors need to be added during production and transportation to prevent polymerization. Existing polymerization inhibitors include quinone inhibitors, polyphenol inhibitors, aromatic amine inhibitors, and free radical inhibitors. Currently, p-benzoquinone and hydroquinone are mainly used as polymerization inhibitors. However, p-benzoquinone is currently expensive, and its quality is unstable and its supply is scarce.

[0004] Chinese patent document CN101312937B discloses a method for preparing vinyl carboxylate. The method mentions that the polymerization inhibitors used for preparing vinyl carboxylate include hydroquinone, hydroquinone monomethyl ether, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol, nitroso compounds, isoacryloyl nitrate, nitrosodiphenylamine, N-nitrosocyclohexylhydroxyamine, methylene blue, phenothiazine, tannic acid, or diphenylamine. The amount of polymerization inhibitor used is generally 1-10,000 ppm.

[0005] Chinese patent document CN116573985B discloses the application of N-oxygen free radical compounds as polymerization inhibitors and polymerization inhibitor compositions. The background section describes that, to prevent the polymerization of olefin monomers, a common method is to add appropriate polymerization inhibitors during the production process to suppress undesirable polymerization reactions. Currently, commonly used polymerization inhibitors in olefin monomer plants include: 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical (HTMPO), 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one, 2-sec-butyl-4,6-dinitrophenol (DNBP), N,N-diethylhydroxylamine (DEHA), hydroquinone (HQ), phenothiazine (PTZ), p-benzoquinone (PBQ), p-hydroxyanisole (MEHQ), copper salts, etc. However, the polymerization inhibition effect of the above-mentioned inhibitors is not entirely ideal.

[0006] An application of an N-oxygen radical compound as a polymerization inhibitor to prevent the polymerization of olefin monomers, wherein the N-oxygen radical compound has the structure shown in Formula 1: Formula 1, in which X is -CONH-, -COO-, -NHCONH-, -NHCSNH-, -SO2NH-, or -NHCOO-; R is a C1-C18 alkyl chain, a C5-C12 cycloalkyl chain, or a C7-C15 phenylalkyl chain, wherein the N-oxygen radical compound includes 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxygen radical, 4-butyryloxy-2,2,6,6-tetramethylpiperidine 1-oxygen radical, 4-acetoxy-2,2,6,6-tetramethylpiperidine 1-oxygen radical, and 4-methanesulfonamide. One or more of -2,2,6,6-tetramethylpiperidine 1-oxy radicals, wherein the N-oxy radical compound with the structure shown in Formula 1 is used in combination with other polymerization inhibitors; the other polymerization inhibitors are one or more of 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radicals, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, N,N'-substituted phenylenediamine, N,N-diethylhydroxylamine, hydroquinone, phenothiazine, p-benzoquinone, p-hydroxyanisole, copper salts, and 4-phenylmethylene-2,6-ditert-butyl-2,5-cyclohexadien-1-one.

[0007] Chinese patent document CN111100001B discloses a compound polymerization inhibitor for vinyl acetate distillation and its application method. The inhibitor comprises component A, component B, and component C, wherein component A is N,N-diphenyl-p-phenylenediamine, component B is 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical (4-OH-TEMPO), and component C is 2,4-dimethyl-6-sec-butylphenol (DNBP). The content of each component by mass percentage is as follows: A 20%, B 50%, C 30%.

[0008] The existing technology has the following shortcomings: Currently, the main inhibitors for the polymerization of ethylene carboxylic acid esters are p-benzoquinone and hydroquinone. P-benzoquinone and hydroquinone are highly toxic and can irritate the skin and eyes. Long-term exposure or inhalation can have adverse effects on health. In addition, hydroquinone is not very effective at inhibiting polymerization. Summary of the Invention

[0009] To simultaneously address the technical problems of poor polymerization inhibition effect and high toxicity, this invention provides a vinyl carboxylate polymerization inhibitor, characterized in that the inhibitor comprises component A and component B, component A being 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one, and component B being a piperidine nitroxide radical compound.

[0010] Preferably, the piperidine nitroxide radical compounds include at least one of piperidine nitroxide ketone, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical and 4-hydroxypiperidine nitroxide radical.

[0011] Preferably, the mixing mass ratio of component A to component B is 1:0.1-2.

[0012] Preferably, the mixing mass ratio of component A to component B is 1:0.5-1.

[0013] Preferably, the mixing mass ratio of component A to component B is 1:0.5.

[0014] A method for inhibiting the polymerization of vinyl carboxylate, characterized in that 1-15 ppm of the vinyl carboxylate polymerization inhibitor is added to the vinyl carboxylate.

[0015] Application of vinyl carboxylate polymerization inhibitors in preventing the polymerization of vinyl carboxylate.

[0016] The present invention has the following beneficial effects: 1. The polymerization inhibitor obtained by compounding 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (BTBC) and piperidine nitroxide free radical compounds has a high polymerization inhibition effect, which can effectively inhibit the polymerization reaction and prevent the formation of explosive polymerization. At the same time, it has the characteristics of low toxicity and is an environmentally friendly polymerization inhibitor, thus balancing the two effects. The polymerization inhibitor of this invention is particularly suitable for the polymerization inhibitor of vinyl carboxylate.

[0017] 2. Compared with some highly toxic chemicals, the low-toxicity polymerization inhibitor of this invention poses less harm to human health and the environment during manufacturing, storage and use. When the low-toxicity polymerization inhibitor is released into the environment, it has less toxicity to aquatic and terrestrial organisms, thus reducing the impact on the ecosystem.

[0018] 3. The environmentally friendly polymerization inhibitor provided by this invention is part of the enterprise's goal of achieving sustainable development and helps to reduce the impact on the environment; at the same time, this invention can extend the processing time of polymers, reduce material waste caused by premature polymerization reaction, and thus reduce waste generation. Detailed Implementation

[0019] The following detailed description illustrates the specific implementation method: Those skilled in the art will understand that polymerization inhibitors are industrial auxiliaries typically used to prevent polymerization. Inhibitor molecules react with chain radicals to form non-radical substances or low-activity free radicals that cannot initiate polymerization, thereby terminating the polymerization.

[0020] To prevent polymerization of olefin monomers during storage and transportation, a small amount of polymerization inhibitor is often added to the monomer, which is then removed before use. Generally, polymerization inhibitors are solid substances with low volatility and can be removed during monomer distillation. Hydroquinone, a commonly used polymerization inhibitor, reacts with sodium hydroxide to form a water-soluble sodium salt, so it can be removed by washing with a 5%–10% sodium hydroxide solution. Inorganic polymerization inhibitors such as cuprous chloride and ferric chloride can also be removed by alkaline washing.

[0021] Inhibitors prevent polymerization from taking place and create an induction period during polymerization (a period during which the polymerization rate is zero). The length of the induction period is directly proportional to the amount of inhibitor. Once the inhibitor is consumed, the induction period ends, and polymerization proceeds at the normal rate when no inhibitor is present.

[0022] Those skilled in the art will recognize that 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (BTBC) is abbreviated as BTBC. The molecular formula is C 21 H 26 O is an important organic compound containing a biaromatic ring, with broad application prospects in medicine, materials, optoelectronics, and biology. Therefore, research on its synthesis process is of great significance.

[0023] Precursor synthesis: The synthesis of BTBC requires cyclohexadiene and benzyl bromide as raw materials. First, benzyl bromide and cyclohexadiene are added to a reaction vessel, along with potassium carbonate and a certain amount of organic solvent. The reaction proceeds under a nitrogen atmosphere to produce 1-benzyl-2,5-cyclohexene. The reaction equation is as follows: C6H5CH2Br+C6H8→C6H5CH2C6H5+HBr Synthesis of BTBC: 1-Benzyl-2,5-cyclohexadiene reacts with butanone in isopropanol, and an appropriate amount of potassium hydroxide and excess sodium iodide are added. The reaction is carried out for 2-3 hours to obtain BTBC.

[0024] Those skilled in the art will understand that carboxylic acid esters are organic compounds prepared by the dehydration of carboxylic acids and alcohols under acid catalysis, or by the reaction of alcohols with acylation reagents (such as acyl chlorides or acid anhydrides). Their structural characteristic lies in the substitution of the -OH group in the carboxyl group of the carboxylic acid molecule with -OR, forming an ester group (-COO-), which is also the functional group of carboxylic acid esters.

[0025] Vinyl acetate, also known as vinyl acetate or vinyl acetic acid, has the structural formula CH2=CHCOOCH3 and is a type of carboxylic acid ethylene ester. At room temperature and pressure, vinyl acetate is a colorless, transparent liquid with a characteristic fruity aroma. It is volatile, slightly soluble in water, and miscible with organic solvents such as ethanol, ether, and carbon tetrachloride. It has wide applications in industrial production and is an important basic raw material.

[0026] Piperidine nitrogen oxide radical compounds: compounds containing a piperidine ring (a six-membered ring structure in which one carbon atom is replaced by a nitrogen atom) and a nitrogen oxide radical group (i.e., an oxygen radical is attached to a nitrogen atom).

[0027] Piperidine nitroxide free radical ketone: refers to nitroxide free radical piperidinone (polymerization inhibitor ZJ-702), whose chemical formula is C9H. 16 NO2, also known as 4-oxo-2,2,6,6-tetramethylpiperidine-1-ox free radical, CAS number 2896-70-0.

[0028] 4-Hydroxypiperidine nitroxide radical: The molecular structure contains a hydroxyl (-OH) substituted piperidine ring, in which the nitrogen atom is covalently bonded to a carbon atom on the ring and carries an oxygen atom, forming a nitroxide radical.

[0029] 4-Hydroxy-2,2,6,6-Tetramethylpiperidine nitroxide radical: also known as polymerization inhibitor 701, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical, nitroxide radical piperidinol, 4-hydroxypiperidineol oxygen radical, molecular formula: C9H 18 NO2, CAS number 2226-96-2.

[0030] A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is a piperidine nitroxide radical compound.

[0031] Piperidine nitroxide radicals include at least one of piperidine nitroxide ketone, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical, and 4-hydroxypiperidine nitroxide radical.

[0032] The mixing mass ratio of component A to component B is 1:0.1-2, and the preferred mixing mass ratio of component A to component B is 1:0.5, 1:1, 1:1.5 and 1:2.

[0033] A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:0.1-2 at room temperature.

[0034] A method for inhibiting the polymerization of vinyl carboxylate involves adding 1-15 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate, preferably 2 ppm, 5 ppm, 8 ppm, 10 ppm, 12 ppm, and 15 ppm.

[0035] Example 1 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is piperidine nitroxide free radical ketone.

[0036] The mixing mass ratio of component A to component B is 1:0.1. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:0.1 at room temperature.

[0037] A method for inhibiting the polymerization of vinyl carboxylate involves adding 15 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0038] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 15ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0039] Example 2 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is piperidine nitroxide free radical ketone.

[0040] The mixing mass ratio of component A to component B is 1:0.5. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:0.5 at room temperature.

[0041] A method for inhibiting the polymerization of vinyl carboxylate involves adding 10 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0042] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0043] Example 3 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is piperidine nitroxide free radical ketone.

[0044] The mixing mass ratio of component A to component B is 1:1. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:1 at room temperature.

[0045] A method for inhibiting the polymerization of vinyl carboxylate involves adding 5 ppm of vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0046] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 8ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0047] Example 4 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical.

[0048] The mixing mass ratio of component A to component B is 1:1. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:1 at room temperature.

[0049] A method for inhibiting the polymerization of vinyl carboxylate involves adding 5 ppm of vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0050] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 5ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0051] Example 5 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical.

[0052] The mixing mass ratio of component A to component B is 1:1. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:1 at room temperature.

[0053] A method for inhibiting the polymerization of vinyl carboxylate involves adding 10 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0054] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0055] Example 6 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical.

[0056] The mixing mass ratio of component A to component B is 1:2. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:2 at room temperature.

[0057] A method for inhibiting the polymerization of vinyl carboxylate involves adding 10 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0058] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0059] Example 7 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is 4-hydroxypiperidine nitroxide radical.

[0060] The mixing mass ratio of component A to component B is 1:1. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:1 at room temperature.

[0061] A method for inhibiting the polymerization of vinyl carboxylate involves adding 10 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0062] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0063] Example 8 A vinyl carboxylate polymerization inhibitor, the polymerization inhibitor comprising component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is 4-hydroxypiperidine nitroxide radical.

[0064] The mixing mass ratio of component A to component B is 1:2. A method for preparing a vinyl carboxylate polymerization inhibitor involves mixing component A and component B at a mass ratio of 1:2 at room temperature.

[0065] A method for inhibiting the polymerization of vinyl carboxylate involves adding 10 ppm of a vinyl carboxylate polymerization inhibitor to the vinyl carboxylate.

[0066] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0067] Comparative Example 1 Add 10 ppm of hydroquinone (HQ) polymerization inhibitor to ethylene carboxylate.

[0068] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of hydroquinone (HQ) polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0069] Comparative Example 2 Add 10 ppm of p-benzoquinone (PBQ) polymerization inhibitor to vinyl carboxylate.

[0070] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) and 10ppm of the polymerization inhibitor p-benzoquinone (PBQ), mix well, place the test tube in a 65℃ constant temperature water bath, start timing, and stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0071] Comparative Example 3 Add 10 ppm of piperidine nitroxide free radical ketone polymerization inhibitor to ethylene carboxylate.

[0072] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of piperidine nitroxide free radical ketone polymerization inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0073] Comparative Example 4 Add 10 ppm of 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical inhibitor to vinyl carboxylate.

[0074] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the vinyl acetate weight of the initiator azobisisobutyronitrile (AIBN) and 10ppm of 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical inhibitor, mix well, place the test tube in a 65℃ constant temperature water bath, start timing, and stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0075] Comparative Example 5 Add 10 ppm of 4-hydroxypiperidine nitroxide radical inhibitor to ethylene carboxylate.

[0076] Induction period test: Add 100g of refined vinyl acetate to a test tube, then add 0.2% of the initiator azobisisobutyronitrile (AIBN) by weight of vinyl acetate, and 10ppm of 4-hydroxypiperidine nitric oxide free radical inhibitor. Mix well, place the test tube in a 65℃ constant temperature water bath, and start timing. Stop timing when vinyl acetate begins to produce gas. The time from the start of timing to the production of gas is the polymerization induction period.

[0077] Table 1. Detection parameters of Examples 1-8 and Comparative Examples 1-5 Examples 1-3 of this invention are polymerization inhibitors composed of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (BTBC) and piperidine nitroxide free radical ketone. Under different ratios, the induction period is longer than that of existing hydroquinone (HQ), p-benzoquinone (PBQ) and piperidine nitroxide free radical ketone alone, and its toxicity is also lower.

[0078] Examples 4-6 of this invention are polymerization inhibitors composed of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (BTBC) and 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radicals. Under different ratios, the induction period is longer than that of existing hydroquinone (HQ), p-benzoquinone (PBQ) and the use of 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radicals alone, and its toxicity is also low.

[0079] Examples 7 and 8 of this invention are polymerization inhibitors composed of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (BTBC) and 4-hydroxypiperidine nitroxide radicals. Under different ratios, the induction period is longer than that of existing hydroquinone (HQ), p-benzoquinone (PBQ) and the use of 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radicals alone, and its toxicity is also lower.

[0080] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A vinyl carboxylate polymerization inhibitor, characterized in that, The polymerization inhibitor comprises component A and component B, wherein component A is 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one and component B is a piperidine nitroxide radical compound.

2. The ethylene carboxylate polymerization inhibitor according to claim 1, characterized in that: The piperidine nitroxide radical compounds include at least one of piperidine nitroxide radical ketone, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical and 4-hydroxypiperidine nitroxide radical.

3. The vinyl carboxylate polymerization inhibitor according to claim 2, characterized in that: The mixing mass ratio of component A to component B is 1:0.1-2.

4. The ethylene carboxylate polymerization inhibitor according to claim 3, characterized in that: The mixing mass ratio of component A to component B is 1:0.5-1.

5. The vinyl carboxylate polymerization inhibitor according to claim 4, characterized in that: The mass ratio of component A to component B is 1:0.

5.

6. A method for inhibiting the polymerization of ethylene carboxylate, characterized in that: The vinyl carboxylate polymerization inhibitor according to any one of claims 1-5 is added to the vinyl carboxylate.

7. The method for inhibiting the polymerization of ethylene carboxylate according to claim 6, characterized in that: Add 1-15 ppm of vinyl carboxylate polymerization inhibitor to vinyl carboxylate.

8. The application of the ethylene carboxylate polymerization inhibitor according to any one of claims 1-5, characterized in that: Application of vinyl carboxylate polymerization inhibitors in preventing the polymerization of vinyl carboxylate.

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