Plasticizer for polyvinyl chloride as well as preparation method and application of plasticizer

Abstract

The invention relates to a plasticizer for polyvinyl chloride as well as a preparation method and application thereof, and belongs to the technical field of plasticizers. The technical problems that in the prior art, a plasticizer is common in compatibility with polyvinyl chloride and prone to migration after being boiled in boiling water for a long time or making contact with a solvent are solved. The plasticizer for PVC comprises the following raw materials: a pyromellitic dianhydride crude product, toluene, 1, 4 butylene glycol, vinyl glycol ether, tribromoneopentyl alcohol, n-butyl alcohol, a hydrogen peroxide aqueous solution, an epoxidation auxiliary agent, an extraction solvent and a catalyst. The molecular structure of the plasticizer contains ester groups and epoxy groups of different structures, the bromine content is high, the plasticizer is good in compatibility with polyvinyl chloride and high in plasticizing efficiency, the contained epoxy groups are high in binding capacity with polyvinyl chloride, the plasticized polyvinyl chloride is high in flame retardant grade, and the flame retardant property is good. And the plasticized polyvinyl chloride material has excellent properties of long-time boiling water boiling resistance and low extraction rate.

Description

Technical Field

[0001] The invention belongs to the technical field of plasticizers, and specifically relates to a plasticizer for polyvinyl chloride (PVC) and a preparation method and application thereof, and in particular relates to the application of the plasticizer for polyvinyl chloride in the preparation of polyvinyl chloride. Background Art

[0002] In the prior art, plasticizer is mainly such as di(2-ethyl)hexyl phthalate (DEHP), small molecules such as butyl benzyl phthalate (BBP), they are generally compatible with PVC, and they do not possess flame retardant properties themselves, in plastic processing, often also need to add flame retardant, not only cause many types of auxiliary agents, mixing difficulty, affect processing and application performance, and because plasticizer molecule and flame retardant molecule are smaller, when boiling for a long time or contacting environments such as solvents, plasticizer or flame retardant migration, loss easily occur, affect the performance of material itself. And macromolecular and epoxy-type plasticizer and various materials such as PVC, polypropylene (PP) compatible ability and bonding ability are stronger, it is more excellent with the material itself comprehensive performance after polymer material miscible, if self can introduce flame retardant group, then can effectively overcome the difficult problem that plasticizer and flame retardant lose after boiling for a long time. How to develop plasticizer products that have good compatibility with PVC, are resistant to long-term boiling water, have low migration, and are flame retardant themselves is the research direction of the industry.

[0003] Meanwhile, pyromellitic anhydride is a very important raw material in industry, mainly used for preparing polyimide resin, high temperature resistant electrical insulating paint, synthetic resin crosslinking agent and epoxy resin curing agent, etc., and the first thing obtained in the preparation process of pyromellitic anhydride is crude pyromellitic anhydride, which is a crude product in the preparation process of pyromellitic anhydride. If a higher purity refined pyromellitic anhydride is needed, it needs to be crystallized with methanol, which will lose 7-10% of the yield, and will also increase the amount of by-products and the processing pressure of environmental protection. If the crude pyromellitic anhydride can be directly used as a raw material to synthesize PVC plasticizer, not only can the production cost be significantly reduced, but also the generation and discharge of pollutants can be reduced, which has good economic and environmental significance. Summary of the invention

[0004] In view of the above problems, the present invention develops a plasticizer for PVC and a preparation method and application thereof. The molecular structure of the plasticizer contains ester groups and epoxy groups of different structures and a high bromine content. The plasticizer not only has good compatibility with PVC and high plasticizing efficiency, but also has a strong ability to bind epoxy groups with PVC. The plasticized PVC has a high flame retardant grade, and the plasticized PVC material has excellent properties of resistance to long-term boiling water and low extraction.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows.

[0006] The plasticizer for PVC of the present invention comprises raw materials:

[0007]

[0008] The invention also comprises a catalyst, which is a mixture of phosphotungstic acid and molybdenum trioxide, and the total amount of the catalyst is 0.5%-0.8% of the crude quality of pyromellitic dianhydride.

[0009] Preferably, the epoxy equivalent of the PVC plasticizer is 468-540 g / mol.

[0010] Preferably, the crude pyromellitic anhydride is a crude product in the preparation process of pyromellitic anhydride, and in the crude pyromellitic anhydride, the purity of pyromellitic anhydride is 90wt%-93wt%, the content of trimellitic anhydride is 5wt%-8wt%, and the content of terephthalic acid is less than 1wt%.

[0011] Preferably, the concentration of the aqueous hydrogen peroxide solution is 30%-35%, and more preferably, the concentration of the aqueous hydrogen peroxide solution is 30%-32%.

[0012] Preferably, the epoxidation aid is ethanol or methanol.

[0013] Preferably, the extraction solvent is cyclohexane.

[0014] Preferably, in the catalyst, the mass ratio of phosphotungstic acid to molybdenum trioxide is 2:0.3-0.5.

[0015] In a second aspect, the present invention also provides a method for preparing the above-mentioned plasticizer for PVC, comprising the following steps:

[0016] (1) adding a formula amount of toluene and crude pyromellitic anhydride to a reaction kettle equipped with an esterification water separator, starting stirring and heating to 100-105° C., then adding a formula amount of 1,4-butenediol and a catalyst, and heating to the boiling point of toluene to carry out an esterification reaction with water;

[0017] (2) sampling and testing the hydroxyl value of the reactants, and when the hydroxyl value of the reactants is lower than 5 mgKOH / g, adding the formulated amount of vinyl glycol ether and tribromoneopentyl alcohol to continue the esterification reaction with water at the boiling point of toluene;

[0018] (3) taking samples and detecting the contents of vinyl glycol ether and tribromoneopentyl alcohol by gas chromatography, and when the contents of vinyl glycol ether and tribromoneopentyl alcohol are both less than 2%, adding a formulated amount of n-butanol to carry out an end-capping esterification reaction;

[0019] (4) Sampling and testing the acid value of the reactant. When the acid value of the reactant is lower than 3 mgKOH / g, cooling to 54-58° C., adding the formulated amount of epoxidation aid, stirring evenly, and then dripping the formulated amount of hydrogen peroxide solution. The dripping time is controlled to be 2-2.5 hours. After the dripping is completed, continue to keep the temperature at 54-58° C. for reaction;

[0020] (5) sampling and testing the iodine value of the reactants, and when the iodine value is lower than 5 g / 100 g, adding one-half to two-thirds of the extraction solvent to extract the reaction system, and performing static stratification to obtain an upper organic phase 1 and a lower aqueous phase 1, and then adding the remaining extraction solvent to the lower aqueous phase 1 for secondary extraction, and after static stratification, obtaining an upper organic phase 2 and a lower aqueous phase 2, and then combining the organic phase 1 and the organic phase 2 to obtain a final organic phase;

[0021] (6) The final organic phase is subjected to reduced pressure distillation under vacuum, and when the volatile matter is less than 1%, the temperature is reduced to below 70° C. and the material is discharged to obtain a plasticizer for PVC.

[0022] Preferably, in step (6), the temperature of the reduced pressure distillation is 102-108° C., and the vacuum degree is controlled at -0.095 MPa to -0.097 MPa.

[0023] In a third aspect, the present invention also provides use of the above-mentioned plasticizer for PVC in the preparation of PVC.

[0024] Compared with the prior art, the technical effects of the present invention are:

[0025] The plasticizer for PVC of the present invention adopts crude pyromellitic anhydride as a raw material. The crude pyromellitic anhydride is a crude product in the preparation process of refined pyromellitic anhydride. The refined pyromellitic anhydride needs to be crystallized with methanol to obtain the refined pyromellitic anhydride. The purity of the refined pyromellitic anhydride is above 99%. The content of pyromellitic anhydride in the crude pyromellitic anhydride is 90-93%, the content of trimellitic anhydride is 5-8%, and the content of terephthalic acid is below 1%. Because the loss is large when preparing high-purity pyromellitic anhydride by refined crystallization, the present invention uses the crude pyromellitic anhydride as a raw material to synthesize the plasticizer to reduce the cost of the product. At the same time, the byproducts in the production process of pyromellitic anhydride can be reduced, thereby reducing environmental pollution. A method is also provided for the development and utilization of the crude pyromellitic anhydride.

[0026] The plasticizer for PVC of the present invention uses organic alcohol raw materials with different molecular structures to carry out esterification chain extension reaction with crude pyromellitic anhydride in stages, and carries out epoxidation reaction on olefin double bonds in plasticizer molecules by means of hydrogen peroxide. The finally obtained plasticizer molecular structure contains ester groups and epoxy groups with different structures and has a high bromine content. The plasticizer has good compatibility with PVC and high plasticizing efficiency. In addition, the plasticized PVC has a high flame retardant grade due to its strong ability to combine with PVC. The plasticized PVC material has excellent performances of long-term boiling resistance and low extraction. DETAILED DESCRIPTION

[0027] In order to further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0028] The plasticizer for PVC of the present invention comprises raw materials: crude pyromellitic anhydride, toluene, 1,4-butene glycol, vinyl glycol ether, tribromoneopentyl alcohol, n-butanol, aqueous hydrogen peroxide solution, epoxidation auxiliary agent, extraction solvent and catalyst.

[0029] The PVC plasticizer of the present invention mainly comprises the following molecular structure:

[0030]

[0031] That is, it contains ester groups and epoxy groups with different structures.

[0032] The epoxy equivalent of the plasticizer of the present invention is 468-540 g / mol.

[0033] The crude pyromellitic anhydride of the present invention is a crude product in the preparation process of pyromellitic anhydride, in which the purity of pyromellitic anhydride is 90wt%-93wt%, the content of trimellitic anhydride is 5wt%-8wt%, and the content of terephthalic acid is less than 1wt%. The crude pyromellitic anhydride is 22-26 parts by weight, such as 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, and 26 parts by weight in some embodiments.

[0034] The toluene in the present invention is 14-18 parts by weight. For example, in some embodiments, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, or 18 parts by weight can be used.

[0035] The 1,4-butenediol of the present invention is 8-10 parts by weight, for example, in some embodiments, it can be 8 parts by weight, 9 parts by weight, or 10 parts by weight.

[0036] The vinyl glycol ether of the present invention is 13-18 parts by weight, such as 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, or 17 parts by weight in some embodiments.

[0037] The tribromoneopentyl alcohol of the present invention is 25-34 parts by weight. For example, in some embodiments, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, and 34 parts by weight can be used.

[0038] The n-butanol of the present invention is 6-9 parts by weight. For example, in some embodiments, 6 parts by weight, 7 parts by weight, 8 parts by weight, or 9 parts by weight may be used.

[0039] The aqueous hydrogen peroxide solution of the present invention is 57-60 parts by weight, such as 57 parts by weight, 58 parts by weight, 59 parts by weight, or 60 parts by weight in some embodiments. The concentration of the aqueous hydrogen peroxide solution is 30-35%, preferably 30%-32%.

[0040] The epoxidation aid of the present invention is 2-3 parts by weight, such as 2 parts by weight or 3 parts by weight in some embodiments. The epoxidation aid is preferably ethanol or methanol.

[0041] The extraction solvent of the present invention is 6-8 parts by weight, such as 6 parts by weight, 7 parts by weight, or 8 parts by weight in some embodiments. The extraction solvent is preferably cyclohexane.

[0042] The catalyst of the present invention is a mixture of phosphotungstic acid and molybdenum trioxide, and the total amount of the catalyst is 0.5%-0.8% of the crude quality of pyromellitic dianhydride. For example, in some embodiments, 0.5%, 0.6%, 0.7%, and 0.8% can be used. In the catalyst, the mass ratio of phosphotungstic acid to molybdenum trioxide is 2:0.3-0.5. For example, in some embodiments, 2:0.3, 2:0.4, and 2:0.5 can be used.

[0043] The present invention also provides a method for preparing the above-mentioned plasticizer for PVC, comprising the following steps:

[0044] (1) adding a formula amount of toluene and crude pyromellitic anhydride to a reaction kettle equipped with an esterification water separator, starting stirring and heating to 100-105° C., then adding a formula amount of 1,4-butenediol and a catalyst, and heating to the boiling point of toluene to carry out an esterification reaction with water;

[0045] (2) sampling and testing the hydroxyl value of the reactants. When the hydroxyl value of the reactants is lower than 5 mgKOH / g, it indicates that the chain extension reaction of 1,4-butenediol is basically completed. At this time, the formulated amount of vinyl glycol ether and tribromoneopentyl alcohol are added to continue the esterification reaction with water at the boiling point of toluene;

[0046] (3) sampling and detecting the contents of vinyl glycol ether and tribromoneopentyl alcohol in the reaction system by gas chromatography. When the contents of vinyl glycol ether and tribromoneopentyl alcohol are both lower than 2%, it indicates that the esterification reaction of vinyl glycol ether and tribromoneopentyl alcohol has been basically completed, and then adding a formula amount of n-butanol to carry out end-capping esterification reaction;

[0047] (4) Sampling and testing the acid value of the reactant. When the acid value of the reactant is lower than 3 mgKOH / g, it indicates that the carboxyl groups on the pyromellitic dianhydride have been basically esterified. The temperature is lowered to 54-58° C., and the epoxidation aid in the formula amount is added. After stirring evenly, the formula amount of hydrogen peroxide aqueous solution is added dropwise. The addition time is controlled to be 2-2.5 hours. After the addition is completed, the reaction is continued at 54-58° C.;

[0048] (5) Sampling and testing the iodine value of the reactants. When the iodine value is lower than 5 g / 100 g, it indicates that the epoxidation reaction of the unsaturated double bonds in the molecular structure of the reactants is basically completed. At this time, one-half to two-thirds of the extraction solvent is added to extract the reaction system, and static stratification is performed to obtain an upper organic phase 1 and a lower aqueous phase 1. The lower aqueous phase 1 is then added with the remaining extraction solvent for secondary extraction. After static stratification, an upper organic phase 2 and a lower aqueous phase 2 are obtained, and then the organic phase 1 and the organic phase 2 are combined to obtain a final organic phase;

[0049] (6) Add the final organic phase to a distillation reactor, raise the temperature to 102-108° C., start the vacuum system at the same time, and perform reduced pressure distillation to remove the solvent and residual small molecule n-butanol. When the volatile matter is less than 1%, release the vacuum system, control the vacuum system at -0.095 MPa to -0.097 MPa, cool to below 70° C., and discharge the material to obtain a plasticizer for PVC.

[0050] The PVC plasticizer of the present invention can be used in the preparation of PVC. It should be noted that the application method is not particularly limited, and the amount and method of use of the plasticizer in the formula for preparing polyvinyl chloride in the prior art can be referred to.

[0051] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0052] In the following examples, various processes and methods not described in detail are conventional methods known in the art. The materials, reagents, devices, instruments, equipment, etc. used in the following examples, if not otherwise specified, can be obtained from commercial sources. In the examples, crude pyromellitic anhydride is used, from Rugao Leheng Chemical Co., Ltd., wherein the purity of pyromellitic anhydride is 91.4wt%, the content of trimellitic anhydride is 6.5wt%, the content of terephthalic acid is 0.8wt%, and the balance is water.

[0053] Example 1

[0054] The plasticizer for PVC comprises the following raw materials: 22 parts by weight of crude pyromellitic anhydride, 14 parts by weight of toluene, 8 parts by weight of 1,4-butene glycol, 13 parts by weight of vinyl glycol ether, 25 parts by weight of tribromoneopentyl alcohol, 6 parts by weight of n-butanol, 57 parts by weight of aqueous hydrogen peroxide, 2 parts by weight of an epoxidation aid, 6 parts by weight of an extraction solvent, and a catalyst whose total amount is 0.5% by weight of the crude pyromellitic anhydride, wherein the catalyst is a mixture of phosphotungstic acid and molybdenum trioxide in a mass ratio of 2:0.3, the concentration of the aqueous hydrogen peroxide is 30wt%, the epoxidation aid is ethanol, and the extraction solvent is cyclohexane.

[0055] The preparation method of the above-mentioned PVC plasticizer comprises the following steps:

[0056] (1) adding a formula amount of toluene and crude pyromellitic anhydride to a reaction kettle equipped with an esterification water separator, starting stirring and heating to 100-105° C., then adding a formula amount of 1,4-butenediol and a catalyst, and heating to the boiling point of toluene to carry out an esterification reaction with water;

[0057] (2) sampling and testing the hydroxyl value of the reactants. When the hydroxyl value of the reactants is lower than 5 mgKOH / g, it indicates that the chain extension reaction of 1,4-butenediol is basically completed. At this time, the formulated amount of vinyl glycol ether and tribromoneopentyl alcohol are added to continue the esterification reaction with water at the boiling point of toluene;

[0058] (3) sampling and detecting the contents of vinyl glycol ether and tribromoneopentyl alcohol in the reaction system by gas chromatography. When the contents of vinyl glycol ether and tribromoneopentyl alcohol are both lower than 2%, it indicates that the esterification reaction of vinyl glycol ether and tribromoneopentyl alcohol has been basically completed, and then adding a formula amount of n-butanol to carry out end-capping esterification reaction;

[0059] (4) Sampling and testing the acid value of the reactant. When the acid value of the reactant is lower than 3 mgKOH / g, it indicates that the carboxyl groups on the pyromellitic dianhydride have been basically esterified. The temperature is lowered to 54-58° C., and the epoxidation aid in the formula amount is added. After stirring evenly, the formula amount of hydrogen peroxide aqueous solution is added dropwise. The addition time is controlled to be 2-2.5 hours. After the addition is completed, the reaction is continued at 54-58° C.;

[0060] (5) Sampling and testing the iodine value of the reactants. When the iodine value is lower than 5 g / 100 g, it indicates that the epoxidation reaction of the unsaturated double bonds in the molecular structure of the reactants is basically completed. At this time, one-half to two-thirds of the extraction solvent is added to extract the reaction system, and static stratification is performed to obtain an upper organic phase 1 and a lower aqueous phase 1. The lower aqueous phase 1 is then added with the remaining extraction solvent for secondary extraction. After static stratification, an upper organic phase 2 and a lower aqueous phase 2 are obtained, and then the organic phase 1 and the organic phase 2 are combined to obtain a final organic phase;

[0061] (6) Add the final organic phase to a distillation reactor, raise the temperature to 102-108° C., start the vacuum system at the same time, and perform reduced pressure distillation to remove the solvent and residual small molecule n-butanol. When the volatile matter is less than 1%, release the vacuum system, control the vacuum system at -0.095 MPa to -0.097 MPa, cool to below 70° C., and discharge the material to obtain a plasticizer for PVC.

[0062] After testing, the obtained plasticizer was a light yellow transparent viscous liquid with an epoxy equivalent of 533 g / mol.

[0063] Example 2

[0064] The plasticizer for PVC comprises the following raw materials: 24 parts by weight of crude pyromellitic anhydride, 15 parts by weight of toluene, 9 parts by weight of 1,4-butene glycol, 15 parts by weight of vinyl glycol ether, 27 parts by weight of tribromoneopentyl alcohol, 7 parts by weight of n-butanol, 58 parts by weight of aqueous hydrogen peroxide, 2 parts by weight of an epoxidation aid, 7 parts by weight of an extraction solvent, and a catalyst whose total amount is 0.6% by weight of the crude pyromellitic anhydride, wherein the catalyst is a mixture of phosphotungstic acid and molybdenum trioxide in a mass ratio of 2:0.4, the concentration of the aqueous hydrogen peroxide is 32wt%, the epoxidation aid is ethanol, and the extraction solvent is cyclohexane.

[0065] The preparation method of the above-mentioned plasticizer for PVC is the same as that in Example 1.

[0066] After testing, the obtained plasticizer was a light yellow transparent viscous liquid with an epoxy equivalent of 478 g / mol.

[0067] Example 3

[0068] The plasticizer for PVC comprises the following raw materials: 25 parts by weight of crude pyromellitic anhydride, 17 parts by weight of toluene, 9 parts by weight of 1,4-butene glycol, 17 parts by weight of vinyl glycol ether, 29 parts by weight of tribromoneopentyl alcohol, 8 parts by weight of n-butanol, 59 parts by weight of aqueous hydrogen peroxide, 3 parts by weight of epoxidation aid, 9 parts by weight of extraction solvent and a catalyst whose total amount is 0.7% by weight of the crude pyromellitic anhydride, wherein the catalyst is a mixture of phosphotungstic acid and molybdenum trioxide in a mass ratio of 2:0.4, the concentration of the aqueous hydrogen peroxide is 33wt%, the epoxidation aid is methanol and the extraction solvent is cyclohexane.

[0069] The preparation method of the above-mentioned plasticizer for PVC is the same as that in Example 1.

[0070] After testing, the obtained plasticizer was a light yellow transparent viscous liquid with an epoxy equivalent of 491 g / mol.

[0071] Example 4

[0072] The plasticizer for PVC comprises the following raw materials: 26 parts by weight of crude pyromellitic anhydride, 18 parts by weight of toluene, 10 parts by weight of 1,4-butene glycol, 18 parts by weight of vinyl glycol ether, 34 parts by weight of tribromoneopentyl alcohol, 9 parts by weight of n-butanol, 60 parts by weight of aqueous hydrogen peroxide, 3 parts by weight of epoxidation aid, 8 parts by weight of extraction solvent and a catalyst whose total amount is 0.8% by weight of the crude pyromellitic anhydride, wherein the catalyst is a mixture of phosphotungstic acid and molybdenum trioxide in a mass ratio of 2:0.5, the concentration of the aqueous hydrogen peroxide is 35wt%, the epoxidation aid is methanol, and the extraction solvent is cyclohexane.

[0073] The preparation method of the above-mentioned plasticizer for PVC is the same as that in Example 1.

[0074] After testing, the obtained plasticizer was a light yellow transparent viscous liquid with an epoxy equivalent of 518 g / mol.

[0075] Comparative Example 1

[0076] Commercially available ordinary industrial grade dioctyl phthalate (DOP) was used as comparative example 1 and was purchased from Shandong Jinhai Chemical Technology Co., Ltd.

[0077] The plasticizing effects of the plasticizers of Examples 1-4 and Comparative Example 1 were tested.

[0078] Test method: Take 100 parts by weight of PVC, 60 parts by weight of plasticizer, and 2 parts by weight of zinc stearate heat stabilizer, accurately weigh and mix them evenly, then add the evenly mixed sample into a mortar, and then place the mortar in a heating jacket to heat it. Stir it continuously and quickly during the heating process. After melting, make a 25mm*25mm*2mm sample. Perform a hardness test according to GB / T2411-2008 "Determination of indentation hardness (Shore hardness) of plastics and hard rubber using a hardness tester". The lower the hardness of the sample, the better the plasticizing effect. The extraction rate test uses n-hexane as the solvent. Take 100mL of n-hexane and put it in a beaker. Prepare a sample with a specification of 25mm*25mm*2mm according to the requirements of the plasticizing performance test. Accurately weigh 10g and put it into 100mL of n-hexane solvent. Take it out after 48 hours, dry it and test the weight. 1 , calculate the extraction rate of plasticizer, the calculation formula is extraction rate a = (10-m 1 ) / 3.7×100%. The boiling water resistance test is based on the 4.50 boiling water resistance test in GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels". The sample is made into 25mm×25mm×2mm according to the plasticizing performance test method. After 2 hours, the surface of the sample is observed and the weight loss percentage of the sample is tested. The lower the weight loss percentage, the better the boiling water resistance. The flame retardant performance is measured by oxygen index according to GB / T 2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method".

[0079] The test results are shown in Table 1.

[0080] Table 1 Comparison of the performance of plasticizers of Examples 1-4 and Comparative Example 1

[0081]

[0082] As can be seen from Table 1, the plasticizers prepared by using crude pyromellitic anhydride as raw materials in Examples 1-4 of the present invention have strong compatibility with PVC, high plasticizing efficiency, and excellent extraction resistance due to the special epoxy group and bromine element contained in the molecular structure, and more esterification groups. After the final product is used to plasticize PVC material, the Shore hardness of the product is significantly reduced, which is lower than that of ordinary commercially available plasticizer products (Comparative Example 1), indicating that the plasticizing effect of the plasticizer of the present invention is better than that of ordinary commercially available plasticizer products. More importantly, its extraction rate for organic solvents is also good, basically about 1%, and its appearance and mass reduction are not obvious after long-term boiling water (12h), and in terms of flame retardant performance, the oxygen index of the PVC material after adding the plasticizer is above 37%, and the flame retardant performance is excellent. And these properties, whether plasticizing performance, extraction rate, long-term boiling water boiling and flame retardant performance, are significantly better than the commercially available ordinary plasticizer products of Comparative Example 1.

[0083] At the same time, the invention uses crude pyromellitic anhydride with relatively low purity as the main raw material, which not only reduces the cost but also reduces environmental pollution, and also provides a method for the development and utilization of crude pyromellitic anhydride.

[0084] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A plasticizer for polyvinyl chloride, characterized in that: Ingredients include: The invention also comprises a catalyst, which is a mixture of phosphotungstic acid and molybdenum trioxide, and the total amount of the catalyst is 0.5%-0.8% of the crude quality of pyromellitic dianhydride.

2. The plasticizer for polyvinyl chloride according to claim 1, characterized in that The epoxy equivalent of the polyvinyl chloride plasticizer is 468-540 g / mol.

3. The plasticizer for polyvinyl chloride according to claim 1, characterized in that The crude pyromellitic anhydride is a crude product in the preparation process of pyromellitic anhydride. In the crude pyromellitic anhydride, the purity of pyromellitic anhydride is 90wt%-93wt%, the content of trimellitic anhydride is 5wt%-8wt%, and the content of terephthalic acid is less than 1wt%.

4. The plasticizer for polyvinyl chloride according to claim 1, characterized in that The concentration of the hydrogen peroxide aqueous solution is 30%-35%.

5. The plasticizer for polyvinyl chloride according to claim 1, characterized in that The epoxidation aid is ethanol or methanol.

6. The plasticizer for polyvinyl chloride according to claim 1, characterized in that The extraction solvent is cyclohexane.

7. The plasticizer for polyvinyl chloride according to claim 1, characterized in that In the catalyst, the mass ratio of phosphotungstic acid to molybdenum trioxide is 2:0.3-0.

5.

8. The method for preparing a plasticizer for polyvinyl chloride according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) adding a formula amount of toluene and crude pyromellitic anhydride to a reaction kettle equipped with an esterification water separator, starting stirring and heating to 100-105° C., then adding a formula amount of 1,4-butenediol and a catalyst, and heating to the boiling point of toluene to carry out an esterification reaction with water; (2) sampling and testing the hydroxyl value of the reactants, and when the hydroxyl value of the reactants is lower than 5 mgKOH / g, adding the formulated amount of vinyl glycol ether and tribromoneopentyl alcohol to continue the esterification reaction with water at the boiling point of toluene; (3) taking samples and detecting the contents of vinyl glycol ether and tribromoneopentyl alcohol by gas chromatography, and when the contents of vinyl glycol ether and tribromoneopentyl alcohol are both less than 2%, adding a formulated amount of n-butanol to carry out an end-capping esterification reaction; (4) Sampling and testing the acid value of the reactant. When the acid value of the reactant is lower than 3 mgKOH / g, cooling to 54-58° C., adding the formulated amount of epoxidation aid, stirring evenly, and then dripping the formulated amount of hydrogen peroxide solution. The dripping time is controlled to be 2-2.5 hours. After the dripping is completed, continue to keep the temperature at 54-58° C. for reaction; (5) sampling and testing the iodine value of the reactants, and when the iodine value is lower than 5 g / 100 g, adding one-half to two-thirds of the extraction solvent to extract the reaction system, and performing static stratification to obtain an upper organic phase 1 and a lower aqueous phase 1, and then adding the remaining extraction solvent to the lower aqueous phase 1 for secondary extraction, and after static stratification, obtaining an upper organic phase 2 and a lower aqueous phase 2, and then combining the organic phase 1 and the organic phase 2 to obtain a final organic phase; (6) distilling the final organic phase under reduced pressure under vacuum, and when the volatile matter is less than 1%, cooling it to below 70° C. and discharging the material to obtain a plasticizer for polyvinyl chloride.

9. The method for preparing a plasticizer for polyvinyl chloride according to claim 8, characterized in that: In step (6), the temperature of the reduced pressure distillation is 102-108° C., and the vacuum degree is controlled at -0.095 MPa to -0.097 MPa.

10. Use of the plasticizer for polyvinyl chloride according to any one of claims 1 to 7 in the preparation of polyvinyl chloride.

Images