Modified stabilizer aid and preparation method thereof

Abstract

The invention belongs to the technical field of stabilizer preparation, and particularly relates to a modified stabilizer additive and a preparation method thereof. The preparation method comprises the following steps: preparing a nitrogen-containing compound, namely 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indole-3-yl) urea-zinc, and proportioning calcium stearate and the 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indole-3-yl) urea-zinc according to a mass ratio of 1: 2, so as to obtain the modified stabilizer. By adding the stabilizer disclosed by the invention, the heat stability of PVC can be remarkably improved. In addition, in a tensile test, a PVC sample added with the stabilizer disclosed by the invention has relatively high tensile strength (the highest tensile strength can reach 20.68 MPa) and elongation at break (the highest elongation at break can reach 394%). The static thermal stabilization time of a PVC sample added with the stabilizer disclosed by the invention in a Congo experiment is 42 minutes longer than that of a blank sample. Therefore, the stabilizer disclosed by the invention can become a very promising potential raw material of the PVC heat stabilizer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of stabilizer preparation, and particularly relates to a modified stabilizer auxiliary agent and a preparation method thereof. BACKGROUND

[0002] It is known that the largest amount of auxiliary agent used in the production process of PVC is plasticizer, and the other is stabilizer. The stabilizer includes heat stabilizer, lubricant, plasticizer, light stabilizer, etc. The heat stabilizer is an indispensable additive in the production process of PVC products. If transparent PVC products are desired, the degradation and discoloration of PVC molecular chain need to be solved, which requires the heat stabilizer to have good compatibility with PVC raw materials and give PVC materials excellent transparency. The heat stabilizer acts in PVC products, causing different refractive indexes and compatibility between different phases, thereby producing different light refraction and further affecting the transparency of PVC products.

[0003] At present, the stabilizer used in the production process is mainly organic tin and metal soap, and in addition, organic stabilizers gradually enter the public view. The organic stabilizer has high designability and can obtain products with more stable performance through structure modification. So far, the uracil derivative in the organic stabilizer has great potential and research value. An organic transparent composite heat stabilizer and a preparation method and application thereof (CN201510750773.6) focus on the heat stability and transparency of PVC materials. This shows that the industry is greatly concerned about and demands environmentally friendly and efficient transparent PVC heat stabilizers. However, the migration and biological toxicity of the heat stabilizer are still problems that need to be solved. For such problems, nitrogen-containing organic heat stabilizers are usually used as auxiliary heat stabilizers and calcium-zinc salt heat stabilizers. It not only can improve the thermal stability of PVC, but also can improve the transparency and early whiteness. More and more researchers study nitrogen-containing organic metal compounds as heat stabilizers. SUMMARY

[0004] In view of the problems in the background art, the thermal stability of PVC and the mechanical properties of PVC are improved, so that the PVC film has better toughness and elasticity.

[0005] In order to achieve the above purpose, the following technical scheme is adopted: the application provides a modified stabilizer auxiliary agent, which comprises the following steps:

[0006] Step (1): 1-bromo-4-nitrobenzene a is added into a round-bottom flask, then cesium carbonate, purified water, 1,4-dioxane and palladium catalyst are added, heated at 75℃ for 30 minutes, and then cyclohexylboronic acid is added to carry out Suzuki coupling reaction for 4 hours to obtain intermediate b;

[0007] Step (2) : Reduction of intermediate (b) with Pd / C under hydrogen atmosphere to obtain intermediate c, which is purified for further use;

[0008] Step (3) : 3-acylation of 5-methyl-1H-indole d with trifluoroacetic anhydride to obtain intermediate e, followed by basic hydrolysis to obtain intermediate f;

[0009] Step (4) : Azidation of intermediate f with DPPA in the presence of ethanol to obtain 5-methyl-1H-indole-3-carbonyl azide g;

[0010] Step (5) : Final Curtius rearrangement of g in refluxing benzene to generate isocyanate and reaction with intermediate c obtained in step (2) to obtain 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea h;

[0011] Step (6) : Next, compound h and zinc acetate dihydrate are dissolved in hot methanol, added to a three-necked flask, and the whole mixture is continuously stirred at 60°C for 2 hours, washed and dried to obtain 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea-zinc, which is then mixed with calcium stearate by melting and heating to obtain the modified stabilizer.

[0012]

[0013] Preferably, the mass ratio of 1-bromo-4-nitrobenzene to cyclohexylboronic acid in step (1) is 1:1.1.

[0014] Preferably, the palladium catalyst in step (1) is selected from one of DPPF palladium dichloride, dichlorobistriphenylphosphine palladium.

[0015] Preferably, the basic hydrolysis solution in step (3) is 20% NaOH aqueous solution.

[0016] Preferably, the washing and drying operation in step (6) is to filter the post-reaction product and wash it with anhydrous ethanol for 3 times, and then dry it in a vacuum oven at 60°C for 5-6 hours.

[0017] Preferably, the mass ratio of compound h to zinc acetate dihydrate in step (6) is 1:1.

[0018] Preferably, the mass ratio of calcium stearate to 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea-zinc is 1:2.

[0019] The beneficial effects of the present application are:

[0020] The poor thermal stability of PVC is due to the defects in its molecular structure. PVC will degrade after heating to produce hydrogen chloride, form double bonds, and eventually form conjugated polyene sequences, thus losing its value for use. The addition of a certain amount of thermal stabilizer can improve the thermal stability of PVC and inhibit thermal degradation. Studies have shown that the thermal degradation of PVC samples mainly occurs in two stages, the first stage occurs at 220-350℃, mainly due to the release of HCl and the evaporation of plasticizers, and the second stage of weight loss occurs at 350-530℃, which is due to the breaking of long carbon chains. The weight loss rate of the PVC sample added with the stabilizer described in the present application is lower in the two stages, the lowest weight loss rate in the first stage is 62.26%, and the lowest weight loss rate in the second stage is 11.31%, which is significantly lower than the comparative example, which means that the addition of the stabilizer described in the present application can significantly improve the thermal stability of PVC.

[0021] In addition, in the tensile test, the PVC sample added with the stabilizer described in the present application has higher tensile strength (up to 20.68 MPa) and elongation at break (up to 394%), which can improve the mechanical properties of PVC and make the PVC film have better toughness and elasticity. Congo red test paper can detect the presence of acid, and the color change range is pH = 3.5-5.2. PVC will degrade at high temperature and release HCl, thus making the Congo red test paper blue. The time when the test paper turns blue is the static thermal stability time of the PVC sample. The PVC sample without the addition of a thermal stabilizer (comparative example two) turns blue after heating for only 4 minutes. The static thermal stability time of the PVC sample added with the stabilizer described in the present application is extended to 46 minutes, which is 42 minutes longer than that of the blank sample. It can be seen that the stabilizer described in the present application can become a very promising potential raw material for PVC thermal stabilizers. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described in detail below in combination with examples. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application.

[0023] It should be noted that the experimental methods used in the implementation examples are all conventional methods unless otherwise specified; and the materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0024] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0~5" represents that all real numbers between "0~5" have been listed herein, and "0~5" is only a shorthand representation of these numerical combinations.

[0025] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined with each other to form new technical solutions if no special description is given.

[0026] In the present application, all the steps mentioned in the present application can be performed in sequence or randomly if no special description is given, but it is preferred to be performed in sequence; for example, the method comprises steps (1) and (2), which means that the method can comprise steps (1) and (2) performed in sequence, or steps (2) and (1) performed in sequence; for example, the method further comprises step (3) mentioned, which means that step (3) can be added to the method in any sequence, for example, the method can comprise steps (1), (2) and (3), or steps (1), (3) and (2), or steps (3), (1) and (2), etc.

[0027] In the present application, the specific values and specific substances in the examples can be combined with other features described in the description part if no special description is given; for example, if the description part mentions that the reaction temperature is 10-100℃, and the example mentions that the reaction temperature is 20℃, then it can be considered that the range of 10-20℃ or the range of 20-100℃ has been specifically disclosed in the present application, and the range can be combined with other features described in the description part to form new technical solutions.

[0028] Example 1;

[0029] Step (1): 1-bromo-4-nitrobenzene 1.01 g was added into a round-bottom flask, followed by cesium carbonate, purified water, 1,4-dioxane and Pd(dppf)Cl2, and then cyclohexylboronic acid 0.64 g was added, and the reaction was heated at 75℃ for 30 minutes, and then a Suzuki coupling reaction was carried out for 4 hours, and the reaction process was monitored by TLC (V petroleum ether:V ethyl acetate = 5:1), and when the raw material was not reduced, the reaction was stopped. After the reaction was completed, the reaction solution was concentrated, the reaction system was extracted with EA (3×30 mL), the organic phase was washed with H2O (2×30 mL) and saturated brine (1×30 mL) in sequence, the combined organic phase was dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and the concentrated crude product was purified (PE:EA = 15:1) to obtain intermediate 1-cyclohexyl-4-nitrobenzene.

[0030] Step (2): The intermediate 1-cyclohexyl-4-nitrobenzene was reduced with Pd / C under a hydrogen atmosphere to obtain 4-cyclohexylphenylamine.

[0031] Step (3): Acylate 5-methyl-1H-indole 3-acylation with trifluoroacetic anhydride to obtain intermediate 2,2,2-trifluoro-1-(5-methyl-1H-indole-3-yl)ethyl-1-one, and then heat it in 20% NaOH aqueous solution to 60°C for 30 minutes to obtain intermediate 5-methyl-1H-indole-3-carboxylic acid.

[0032] Step (4): In the presence of ethanol, the intermediate 5-methyl-1H-indole-3-carboxylic acid was azidated with DPPA to obtain 5-methyl-1H-indole-3-carbonyl azid.

[0033] Step (5): Finally, the Curtius rearrangement of 5-methyl-1H-indole-3-carbonyl azide is reacted with the intermediate 4-cyclohexylaniline obtained in step (2) to give 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indole-3-yl)urea in refluxed benzene to generate isocyanate.

[0034] Step (6): Next, 4-cyclohexylaniline was reacted to obtain 0.69 g of 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indole-3-yl)urea and 0.22 g of zinc acetate dihydrate, which were dissolved in 5 mL of hot methanol and added to a three-necked flask. All the mixture was stirred continuously at 60 °C for 2 hours. The product after reaction was filtered and washed three times with anhydrous ethanol. Then it was dried in a vacuum oven at about 60 °C for 6 hours to obtain 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indole-3-yl)urea-zinc. Subsequently, it was melt-heated and mixed with calcium stearate to obtain modified stabilizer sample 1.

[0035] Example 2;

[0036] Step (1): 1.01 g of 1-bromo-4-nitrobenzene was added to a round-bottom flask, followed by cesium carbonate and dichlorotriphenylphosphine palladium. The mixture was heated at 75 °C for 30 minutes, and then 0.64 g of cyclohexylboronic acid was added for coupling reaction for 4 hours. The reaction process was monitored by TLC (V petroleum ether:V ethyl acetate = 5:1). The reaction was stopped when the starting material stopped decreasing. After the reaction was completed, the reaction solution was concentrated, and the reaction system was extracted with EA (3 × 30 mL). The organic phase was washed successively with H2O (2 × 30 mL) and saturated brine (1 × 30 mL). The combined organic phases were dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and the concentrated crude product (PE:EA = 15:1) was purified to obtain the intermediate 1-cyclohexyl-4-nitrobenzene.

[0037] Step (2): Reduce intermediate 1-cyclohexyl-4-nitrobenzene with Pd / C under a hydrogen atmosphere to obtain 4-cyclohexylaniline.

[0038] Step (3): Acylation of 5-methyl-lH-indole-3-carboxylic acid with trifluoroacetic anhydride to give the intermediate 2,2,2-trifluoro-l-(5-methyl-lH-indol-3-yl)ethan-l-one, followed by hydrolysis with 20% aqueous NaOH at 60 °C for 30 min to give the intermediate 5-methyl-lH-indole-3-carboxylic acid.

[0039] Step (4): Azidation of the intermediate 5-methyl-lH-indole-3-carboxylic acid with DPPA in the presence of ethanol to give 5-methyl-lH-indole-3-carbonyl azide.

[0040] Step (5): Finally, Curtius rearrangement of 5-methyl-lH-indole-3-carbonyl azide in refluxing benzene to give the isocyanate and reaction with the intermediate 4-cyclohexylphenylamine obtained in step (2) to give l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea.

[0041] Step (6): Next, l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea 0.69 g and zinc acetate dihydrate 0.22 g were dissolved in 5 mL of hot methanol and added to a three-necked flask, the whole mixture was continuously stirred at 60 °C for 2 h, the post-reaction product was filtered and washed with anhydrous ethanol for 3 times, then dried in a vacuum oven at about 60 °C for 5 h to give l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea-zinc, followed by melting and heating mixing with calcium stearate to give the modified stabilizer sample 2.

[0042] Example Three;

[0043] Step (1): 1-bromo-4-nitrobenzene 1.01 g was added to a round-bottom flask, followed by cesium carbonate, purified water, 1,4-dioxane and Pd(dppf)Cl2, after heating at 75 °C for 30 min, cyclohexylboronic acid 0.64 g was added to carry out Suzuki coupling reaction for 4 h, TLC (V petroleum ether:V ethyl acetate = 5:1) was used to monitor the reaction process, when the raw material was not reduced, the reaction was stopped. After the reaction was completed, the reaction solution was concentrated, the reaction system was extracted with EA (3 x 30 mL), the organic phase was washed with H2O (2 x 30 mL), saturated brine (1 x 30 mL) in turn, the combined organic phase was dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and the concentrated crude product was purified (PE:EA = 15:1) to give the intermediate 1-cyclohexyl-4-nitrobenzene.

[0044] Step (2): The intermediate 1-cyclohexyl-4-nitrobenzene was reduced with Pd / C under a hydrogen atmosphere to give 4-cyclohexylphenylamine.

[0045] Step (3): Acylation of 5-methyl-lH-indole-3-carboxylic acid with trifluoroacetic anhydride to give the intermediate 2,2,2-trifluoro-l-(5-methyl-lH-indol-3-yl)ethan-l-one, followed by heating in 20% aqueous NaOH at 60 °C for 30 min to give the intermediate 5-methyl-lH-indole-3-carboxylic acid.

[0046] Step (4): Azidation of the intermediate 5-methyl-lH-indole-3-carboxylic acid with DPPA in the presence of ethanol to give 5-methyl-lH-indole-3-carbonyl azide.

[0047] Step (5): Final Curtius rearrangement of 5-methyl-lH-indole-3-carbonyl azide in refluxing benzene to generate the isocyanate and reaction with the intermediate 4-cyclohexylphenylamine obtained in step (2) to give l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea.

[0048] Step (6): Next, l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea 0.69 g and zinc acetate dihydrate 0.22 g were dissolved in 5 mL of hot methanol and added to a three-necked flask, the whole mixture was continuously stirred at 60 °C for 2 h, the post-reaction product was filtered and washed with anhydrous ethanol for 3 times, then dried in a vacuum oven at about 60 °C for 5 h to give l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea-zinc, followed by melting and heating mixing with calcium stearate to give the modified stabilizer sample 3.

[0049] Comparative Example One;

[0050] Step (1): 1-bromo-4-nitrobenzene 1.01 g was added to a round-bottom flask followed by cesium carbonate, dichlorobistriphenylphosphine palladium, heating at 75 °C for 30 min, then cyclohexylboronic acid 0.64 g was added to carry out the coupling reaction for 4 h, TLC (V petroleum ether:V ethyl acetate = 5:1) was used to monitor the reaction process, when the raw material was not reduced, the reaction was stopped. After the reaction was completed, the reaction solution was concentrated, the reaction system was extracted with EA (3 x 30 mL), the organic phase was washed with H2O (2 x 30 mL) and saturated brine (1 x 30 mL) successively, the combined organic phase was dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and the concentrated crude product was purified (PE:EA = 15:1) to give the intermediate 1-cyclohexyl-4-nitrobenzene.

[0051] Step (2): The intermediate 1-cyclohexyl-4-nitrobenzene was reduced with Pd / C under a hydrogen atmosphere to give 4-cyclohexylphenylamine.

[0052] Step (3): Acylation of 5-methyl-lH-indole with trifluoroacetic anhydride to give the intermediate 2,2,2-trifluoro-l-(5-methyl-lH-indol-3-yl)ethan-l-one, followed by hydrolysis with 20% aqueous NaOH at 60°C for 30 min to give the intermediate 5-methyl-lH-indole-3-carboxylic acid.

[0053] Step (4): Azidation of the intermediate 5-methyl-lH-indole-3-carboxylic acid with DPPA in the presence of ethanol to give 5-methyl-lH-indole-3-carbonyl azide.

[0054] Step (5): Final Curtius rearrangement of 5-methyl-lH-indole-3-carbonyl azide in refluxing benzene to give the isocyanate which was reacted with the intermediate 4-cyclohexylphenylamine obtained in Step (2) to give l-(4-cyclohexylphenyl)-3-(5-methyl-lH-indol-3-yl)urea, followed by melting and heating with calcium stearate to give the modified stabilizer sample 4.

[0055] Performance test

[0056] The modified stabilizer samples prepared in the examples were dissolved in dioctyl phthalate, added to PVC powder and PVC paste at 1:1, stirred well, and then spread on a glass plate and dried at 120°C for 1 hour to form a PVC film (5 mm x 5 mm x 1 mm). Commercially available PVC films were used as Comparative Examples 2 for performance testing.

[0057] Experiment 1;

[0058] Thermogravimetric analysis

[0059] Thermogravimetric analysis was performed by placing the PVC sample in a small crucible and using an 1100 SFTG instrument (Mettler-Toledo Co., Switzerland). The PVC sample was heated from 50°C to 600°C at a heating rate of 20°C / min under a N2atmosphere at a flow rate of 50 mL / min.

[0060] Table 1 Results of the thermogravimetric analysis

[0061]

[0062] Experiment 2;

[0063] Mechanical property test

[0064] Tensile test

[0065] According to ISO 1184-1983 standard, the PVC film samples prepared by Example 1 to Example 3, Comparative Example 1 and commercially available PVC film as Comparative Example 2 were placed in the two clamps of the testing machine, the longitudinal axis of the sample was aligned with the center line of the upper and lower clamps, and the tension was appropriate to prevent the sample from slipping or breaking. The testing machine was started, and the required load and corresponding elongation value between the marks were read after the sample was broken. The tensile strength was represented by σ (Formula 1), and the elongation at break was represented by ε (Formula 2). The results are shown in Table 2.

[0066] σ = p / bd (Formula 1)

[0067] p: maximum load b: sample width d: sample thickness

[0068] ε = (L-L0) / L0 (Formula 2)

[0069] L: distance between marks when the sample is broken L0: original mark distance of the sample

[0070] Table 2 Experimental results of tensile strength and elongation at break of PVC film samples

[0071] Serial No. Tensile strength (MPa) Elongation at break (%) Example 1 19.35 385 Example 2 20.68 394 Example 3 20.51 391 Comparative Example 1 12.24 321 Comparative Example 2 10.98 307

[0072] Experiment Three

[0073] Congo red experiment

[0074] According to GB / T 2917.1-2002 "Determination of Hydrogen Chloride and Any Other Acidic Products Evolved at Elevated Temperature by Congo Red Method for Blends and Products Based on Poly (Vinyl Chloride) Homopolymer and Copolymer", the samples prepared in Example 1 to Example 3, Comparative Example 1 to Comparative Example 2 were subjected to discoloration experiment on Congo red test paper at 200°C, and the time for Congo red to completely turn blue was recorded (the experiment was repeated three times and the average value was taken). The results are shown in Table 3 below.

[0075] Table 3 Congo red discoloration time

[0076] Serial No. Congo red average discoloration time (min) Example 1 45 Example 2 45 Example 3 46 Comparative Example 1 9 Comparative Example 2 4

[0077] The above describes one embodiment of the present application in detail, but the content described is only the preferred embodiment of the present application and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made within the scope of the present application should still be included in the patent coverage of the present application.

Claims

1. A modified stabilizer aid characterized in that, The process comprises the following steps: Step (1): 1-bromo-4-nitrobenzene a is added into a round bottom flask, followed by cesium carbonate, purified water, 1,4-dioxane and palladium catalyst, heated at 75°C for 30 minutes, then cyclohexylboronic acid is added to perform Suzuki coupling reaction for 4 hours to obtain intermediate b; Step (2): intermediate (b) is reduced with Pd / C under hydrogen atmosphere to obtain intermediate c, which is purified for standby; Step (3): 5-methyl-1H-indole d is subjected to 3-acylation with trifluoroacetic anhydride to obtain intermediate e, followed by basic hydrolysis to obtain intermediate f; Step (4): intermediate f is subjected to azidation with DPPA in the presence of ethanol to obtain 5-methyl-1H-indole-3-carbonyl azide g; Step (5): finally, Curtius rearrangement of g in refluxing benzene generates isocyanate, which is reacted with intermediate c obtained in step (2) to obtain 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea h; Step (6): next, compound h and zinc acetate dihydrate are dissolved in hot methanol, added into a three-necked flask, and all the mixture is continuously stirred at 60°C for 2 hours of reaction, washed and dried to obtain 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea-zinc, which is then mixed with calcium stearate by melting and heating to obtain the modified stabilizer.

2. The modified stabilizer package of claim 1, wherein, The mass ratio of 1-bromo-4-nitrobenzene to cyclohexylboronic acid in step (1) is 1:1.

1.

3. The modified stabilizer package of claim 1, wherein, The palladium catalyst in step (1) is selected from one of DPPF palladium dichloride and dichlorobistriphenylphosphine palladium.

4. The modified stabilizer package of claim 1, wherein, The solution for basic hydrolysis in step (3) is 20% NaOH aqueous solution.

5. The modified stabilizer package of claim 1, wherein, The operation of washing and drying in step (6) is that the post-reaction product is filtered and washed with anhydrous ethanol for 3 times, and then dried in a vacuum oven at 60°C for 5-6 hours.

6. The modified stabilizer package of claim 1, wherein, The mass ratio of compound h to zinc acetate dihydrate in step (6) is 1:

1.

7. The modified stabilizer package of claim 1, wherein, The mass ratio of calcium stearate to 1-(4-cyclohexylphenyl)-3-(5-methyl-1H-indol-3-yl) urea-zinc is 1:2.

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