Preparation method of hindered bisphenol monoester antioxidant

Abstract

The invention discloses a preparation method of a hindered bisphenol monoester type novel antioxidant, which adopts bisphenol, carboxylic acid, a chlorination reagent and an organic solvent as raw materials and organic amine as an acid-binding agent. The preparation method comprises the following steps: mixing bisphenol, carboxylic acid and a solvent into a solution, carrying out an esterification reaction in a feeding manner of alternately dropwise adding a chlorination reagent and an acid-binding agent, filtering to remove a catalyst after the reaction is finished, distilling to remove the reaction solvent, recrystallizing with ethanol with a certain concentration, filtering and drying to obtain the hindered bisphenol monoester antioxidant. The method is an esterification process for directly preparing bisphenol monoester by a multi-component one-pot method, the operation of the process is simplified, the product yield is high, the cost is low, the solvent can be recycled, and the prepared product has excellent oxidation resistance on the synthesis of ABS (Acrylonitrile Butadiene Styrene) resin.

Description

Technical Field

[0001] The invention relates to a method for preparing a hindered bisphenol monoester antioxidant, and more specifically to the application of a phenolic antioxidant type chemical additive in ABS production. Background Art

[0002] Polymer materials are oxidatively degraded due to their different molecular structures, different polymerization processes, and differences in processing technology, and are often degraded due to the effects of light, oxygen, and heat during storage and use. Its own weather resistance and durability affect its normal performance. Adding antioxidants can effectively alleviate the self-oxidation rate of polymer materials and make them have longer and better performance.

[0003] Antioxidants are plastic additives that can effectively reduce the speed of the self-oxidation reaction of plastic materials and delay the aging and degradation of plastic materials. Their applications involve almost all polymer products. There are many types of antioxidants, usually including phenolic antioxidants, phosphorus and sulfur auxiliary antioxidants, and metal ion passivators. Phenolic antioxidants are the most widely used antioxidants.

[0004] The mechanism of adding phenolic antioxidants to polymers is to capture the free radicals R formed during the chain reaction stage. . and ROO . , so that they will not cause a destructive chain reaction; antioxidants can also decompose hydroperoxide ROOH to generate stable inactive products. According to the mechanism of action, antioxidants can be divided into primary antioxidants and auxiliary antioxidants. The primary antioxidant can react with free radicals R . and ROO . Reaction, interrupting the growth of active chains. Auxiliary antioxidants can inhibit and delay the generation of free radicals during the initiation process, decompose hydroperoxides, and passivate metal ions remaining in the polymer. Hindered phenol antioxidants are generally primary antioxidants. This type of antioxidant is a compound with substituents on one or both sides of the hydroxyl group (-OH) on the benzene ring. Due to the steric hindrance of the -OH, the H atom is easy to fall off the molecule and react with the peroxide free radical (ROO . ), alkoxy free radicals (RO . ), hydroxyl radical ( . OH) and other substances to deactivate it, thereby terminating the chain reaction of thermal oxidative aging. This mechanism is called the chain termination donor mechanism. During the polymer aging process, if the peroxide free radical can be effectively captured, the oxidation process can be terminated. However, the reaction rate of generating peroxide free radicals is extremely fast, so in the presence of oxygen, the free radical scavenger will become ineffective. In the presence of hindered phenolic antioxidants, one peroxide free radical (ROO .) will take away a proton from the polymer (RH), interrupting this series of free radical reactions, which is the controlling step of auto-oxidation. When a hindered phenol antioxidant is added, it is easier to provide protons than those polymers, that is, it provides a more favorable reaction to form phenol oxygen free radicals, which makes the polymer relatively stable and will not be further oxidized.

[0005] The current development direction of hindered phenol antioxidants mainly includes high relative molecular weight antioxidants, reactive antioxidants and composite antioxidants. High relative molecular weight means that polymer materials are usually processed and used under high temperature conditions, so antioxidants must have good thermal stability. Since polymer compounds have the advantages of low volatility, resistance to extraction, and especially resistance to high temperatures, the method of increasing the relative molecular weight of antioxidants to improve their thermal stability is a new trend in recent antioxidant research. However, the larger the relative molecular weight, the better, because oxidation mainly occurs on the surface of the product. When the surface antioxidant is exhausted, whether the antioxidant inside the product can migrate to the surface in time becomes the key to its effectiveness, so the relative molecular weight of the antioxidant is usually below 1500. The high relative molecular weight antioxidant 1010 has significantly improved hydrolysis resistance, migration resistance, and extraction resistance compared to the low relative molecular weight antioxidant 1076. Reactive antioxidants refer to antioxidants that, in addition to being consumed by playing a stabilizing role, will also deteriorate or react with chemical substances under the action of light, heat, etc., and will undergo molecular migration and be extracted by solvents during the use of the product, thereby reducing the efficiency of the antioxidant. For this reason, people hope to develop a type of permanent stabilizer, namely reactive antioxidants, which can polymerize with monomers, graft hindered phenol groups onto polymer chains, become part of the polymer, and synthesize polymeric antioxidants, thereby solving the defects of antioxidant volatilization, extraction, migration, etc. This will be another trend in the development of antioxidants. At present, the existing reactive antioxidants include NDPA and DENA developed by the UK, which contain nitroso groups in the molecules; and TAP, DAC and DBA developed by Japan's Ouchi Emerging Chemical Company, which are a series of phenolic compounds containing allyl groups. Composite antioxidants refer to that although a large number of composite stabilizers have appeared so far, their synergistic mechanism is still not very clear, so people's selection of polymer stabilization formulas is mainly based on experience and actual application effects. The antioxidant Irganox B series produced by Ciba Specialty Chemicals has been industrialized and achieved good results. However, with the further in-depth study of the theory of carbon free radical scavengers for polymers, a new ternary composite antioxidant formula has been proposed, which is a carbon free radical scavenger + primary antioxidant + auxiliary antioxidant. The new generation of stabilization formula developed will be one of the development trends of polymer anti-aging formula in the future.

[0006] Assisted bisphenol 2246 antioxidant is a general-purpose strong hindered phenol-aldehyde antioxidant with the chemical name of 2,2'-methylenebis(4-methyl-6-tert-butylphenol). It is non-polluting, non-toxic and non-staining to products and has excellent protection against heat, oxygen, cracking and aging. It is often used in white or brightly colored rubber and plastic products (polyethylene, polypropylene, polyoxymethylene, ABS resin and chlorinated polyether, etc.), especially for rubber products aging under sunlight. It has the greatest protective effect and has no effect on vulcanization and plasticity. It is easily dispersed in water and easy to use.

[0007] The chemical name of the assisted bisphenol monoester 3052 antioxidant is 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate. Antioxidant 3052 is a bisphenol monoacrylate dual structure antioxidant, which has the dual functions of antioxidant and carbon free radical scavenger. Compared with other hindered phenol antioxidants, it has excellent carbon free radical scavenging ability and inhibits the initial auto-oxidation chain reaction. Especially in high-temperature processing under anoxic conditions, it inhibits the "fish eye" problem caused by high-temperature processing. It is suitable for thermoplastics, rubbers, adhesives and polymer blends, especially for ABS, SBS, SMA, SBR, NBR, TPEE, TPES, HIPS, EPDM. ABS resin is a copolymer of three monomers: acrylonitrile (A)-butadiene (B)-styrene (C). It is an important polymer material with the characteristics of high strength, good toughness, and easy processing. It is widely used in the fields of automobiles, electrical appliances, building materials and machinery. In the production process of ABS resin, it plays a vital role in improving the performance and quality of ABS products. Adding antioxidant 3052 to ABS resin can greatly improve the thermal oxygen stability of the material, solve the problems of fading, yellowing, hardening and cracking, maintain the mechanical properties of the material such as impact strength and elongation, prevent the aging of ABS resin and extend its service life.

[0008] Multicomponent reaction refers to a reaction process in which three or more raw materials are added to a reactor in a single synthetic operation to generate a new class of compounds containing the main structural fragments of all substrates. There is no need to separate the intermediates during the reaction, the experimental process is simple to operate, the raw materials are cheap and easy to obtain, the atom economy is high, and the large-scale use of organic solvents is avoided. This type of reaction has good chemical selectivity, regioselectivity and stereoselectivity, and provides a new synthetic method for synthesizing diverse and complex organic molecules. Multicomponent synthesis methods are widely used in many fields and have played an important role in life sciences, medicine and organic synthesis.

[0009] The preparation of assisted bisphenol monoester 3052 antioxidant is prepared by esterification reaction of assisted bisphenol 2246 as raw material. There are two methods for preparing this type of antioxidant 3052:

[0010] One is to prepare bisphenol monoester antioxidant by direct esterification of acyl chloride and bisphenol 2246. The disadvantage is that acyl chloride is expensive, and acyl chloride is highly irritating and difficult to store, so it is not suitable for large-scale production.

[0011] Another method is to put bisphenol 2246, organic acid, chlorination reagent and reaction aid in a reaction vessel, i.e., a multi-component one-pot method, and heat and stir to prepare bisphenol monoester antioxidant. Disadvantages: poor product selectivity and low overall yield.

[0012] There are many ways to add materials in a multi-component one-pot method. It is an urgent problem for technicians in this field to provide a one-pot method for preparing hindered bisphenol monoester antioxidant 3052 with high raw material utilization, low cost, simple process, green environmental protection and selective addition. Summary of the invention

[0013] In view of the deficiencies in the prior art, the present invention provides a method for preparing an antioxidant of assisted phenol monoester type by a multi-component one-pot process.

[0014] The preparation method adopted in the present invention comprises the following steps: using bisphenol, carboxylic acid and chlorination reagent as raw materials, an organic base as an acid absorbent, and a liquid organic matter as a solvent; the reaction temperature is 30-40°C, the reaction time is 0.5-3h, and after the reaction is completed, the catalyst is removed by filtration under reduced pressure, the solvent is removed by distillation, and crystals are precipitated; the crystalline material is dried and recrystallized from ethanol to obtain a white solid, thereby obtaining a bisphenol monoester antioxidant product.

[0015] In the method of the present invention, the hindered bisphenol is 2246, the carboxylic acid is acrylic acid, the chlorination agent is phosphorus oxychloride or solid phosgene, and the acid absorbent is triethylamine. The molar ratio of bisphenol: acrylic acid: phosphorus oxychloride (solid phosgene): triethylamine is 1:1.2-1.5:0.8-0.9:3-3.5, and the reaction solvent is dichloromethane and toluene.

[0016] The specific steps include:

[0017] In a 250mL dry four-necked flask with magnetic stirring and a spherical condenser, add a certain amount of assisted bisphenol 2246, acrylic acid, and solvent solution, stir to make the added materials become a solution, mix and dissolve the chlorination agent and a certain amount of solvent, respectively drip the chlorination agent solution and the acid binding agent triethylamine solution, after the dropwise addition is completed, the system is heated to a certain temperature for maturation. After the maturation reaction is completed, the reaction solution is cooled to room temperature, the white solid is filtered and precipitated as triethylamine hydrochloride, the filtrate is distilled to remove the solvent, and the solvent can be recycled to obtain the antioxidant hindered bisphenol monoester crude product. The antioxidant hindered bisphenol monoester crude product is washed with a certain concentration of ethanol, filtered and dried to obtain a white powder as the target product antioxidant hindered bisphenol monoester, which has a low yellowing resistance index for styrene ABS resin.

[0018] The purity of the assisted phenol antioxidant 3052 can be detected by high performance liquid chromatography (HPLC). The test process uses V (methanol): V (water) = 95:5 as the mobile phase, the flow rate is 1.0 ml / min, and the detection wavelength is 208 nm. The method is simple to operate, rapid, highly sensitive, precise, and cost-saving. It is convenient for the promotion and application of the factory inspection, procurement, use, and other links of the 3052 antioxidant type.

[0019] The standard for measuring yellowing resistance is the yellowness index. The industry standard is GB / T7921-2008, and the national standard is GB / T 3979-2008. The ABS resin pellets are processed in an injection molding machine and are injection molded into 9cm diameter and 6mm thick disc samples at 220℃ (mold dwelling 40s) and 250℃ (mold dwelling 180s). The two samples are tested on a HunterLab colorimeter to measure the L, a, and b values. The yellowness index of the antioxidant and the thermal oxidation resistance in the material are measured based on the L, a, and b values ​​of the two samples.

[0020] The experiment used two sets of shear section temperatures of 220℃ and 250℃.

[0021]

[0022] The calculation formula is:

[0023] Among them, Δa=a 250℃ -a 220℃ , Δb=b 250℃ -b 220℃ . Where L is lightness, a is red-green index, b is yellow-blue index, ΔE is heat-oxidation color difference index, which represents the total change of sample color. The larger the value, the greater the color change, that is, the worse the material's heat-oxidation resistance. In the industrial evaluation process, when ΔE reaches a standard of less than 2.0, it is qualified, and less than 1.6 is excellent. The difference in the antioxidant's ability to resist heat-oxidation coloring of ABS resin is characterized by testing the color difference value of ABS samples under the above two conditions. In the production of ABS resin, its heat-oxidation color difference index is less than 2.0, reaching an excellent level.

[0024] The invention has a simple process route, a selective multi-component one-pot process, a high product yield, a small impact on the environment, is easy to industrialize, and is conducive to mass production.

[0025] Specific implementation: The present invention will be further described below in conjunction with embodiments.

[0026] Example 1

[0027] 80g of 2246 type bisphenol A, 20g of acrylic acid, and 143g of solvent dichloromethane are placed in a three-necked flask, heated to 25°C, and 27g of chlorination reagent phosphorus oxychloride solution and 87g of triethylamine solution are added dropwise, and the temperature is kept at 35°C for 2h after the addition is completed. After cooling, the filtrate is filtered under reduced pressure, and the filtrate is distilled. After the crystals are dried, they are recrystallized with 85% ethanol. The product antioxidant is a white powder with a yield of 85%. The purity is 98% as detected by high performance liquid chromatography (HPLC), and the melting point is 130-131°C. It is evaluated for application in ABS resin production. The yellowing resistance index is 1.6 according to the GB / T3979 method, and the antioxidant effect is good.

[0028] Example 2

[0029] 160g of 2246 type bisphenol A, 40g of acrylic acid, and 290g of solvent dichloromethane are placed in a three-necked flask, heated to 25°C, and 54g of chlorination reagent phosphorus oxychloride solution and 160g of triethylamine solution are added dropwise respectively. After the addition is completed, the mixture is kept at 40°C for 2h, cooled and filtered under reduced pressure, the filtrate is distilled, the crystals are dried and recrystallized with 85% ethanol, and the product antioxidant is a white powder with a yield of 87%. The purity is 98% as detected by high performance liquid chromatography (HPLC), and the melting point is 130-132°C. It is applied and evaluated in the production of ABS resin. The yellowing resistance index is 1.7 as tested by GB / T 3979 method, and the antioxidant effect is good.

[0030] Example 3

[0031] 200 kg of 2246 type bisphenol A, 50.4 kg of acrylic acid and 850 kg of solvent dichloromethane were placed in a 3m 3 In the reactor, after nitrogen replacement, it is heated to 25°C, and 69kg of chlorination reagent phosphorus oxychloride solution and 210kg of triethylamine solution are added dropwise by a dropping device. After the addition is completed, it is kept at 35°C for 2h, and filtered under reduced pressure after cooling. The filtrate is distilled under reduced pressure, and the crystals are dried and recrystallized with 85% ethanol. The product is a white powder with a yield of 83%. The purity is 98% detected by high performance liquid chromatography (HPLC) and the melting point is 131-132°C. It is applied and evaluated in the production of ABS resin. The yellowing resistance index is 1.5 according to the GB / T 3979 method during the evaluation process, and the antioxidant effect is good.

[0032] Example 4

[0033] In a 250ml dry four-necked flask with magnetic stirring and a spherical condenser, add 5g of 2246 bisphenol A, 6.80g of acrylic acid, and 40g of dichloromethane, stir to make the added materials become a solution, mix and dissolve 5.45g of solid phosgene and 6.6g of dichloromethane, then drop solid phosgene, dichloromethane solution and a certain amount of 5.45g of triethylamine solution, after the dropwise addition is completed, the system is heated to a certain temperature for aging, after the aging reaction is completed, the reaction solution is cooled to room temperature, the white solid precipitated by filtration is triethylamine hydrochloride, the filtrate is distilled to remove dichloromethane, and the crude product of antioxidant 3052 can be obtained. The crude product of antioxidant 3052 is washed with a certain concentration of ethanol, filtered and dried to obtain a white powder as the target product antioxidant 3052. The yield is 80%, and the product purity is more than 98% according to liquid chromatography analysis, and the melting point is 131-132°C. The application evaluation was carried out in the production of ABS resin. The yellowing resistance index was tested according to the GB / T3979 method and the result was 1.4, indicating a good antioxidant effect.

[0034] Example 5

[0035] 160 g of 2246 type bisphenol A, 40 g of acrylic acid, and 350 g of solvent toluene are placed in a three-necked flask, heated to 25°C, and 54 g of solid phosgene, 150 g of toluene solvent, and 160 g of triethylamine solution are added dropwise, and the temperature is kept at 40°C for 2 hours after the addition is completed. After cooling, the filtrate is filtered under reduced pressure, and the filtrate is distilled. After the crystals are dried, they are recrystallized with 85% ethanol. The product antioxidant is a white powder with a yield of 84%. The purity is 99% as detected by high performance liquid chromatography (HPLC), and the melting point is 130-133°C. It is evaluated for application in ABS resin production. The yellowing resistance index is 1.5 according to the GB / T 3979 method, and the antioxidant effect is good.

[0036] The results show that the yellowing resistance index of the hindered phenol bisphenol monoester type antioxidant prepared by the present invention is less than 2.0, and has high antioxidant performance.

[0037] Each example in this specification is verified and described by increasing the raw materials. The experimental results show that the process conditions are repeatable and can be expanded according to the rules.

[0038] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a hindered bisphenol monoester antioxidant, using bisphenol, carboxylic acid and chlorination reagent as raw materials, organic amine as acid binding agent, and solvent as non-aqueous solvent. The specific steps include: mixing bisphenol, carboxylic acid and solvent in a four-necked flask with stirring, temperature display and reflux, alternately adding chlorinated solvent solution and acid absorbent, and keeping the reaction at an appropriate temperature for 0.5 to 3 hours; cooling, filtering under reduced pressure to remove the catalyst, distilling to remove the solvent and precipitating crystals to obtain a crude product. The reaction solvent can be recycled. The crude product is dried and recrystallized to obtain a white solid as the target product, that is, a new type of hindered bisphenol monoester antioxidant product, which has a high antioxidant capacity for ABS resin products and a low yellowing resistance index.

2. The method for preparing the bisphenol monoester antioxidant according to claim 1, characterized in that The ratio of the carboxylic acid, the chlorination agent and the acid binding agent is 1:1.2 to 1.5:

1.

3. The method for preparing the hindered bisphenol monoester antioxidant according to claim 1, characterized in that The ratio of the bisphenol to the carboxylic acid is 1:1.1-1.

3.

4. The method for preparing the hindered bisphenol monoester antioxidant according to claim 1, characterized in that The chlorinating agent is phosphorus oxychloride, thionyl chloride and solid phosgene.

5. The method for preparing the hindered bisphenol monoester antioxidant according to claim 1, characterized in that The acid absorbent is triethylamine.

6. The method for preparing the hindered bisphenol monoester antioxidant according to claim 1, characterized in that The yellowing resistance index for ABS resin products is below 2.0.

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