一种对苯二胺的精制方法(一） 技术领域本发明涉及一种对苯二胺的精制方法，尤其是对品质要求较高的诸如生产对位芳纶、显像等用的对苯二胺的精制方法。 Kind of purification method phenylenediamine (a) Technical Field The present invention relates to a method for purifying p-phenylenediamine, especially for the production of high quality requirements, such as para-aramid, and the like used in developing terephthaloyl the method of purifying an amine. (二） 背景技术对苯二胺是一种用途广泛的中间体，可用于生产染料、颜料、染发剂、 橡胶防老剂、对位芳纶、生产聚氨酯的原料对苯二异氰酸酯等，此外还是常用的检验铁和铜的灵敏试剂，是汽油阻聚及彩色照相的偶合剂等的原料。 (B) Background Art p-phenylenediamine is a versatile intermediate for the production of dyes, pigments, dyes, rubber antioxidant, a para-aramid, a raw material for producing polyurethane terephthaloyl diisocyanate and the like, or used in addition the iron and copper sensitive test agent, and polymerization gasoline color photographic material of the coupling agent. 通常，对苯二胺采用对硝基氯苯氨化后的对硝基苯胺还原制得。 Typically, use of p-phenylenediamine p-nitroanilide Reduction to give the amide nitrochlorobenzene. 为得到高纯对苯二胺原料，经还原得到的对苯二胺产品都需要提纯精制，国内传统工艺采用熔铸体冷却法，但存在产品品质差、操作环境差、经济效益低等缺点。 To obtain high-purity para-phenylenediamine starting material, obtained by reduction of p-phenylenediamine products need refined purification, traditional domestic process using cooled casting method, but there is a difference of product quality, poor operating environment, and low economic disadvantage. 基于熔铸体结晶的缺陷，人们开发了精馏分离的工艺，但是精馏工艺对于沸点相近的对苯二胺物系，常规精馏往往需要较高的块理论板和很高的回流比，可达到一定纯度的产品的要求，但仍不能满足高纯度产品的要求；而且，对于热敏性物系的分离提纯需要较高的真空度，由于汽化热一般为熔融热的3-5倍，再考虑回流比的影响，因此精馏过程的能耗要高于熔融结晶。 Based cast crystal defects, have been developed to distillation separation process, but the process for the distillation of close boiling p-phenylenediamine-based material, a conventional distillation often requires a higher theoretical plates and a high reflux ratio, can be certain purity requirements of the product, but still can not meet the requirements of high purity product; and, heat-sensitive materials for the separation and purification system requires a high degree of vacuum, since the heat of vaporization is generally 3-5 times the heat of fusion, and then refluxed for consideration Effect of ratio, and therefore the energy consumption of distillation processes to above the melt crystallization. 基于对苯二胺具有易氧化变色的特点，国内外关于对苯二胺的研究重点都在结晶提纯方面。 Based on the characteristics of having easily oxidized p-phenylenediamine color, domestic and foreign research focuses on p-phenylenediamine in terms of purification by crystallization. 徐耀良在中国专利号CN100358860C中描述了一种结晶精制对苯二胺的方法，对苯二胺在溶剂水中经溶解、冷却结晶，形成颗粒状结晶体，再经分离和真空干燥为成品。 Xuyao Liang described in Chinese Patent No. CN100358860C in a crystallization purification method phenylenediamine, p-phenylenediamine was dissolved in a solvent of water, cooling crystallization, granular crystals formed, and then isolated and dried in vacuo for the finished product. 国外开发出用水/二甲苯二元溶剂抽提对苯二胺粗品。 Foreign developed with a water / xylene binary solvent extraction of the crude p-phenylenediamine. 杂质溶解于二甲苯中，对苯二胺溶解于水中，蒸发水分得产品对苯二胺。 Impurities dissolved in xylene, p-phenylenediamine was dissolved in water, the water was evaporated to give the product p-phenylenediamine. 溶液结晶法需要使用溶剂，在溶剂结晶过程中，除结晶操作单元以外，还需要离心、干燥和溶剂回收等操作单元，因此流程长，主体设备较多， 存在投资高、精制过程能耗较高、废水排放的环境问题。 Crystallization method requires use of a solvent solution in a solvent crystallization process, in addition to the crystallization unit operation, need centrifugation, drying and solvent recovery unit operation, etc., so long flow more main equipment, the presence of high investment and high energy consumption during refining environmental issues wastewater discharge. 由于熔融结晶在分离提纯某些有机物方面显示了巨大的优越性，在特定物系的分离中发挥了重要的作用，已用于二氯苯、硝基氯苯、精蔡、双酚A、对二甲苯、氯乙酸、丙烯酸等产品的分离精制，但在对苯二胺物系的提纯精制中尚无应用的先例。 Since the melt crystallization shows great advantages in the separation and purification of certain organic, separating the specific object based play an important role in, it has been used dichlorobenzene, nitrochlorobenzene, fine Cai, bisphenol A, separated and purified xylene, chloroacetic acid, acrylic acid and other products, but the purification was purified p-phenylenediamine-based applications in no precedent. 对苯二胺在冷却过程中，分子活动能力受到阻碍，很难形成自己的晶核，为了保证结晶装置的生产能力，通常结晶难以达到平衡状态，受传热、传质和结晶动力学控制，晶体不可避免地会产生包藏现象，含有杂质的母液被包藏，夹杂在晶体中，或粘附在晶体表面，使得晶体纯度下降，偏离平衡组成，分离效果明显下降。 P-phenylenediamine in the cooling process, the molecules hampered activity is difficult to form their own nuclei, in order to ensure the production capacity of the mold apparatus, it is generally difficult to achieve equilibrium crystallization, by heat transfer, mass transfer and kinetically controlled crystallization, crystal inevitably produce the phenomenon of occluded mother liquor containing impurities is occluded, the inclusion in the crystal, or adhering to the crystal surface, so that the purity of the crystal decreased, deviation from the equilibrium composition, separation decreased. (三）发明内容本发明的目的在于克服上述不足，提供一种产品品质好、生产周期短、 生产收率高、生产成本低、环境效应好的对苯二胺的精制方法。 Objective (c) of the present invention is to overcome the above disadvantages, to provide a good quality product, short production period, high production yield, low production cost, good environmental effects method for purifying p-phenylenediamine. 本发明所述的对苯二胺的精制方法，将精馏和熔融结晶进行结合，利用精馏产品冷凝液直接进行熔融结晶提纯，通过至少一次结晶及发汗的分步结晶获得高纯产品。 A method for purifying p-phenylenediamine, distillation and melt crystallization to the present invention in conjunction with the use of condensed liquid distillation product directly purified by melt crystallization, the crystalline product of high purity is obtained at least once by fractional crystallization and sweating. 所述方法包括以下步骤：(1) 熔融结晶：将精馏分离得到的对苯二胺粗品加入结晶器中，加热至全部熔融后，以1.0〜5.0°C/h速度缓慢降温结晶，冷却至120〜125"C保持5〜12h，结晶后排出母液，得到对苯二胺晶层l;(2) 发汗：加热步骤（1)得到的对苯二胺晶层1至130〜14(TC使部分熔融（此步骤称为"发汗过程"，熔融得到的液体称为"发汗残液"）；可采用分级发汗，发汗初始时维持较低温度，稳定一段时间后，将温度升高，在此温度保持一段时间，如此直到温度升至纯品的熔点附近；(3) 排出发汗残液，得到对苯二胺晶层2;(4) 加热步骤（3)得到的对苯二胺晶层2至全部熔融，得到对苯二胺晶层3;(5) 收集的对苯二胺晶层3经冷却、切片，得精制后的对苯二胺成p叫o所述步骤（1)中母液可经收集到储槽后回用。所述步骤（2)中发汗残液经蒸馏后回收作为下一次精制苯二胺时 Said method comprising the steps of: (1) Melt Crystallization: Distillation of p-phenylenediamine obtained crude crystals were added, and heated until all melted to 1.0~5.0 ° C / h slow cooling crystallization, cooled to 120~125 "C holding 5~12h, discharging the mother liquor after crystallization, the crystal layer of p-phenylenediamine to give l; (2) sweating: the heating step (1) to give p-phenylenediamine crystal layer 1 to 130~14 (TC so partial melting (this step is referred to as "sweating process", molten liquid obtained is called "raffinate sweating"); the grade employed sweating, sweating maintain a low initial temperature, stability over time, the temperature was raised in this temperature was maintained for some time, and so on until the temperature was raised close to the melting point of the pure product; (3) discharging sweating the residue obtained crystal layer 2 p-phenylenediamine; p-phenylenediamine crystal layer 2 (4) a heating step (3) to give the all melt to give crystal layer, 3 p-phenylenediamine; (5) -p-phenylenediamine crystal layer 3 is cooled, sliced, to obtain the purified p-phenylenediamine as p o called the step (1) the mother liquor collected when recyclable collected to the reservoir. the step (2) a sweating residue after distillation is recovered as the purified phenylenediamine 骤（1)中结晶器进料。所述步骤（2)发汗级数采用2〜4级。所述发汗级数为2〜4级是指升温发汗过程分为2~4个温度段进行，以一定速率升温至每个温度段的温度端值后，保温一段时间（至少20分钟），再升温至下一个温度段的温度端值。所述步骤（1) ~ (4)的操作可重复进行1~3次，上一级得到纯化的对苯二胺熔融液与下一级的部分发汗液混合，作为次一级熔融结晶的原料，至得到所需纯度的产品，再进行步骤（5)操作。所述方法需在密闭和氮气存在下进行，所用结晶器、储槽和管道均需氮气置换和密封。具体的，所述方法如下： (1)熔融结晶：将精馏分离得到的对苯二胺粗品加入结晶器中，加热至143±2°C，使物料全部熔融，待物料和导热介质温度恒定，以2〜5"C /h速度降温，冷却至14(TC后，以1〜3'C/h速度缓慢降温，冷却至120〜125。C保持5〜12h，结晶后开启阀 Crystallizer feed step (1). The step (2) Sweating ~ 4 series stages employed. The class perspiration degree is 2 ~ 4 means a heating sweating process is divided into two to four segments temperature, after warming to the temperature of the end of the segment values for each temperature at a rate, holding time (at least 20 minutes), then heated to a temperature of the end value of the temperature ranges. the operation of step (1) to (4) may be repeated for 1 to 3 times to obtain a purified on a melt-phenylenediamine mixed with a lower portion of the sweated, as a secondary raw material of a melt crystallization to obtain the desired product purity, then proceeding to step (5 ) operating the method be carried out under the presence of nitrogen and sealed, the mold used, reservoir and piping required to nitrogen substitution, and sealing specifically, the method is as follows: (1) melt crystallization: the distillation isolated p-phenylenediamine was added crude crystallizer and heated to 143 ± 2 ° C, so that all the molten material, and the material to be a constant temperature heat transfer medium to 2~5 "C / h cooling rate, cooling to 14 (after TC, to 1~3'C / h slow cooling was cooled to 120~125.C holding 5~12h, opening the valve after crystallization 排出母液，得到对苯二胺晶层l;(2) 发汗：加热步骤（1)得到的对苯二胺晶层1以1〜3'C/h速度升温至130〜140°C，采用2〜4个温度梯度，在每个温度梯度保持一段时间(各20min以上），总时间l~3h (此总时间是指在各温度梯度保持的总时间，不包括升温过程中所用的时间），使部分熔融，排出发汗残液，得到对苯二胺晶层2;(3) 步骤（2)得到的对苯二胺晶层2熔融后重复进行步骤（1)〜（2) 操作1~3次，上一级得到纯化的对苯二胺熔融液与次级熔融结晶的部分发汗液混合，作为次级熔融结晶的原料，重复进行熔融结晶， 至得到所需纯度的产品，得到对苯二胺晶层3;(4) 加热步骤（3)得到的对苯二胺晶层3至全部熔融，冷却、切片， 得精制后的对苯二胺成品。 Discharging mother liquor to obtain p-phenylenediamine crystal layer L; (2) Sweating: the heating step (1) to give p-phenylenediamine crystal layer 1 1~3'C / h heating rate to 130~140 ° C, using 2 ~ 4 a temperature gradient, the gradient a period of time (over 20min each) at each temperature, the total time l ~ 3h (this total time is the total time at each temperature gradient is maintained, not including the time used in the heating process), so that partial melting, sweating residue discharged, to obtain p-phenylenediamine crystal layer 2; (3) step (2) after the second molten crystal layer phenylenediamine repeating steps (1) to give to (2) operation 1 to 3, times to obtain a purified on a p-phenylenediamine sweat melt mixing of the secondary part hair melt crystallization, as a raw material of a secondary melt crystallization, melt crystallization was repeated to give the desired product purity, obtained terephthaloyl amine crystal layer 3; (4) a heating step (3) obtained phenylenediamine crystal layer 3 until all melted, cooled, sliced, to obtain the purified p-phenylenediamine finished pair. 本发明采用精馏与熔融结晶结合的工艺对对苯二胺进行精制，通过控制操作参数，可获得99.99〜99.999%的高纯度、高品质的对苯二胺产品， 产品质量满足聚合级产品质量要求，获得了仅采用精馏工艺无法实现的高品质对苯二胺。 The present invention uses distillation and melt crystallization processes for the binding of the purified p-phenylenediamine, by controlling the operation parameters obtained 99.99~99.999% high purity, high quality p-phenylenediamine product, product quality to meet polymer-grade product quality required to obtain a p-phenylenediamine rectification process can not be achieved using only high quality. 操作在密闭反应器中进行，切断了与对苯二胺发生氧化反应的源头(空气等），防止发生氧化反应。 Operating in a closed reactor, the source of cut (air) oxidation reaction of p-phenylenediamine and prevent oxidation reactions. 整个结晶系统无移动部件且采用计算机进行自动控制，减少了劳务成本和维修费用，与其它精制工艺相比，可提高了高纯度产品的收率，降低原料消耗和精制过程的能耗，显著降低高纯度对苯二胺的生产成本。 Overall crystallization system has no moving parts and the use of automatic computer controlled, reducing maintenance costs and labor costs, compared to other purification processes, can improve the yield of high purity product, raw material consumption and reduce the energy consumption of the refining process, a significant reduction production cost of high-purity p-phenylenediamine. 由于熔融结晶不需要溶剂，避免了溶液结晶产生废水对环境的影响， 所以减少了对环境的污染；生产工艺改善劳动环境，保护职工健康。 Since no solvent melt crystallization, the crystallization solution to avoid the impact of waste on the environment, thus reducing environmental pollution; production processes improve the working environment, protection of worker health. 本发明有益效果主要体现在：产品纯度高，且可根据不同规格要求安排生产，高纯度产品收率高，成本低，操作在无溶剂条件下进行、污染少。 Advantageous effects of the present invention is mainly embodied in: high product purity, and may be required for production according to different specifications, high purity product yield, low cost, operation is carried out without a solvent, and less pollution. (四） 附图说明图l为精馏、熔融结晶装置工艺示意图； 图2为结晶工艺流程图。 (Iv) Brief Description of the Figure l is a distillation, melt crystallization process schematic apparatus; FIG. 2 is a process flow diagram crystals. (五） 具体实施方式下面结合具体实施例对本发明进行进一步描述，但本发明的保护范围并不仅限于此：实施例1:对硝基苯胺催化加氢产品脱除水分和溶剂，与第一级熔融结晶的母液混合进入精馏塔，在真空度约0.096MPa下，经减压精馏脱除低沸物等前馏分，塔釜液进入第二精馏塔，精馏蒸出对苯二胺，冷凝，得到纯度99%的对苯二胺，放入（1)号中间槽，用于后续的结晶纯化（流程参见图2);所用结晶器、储槽和管道均密封，并且用氮气置换其中原有的空在3000L不锈钢制列管式降膜结晶器、储槽和管道系统（参见图l) 中：将（1)号中间槽的精馏所得对苯二胺冷凝液、 一级结晶的第二级发汗液、二级结晶的母液和第一级发汗液的混合液放入反应器，加入约1200公斤；使用导热油作热载体对结晶器进行加热到144°C，使物料保持熔融状态，待熔融液和导热油温度 Specific Example (E) in conjunction with the following specific embodiments of the present invention will be further described, but the scope of the present invention is not limited thereto: Example 1: p-nitroaniline removed by catalytic hydrogenation products and water solvent, with a first stage melt crystallization mother liquor was mixed into the rectification column, under a vacuum of about 0.096MPa, by reduced pressure distillation to remove low boiling fractions, and the like before, the column bottom liquid into the second fractionator, distillation distilled para-phenylenediamine condensed with a purity of 99% p-phenylenediamine, and placed in (1) the middle grooves, purified by subsequent crystallization (Scheme see FIG. 2) is used; the mold used, and reservoir pipes are sealed, purged with nitrogen and treated with wherein the original empty column made 3000L stainless steel tube falling film crystallizer, tanks and piping systems (see FIG. l) in: the resulting distillation No. (1) to the intermediate groove phenylenediamine condensate, a crystalline sweated a second stage, the mother liquor and the first stage of the two crystals of the sweated liquid mixture was placed in a reactor, the addition of about 1200 kg; the use of heat transfer oil as a heat carrier for heating the mold to 144 ° C, holding the material molten state, until the melt temperature and thermal oil 定，通过调节导热油温度使熔融液以5'C/h 速度缓慢降温，冷却至14(TC时放慢冷却速度，将降温速度保持2.5。C/h， 继续缓慢降温冷却至120~125°C，保持5〜12h;开启放料阀门放母液，母液进入初级母液中间槽；提高导热油温度，根据温度控制程序，采用二级发汗，第一级发汗物料温度提高到132'C，第2级发汗温度提高到138°C，第一级发汗液放入l号母液储槽收集，第二级发汗液放入（1)号中间槽；提高导热油温度， 加热晶层，使结晶全部熔化，自然排放，熔融液排入（2)号中间槽，得到约99.9%的间苯二胺，用作二级结晶的进料液；二级熔融结晶采用与一级结晶相同的工艺，结晶母液排入（1)号中间槽，发汗温度调整为135t:和139.2°C，第一级发汗液排入（1)中间槽， 第二级发汗液排入（2)号中间槽；加热晶层，使结晶全部熔化，自然排放，用收集罐收集产品；熔 Set by adjusting the temperature of the molten liquid HTF to 5'C / h slow cooling is cooled to 14 (TC slow cooling rate when the cooling rate holding 2.5.C / h, continued slowly cooled down to 120 ~ 125 ° C, holding 5~12h; open discharge valve discharge liquor, mother liquor into the primary intermediate tank; HTF temperature increase, according to a temperature control program, using two sweating, sweating a first stage temperature of the material increased to 132'C, the second sweating stage temperature was raised to 138 ° C, the first stage of the sweated into the collection reservoir No. l liquor, sweated liquid and placed in a second stage (1) intermediate groove; improved thermal oil temperature, heating crystal layer, a crystal completely melted , natural emissions, into the melt (2) of the middle slot, to give about 99.9% of m-phenylenediamine, used as feed two liquid crystal; two melt crystallization using the same process as a crystallization, the crystallization mother liquor No. into (1) an intermediate tank, the temperature is adjusted to sweating 135t: and 139.2 ° C, the sweated into the first stage (1) the middle groove, the sweated into the second stage (2) of the intermediate tank; heating the crystal layer the crystals completely melted, natural emissions, product is collected with the collecting tank; melting 产品采用切片机快速冷却切片，包装，间苯二胺纯度99.99%。单级结晶产品收率约70%,经过二级组合套用后，产品总收率可达到约90%。通过结晶级数以及发汗温度和发汗级数的调整，可根据用户的要求生产出符合各种需求的产品。上述二级结晶的产品如采用三级发汗，发汗终温提高到139.6。C，产品纯度可达到99.995%，依此工艺，采用三级结晶间苯二胺纯度可达到99.999%。 Products using rapid cooling microtome slicing, packaging, m-phenylenediamine, 99.99% purity single-stage crystallization product yield of about 70% after two compositions apply, total yield can be up to about 90% by crystallization stages and sweating and perspiration temperature adjustment stages, it can be produced according to the request of various products that meet the requirements above two crystalline products such as using three sweating, sweating final temperature increase to 139.6.C, up to 99.995% purity , so the process, using the three-tiered phenylenediamine crystalline purity of 99.999%.