Waste offset printing ink recovery treatment method and application

Abstract

The invention discloses a waste offset printing ink recovery treatment method and application, and belongs to the technical field of printing ink, the recovery treatment method comprises the following steps: mixing and stirring waste offset printing ink and n-hexane through pretreatment, and removing solid-phase slag through centrifugal separation to obtain a liquid phase; concentrating the liquid phase, recovering the solvent and reserving concentrated slurry; secondly, directionally dissolving the low-molecular resin and the high-molecular resin by butyl acetate and ethylene glycol diacetate respectively through two-stage counter-current extraction and centrifugal separation to obtain a low-molecular resin solution, a high-molecular resin solution and pure pigment slurry; mixing the two resin solutions, recovering the solvent through multi-tower rectification, and refining through short-path molecular distillation to obtain regenerated resin; and finally, performing ultrasonic purification, modification and spray drying on the pigment slurry to obtain the regenerated pigment. According to the waste offset printing ink recycling treatment method and application, an efficient and reliable solution is provided for recycling of waste offset printing ink.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ink, in particular to a waste offset printing ink recycling method and application. BACKGROUND

[0002] In the printing industry, offset printing ink is widely used in the printing of substrates such as paper and cardboard due to its good film-forming property and strong adhesion. However, a large amount of waste offset printing ink is generated during production, storage, and use, including expired and deteriorated inventory ink, residual ink from cleaning of printing equipment, and waste ink from defective products. According to industry statistics, the amount of waste ink generated during the use of 10,000 tons of offset printing ink can reach 800-1200 tons. If not properly treated and disposed of, it not only causes serious waste of valuable resources such as resins and pigments, but also causes multiple environmental and safety problems, becoming a key pain point restricting the green development of the printing industry.

[0003] Currently, the treatment methods for waste offset printing ink mainly include harmless disposal and resource recycling, but both methods have significant technical defects:

[0004] On the one hand, traditional harmless disposal mainly relies on incineration and landfill. During the incineration process, volatile solvents (such as ethanol and xylene) in the ink release a large amount of VOCs (volatile organic compounds), and some pigments (such as azo pigments containing heavy metals) also decompose to produce toxic gases, causing air pollution. When landfill disposal is used, resins and pigments in the ink easily penetrate into the soil and groundwater, leading to soil heavy metal exceeding standards and increasing the chemical oxygen demand of groundwater, which violates the requirements of the Solid Waste Pollution Control Law for reduction, resource utilization, and harmlessness, and completely loses the value of resource recycling.

[0005] On the other hand, existing resource recycling technologies cannot balance the relationship between recycling efficiency, product performance, and environmental safety:

[0006] Physical sedimentation method: By standing and filtering, large particle impurities (such as paper fibers and metal scraps) in waste ink are removed, but resins and pigments cannot be separated. The recycled product can only be used as a low-value filler, and the functions of resins and pigments are not effectively preserved, with a resource utilization rate of less than 30%.

[0007] High-temperature pyrolysis-distillation method: By high-temperature (300-500℃) pyrolysis of ink components, followed by distillation to separate solvents and resins, but high temperature can cause resin molecular chain breakage and pigment carbonization. The film-forming property of regenerated resins is only 60-70% of that of original resins, and the color strength of regenerated pigments is lost by more than 20%. Moreover, the high-temperature process has very high energy consumption, with a unit processing cost 2-3 times that of traditional disposal, which is economically inefficient. Therefore, there is an urgent need for a method that can achieve directional separation and efficient recovery of resins and pigments while ensuring that the regenerated products meet the printing requirements. SUMMARY

[0008] The application aims to provide a waste offset printing ink recycling method and application, which realizes source safety protection, resource directional separation and recycling, and high-value regeneration of pigments and resins through multi-dimensional and deep cooperation of safe pretreatment, solvent circulation, gradient extraction, resin refining, pigment purification and environmental protection treatment, avoids the risk of combustion and explosion and secondary pollution, guarantees the quality of regenerated products, effectively breaks through the bottleneck of low recovery rate, poor performance and high risk of traditional process, and provides an efficient and reliable solution for waste offset printing ink resource utilization.

[0009] To achieve the above-mentioned purpose, the application provides a waste offset printing ink recycling method, which comprises the following steps:

[0010] S1, pretreating waste offset printing ink to obtain solid residue and liquid phase;

[0011] S2, recycling and concentrating the liquid phase obtained in S1 to obtain concentrated slurry;

[0012] S3, gradient dissolving and centrifugal separation of the concentrated slurry obtained in S2 to obtain low molecular resin solution, high molecular resin solution and pure pigment slurry;

[0013] S4, rectification and refining of the mixture of the low molecular resin solution and the high molecular resin solution obtained in S3 to obtain regenerated resin;

[0014] S5, purifying and modifying the pigment slurry obtained in S3 to obtain regenerated pigment.

[0015] Preferably, the specific operation of S1 is as follows: the waste offset printing ink is put into a closed conditioning kettle, and n-hexane with a mass ratio of 1:1-1.5 to the waste offset printing ink is injected, and stirring is carried out at 40-50℃, 200-300r / min and under nitrogen protection for 20-30min, then the material is pumped into a horizontal screw centrifuge to separate the solid residue and the liquid phase.

[0016] Preferably, the specific operation of S2 is as follows: the liquid phase obtained in S1 is placed in a falling film evaporator and concentrated at 70-80℃ under a vacuum degree of-0.09MPa, the solvent recovery rate is ≥98%, the evaporated pure n-hexane is returned to the closed conditioning kettle, and the residual concentrated slurry is sent to an intermediate storage tank with heat preservation.

[0017] Preferably, the specific operation of S3 is as follows:

[0018] S31, the concentrated slurry enters a two-stage countercurrent extraction system from the storage tank, and after mixing with butyl acetate in the first-stage countercurrent extraction system, the concentrated slurry enters a disc separator to separate low molecular resin solution and heavy phase residue;

[0019] The heavy phase residue obtained in S32 and S31 enters a second stage countercurrent extraction system, is mixed with ethylene glycol diacetate, and is separated by a disc centrifuge to obtain pigment slurry and high molecular resin solution.

[0020] Preferably, in S31, the mixing temperature is 40-45 DEG C, the mixing time is 20-40 min, and the mass of butyl acetate is 0.8-1 times the mass of the concentrated slurry.

[0021] In S32, the mixing temperature is 50-55 DEG C, the mixing time is 40-60 min, and the mass of ethylene glycol diacetate is 0.6-0.8 times the mass of the heavy phase residue.

[0022] The rotating speed of the disc centrifuge in S31 and S32 is 4000-5000 rpm.

[0023] Preferably, the specific operation of S4 is as follows: the low molecular resin solution obtained in S31 and the high molecular resin solution obtained in S32 are mixed, and are subjected to distillation by a multi-tower series rectification system under the conditions of a vacuum degree of -0.095 MPa and a tower top temperature of 70-75 DEG C, butyl acetate is first separated out and is refluxed into the first stage countercurrent extraction system, then the temperature is increased to make the tower top temperature be 120-125 DEG C, ethylene glycol diacetate is separated out and is refluxed into the second stage countercurrent extraction system, and the resin remaining in the tower kettle is subjected to high vacuum short path molecular distillation to obtain regenerated resin.

[0024] Preferably, the specific operation of S5 is as follows: the pigment slurry is put into an ultrasonic reaction kettle, a mixed solution with a mass ratio of 1:1.5-2 to the pigment slurry is added, the mixed solution is composed of a water solution of 5% citric acid and 0.5% environmental protection chelating agent, the treatment is carried out at 40-60 DEG C and 30-50 KHz for 30-45 min, the treated pigment slurry is filtered to obtain wet pigment filter cake, 1-1.5% titanate coupling agent is added to the pigment filter cake, and the reaction is carried out at 60-80 DEG C for 40-45 min, and then the regenerated pigment is obtained by spray drying at 180 DEG C inlet air temperature / 80 DEG C outlet air temperature.

[0025] Further, the wastewater after the treated pigment slurry is filtered is subjected to precipitation treatment by adjusting pH and sodium sulfide, the heavy metal concentration is less than or equal to 0.1 mg / L, and the clean water recycling rate is greater than or equal to 80%.

[0026] The application also provides a waste offset printing ink, and the regenerated resin and the regenerated pigment obtained by the waste offset printing ink recycling treatment method are applied to the fields of printing and coating.

[0027] The application reduces the viscosity of the ink under the protection of nitrogen by using the selective dissolution characteristics of n-hexane for grease impurities in the ink, and lays a foundation for subsequent separation by combining the high-efficiency separation of solid residues and liquid phases by a horizontal screw centrifuge.

[0028] According to the difference in solubility of low-molecular resins and high-molecular resins in different solvents: the low-molecular resins are easily soluble in butyl acetate, and the high-molecular resins are more easily soluble in diethylene glycol diacetate (DAA), directional dissolution of the two types of resins is realized through secondary countercurrent extraction, and the resin solution and pigment slurry are separated by the centrifugal force field (density difference driving) of a disc centrifuge, so that the problem that the traditional single solvent cannot simultaneously consider the separation of resins with different molecular weights is solved.

[0029] According to the boiling point difference of butyl acetate and DAA, the solvent is recovered by multi-tower series vacuum rectification (low-boiling-point first distillation), the separation temperature is reduced to avoid resin degradation, residual resins are subjected to high-vacuum short-path molecular distillation, and trace impurities and low-molecular degradation products are removed by using the difference in molecular free path, so that the film-forming property of the resins is restored.

[0030] The fillers (such as calcium carbonate) attached to the surface of the pigments are removed by the acidic dissolution of citric acid, and the chelation of GLDA directionally captures heavy metal ions; the ultrasonic treatment disperses the pigment agglomerates by cavitation effect, increases the specific surface area, facilitates the formation of a coating layer of titanate coupling agent on the surface of the pigments, and repairs the dispersibility and coloring performance of the pigments, and finally realizes the morphological stabilization of the pigments by spray drying.

[0031] Therefore, the waste offset printing ink recycling method and application have the following beneficial effects:

[0032] (1) The combination of the secondary countercurrent extraction system and the rectification system realizes the efficient and high-purity separation and recovery of the components in the waste offset printing ink, the solvent recovery rate is greater than or equal to 98%, closed-loop recycling can be realized, and the production cost is greatly reduced;

[0033] (2) The regenerated resins obtained have high purity, and the regenerated pigments have good tinting strength, which can be directly used as raw materials for manufacturing inks and coatings, realizing the transformation from waste treatment to resource recovery;

[0034] (3) The secondary countercurrent extraction system is adopted to dissolve the low-molecular resins and the high-molecular resins, solving the problems of low extraction efficiency and complex product components in the traditional single solvent extraction.

[0035] The technical solutions of the application are further described below through examples. DETAILED DESCRIPTION

[0036] The technical solutions of the application are further described below through examples.

[0037] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the ordinary meaning as understood by a person having ordinary skill in the art to which the present application pertains.

[0038] The same batch of waste offset printing ink (composition: alkyd resin 27%, phthalocyanine blue pigment 11%, ethanol solvent 30%, barium sulfate filler 26%, impurities 6%, total mass 100 kg) was used in the examples and comparative examples. The core detection indexes included solvent recovery rate, resin recovery rate / purity / film forming property, pigment recovery rate / color strength, VOCs emission, and the detection standards were referred to QB / T2825-2017 (offset printing ink), GB / T25251-2010 (resin for coatings), and GB / T13451.2-2008 (pigment color strength), respectively.

[0039] In the present application, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in the art and can be purchased through commercial channels.

[0040] Example 1

[0041] The present application provides a waste offset printing ink recycling method, comprising the following steps:

[0042] S1, the waste offset printing ink is put into a closed conditioning kettle, and n-hexane with a mass ratio of 1:1-1.5 to the waste offset printing ink is injected, and stirring is carried out at 45℃, 250r / min and under nitrogen protection for 25min. After stirring, the material is pumped into a horizontal screw centrifuge, and 5.8kg of solid phase slag and 194.2kg of liquid phase are separated out.

[0043] S2, the liquid phase obtained in S1 is placed in a falling film evaporator and concentrated at 75℃ under a vacuum degree of-0.09MPa. The solvent recovery rate is 98.5%, the pure n-hexane evaporated is returned to the closed conditioning kettle, and the remaining 95.7kg of concentrated slurry is sent to a heat-insulated intermediate storage tank.

[0044] S3, gradient dissolution:

[0045] S31, the concentrated slurry enters a two-stage countercurrent extraction system from the storage tank. The concentrated slurry is stirred with 0.9 times the mass of the concentrated slurry of butyl acetate at 42℃ for 30min in the first-stage countercurrent extraction system, and after mixing, is separated in a disc separator at 4500rpm to obtain 128.3kg of low molecular resin solution and 53.5kg of heavy phase residue.

[0046] S32, the heavy phase residue obtained in S31 was introduced into a second stage countercurrent extraction system and stirred with 0.7 times the mass of the heavy phase residue of ethylene glycol diacetate at 52°C for 50 min. After mixing, the mixture was separated by a disc centrifuge at 4500 rpm to obtain 62.1 kg of pigment slurry and 28.8 kg of high molecular resin solution.

[0047] S4, the low molecular resin solution obtained in S31 and the high molecular resin solution obtained in S32 were mixed and then distilled by a multi-tower series rectification system under the conditions of a vacuum degree of -0.095 MPa and a tower top temperature of 72°C. 85.8 kg of butyl acetate was first separated and returned to the first stage countercurrent extraction system, and then the temperature was increased to separate 37.2 kg of ethylene glycol diacetate and return it to the second stage countercurrent extraction system. The resin remaining in the tower kettle was subjected to high vacuum short path molecular distillation (pressure < 1 Pa) to obtain 24.8 kg of regenerated resin (recovery rate 91.9%, purity 95.6%, and film forming ability 91.2% of that of a brand new resin used in the production of waste offset printing ink).

[0048] S5, the pigment slurry was introduced into an ultrasonic reaction kettle, and a mixed solution with a mass ratio of 1:1.8 to the pigment slurry was added. The mixed solution was composed of a 5% mass fraction of citric acid and a 0.5% mass fraction of environmentally friendly chelating agent in water. The treatment was carried out at 50°C and 40 KHz for 35 min. After treatment, the pigment slurry was filtered to obtain a wet pigment filter cake. A 1.2% mass fraction of titanate coupling agent was added to the pigment filter cake, and the reaction was carried out at 700°C for 40 min. After the reaction, spray drying was carried out at an inlet air temperature of 180°C and an outlet air temperature of 80°C to obtain 9.9 kg of regenerated pigment (recovery rate 90%, tinting strength 92.5% of the standard), and the VOCs emission was 18.3 mg / m 3 .

[0049] Example 2

[0050] The only difference between this example and Example 1 is that the mass ratio of n-hexane to waste ink in S1 is 1:1.2 (120 kg), the amount of butyl acetate in S31 is 1.0 times the mass of the concentrated slurry, and the mass ratio of the mixed solution to the pigment slurry in S5 is 1:2.

[0051] The solid phase residue removal rate was 97.1%, the n-hexane recovery rate was 98.7%, the regenerated resin was 25.1 kg (recovery rate 93.0%, purity 95.3%, film forming property 90.8%), the regenerated pigment was 10.0 kg (recovery rate 90.9%, tinting strength 92.8%), and the VOCs emission was 17.8 mg / m 3 .

[0052] Example 3

[0053] The only difference between this example and Example 1 is that the mixing time of S32 is 40 min, the top temperature of S4 is first 70°C and then 120°C, and the ultrasonic frequency of S5 is 35 kHz.

[0054] The solid phase residue removal rate is 96.5%, the n-hexane recovery rate is 98.4%, the regenerated resin is 24.6 kg (recovery rate 91.1%, purity 95.1%, film-forming property 90.5%), the regenerated pigment is 9.8 kg (recovery rate 89.1%, tinting strength 92.1%), and the VOCs emission is 18.5 mg / m 3 .

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that no nitrogen is passed in S1 (oxygen content 21%), and the rest of the conditions are the same.

[0057] During stirring, an explosive mixture is formed due to the volatilization of n-hexane, triggering a safety alarm of the equipment to stop, and the subsequent process cannot be completed; if forced to operate, the VOCs emission increases to 45.6 mg / m 3 , and the resin degrades due to local high temperature, and the film-forming property of the regenerated resin is only 78.3%.

[0058] Comparative Example 2

[0059] The only difference between this comparative example and Example 1 is that the secondary countercurrent extraction of S3 is cancelled, and only butyl acetate (123.5 kg) is used for single-stage dissolution (stirring at 48°C for 40 min), and the rest of the conditions are the same.

[0060] The resin cannot effectively separate the low molecular weight / high molecular weight components, the purity of the regenerated resin is only 82.7% (containing a large amount of pigment impurities), the recovery rate is 75.3% (20.3 kg), and the film-forming property is 76.5%; the pigment is entrained with the resin, the tinting strength is only 81.2%, and the solvent recovery rate decreases to 89.2% (which cannot be effectively reused).

[0061] Comparative Example 3

[0062] The only difference between this comparative example and Example 1 is that the mixed solution of S5 is replaced with 5% dilute nitric acid (111.8 kg) without GLDA, and the rest of the conditions are the same.

[0063] The heavy metal removal rate is only 75.3% (Example 1 is 99.2%), the washing wastewater contains nitrate (concentration 1200 mg / L), which cannot be reused; the regenerated pigment is corroded by nitric acid, the tinting strength decreases to 83.6%, and nitrogen oxides (NOx concentration 8.2 mg / m 3 ) are detected in the exhaust gas, which does not meet the environmental protection standards.

[0064] Comparative Example 4

[0065] The only difference between this comparative example and Example 1 is that the S4 kettle resin is directly used as a regenerated resin without short-path molecular distillation, and the rest of the conditions are the same.

[0066] The regenerated resin contains trace amounts of solvents (0.8%) and low molecular weight impurities, with a purity of only 86.4%, a film-forming property of 79.3%, and a drying time of 3.5 h when used in offset ink (1.8 h for Example 1), which does not meet the QB / T2825-2017 standard.

[0067] Comparative Example 5

[0068] The only difference between this comparative example and Example 1 is that the S4 rectification vacuum is 0 (atmospheric pressure), the butyl acetate is separated at a top temperature of 126°C, and the ethylene glycol diacetate is separated at a top temperature of 190°C, and the rest of the conditions are the same.

[0069] The resin is cross-linked and degraded due to high temperature (190°C), and the recovery rate of the regenerated resin is only 68.5% (18.5 kg), the purity is 88.3%, and the film-forming property is 65.7%; the energy consumption for solvent recovery is increased by 210% compared to Example 1, and the VOCs emission is increased to 32.7 mg / m 3 .

[0070] As can be seen from Comparative Examples 1-3 and Comparative Examples 1-5, Examples 1-3 avoid the risk of combustion and explosion in Comparative Example 1 by nitrogen protection, and the VOCs emission is reduced by more than 60%;

[0071] Compared to the single-stage extraction of Comparative Example 2, the two-stage countercurrent extraction of Examples 1-3 has a 22% increase in resin recovery rate, a 15% increase in purity, and a 14% increase in pigment color strength;

[0072] Compared to Comparative Example 3 and Comparative Example 3 without rectification at atmospheric pressure, the product resin obtained by vacuum rectification and short-path molecular distillation in Examples 1-3 has a 40% increase in film-forming property and a 65% reduction in energy consumption;

[0073] Compared to the nitric acid system of Comparative Example 4, the citric acid and environmentally friendly chelating agent system of Examples 1-3 has a 32% increase in heavy metal removal rate, realizes wastewater reuse, and a 11% increase in pigment color strength.

[0074] The regenerated resin and regenerated pigment prepared in Example 1 are applied to the printing industry, and the specific operation is as follows:

[0075] The regenerated resin prepared in Example 1 is mixed with n-hexane, stirred at 50°C and 800 r / min for 30 min until completely dissolved, then the regenerated pigment and dispersant are added, and the three-roll mill is ground for 3 times to control the pigment particle size ≤5 μm, and finally the drier is added, stirred at 30°C and 500 r / min for 15 min to obtain the regenerated offset ink.

[0076] The recycled offset ink is applied to a sheet-fed offset printing machine, and the printing substrate is 250g / m 2 The kraft paper has the following test results:

[0077] Coloring power: 92.3% compared with fresh ink, and the color of the printed pattern is uniform;

[0078] Drying performance: under the condition of 25 DEG C and RH 60%, the surface drying time is 45 min, the real drying time is 1.8 h, which is close to 1.7 h of fresh ink;

[0079] Adhesion: the grading method is used for testing (GB / T9286-1998), and the grade is 0, without falling off;

[0080] Rubbing resistance: after being rubbed by rubber for 50 times (pressure 500g), there is no obvious discoloration;

[0081] Environmental protection index: the VOCs emission is 38g / L, which meets the standard (≤100g / L) of QB / T2825-2017 Offset Printing Ink.

[0082] Therefore, the application adopts the above-mentioned waste offset printing ink recycling method and application, and realizes the source safety protection, resource directional separation and recycling utilization of waste offset printing ink treatment, and the high-value regeneration of pigment and resin through the multi-dimensional deep cooperation of safety pretreatment-solvent circulation-gradient extraction-resin refining-pigment purification-environmental protection treatment, which not only avoids the risk of explosion and secondary pollution, but also guarantees the quality of regenerated products, effectively breaks through the bottleneck of low recovery rate, poor performance and high risk of traditional process, and provides an efficient and reliable solution for waste offset printing ink resource utilization.

[0083] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for recycling waste offset ink, characterized by: The method comprises the following steps: S1, pretreating waste offset printing ink to obtain solid residue and liquid phase; S2, recycling and concentrating the liquid phase obtained in S1 to obtain concentrated slurry; S3, gradient dissolving and centrifugal separation of the concentrated slurry obtained in S2 to obtain low-molecular resin solution, high-molecular resin solution and pure pigment slurry; S4, rectifying and refining the mixture of the low-molecular resin solution and the high-molecular resin solution obtained in S3 to obtain regenerated resin; S5, purifying and modifying the pigment slurry obtained in S3 to obtain regenerated pigment.

2. The method for reclaiming waste offset printing ink according to claim 1, characterized in that: The specific operation of S1 is as follows: the waste offset printing ink is put into a closed conditioning kettle, and n-hexane with a mass ratio of 1:1-1.5 to the waste offset printing ink is injected, and stirring is carried out at 40-50℃, 200-300r / min and under nitrogen protection for 20-30min, then the material is pumped into a horizontal screw centrifuge to separate the solid residue and the liquid phase.

3. The method for reclaiming waste offset printing ink according to claim 1, characterized in that: The specific operation of S2 is as follows: the liquid phase obtained in S1 is placed in a falling film evaporator and concentrated at 70-80℃ and a vacuum degree of-0.09MPa, the solvent recovery rate is ≥98%, the evaporated pure n-hexane is returned to the closed conditioning kettle, and the residual concentrated slurry is sent to an intermediate storage tank with heat preservation.

4. The method for reclaiming waste offset printing ink according to claim 1, characterized in that: The specific operation of S3 is as follows: S31, the concentrated slurry from the storage tank enters a two-stage countercurrent extraction system, and after mixing with butyl acetate in the first-stage countercurrent extraction system, the concentrated slurry enters a disc centrifuge to separate low-molecular resin solution and heavy phase residue; S32, the heavy phase residue obtained in S31 enters the second-stage countercurrent extraction system, mixes with ethylene glycol diacetate, and then is separated by a disc centrifuge to obtain pigment slurry and high-molecular resin solution.

5. The method for reclaiming waste offset printing ink according to claim 4, characterized in that: In S31, the mixing temperature is 40-45℃, the mixing time is 20-40min, and the mass of butyl acetate is 0.8-1 times that of the concentrated slurry; In S32, the mixing temperature is 50-55℃, the mixing time is 40-60min, and the mass of ethylene glycol diacetate is 0.6-0.8 times that of the heavy phase residue; The rotating speed of the disc centrifuge in S31 and S32 is 4000-5000rpm.

6. The method for reclaiming waste offset printing ink according to claim 4, characterized in that: The specific operation of S4 is as follows: the low-molecular resin solution obtained in S31 and the high-molecular resin solution obtained in S32 are mixed and then distilled by a multi-tower series rectification system at a vacuum degree of-0.095MPa and a tower top temperature of 70-75℃, butyl acetate is first separated and returned to the first-stage countercurrent extraction system, then the temperature is increased to separate ethylene glycol diacetate at a tower top temperature of 120-125℃ and return it to the second-stage countercurrent extraction system, and the resin remaining in the tower kettle is obtained after high-vacuum short-path molecular distillation to obtain regenerated resin.

7. The method for reclaiming waste offset printing ink according to claim 1, wherein: The specific operation of S5 is: the pigment slurry is put into an ultrasonic reactor, and a mixed solution with a mass ratio of 1:1.5-2 to the pigment slurry is added, the mixed solution is composed of a water solution of 5% mass fraction of citric acid and 0.5% mass fraction of an environmentally friendly chelating agent, and the pigment slurry is treated at 40-60 ℃ and 30-50 KHz for 30-45 min; the treated pigment slurry is filtered to obtain a wet pigment filter cake, 1-1.5% mass fraction of a titanate coupling agent is added to the pigment filter cake, and the mixture is reacted at 60-80 ℃ for 40-45 min; after the reaction is completed, spray drying is performed at 180 ℃ inlet air temperature / 80 ℃ outlet air temperature, and the regenerated pigment is obtained.

8. Use of waste offset ink, characterized in that: The regenerated resin and the regenerated pigment obtained by the waste offset printing ink recycling method according to any one of claims 1-7 are applied to the fields of printing and coating.