Method for extruding and blending ABS (Acrylonitrile Butadiene Styrene) wet powder

Abstract

The invention relates to the field of ABS (Acrylonitrile Butadiene Styrene) resin preparation, and discloses an ABS wet powder extrusion blending method which comprises the following steps: continuously feeding a premixed material containing ABS wet powder and SAN (Styrene Acrylonitrile Butadiene Styrene) resin into an extruder, heating, mixing and extruding to obtain ABS resin particles; wherein the extruder is provided with t sections of barrel bodies; the temperature of the first cylinder is not more than 80 DEG C, the temperature of the second cylinder is not more than 150 DEG C, and the temperature of the third cylinder is not more than 180 DEG C; discharging the generated water vapor from a fourth section barrel and a sixth section barrel of the extruder; generated volatile components are discharged from the (t-3) th section of barrel and the (t-1) th section of barrel; adding an auxiliary deliming agent into the (t-2) th section of the barrel; in the premixed material, the content of the ABS wet powder is less than or equal to 30wt%, and the water content of the ABS wet powder is less than or equal to 25wt%. Aiming at extrusion blending of high-water-content ABS wet powder, continuous and stable feeding can be achieved, water vapor and volatile components are effectively separated and removed, and the resin blending effect is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of emulsion grafting ABS resin preparation, and particularly relates to a method for ABS wet powder material extrusion blending. BACKGROUND

[0002] ABS resin is a two-phase structure in which ABS rubber phase is dispersed in SAN resin phase. Currently, ABS resin production mainly adopts emulsion grafting-body SAN blending process and continuous body process. In the continuous body process, the polymerized rubber is dissolved in polymerized monomers, so that the problem of blending extrusion is basically not involved. However, the continuous body process has the problems of special equipment structure and few product types, and the application field is limited, so the process is not widely used. The emulsion grafting-body SAN blending process has the characteristics of mature technology, various product types, excellent product performance, easy product grade switching, etc. More than 85% of ABS products are produced by this process.

[0003] The emulsion grafting-body SAN blending process includes four parts of rubber synthesis, ABS graft polymer synthesis, SAN resin synthesis and mixing and blending extrusion. The SAN resin is usually synthesized by the body process, and the ABS graft polymer is first synthesized by the emulsion polymerization process to form polybutadiene rubber particles, and then the styrene and acrylonitrile are grafted on the outer layer of the rubber particles to form the ABS graft polymer. The ABS graft polymer and the SAN resin are mixed to form the ABS resin. In the traditional emulsion grafting-body SAN blending process, the ABS graft polymerization and the SAN polymerization are independent of each other. The ABS graft polymer dry powder and the SAN resin particles are produced, and then blended by the extruder. Each process unit of the process is independent, the operation flexibility is large, the production is flexible, and the process is suitable for the production of special materials, special grades, small batches and colored products. The process is also called dry process.

[0004] The traditional ABS graft polymer production is mainly through air or nitrogen boiling bed drying process, which is: the coagulated ABS graft polymer slurry is pumped to a vacuum belt filter for cleaning and filtering, removing electrolyte, emulsifier and other water-soluble substances added during the reaction process, and filtering the slurry to form a filter cake with a water content of about 50% by weight, the filter cake falls into an extrusion dewatering machine or a centrifugal dewatering machine by gravity, and is further dewatered to 10-30% by weight, the dewatered material is crushed into fine powder by a crusher, the fine powder is added to a boiling bed dryer, the dried powder has a water content of less than 1% by weight, and the dry powder is stored in a silo and intermittently fed by air conveying pipeline according to the operation of the extruder. The boiling bed drying process has high energy consumption, high material consumption and serious environmental pollution, and there is a safety hazard of powder combustion and explosion, and the drying process also causes the powder to age, thereby reducing the product performance, especially affecting the whiteness of the final product.

[0005] An effective way to solve the safety hazard in the drying process of ABS graft polymer is to cancel the boiling bed drying process, and currently the wet extrusion process is generally used internationally, that is, ABS graft polymer wet powder and SAN resin particles or molten SAN resin are blended through an extruder. The wet extrusion process has the characteristics that the ABS graft polymer does not need to be dried, and the ABS graft polymer powder with a certain water content is directly added to the extruder, and the dehydrated and molten blending is realized in the extruder to produce ABS resin.

[0006] CN1157772A discloses a method for preparing thermoplastic plastic, which comprises: treating an elastic component A with a water content of less than 60% by weight by mechanical dewatering, and mixing the mechanically dewatered elastic component A' with a thermoplastic polymer B in a screw device. The method combines extrusion dewatering and wet extrusion blending, and the extruder is provided with two liquid water dewatering cylinders and two gaseous water dewatering cylinders, which is suitable for high water content ABS wet powder, but liquid water flows out during the extrusion process, which may carry a small amount of powder, and the capacity of the extrusion equipment is low.

[0007] “ABS Resin Wet Extrusion Process and Product Performance Research” (Changchun University of Technology, Master's Thesis, Niu Qiusheng) prepares ABS resin by wet extruder melt blending. Due to the high water content of the raw material, the wet extruder feeding port is improved to an open inclined feeding port, and three exhaust ports are added to the machine body to ensure that the water vapor is successfully and completely discharged. However, these improvements cannot completely solve the problems of difficult continuous and stable feeding of wet powder and material carried during water vapor discharge.

[0008] In addition, part of the industrialized wet extrusion technology adopts side feeding method, that is, ABS wet powder is fed in the fifth barrel of the extruder. This method has two shortcomings, one is that the residence time of wet powder in the extruder is short, which cannot meet the production of high load or high rubber content formula; the other is that the dispersion of rubber in SAN resin is uneven.

[0009] Currently, the water content of ABS wet powder in the mainstream wet extrusion process in the industry is controlled to be less than or equal to 15% by weight, and the wet extrusion process matched with the wet powder with such water content cannot meet the extrusion processing of ABS wet powder with high water content (more than 20% by weight). A large amount of water vapor backflow may occur during the extrusion and blending of high water content wet powder, which may cause material bridging, thereby affecting the continuous stability of feeding, and it is difficult to effectively separate and remove water vapor and volatile components, and the blending and dispersion effect of the blended material is not ideal. SUMMARY

[0010] The present application provides a method for extrusion and blending of ABS wet powder, which is suitable for extrusion and blending of ABS wet powder with high water content and SAN resin and other substances, aiming at solving the problems of water vapor backflow affecting the continuous feeding stability of the material, difficulty in effectively separating and removing water vapor and volatile components, and poor resin blending effect in the existing wet extrusion process for processing high water content ABS wet powder.

[0011] In order to achieve the above-mentioned purpose, the present application provides a method for extrusion and blending of ABS wet powder, comprising:

[0012] The pre-mixed material containing ABS wet powder and SAN resin is continuously fed into the extruder, and after heating and mixing, ABS resin particles are obtained from the die of the extruder;

[0013] The extruder is provided with t barrels, wherein 11≤t≤15, and t is an odd number;

[0014] The pre-mixed material is fed from the first barrel of the extruder, the temperature of the first barrel of the extruder is less than or equal to 80℃, the temperature of the second barrel is less than or equal to 150℃, and the temperature of the third barrel is less than or equal to 180℃;

[0015] During the heating and mixing process, the generated water vapor is discharged from the fourth barrel and the sixth barrel of the extruder, the generated volatile components are discharged from the t-3 barrel and the t-1 barrel of the extruder, and the deashing agent is added in the t-2 barrel of the extruder;

[0016] The content of the ABS wet powder in the pre-mixed material is less than or equal to 30% by weight;

[0017] The water content of the ABS wet powder is less than or equal to 25% by weight.

[0018] The ABS wet powder material extrusion blending method provided by the application has the following beneficial effects:

[0019] (1) The high water content ABS wet powder material is processed, and the water content in the wet powder material can be up to 25% by weight;

[0020] (2) The problem of water vapor gasification and backflow along the feeding system of the extruder, and further causing the bridging of the material, is effectively solved, and the continuous and stable feeding of the high water content material is realized;

[0021] (3) The moisture in the feeding and the volatiles separated out are fully released and separated, and are discharged from the extruder through a specific position; further, through the cooperation of the lateral reverse thrust air exhaust device at the specific position, the material is not taken out in the process of discharging the moisture;

[0022] (4) On the basis of realizing the continuous and stable feeding of the high water content material and the removal of the moisture, the components in the feeding are fully mixed and dispersed, and the quality of the extrusion blend product is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the double screw extruder used in embodiment 1 of the application.

[0024] Figure 2 is a structural schematic diagram of the lateral reverse thrust air exhaust device used in the ABS wet powder material extrusion blending method of the application.

[0025] REFERENCE SIGNS

[0026] 1, first section cylinder 2, second section cylinder 3, third section cylinder

[0027] 4, fourth section cylinder 5, fifth section cylinder 6, sixth section cylinder

[0028] 7, seventh section cylinder 8, eighth section cylinder 9, ninth section cylinder

[0029] 10, tenth section cylinder 11, eleventh section cylinder 12, eighth section cylinder second air exhaust port

[0030] 13, tenth section cylinder second air exhaust port 14, moisture removal aid inlet 15, feeding pipeline

[0031] 16, extruder main motor 17, extruder screw 18, reverse thrust double screw

[0032] 19, first air exhaust port DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any ranges of values disclosed herein are not to be constrained to the exact values recited as the endpoints of the ranges. The endpoints of the ranges of values will be understood to be approximate values and will be understood to include values approximately close thereto. For ranges of numerical values, the endpoints of the ranges are combined with the individual points to form new ranges of values that are considered to be specifically disclosed herein.

[0034] The present application provides a method for ABS wet powder extrusion blending, comprising:

[0035] The pre-mixed material containing ABS wet powder and SAN resin is continuously fed into an extruder, and after heating and mixing, the ABS resin particles are obtained from the die of the extruder.

[0036] The extruder is provided with t sections of cylinder, wherein 11≤t≤15, and t is an odd number.

[0037] The pre-mixed material is fed from the first section of cylinder of the extruder, and the temperature of the first section of cylinder of the extruder is ≤80℃, the temperature of the second section of cylinder is ≤150℃, and the temperature of the third section of cylinder is ≤180℃.

[0038] During the heating and mixing process, the water vapor generated is discharged from the fourth section of cylinder and the sixth section of cylinder of the extruder, the volatile matter generated is discharged from the t-3 section of cylinder and the t-1 section of cylinder of the extruder, and the deashing agent is added in the t-2 section of cylinder of the extruder.

[0039] The content of the ABS wet powder in the pre-mixed material is ≤30wt%.

[0040] The water content of the ABS wet powder is ≤25wt%.

[0041] According to the present application, the source of the ABS wet powder is not particularly limited, and the ABS wet powder prepared by emulsion grafting method is preferably used. In the existing wet extrusion process, the water content of the ABS wet powder used is generally not higher than 15wt%, while the water content of the ABS wet powder treated by the method of the present application can reach 25wt%, preferably 5-25wt%.

[0042] According to the present application, in order to avoid water on the die after extrusion blending, the maximum proportion of the ABS wet powder in the pre-mixed material is not more than 30wt%, preferably 1-30wt%.

[0043] According to the present application, the ABS wet powder material is obtained after extrusion, and the particles of the ABS wet powder material are cylindrical, preferably with a cylindrical diameter of 1-10 mm and a cylindrical length of 1-10 mm, further preferably with a cylindrical diameter of 1-3 mm and a cylindrical length of 1-3 mm. The smaller the particle size of the ABS wet powder material, the more conducive to the stable feeding of the wet powder material to the extruder and the stable and efficient removal of moisture in the extruder.

[0044] In the present application, for the particle size of the ABS wet powder material, the cylindrical diameter refers to the maximum value of the diameters of the upper circle and the lower circle of the cylinder, and the cylindrical length refers to the vertical distance between the centers of the upper circle and the lower circle.

[0045] According to the present application, the extruder preferably adopts a double-screw extruder. According to the functions mainly performed by each region in the extruder, the extruder can be sequentially divided into a wet powder material feeding region, a gasified moisture removal region, a blending and dispersing region, a devolatilization assisting region, an extruded and pressurized resin filtering region, and a die extrusion region along the feeding to discharging direction.

[0046] In the present application, the weighing and feeding of the ABS wet powder material are preferably performed by using a continuous weighing and feeding method with a loss-on-ignition balance, so as to facilitate the continuous and stable feeding of the wet powder material. In the existing wet extrusion process, after the wet powder material enters the extruder, the moisture is gasified by heat, and the gasified water vapor can be discharged from the feeding opening of the extruder, which causes the bridging of the material at the feeding opening, so that the feeding process cannot be continuously and stably performed, and thus the continuous production is affected. In order to solve this problem, the present application mainly takes measures from three aspects: first, the ABS wet powder material is pre-mixed with SAN resin and other main raw material components, and the pre-mixed material is fed together, so as to avoid the uneven feeding of the wet powder material, the fluctuation of the gasification amount of the moisture, and the fluctuation of the water vapor pressure in the extruder; second, the temperature of the feeding section of the extruder is reduced, so that the gasification point of the moisture in the wet powder material is far away from the feeding opening; and third, the screw combination is designed to guide the movement of the water vapor, so that the gasified water vapor moves in the direction of the screw advancement.

[0047] According to the present application, for the pre-mixing of the ABS wet powder material and the SAN resin, the pre-mixing can be preferably performed by using a method in which two continuous loss-on-ignition balances continuously feed materials to one feeding pipeline, and the materials have a certain degree of frictional contact, so as to realize the pre-mixing.

[0048] According to the present application, the ABS wet powder and the SAN resin are fed through the same feeding pipeline, and in the initial stage of feeding, the SAN resin is fed first than the ABS wet powder. Further, the weight ratio of the ABS wet powder:SAN resin is 1:(2.3-20). By using the above feeding mode and the control of the feeding amount of the SAN resin being greater than the feeding amount of the ABS wet powder, the feeding mode of the SAN resin as the carrier can be formed, which is beneficial to obtain better premixing effect.

[0049] According to the present application, for the ABS wet powder and the SAN resin being fed through the same feeding pipeline, it is preferred that the feeding pipeline has a certain cutting angle, so that the material has a certain degree of friction on the pipe wall, which is more beneficial to fully mix. Preferably, the angle between the feeding pipeline and the vertical direction is 5-15°, preferably 9-10°, which is beneficial to obtain better premixing effect.

[0050] According to the present application, in some embodiments of the present application, in the case that the angle between the feeding pipeline and the vertical direction is less than 9°, a vibration device can also be arranged on the feeding pipeline, which is more beneficial to the dispersion and mixing of the material, and further improves the premixing effect.

[0051] In the present application, by the premixing, the ABS wet powder and the SAN resin can be relatively uniformly fed into the extruder, which avoids the concentration of water vaporization and stabilizes the water vapor pressure after vaporization, which is beneficial to improve the water content of the ABS wet powder (up to 25 wt%) that can be processed by the method of the present application.

[0052] According to the present application, in order to eliminate the risk of toxic gas release caused by high-temperature decomposition and combustion of the ABS grafted powder due to the separate extrusion of the ABS grafted powder by the extruder, and to solve the situation that the extruder lacks SAN resin feeding due to the failure of the feeder, it is preferred to arrange two SAN resin feeders, so that when one of them fails, a part of the SAN resin can still be added into the extruder. In addition, the two SAN resin feeders can also realize the feeding of two different SAN resins, and further realize the production of ABS resins with different properties.

[0053] In the present application, the position of water vaporization in the wet powder in the extruder is controlled by controlling the barrel temperature of the extruder. Generally, the first barrel section where the feeding port of the twin-screw extruder is located is not provided with a heating device, only with cooling water, and is not provided with temperature display and control, and the second barrel section is heated and controlled. In order to avoid the water in the wet powder from vaporizing too early, the vaporization point is moved in the direction of the material advancing in the extruder, which can be achieved by controlling the temperature of the front barrel section of the extruder. Specifically, the temperature of the first barrel section of the extruder can be controlled to be ≤80℃, the temperature of the second barrel section of the extruder can be controlled to be ≤150℃, and the temperature of the third barrel section of the extruder can be controlled to be ≤180℃. Preferably, the temperature of the first barrel section of the extruder is 25-50℃, the temperature of the second barrel section of the extruder is 50-100℃, and the temperature of the third barrel section of the extruder is 100-120℃. In order to achieve the above temperature control, the heating device of the second barrel section of the extruder can be removed, and a temperature control system, such as a cooling water control system, can be provided on the first barrel section and the second barrel section to monitor the barrel temperature and the cooling water flow, so as to ensure that the temperature of the second barrel section is lower than 150℃ (preferably lower than 100℃) to prevent a large amount of water from vaporizing. By moving the water vaporization point backward, the water vaporization point is away from the feeding port, thereby increasing the resistance of the vaporized water returning from the feeding port.

[0054] According to the present application, the temperature of the remaining barrel sections of the extruder, except the first barrel section, the second barrel section and the third barrel section, is 200-270℃, preferably 210-230℃.

[0055] According to the present application, preferably, the screw filling ratio of the first barrel section (i.e. the feeding section) of the extruder is 50-85% by volume, preferably 65-75% by volume.

[0056] According to the present application, preferably, the compression ratio of the second barrel section (i.e. the solid conveying section) of the extruder is 1:(0.5-0.8).

[0057] In the present application, by controlling the compression ratio of the solid conveying section and the screw filling ratio of the feeding section of the extruder to be within the above range, a sealed plug is formed by the solid material, and the resistance of the water vapor (vaporized water) backflow is increased.

[0058] According to the present application, along the direction from the feeding to the discharging, the last section of the third barrel section and the fourth barrel section of the extruder are provided with shear blocks, and the screw filling ratio of the last section of the second barrel section to the fifth barrel section of the extruder gradually decreases from 90% by volume to 70% by volume. By adopting this screw combination design, the water in the material can be fully exposed, and the water vapor diffusion channel is increased to guide the water vapor to be discharged along the designed channel (screw advancing direction).

[0059] In the present application, the water in the ABS wet powder material starts to be largely gasified at the third section cylinder of the extruder, where the material is melted and plasticized under the heating of the cylinder and the shearing action of the extruder screw, the polymer melt interface is constantly renewed by the screw shearing, and the water in the ABS wet powder material is gasified by heat. In the existing wet extrusion process, the water vapor formed by gasification cannot be completely separated and discharged, and is easily wrapped in the molten resin. To solve the problem of full separation of gasified water, the present application mainly takes measures from three aspects, one is to design a reasonable water vapor diffusion channel (i.e. the screw filling ratio of the control feeding section and the design of the screw combination), so that the separated water vapor is discharged in time to avoid being wrapped into the resin by the screw shearing again; two is to connect the exhaust port with the external exhaust system and / or vacuum system to increase the power of water vapor removal; three is to increase the screw shearing elements of the extruder to realize the full renewal of the molten resin interface and promote more water to be separated from the resin, solving the problem of large diffusion resistance of water vapor in the molten resin. Through these measures, the water can be fully separated, and the unstable phenomena such as strip shaking and strip explosion caused by the water carried by the discharge of the extruder can be avoided.

[0060] According to the present application, the fourth section cylinder and the sixth section cylinder of the extruder are respectively provided with a lateral reverse push exhaust device for discharging water vapor and pushing the material taken out by the water vapor back to the extruder. In the existing wet extrusion process, the separated water vapor will take out the material in the process of separating from the extruder, causing the exhaust port to be blocked, and the present application realizes the discharge of only water vapor and prevents the discharge of material by adopting a lateral reverse push exhaust device with a specific structure.

[0061] According to the present application, as Figure 2As shown, the lateral reverse push double screw exhaust device is provided with a reverse push double screw and a first exhaust port, the first exhaust port is located at the lower part of the lateral reverse push double screw exhaust device, and the outlet pipeline of the first exhaust port is horizontally inclined downward. In the present application, preferably, the lateral reverse push double screw exhaust device adopts a reverse push double screw with the same diameter as the extruder, so that the size of the reverse push screw and the exhaust channel can be maximized, the length of each reverse push screw is about 4D, the head of the screw is provided with a compression section with small lead, and the remaining part is provided with a large lead. The material in the extruder only contacts the head of the reverse push screw, and the reverse push screw is provided with a variable frequency speed regulating device to obtain sufficient speed to push the material back into the extruder. By using the above design, the lateral reverse push double screw exhaust device has sufficient exhaust space and sufficient ability to push back the material. In addition, in order to avoid condensation of water vapor in the lateral reverse push double screw exhaust device, a heating temperature control device is preferably arranged on the cylinder body of the lateral reverse push double screw exhaust device. In the present application, by arranging the first exhaust port at the lower part of the lateral reverse push double screw exhaust device, and the outlet pipeline of the first exhaust port is horizontally inclined downward, the backflow of condensed water into the extruder can be avoided.

[0062] According to the present application, preferably, the screw rotation speed of the reverse push double screw in the lateral reverse push double screw exhaust device is 100-600 rpm. The specific rotation speed of the reverse push double screw is associated with the torque of the extruder, and the torque increases, so the rotation speed of the reverse push double screw also increases. By observing the outlet regularly, if there is material overflow, the rotation speed of the reverse push double screw is increased.

[0063] According to the present application, the first exhaust port of the lateral reverse push exhaust device of the fourth section cylinder is connected to the tail gas exhaust system of the extruder die.

[0064] According to the present application, the first exhaust port of the lateral reverse push exhaust device of the sixth section cylinder is connected to a low vacuum system.

[0065] According to the present application, by connecting the exhaust ports of the fourth section cylinder and the sixth section cylinder in the extruder to the tail gas exhaust system of the extruder die and the low vacuum system respectively, the exhaust power of the water vapor formed by gasification can be greatly increased, and the water vapor can be discharged from the extruder in time.

[0066] In the present application, the low vacuum system is not particularly limited and can be any device that can provide a low vacuum environment, including but not limited to a water ring vacuum pump system, a steam jet vacuum system, etc. Preferably, the vacuum degree of the low vacuum system is 40-70 kPa, and further preferably 40-50 kPa.

[0067] According to the present application, preferably, the sufficient renewal of the interface of the molten resin can be achieved by increasing the screw shearing elements of the extruder, so that more moisture can be separated from the resin, and the problem of large diffusion resistance of water vapor in the molten resin is solved.

[0068] According to the present application, the devolatilizing agent is added in the t-2 section barrel of the extruder, and further, the t-3 section barrel and the t-1 section barrel of the extruder are respectively provided with a second exhaust port, and the second exhaust port is connected to a high vacuum system. In the present application, by adding the devolatilizing agent in the barrel between the two second exhaust ports at a specific position, the volatile components separated out from the renewal of the resin interface can be discharged from the two second exhaust ports, and a better effect of separating and discharging the volatile components is obtained.

[0069] In the present application, the devolatilizing agent is not particularly limited, and conventional choices in the art can be used, such as desalted water, nitrogen, etc., which can carry away the volatile components separated out from the renewal of the resin interface. Preferably, the addition point of the devolatilizing agent is below the t-2 section barrel, and preferably at the position of screw shearing.

[0070] According to some specific embodiments of the present application, for the case that the extruder is provided with 11 section barrels, one second exhaust port is arranged in the eighth section barrel and the tenth section barrel respectively, and the devolatilizing agent is added in the ninth section barrel; for the case that the extruder is provided with 13 section barrels, one second exhaust port is arranged in the tenth section barrel and the twelfth section barrel respectively, and the devolatilizing agent is added in the eleventh section barrel; for the case that the extruder is provided with 15 section barrels, one second exhaust port is arranged in the twelfth section barrel and the fourteenth section barrel respectively, and the devolatilizing agent is added in the thirteenth section barrel.

[0071] In the present application, the second exhaust ports on the t-3 section barrel and the t-1 section barrel of the extruder can be connected to one high vacuum system in a parallel manner.

[0072] According to a preferred embodiment of the present application, the extruder is provided with 11 section barrels.

[0073] In the present application, the high vacuum system is not particularly limited, and can be any device that can provide a high vacuum environment, including but not limited to a water ring vacuum pump system, a steam jet vacuum system, etc. Preferably, the vacuum degree of the high vacuum system is 10-40 kPa, and further preferably 15-25 kPa.

[0074] According to the present application, preferably, the rotation speed of the screw of the extruder can be 100-600 revolutions per minute.

[0075] According to the application, the torque of the extruder can be 50-80%, which is beneficial to better extrusion dewatering effect and blending dispersion effect.

[0076] According to the application, preferably, the premixing material further contains an additive capable of improving the performance of the extrusion blended product, which can include but is not limited to lubricants and antioxidants.

[0077] In the application, the lubricant is defined widely, and preferably, the lubricant can be at least one selected from N,N'-ethylene bis stearamide, oleic acid amide, pentaerythritol distearate, pentaerythritol tetrastearate, ethylene glycol distearate, glycerol distearate, diethylene glycol distearate, magnesium stearate, calcium stearate, zinc stearate and fluoroelastomer.

[0078] In the application, the antioxidant is defined widely, and preferably, the antioxidant can be at least one selected from hindered phenolic antioxidants, phosphite antioxidants and thioester antioxidants.

[0079] According to the application, the amount of the additive can be selected according to the specific use of the ABS resin product. Each component in the additive can be added by a loss on drying balance through mixing. Preferably, in the premixing material, the weight ratio of the ABS wet powder material to the additive is 1:(0.02-0.1).

[0080] According to the application, preferably, each component in the additive is fed in the form of an additive package, for example, the lubricant, antioxidant and the like can be uniformly mixed in proportion and then extruded into particles with a diameter of 3mm and a length of 3mm. The additive package can effectively avoid the loss of the additive during the exhaust process of the fourth section cylinder and the sixth section cylinder.

[0081] The method for ABS wet powder material extrusion blending provided by the application not only can meet the blending extrusion of ABS wet powder material with a conventional water content, but also can perform blending extrusion on ABS wet powder material with a high water content (up to 25% by weight), expand the application range of the production line, solve the problems of poor continuous feeding stability, difficult effective separation and removal of water vapor and volatile components, and unsatisfactory resin blending effect when high water content material is used, realize efficient and continuous and stable ABS resin wet extrusion, can achieve the effect of dry powder material blending extrusion, and effectively improve the product quality of the wet extrusion process. In addition, the method provided by the application has a simple process and simple equipment structure, can meet the continuous production requirement, and has low equipment operation cost.

[0082] The method for ABS wet powder material extrusion blending provided by the application not only is suitable for large device continuous production, but also is suitable for the extrusion process of small production line processing water-containing material, and meets the demand of recycling and utilizing water-containing material.

[0083] The present application will be described in detail below by way of examples. In the following examples and comparative examples, unless otherwise specified, the methods are conventional methods; the reagents and materials used, unless otherwise specified, are commercially available.

[0084] Example 1

[0085] Raw material situation:

[0086] ABS wet powder: The particles of the ABS wet powder are cylindrical particles with a diameter of 3 mm and a length of 3 mm, and the water content is 22 wt%.

[0087] SAN resin: The particles of the SAN resin are cylindrical particles with a diameter of 3 mm and a length of 3 mm, and the water content is less than or equal to 0.5 wt%.

[0088] Auxiliaries: EBS (N,N'-ethylene bis stearamide), antioxidant 168 and antioxidant 1010, the forms of the auxiliaries and the proportions of the components (by weight) are shown in Table 1.

[0089] Table 1

[0090] Charge form EBS Antioxidant 168 Antioxidant 1010 Total Additive package 81.3 12.5 6.2 100

[0091] Equipment situation:

[0092] 1. The diameter of the loss-in-weight feeding line of the ABS wet powder is 200 mm, the diameter of the loss-in-weight feeding line of the SAN resin is 300 mm (two SAN resin feeders are provided), the diameter of the common feeding line is 450 mm, the angle between the common feeding line and the vertical direction of the extruder is 15°, and each component of the auxiliaries is mixed and added to the common feeding line through the loss-in-weight feeder.

[0093] 2. Extruder configuration: double-screw extruder (structure shown in Figure 1 ), the diameter of the screw is 133 mm, the length-diameter ratio of the screw is 40D, 11 barrel sections are provided, a feeding port is provided on the first barrel section, a temperature control system (cooling water control system) is provided on the first barrel section and the second barrel section, a side reverse thrust exhaust device is provided on the fourth barrel section and the sixth barrel section (the first exhaust port of the side reverse thrust exhaust device of the fourth barrel section is connected to the exhaust air system of the extruder die, and the first exhaust port of the side reverse thrust exhaust device of the sixth barrel section is connected to the low vacuum system); the eighth barrel section and the tenth barrel section are respectively provided with upward second exhaust ports, and the two second exhaust ports are connected to the high vacuum system in parallel; a devolatilization aid injection port is provided below the ninth barrel section, and the devolatilization aid is added at the position of the screw shearing;

[0094] The screw rotation speed of the extruder was 400 rpm, and the torque was 70%; the die pressure of the extruder was controlled at about 65 bar, the temperature of each barrel was shown in Table 2, and the resin temperature of the eleventh barrel of the extruder was controlled at about 260℃.

[0095] 3. Lateral reverse thrust exhaust device: as shown in Figure 2 Figure, provided with a reverse thrust double screw and a first exhaust port, wherein the first exhaust port is located at the lower part of the lateral reverse thrust double screw exhaust device, and the outlet pipeline of the first exhaust port is horizontally inclined downward; the diameter of the reverse thrust double screw is 133 mm, and the screw length-diameter ratio is 4D; the head of the reverse thrust double screw is provided with a compression section small lead thread, and the rest is a large lead thread; the rotation speed of the reverse thrust double screw is 200 rpm; the barrel is provided with a heating temperature control device, and the barrel temperature is 200℃.

[0096] 4. First vacuum system (low vacuum system): the vacuum degree is 50 kPa.

[0097] 5. Second vacuum system (high vacuum system): the vacuum degree is 20 kPa.

[0098] Table 2

[0099]

[0100] Extrusion blending process:

[0101] The above-mentioned ABS wet powder material, SAN resin, and additive package were weighed by a loss-on-ignition balance according to a certain proportion, pre-mixed, and the ABS wet powder material and SAN resin were fed through the same feeding pipeline, and in the initial stage of feeding, the SAN resin was fed first, and then the ABS wet powder material was fed, to obtain a pre-mixed material (in the pre-mixed material, the weight ratio of ABS wet powder material to SAN resin was 1:3, and the weight ratio of ABS wet powder material to additive was 1:0.07);

[0102] The premix is continuously fed from the first barrel of the extruder, and the moisture is vaporized to form water vapor through heating and mechanical friction of the extruder. The water vapor is discharged through the side reverse-pushing exhaust device of the fourth barrel and the sixth barrel (the side reverse-pushing exhaust device simultaneously pushes the material brought out by the water vapor back into the extruder). The water vapor discharged from the fourth barrel is drawn away by the tail gas exhaust system of the extruder die through the first exhaust port of the side reverse-pushing exhaust device, and the water vapor discharged from the sixth barrel is drawn away by the low vacuum system through the first exhaust port of the side reverse-pushing exhaust device. The material is heated and mixed in the extruder, and the devolatilizing agent (desalted water, accounting for 0.5% by weight of the premix) is added in the ninth barrel to assist the extruder in removing the volatile components in the resin. The volatile components carried by the devolatilizing agent are drawn away by the high vacuum system through the second exhaust port of the eighth barrel and the tenth barrel. The molten resin after devolatilization is extruded in the form of a strip from the die after being filtered by the extruder under pressure, and the extruded resin strip is cut into particles after being water-cooled to form ABS resin particles (denoted as P1).

[0103] The screw filling ratio of the first barrel (the feeding section) of the extruder is 70% by volume, and the compression ratio of the second barrel (the solid conveying section) is 1:0.8. The last section of the third barrel and the fourth barrel of the extruder are provided with shear blocks to fully expose the moisture inside the material through shearing. The screw filling ratio of the last section of the second barrel of the extruder is 90% by volume, and the screw filling ratio of the fifth barrel is 70% by volume. The screw filling ratio gradually decreases between the above two parts.

[0104] The above extrusion blending process is continuously carried out for 24 hours at a feeding amount (total feeding amount of all raw materials) of 5000 kg / h. The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip, and the exhaust condition of the barrel during the extrusion blending process are shown in Table 5.

[0105] Example 2

[0106] The raw materials and equipment of Example 1 are used, and the extrusion blending process is carried out according to the method and parameters of Example 1, except that the feeding ratio is changed so that the weight ratio of ABS wet powder material: SAN resin in the premix is 1:2.3, and the weight ratio of ABS wet powder material: auxiliary agent is 1:0.1. The content of ABS wet powder material in the premix is 30% by weight. The other steps and conditions are the same as those of Example 1, and ABS resin particles (denoted as P2) are obtained.

[0107] The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip, and the exhaust condition of the barrel during the extrusion blending process are shown in Table 5.

[0108] Example 3

[0109] The extrusion blending process was carried out by using the equipment of Example 2 and following the method and parameters of Example 2, except that the water content of the ABS wet powder was 25% by weight (other parameters except water content were unchanged). The other raw materials, steps and conditions were the same as in Example 2, to obtain ABS resin particles (denoted as P3).

[0110] The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0111] Example 4

[0112] The extrusion blending process was carried out by using the equipment of Example 2 and following the method and parameters of Example 2, except that the water content of the ABS wet powder was 15% by weight (other parameters except water content were unchanged). The other raw materials, steps and conditions were the same as in Example 2, to obtain ABS resin particles (denoted as P4).

[0113] The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0114] Example 5

[0115] The extrusion blending process was carried out by using the equipment of Example 2 and following the method and parameters of Example 2, except that the water content of the ABS wet powder was 20% by weight (other parameters except water content were unchanged). The other raw materials, steps and conditions were the same as in Example 2, to obtain ABS resin particles (denoted as P5).

[0116] The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0117] Example 6

[0118] The extrusion blending process was carried out by using the raw materials and equipment of Example 2 and following the method of Example 2, except that the vacuum degree of the low vacuum system was 70 kPa. The other steps and conditions were the same as in Example 2, to obtain ABS resin particles (denoted as P6).

[0119] The reverse steam phenomenon at the feeding port of the extruder, the running condition of the die strip and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0120] Example 7

[0121] The extrusion blending process was carried out by using the raw materials and equipment of Example 2 and following the method of Example 2, except that the setting temperature of each cylinder was shown in Table 3. The other steps and conditions were the same as in Example 2, to obtain ABS resin particles (denoted as P7).

[0122] Table 3

[0123]

[0124] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die, and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0125] Example 8

[0126] The extrusion blending process was carried out using the raw materials and equipment of Example 2, and according to the method of Example 2, except that the screw rotation speed of the extruder was 340 rpm, and the torque was 85%. The other steps and conditions were the same as in Example 1, and ABS resin particles were obtained (denoted as P8).

[0127] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die, and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0128] Example 9

[0129] The extrusion blending process was carried out using the raw materials and equipment of Example 2, and according to the method of Example 2, except that the vacuum degree of the low vacuum system was 100 kPa. The other steps and conditions were the same as in Example 2, and ABS resin particles were obtained (denoted as P9).

[0130] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die, and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0131] Comparative Example 1

[0132] The extrusion blending process was carried out using the equipment of Example 2, and according to the method and parameters of Example 2, except that the water content of the ABS wet powder material was 30% by weight (other parameters except for the water content were unchanged). The other raw materials, steps, and conditions were the same as in Example 2, and ABS resin particles were obtained (denoted as D1).

[0133] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die, and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0134] Comparative Example 2

[0135] The extrusion blending process was carried out using the raw materials and equipment of Example 3, and according to the method and parameters of Example 3, except that the feeding ratio was changed, so that in the pre-mixed material, the weight ratio of ABS wet powder material: SAN resin was 1:1.5, and the weight ratio of ABS wet powder material: additives was 1:0.1, and the content of ABS wet powder material in the pre-mixed material was 38.5% by weight. The other steps and conditions were the same as in Example 3, and ABS resin particles were obtained (denoted as D2).

[0136] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0137] Comparative Example 3

[0138] The extrusion blending process was carried out using the raw materials and equipment of Example 2 and according to the method of Example 2, except that the temperature of each cylinder was set as shown in Table 4. The other steps and conditions were the same as in Example 2, and ABS resin particles (denoted as D3) were obtained.

[0139] Table 4

[0140]

[0141] The back-steam phenomenon of the feeding port of the extruder, the running condition of the strip in the die and the exhaust condition of the cylinder during the extrusion blending process are shown in Table 5.

[0142] Table 5

[0143]

[0144] Table 5 (continued)

[0145]

[0146]

[0147] Test Example

[0148] The ABS resins P1-P9 and D1-D3 prepared in Examples 1-9 and Comparative Examples 1-3 were injection molded into test bars of the size specified in GB / T 20417.2-2006 (Acrylonitrile-butadiene-styrene (ABS) moulding and extrusion materials - Part 2: Preparation of test specimens and determination of properties) by the same process conditions. The injection molding temperature was 200℃, the injection molding pressure was 100 MPa, the injection molding speed was 50-100 mm / s, and the injection molding time was 10 s. The obtained test bars were tested for Charpy impact strength, melt flow rate and whiteness, respectively, wherein,

[0149] Charpy impact strength: determined according to the method specified in GB / T 1043.1-2008;

[0150] Melt flow rate (220℃, 10 kg): determined according to the method specified in GB / T 3682.1-2018;

[0151] Whiteness test: determined according to the method specified in GB / T 2913-1982;

[0152] The test results are shown in Table 6.

[0153] Table 6

[0154]

[0155] Table 6

[0156]

[0157] As can be seen from Table 5 and Table 6, the ABS wet powder material extrusion blending method of the present application shown in Examples 1-9 can effectively ensure the continuous and stable feeding of the ABS wet powder material and the stable discharge of water vapor, is conducive to stable and continuous production, and can realize full mixing and dispersion of each component in the feed, ensure the quality of the extrusion blend product, and the water content in the wet powder material can reach 25 wt% at the highest using the method of the present application.

[0158] In particular, the water content of the ABS wet powder material in Comparative Example 1 reached 30 wt%, and the feeding port showed reverse steam phenomenon. In Comparative Example 2, the proportion of ABS wet powder material was too high, the dehydration load increased, the feeding port showed reverse steam phenomenon, and the water was not discharged in time, resulting in water being extruded from the extruder die, forming a burst strip, a shake strip, and strip adhesion. In Comparative Example 3, the temperature of the first three segments of the cylinder was too high, causing the water to vaporize prematurely, the vaporized water to diffuse upward along the feeding system, and the material to bridge, resulting in production interruption.

[0159] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method of ABS wet powder extrusion blending, characterized by, The application relates to a method for preparing ABS resin particles. The method comprises the following steps: a premixed material containing ABS wet powder and SAN resin is continuously fed into an extruder, heated and mixed, and then extruded from a die of the extruder to obtain ABS resin particles; wherein the extruder is provided with t-section cylinders, wherein 11<=t<=15, and t is an odd number; the premixed material is fed from the first section cylinder of the extruder; the temperature of the first section cylinder of the extruder is <=80 DEG C, the temperature of the second section cylinder is <=150 DEG C, and the temperature of the third section cylinder is <=180 DEG C; in the heating and mixing process, water vapor is discharged from the fourth section cylinder and the sixth section cylinder of the extruder; volatile components are discharged from the t-3 section cylinder and the t-1 section cylinder of the extruder; and a deashing agent is added into the t-2 section cylinder of the extruder; the content of the ABS wet powder in the premixed material is <=30% by weight; 2. The method of claim 1, wherein, the water content of the ABS wet powder is <=25% by weight. the content of the ABS wet powder in the premixed material is 1-30% by weight; 3. The method of claim 1 or 2, wherein, and / or, the water content of the ABS wet powder is 5-25% by weight.

4. The method of claim 1 or 2, wherein, the ABS wet powder particles are in a cylindrical shape, the diameter of the cylinder is 1-10 mm, and the length of the cylinder is 1-10 mm. the weight ratio of the ABS wet powder to the SAN resin is 1:(2.3-20); 5. The method of claim 4, wherein, and / or, the ABS wet powder and the SAN resin are fed through the same feeding pipeline, and in the initial stage of feeding, the SAN resin is fed first.

6. The method of claim 1 or 2, wherein, the angle between the feeding pipeline and the vertical direction is 5-15 DEG. the temperature of the first section cylinder of the extruder is 25-50 DEG C, the temperature of the second section cylinder is 50-100 DEG C, and the temperature of the third section cylinder is 100-120 DEG C; 7. The method of claim 6, wherein, and / or, the temperature of the remaining cylinders of the extruder, except the first section cylinder, the second section cylinder and the third section cylinder, is 200-270 DEG C. the screw filling ratio of the first section cylinder of the extruder is 50-85% by volume; 8. The method of claim 7, wherein, and / or, the compression ratio of the second section cylinder of the extruder is 1:(0.5-0.8).

9. The method of claim 1 or 2, wherein, the last section of the third section cylinder and the fourth section cylinder of the extruder are provided with shearing blocks, and the screw filling ratio of the last section of the second section cylinder to the fifth section cylinder of the extruder gradually changes from 90% by volume to 70% by volume. the fourth section cylinder and the sixth section cylinder of the extruder are respectively provided with a side reverse pushing exhaust device for discharging water vapor and pushing the material carrying the water vapor back into the extruder; 10. The method of claim 9, wherein, preferably, the side reverse pushing double screw exhaust device is provided with a reverse pushing double screw and a first exhaust port, the first exhaust port is located at the lower part of the side reverse pushing double screw exhaust device, and the outlet pipeline of the first exhaust port is horizontally downward inclined.

11. The method of claim 9 or 10, wherein, the rotating speed of the reverse pushing double screw in the side reverse pushing double screw exhaust device is 100-600 rpm. the first exhaust port of the side reverse pushing exhaust device of the fourth section cylinder is connected to the tail gas exhaust system of the die of the extruder; and / or, the first exhaust port of the side reverse pushing exhaust device of the sixth section cylinder is connected to a low vacuum system. Preferably, the vacuum degree of the low vacuum system is 40-70 kPa, and further preferably 40-50 kPa.

12. The method of claim 1 or 2, wherein, The t-3 section barrel and the t-1 section barrel of the extruder are respectively provided with a second exhaust port, and the second exhaust port is connected to a high vacuum system. Preferably, the vacuum degree of the high vacuum system is 10-40 kPa, and further preferably 15-25 kPa.

13. The method of claim 1 or 2, wherein, The screw rotation speed of the extruder is 100-600 rpm. And / or, the torque of the extruder is 50-80%, and preferably 60-75%.

14. The method of claim 1 or 2, wherein, The premix material further contains an additive, and the additive includes a lubricant and / or an antioxidant. And / or, the weight ratio of the ABS wet powder material to the additive is 1:(0.02-0.1). And / or, each component in the additive is fed in the form of an additive package.

15. The method of claim 14, wherein, The lubricant is selected from at least one of N,N'-ethylene bis-stearamide, oleic acid amide, pentaerythritol distearate, pentaerythritol tetrastearate, ethylene glycol distearate, glycerol distearate, diethylene glycol distearate, magnesium stearate, calcium stearate, zinc stearate, and fluoroelastomer. And / or, the antioxidant is selected from at least one of a hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant.

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