A filler-free screw extruder cleaning agent and its preparation method and application

Abstract

The present invention discloses a filler-free screw extruder cleaning agent, a preparation method and an application thereof, and belongs to the technical field of polymer materials. The resin mixture in the present invention has a suitable viscosity. After being melted at a certain temperature, carbon deposits and residual materials can be loosened by soaking. Its viscosity is used to provide a strong shear force, which effectively washes out residual materials in the screw. The surfactant and lubricant contained in the auxiliary agent help to further improve the washing and color-changing ability of the cleaning agent and reduce its residue in the screw. The formula of the present invention is filler-free. Compared with the existing technology, it will not damage the screw and at the same time ensure the low residue of the product. The overall production process is simple, the raw material price is low and it is easy to promote. The foaming agent does not produce toxic gas, and it is economical and environmentally friendly to use.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a filler-free screw extruder cleaning agent and a preparation method and application thereof. Background Art

[0002] When producing and processing thermoplastic resin products, extruders or injection molding machines need to switch between resin mixtures of different types, brands, or colors to meet different production needs. This requires that the previous batch of raw materials needs to be completely and quickly discharged from the equipment to save time and labor costs.

[0003] The cleaning of twin-screw extruder is mainly to clean the materials remaining on the screw and barrel. These materials are often closely bonded to the screw and barrel. They include degradation products and carbonization of resins at high temperatures, as well as pigments and other additives added during production. Especially during the production and processing of colored plastic products, the residue of pigments in the screw will cause significant color deviation and result in unqualified products.

[0004] Due to the high degree of residue adhesion, physical removal by screw disassembly is cumbersome and time-consuming, failing to meet the requirements of continuous production. Therefore, in practice, screw cleaners are primarily used to remove residue. Currently, commercially available screw cleaners and published patents primarily utilize physical friction-based cleaners, which contain large amounts of abrasive fillers such as glass fiber and calcium carbonate. During use, mechanical friction between the filler and the screw accelerates screw damage. Furthermore, these fillers exhibit poor fluidity and compatibility with the resin, resulting in significant self-residue in the absence of shear forces at the die head, necessitating die disassembly or flushing with a large amount of resin.

[0005] In their long-term production experience with colored polyester masterbatches, the inventors discovered that certain resins, when mixed, possess the appropriate viscosity to effectively remove residual material from the screw while exhibiting good compatibility with polyester and preventing residue from forming in the die. These resin mixtures, melted at a certain temperature, are then soaked to loosen carbon deposits and residual material. The higher-viscosity resin mixture generates strong shear forces as the screw rotates, providing a powerful cleaning effect on the screw and barrel. The filler-free formulation ensures low residue. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a filler-free screw extruder cleaning agent.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0010] 40-60 parts of base resin, 5-20 parts of washing resin, 5-30 parts of thermoelastic resin, 2-15 parts of compatibilizing resin, and 5-15 parts of compounding auxiliary agent.

[0011] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the base resin includes one or more of general-grade polystyrene, high-impact polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, and polybutylene terephthalate.

[0012] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the washing resin includes one or more of polypropylene, high-density polyethylene, low-density polyethylene, and polymethyl methacrylate.

[0013] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the thermoelastic resin includes one or more of styrene-butadiene-styrene triblock copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene / butylene-styrene block copolymer, and hydrogenated styrene / isoprene copolymer.

[0014] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the compatibilizing resin includes one or more of maleic anhydride grafted polypropylene, maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer, and maleic anhydride grafted polystyrene.

[0015] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the compounding auxiliary agent, in parts by mass, includes:

[0016] 5-10 parts of anionic surfactant, 15-30 parts of nonionic surfactant, 5-10 parts of foaming expansion agent, 50-70 parts of lubricant, and 0-5 parts of inorganic reinforcing agent.

[0017] As a preferred embodiment of the filler-free screw extruder cleaning agent of the present invention, the anionic surfactant comprises one or more of sodium lauryl sulfate, sodium lauryl sulfonate, and sodium dodecylbenzene sulfonate;

[0018] The nonionic surfactant includes one or more of sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester;

[0019] The foaming expansion agent includes one or more of sodium bicarbonate, ammonium bicarbonate, azodicarbonamide, and azobisisobutyronitrile;

[0020] The lubricant includes one or more of stearic acid soap, ethylene bisstearamide, and polyethylene glycol;

[0021] The inorganic reinforcing agent includes one or more of calcium carbonate and barium sulfate.

[0022] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a filler-free screw extruder cleaning agent.

[0023] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0024] After mixing the compounded additives, dry them in an oven at 80°C for 1-3 hours, then stir them in a high-speed mixer for 3-6 minutes to obtain an additive mixture;

[0025] Place the base resin, washing resin, thermoelastic resin, compatibilizing resin and additive mixture in a high-speed mixer and stir for 6 to 9 minutes to obtain a premix;

[0026] The premix is placed in an extruder and extruded, pelletized and air-cooled to obtain a screw cleaning agent;

[0027] Wherein, the extrusion temperature is 180~230℃.

[0028] As a preferred embodiment of the method for preparing the filler-free screw extruder cleaning agent of the present invention, the compounding auxiliary agent comprises, in parts by mass,

[0029] 5-10 parts of anionic surfactant, 15-30 parts of nonionic surfactant, 5-10 parts of foaming expansion agent, 5-70 parts of lubricant, and 0-5 parts of inorganic reinforcing agent.

[0030] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of a filler-free screw extruder cleaning agent, comprising placing the cleaning agent in an extruder, maintaining a constant screw speed at 230-300°C, and extruding until the extrudate is white.

[0031] Beneficial effects of the present invention:

[0032] (1) The resin mixture of the present invention has a suitable viscosity. When used at a temperature above 230°C, the resin softens and melts, and can loosen carbon deposits and residual materials through immersion. Its viscosity provides a strong shear force, which effectively washes out residual materials in the screw. At this temperature, the foaming agent contained in the additive is highly efficient and can greatly improve the swelling capacity of the resin composition, better adhere to the surface and inner cavity of the screw, and the surfactant and lubricant help to further improve the cleaning and color changing ability of the cleaning agent and reduce its residue in the screw.

[0033] (2) The formula of the present invention does not contain fillers. Compared with the existing technology, it will not damage the screw and at the same time ensure the low residue of the product. The overall production process is simple, the raw materials are cheap and easy to promote, and the foaming agent does not produce toxic gases, making it economical and environmentally friendly to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0035] Figure 1 These are the effects of the cleaning agent obtained in Example 1 of the present invention cleaning the blue pigment polyester mixture extruded at different time periods. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0039] The abbreviations of the raw materials used in the present invention correspond to their Chinese names and models as shown in the table.

[0040] Table 1 Correspondence between raw material abbreviations and Chinese names

[0041]

[0042] The matrix resin used in the present invention is low-fluidity polystyrene and its copolymer resin, with a melt flow rate of 1.5-2.2 g / 10 min;

[0043] The thermoelastic resin and compatibilizing resin used in the present invention are polystyrene derivatives;

[0044] The resin grades used in the present invention can be:

[0045] SECCO GPPS351, TAIRIREX® GP550N, TAIRRISAN® NX3200, KIBISAN® PN-127, Lucene™ SM600, Lucene™ SM800, ExxonMobil TM HD6950YN, ExxonMobil TM LL-5002, SINOPECDFDA-7042, SINOPEC DFDA-7050, LGSBS 411S, SINOPEC SBS 1401, TAIPOL® SEBS 6151, Changhong Hi-Tech SEBS CH520, SINOPEC SEBS YH-4051, Huawen® SMA-130, Huawen® SMA-150, LG PMMA HI855HS, LG PMMA HP202.

[0046] The polyethylene terephthalate resin used in the present invention is FC510, produced by Sinopec Yizheng Chemical Fiber Co., Ltd.

[0047] Pigment Type: Pigment Blue 15.

[0048] Example 1

[0049] This embodiment provides a method for preparing a filler-free screw extruder cleaning agent, comprising the following steps:

[0050] 1) Compound the additives according to the following formula:

[0051] Active agent: 7 parts of sodium lauryl sulfate, 27 parts of sorbitan stearate;

[0052] Foaming agent: 1.5 parts of sodium bicarbonate, 4.5 parts of azodicarbonamide, 1 part of sodium hexametaphosphate;

[0053] Lubricant: 55 parts of zinc stearate;

[0054] Reinforcing agent: 4 parts of calcium carbonate;

[0055] After drying each auxiliary agent in an oven at 80° C. for 3 hours, the auxiliary agent was placed in a high-speed mixer and stirred for 6 minutes to obtain a uniformly mixed composite auxiliary agent.

[0056] 2) Prepare the premix according to the following formula:

[0057] Matrix resin: GPPS 10 parts, SAN 43 parts;

[0058] Washing resin: HDPE 5 parts, LDPE 5;

[0059] Thermoelastic resin: SBS 5 parts, SEBS 15 parts;

[0060] Compatibilizing resin: SMA 5 parts;

[0061] 12 parts of compounding auxiliary agent;

[0062] The resins and compounding additives were placed in a high-speed mixer and stirred for 9 minutes to obtain a premix. The premix was placed in a twin-screw extruder and extruded. The screw aspect ratio was 44, the screw diameter was 22 mm, the temperatures of each zone to the die head were 190°C, 195°C, 195°C, 195°C, 190°C, 190°C, and 190°C, the screw speed was 360 rpm, and after grinding, pelletizing, and air cooling, a filler-free screw extruder cleaning agent was obtained.

[0063] Example 2

[0064] The difference between this embodiment and embodiment 1 is that the formula of the base resin and the thermoelastic resin in the premix is adjusted, specifically:

[0065] Matrix resin: GPPS 9 parts, SAN 41 parts;

[0066] Washing resin: 5 parts HDPE, 5 parts LDPE:

[0067] Thermoelastic resin: SBS 8 parts, SEBS 15 parts;

[0068] Compatibilizing resin: SMA 5 parts;

[0069] 12 parts of compounding auxiliary agent;

[0070] The remaining processes are the same as those in Example 1 to prepare the cleaning agent of this example.

[0071] Example 3

[0072] The difference between this embodiment and embodiment 1 is that the resin formula in the premix is adjusted, specifically:

[0073] Base resin: GPPS 8 parts, SAN 35 parts;

[0074] Washing resin: 6 parts of HDPE, 6 parts of LDPE;

[0075] Thermoelastic resin: SBS 9 parts, SEBS 14.5 parts;

[0076] Compatibilizing resin: SMA 5 parts, PMMA 5 parts;

[0077] 11.5 parts of compounding auxiliary agents.

[0078] The rest of the preparation process is the same as that in Example 1 to prepare the cleaning agent of this example.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that no compounding auxiliary agent is added in this comparative example, and the proportions of other resins are adaptively adjusted. The rest of the preparation process is the same as that of Example 1, specifically:

[0081] Matrix resin: GPPS 10 parts, SAN 50 parts;

[0082] Washing resin: 5 parts of HDPE, 5 parts of LDPE;

[0083] Thermoelastic resin: SBS 10 parts, SEBS 15 parts;

[0084] Compatibilizing resin: SMA 5 parts;

[0085] The extrusion process was the same as that in Example 1 to prepare the cleaning agent of this comparative example.

[0086] Comparative Example 2

[0087] The difference between this comparative example and Example 1 is that the formula of the compounded auxiliary agent is adjusted, no active agent is added, and the ratio of other auxiliary agents and resin is adaptively adjusted. The rest of the preparation process is the same as that of Example 1, specifically:

[0088] 1) Compound the additives according to the following formula:

[0089] Foaming agent: 2.3 parts of sodium bicarbonate, 6.8 parts of azodicarbonamide, 1.5 parts of sodium hexametaphosphate;

[0090] Lubricant: 83.4 parts of zinc stearate;

[0091] Reinforcing agent: 6 parts of calcium carbonate;

[0092] After drying each auxiliary agent in an oven at 80° C. for 3 hours, the auxiliary agent was placed in a high-speed mixer and stirred for 6 minutes to obtain a uniformly mixed composite auxiliary agent.

[0093] 2) Prepare the premix according to the following formula:

[0094] Base resin: GPPS 10 parts, SAN 47.1 parts;

[0095] Washing resin: 5 parts of HDPE, 5 parts of LDPE;

[0096] Thermoelastic resin: SBS 5 parts, SEBS 15 parts;

[0097] Compatibilizing resin: SMA 5 parts;

[0098] 7.9 parts of compounding additives

[0099] The extrusion process was the same as that in Example 1 to prepare the cleaning agent of this comparative example.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that the formula of the compounded auxiliary agent is adjusted, no foaming agent is added, and the proportions of other auxiliary agents and resin are adaptively adjusted. The rest of the preparation process is the same as that of Example 1, specifically:

[0102] Active agent: 7.5 parts of sodium lauryl sulfate, 29 parts of sorbitan stearate;

[0103] Lubricant: 59 parts of zinc stearate;

[0104] Reinforcing agent: 4.5 parts of calcium carbonate.

[0105] The remaining processes were the same as in Example 1 to prepare the cleaning agent of this comparative example.

[0106] Comparative Example 4

[0107] The difference between this comparative example and Example 1 is that the formula of the compounded auxiliary agent is adjusted, no lubricant is added, and the ratio of other auxiliary agents and resin is adaptively adjusted. The rest of the preparation process is the same as that of Example 1, specifically:

[0108] Active agent: 15.6 parts of sodium lauryl sulfate, 60 parts of sorbitan stearate;

[0109] Foaming agent: 3.3 parts of sodium bicarbonate, 10 parts of azodicarbonamide, 2.2 parts of sodium hexametaphosphate;

[0110] Reinforcing agent: 8.9 parts of calcium carbonate;

[0111] After drying each auxiliary agent in an oven at 80° C. for 3 hours, the auxiliary agent was placed in a high-speed mixer and stirred for 6 minutes to obtain a uniformly mixed composite auxiliary agent.

[0112] 3) Prepare the premix according to the following formula:

[0113] Base resin: GPPS 10 parts, SAN 49.6 parts;

[0114] Washing resin: 5 parts of HDPE, 5 parts of LDPE;

[0115] Thermoelastic resin: SBS 5 parts, SEBS 15 parts;

[0116] Compatibilizing resin: SMA 5 parts;

[0117] 5.4 parts of compounding auxiliary agent.

[0118] The remaining processes were the same as in Example 1 to prepare the cleaning agent of this comparative example.

[0119] Comparative Example 5

[0120] This comparative example differs from Example 1 in that the formula of the compounded auxiliary agent is changed, no reinforcing agent is added, and the ratio of other auxiliary agents and resin is adaptively adjusted. The rest of the preparation process is the same as that of Example 1, specifically:

[0121] Active agent: 8 parts of sodium lauryl sulfate, 28 parts of sorbitan stearate;

[0122] Foaming agent: 1.5 parts of sodium bicarbonate, 4.5 parts of azodicarbonamide, 1 part of sodium hexametaphosphate;

[0123] Lubricant: 57 parts of zinc stearate.

[0124] The remaining processes were the same as those in Example 1 to prepare the cleaning agent of this comparative example. The cleaning agent of this comparative example had slightly poor formability during granulation, and occasionally had uneven particle sizes during strand cutting.

[0125] Example 4

[0126] This example uses colored polyethylene terephthalate resin (PET) as the cleaning object, provides a method for using the cleaning agent prepared by the present invention, and tests its cleaning effect, specifically:

[0127] Using a twin-screw extruder, 200 g of masterbatch with a pigment blue 15 content of 20% prepared from pigment blue 15 and PET chips and 1800 g of PET chips were mixed evenly and extruded for 30 minutes. The screw diameter was 22 mm, the L / D was 44, the extrusion temperatures in each zone were 250°C, 270°C, 270°C, 270°C, 250°C, 250°C, and 250°C, and the screw speed was 360 rpm.

[0128] While maintaining the above extrusion temperature and screw speed, the cleaning agents of Examples 1 to 3 and Comparative Examples 1 to 5 were added and extruded until the extrudate turned white, which completed the cleaning.

[0129] like Figure 1As shown, (a) to (i) are the effects of the cleaning agent prepared in Example 1 of the present invention on cleaning the blue pigment polyester mixture extruded at different time periods. It can be seen that as the amount of extrudate increases, the color of the extrudate approaches white, indicating that the cleaning agent of the present invention can effectively wash away the residual material in the screw.

[0130] Cleaning effect test:

[0131] While maintaining the same extrusion temperature and screw speed in each zone as during cleaning, add 1 kg of polyethylene terephthalate (PET) chips for flushing. Observe whether the flushing material at the screw and ground mouth at the air outlet contains any residual cleaning agent. Record the amount of extruded material used when it turns nearly white, the amount of polyethylene terephthalate chips used when there is no residual cleaning agent at the die extrusion site after flushing, and the color and degree of residue at the die when there is still residue after flushing with 1 kg of polyethylene terephthalate. The cleaning effect is shown in Table 2.

[0132] Table 2 Comparison of cleaning effects of cleaning agents with different additive formulas

[0133]

[0134] (Note: (O: no residue; V: small amount of residue; M: obvious residue; P: large amount of streaky residue))

[0135] As can be seen from the test results in Table 2, the cleaning agents prepared in Examples 1 to 3 of the present invention all have excellent cleaning effects. Since the polystyrene derivative resin compound selected in the resin of the present invention has good compatibility with washing resins such as polyethylene and polyethylene terephthalate to be washed residues, in the presence of the compounding auxiliary agent, it can effectively clean and reduce residues during polyester processing and color change.

[0136] The cleaning agents of Comparative Examples 1 to 5 were significantly less effective than those of Examples 1 to 3 in cleaning blue polyethylene terephthalate in a twin-screw extruder. This is because the various additives, when compounded with the resin, can react with the resin. For example, the active agent can wet the pigment and other pollutants; the foaming agent can improve the expansion performance of the cleaning agent and enhance its ability to clean residual materials; the combination of the lubricant and the resin can reduce the corrosion and wear of the cleaning agent on the equipment; the reinforcing agent component can reduce the fluidity of the cleaning agent, improve the cleaning effect, and enhance the formability of the cleaning agent. The synergistic combination of the additives gives the cleaning agent the best cleaning effect.

[0137] Comparative Example 6

[0138] The difference between this comparative example and Example 1 is that the resin formula is adjusted, no base resin is added, and the ratio of other resin combinations is adaptively adjusted, specifically:

[0139] Washing resin: 25 parts of HDPE, 25 parts of LDPE;

[0140] Thermoelastic resin: SBS 10 parts, SEBS 18 parts;

[0141] Compatibilizing resin: SMA 10 parts;

[0142] 12 parts of compounding auxiliary agent;

[0143] The remaining processes were the same as those in Example 1 to prepare the cleaning agent of this comparative example. However, the cleaning agent had poor formability during granulation and occasionally broke into pieces, making it difficult to prepare in batches, thereby increasing the difficulty of preparation.

[0144] Comparative Example 7

[0145] The difference between this comparative example and Example 1 is that the resin formula is adjusted, the washing resin is not added, and the ratio of other resin combinations is adaptively adjusted, specifically:

[0146] Base resin: GPPS 15 parts, SAN 30 parts;

[0147] Thermoelastic resin: SBS 15 parts, SEBS 18 parts;

[0148] Compatibilizing resin: SMA 10 parts;

[0149] 12 parts of compounding auxiliary agent;

[0150] The remaining processes were the same as in Example 1 to prepare the cleaning agent of this comparative example.

[0151] Comparative Example 8

[0152] The difference between this comparative example and Example 1 is that the resin formula is adjusted, no compatibilizing resin is added, and the ratio of other resin combinations is adaptively adjusted, specifically:

[0153] Base resin: GPPS 9 parts, SAN 46 parts;

[0154] Washing resin: 5 parts of HDPE, 5 parts of LDPE;

[0155] Thermoelastic resin: SBS 8 parts, SEBS 15 parts;

[0156] 12 parts of compounding auxiliary agent;

[0157] The remaining processes were the same as in Example 1 to prepare the cleaning agent of this comparative example.

[0158] Comparative Example 9

[0159] The difference between this comparative example and Example 1 is that the resin formula is adjusted, no thermoelastic resin is added, and the ratio of other resin combinations is adaptively adjusted, specifically:

[0160] Base resin: GPPS 15 parts, SAN 25 parts;

[0161] Washing resin: 20 parts of HDPE, 15 parts of LDPE;

[0162] Compatibilizing resin: SMA 13 parts;

[0163] 12 parts of compounding auxiliary agent;

[0164] The remaining processes were the same as in Example 1 to prepare the cleaning agent of this comparative example.

[0165] Comparative Example 10

[0166] In this comparative example, PP resin was used as the blank control group.

[0167] The cleaning effects of the cleaning agents of Comparative Examples 6 to 10 were tested with reference to the method of use in Example 4 and compared with Example 1.

[0168] Cleaning effect test:

[0169] Add 1 kg of polyethylene terephthalate (PET) chips for flushing, and observe whether there is any residual cleaning agent in the flushing material at the screw and ground mouth at the air outlet. Record the amount of extruded material used when it is almost white, the amount of polyethylene terephthalate chips used when there is no residual cleaning agent at the extrusion site of the die head after flushing, and the color and residual degree of the die head when there is still residue after flushing with 1 kg of polyethylene terephthalate. The cleaning effect is shown in Table 3.

[0170] Table 3 Comparison of cleaning effects of cleaning agents with different resin formulations

[0171]

[0172] (Note: (O: no residue; V: small amount of residue; M: obvious residue; P: large amount of streaky residue))

[0173] The results in Table 3 show that the present invention considers synergy with the resin when selecting and optimizing the resin to achieve the best cleaning effect. Experiments have found that when the base resin is not added, the cleaning agent is difficult to form, indicating that the base resin is one of the essential components of the cleaning agent. When the washing resin is not added, the cleaning effect is significantly reduced, thus indicating that the washing resin in the present invention can cooperate with other resins to adsorb pollutants and improve the cleaning ability of the cleaning agent. When the compatibilizing resin is not added, the compatibility between the various raw materials deteriorates, and when the thermoelastic resin is not added, the swelling capacity of the cleaning agent decreases. These changes will significantly reduce the cleaning effect of the resulting cleaning agent.

[0174] In summary, in the long-term practical production of colored polyester masterbatch, the inventors have discovered that some resins have a suitable viscosity when mixed and can effectively wash away residual materials in the screw while having good compatibility with polyester and will not remain at the die head.

[0175] Based on this discovery, the inventors further conducted a lot of research and finally obtained the formula of the filler-free extruder cleaning agent of the present invention. A variety of resins are used in the formula, including compatibilizing resins, washing resins, elastomeric resins, etc. These resins have different functions and advantages. For example, the compatibilizing resin can increase the polarity of the resin carrier, improve the uniformity of the dispersion of each component, improve the wetting ability of the additive to the pigment, and improve the cleaning effect; the high viscosity of the washing resin can adhere to the pollutants while the additive wets them, purifying the cleaning screw; the elastomeric resin can effectively increase the swelling ability of the cleaning agent, improve the cleaning effect and reduce the adhesion of the cleaning agent to metal (screw), reducing the residue of the cleaning agent in the screw. The base resin has good compatibility with other resin components in the cleaning agent and high compatibility with polyester. It has a low melt index and when compounded with the additive, the overall material still has a high viscosity, which enhances the effective shearing of the screw on the cleaning agent, etc.

[0176] At the same time, when selecting and optimizing compounding auxiliary agents, their synergistic effect with the resin is also considered to achieve better cleaning effect. In the research of the present invention, the compounding of the active agent and the resin can improve the wetting performance of the cleaning agent on the pigment, thereby improving the cleaning effect; the compounding of the foaming agent and the resin can enhance the expansion behavior of the cleaning agent during use and enhance the cleaning ability of the cleaning agent on the inner cavity of the screw; the compounding of the lubricant and the resin can further enhance the compatibility of each component and the wetting and dispersing ability of the pigment, thereby improving the cleaning effect and reducing the corrosion and wear of the cleaning agent on the equipment.

[0177] The formula of the present invention is filler-free. Compared with the existing technology, it will not damage the screw and ensure the low residue of the product. The overall production process is simple, the raw materials are low-priced and easy to promote, and the foaming agent does not produce toxic gases, so it is economical and environmentally friendly to use.

[0178] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention 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 invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A screw extruder cleaning agent, characterized in that: Calculated by mass, it is composed of 40-60 parts of base resin, 5-20 parts of washing resin, 5-30 parts of thermoelastic resin, 2-15 parts of compatibilizing resin, and 5-15 parts of compounding auxiliary agent; Wherein, the matrix resin is selected from one or more of general-purpose polystyrene, high-impact polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, and polybutylene terephthalate; The washing resin is selected from one or more of polypropylene, high-density polyethylene, low-density polyethylene, and polymethyl methacrylate; The thermoelastic resin is selected from one or more of styrene-butadiene-styrene triblock copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene / butylene-styrene block copolymer, and hydrogenated styrene / isoprene copolymer; The compatibilizing resin is selected from one or more of maleic anhydride grafted polypropylene, maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer, and maleic anhydride grafted polystyrene; The compounding auxiliary agent is composed of 5 to 10 parts of anionic surfactant, 15 to 30 parts of nonionic surfactant, 5 to 10 parts of foaming agent, 50 to 70 parts of lubricant, and 0 to 5 parts of inorganic reinforcing agent in parts by mass; Among them, the anionic surfactant is selected from one or more of sodium lauryl sulfate, sodium lauryl sulfonate, and sodium dodecylbenzene sulfonate; the nonionic surfactant is selected from one or more of anhydrous sorbitan fatty acid esters and polyoxyethylene anhydrous sorbitan fatty acid esters; the foaming expansion agent is selected from one or more of sodium bicarbonate, ammonium bicarbonate, azodicarbonamide, azobisisobutyronitrile, and sodium hexametaphosphate; the lubricant is selected from one or more of stearic acid soap, ethylene bisstearamide, and polyethylene glycol; and the inorganic reinforcing agent is selected from one or more of calcium carbonate and barium sulfate.

2. The method for preparing a screw extruder cleaning agent according to claim 1, wherein: After mixing the compounded additives, dry them in an oven at 80°C for 1-3 hours, then stir them in a high-speed mixer for 3-6 minutes to obtain an additive mixture; Place the base resin, washing resin, thermoelastic resin, compatibilizing resin and additive mixture in a high-speed mixer and stir for 6 to 9 minutes to obtain a premix; The premix is placed in an extruder and extruded, pelletized, and air-cooled to obtain a screw extruder cleaning agent; Wherein, the extrusion temperature is 180~230℃.

3. The use of the screw extruder cleaning agent according to claim 1 in cleaning a screw extruder, characterized in that: The method includes placing the cleaning agent in an extruder, maintaining a constant screw speed at 230-300° C., and extruding until the extrudate is white.

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