Double-screw extrusion pelletizing process for copolymerized polycarbonate with capacity of 5t / h

Abstract

The invention provides an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in the preparation process of copolymerized polycarbonate. The invention also provides a double-screw extrusion pelletizing process of copolymerized polycarbonate, and stable operation of the double-screw extruder is realized by adjusting and controlling operation parameters, an extrusion formula and a screw combination of copolymerized PC semi-finished product flocculus in the double-screw extruder and coordinating and matching the operation parameters, the extrusion formula and the screw combination of the copolymerized PC semi-finished product flocculus in the double-screw extruder. By adopting the twin-screw extrusion pelletizing process provided by the invention, a copolymerized siloxane polycarbonate semi-finished product flocculus is well plasticized in a machine barrel, the material throwing phenomenon at a vacuum sight glass opening of an extruder is eliminated, and high vacuum degree and negative pressure are maintained, so that the content of water vapor and small molecules is reduced, bubbles in a material strip are eliminated, and the material strip collapse phenomenon at a die head is eliminated; similarly, the problem of frequent collapse of die head material strips in the extrusion granulation process of brominated PC is also eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of a copolycarbonate twin-screw extrusion pelletizing process, relates to an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in a copolycarbonate preparation process, and a copolycarbonate twin-screw extrusion pelletizing process, and particularly relates to a copolycarbonate twin-screw extrusion pelletizing process with a production capacity of 5 t / h. Background Art

[0002] Polycarbonate (PC for short) is a high molecular polymer containing carbonate groups in the molecular chain. According to the structure of the ester group, it can be divided into aliphatic, aromatic, aliphatic-aromatic and other types. At present, aromatic polycarbonate has been industrialized due to its excellent properties, and due to the particularity of the structure of polycarbonate, it has become the fastest growing general engineering plastic among the five major engineering plastics. At present, the three main application areas of PC engineering plastics are glass assembly industry, automobile industry and electronics and electrical industry, followed by industrial machinery parts, CDs, packaging, office equipment such as computers, medical and health care, films, leisure and protective equipment, etc. PC can also be used as door and window glass, and is widely used in protective windows of banks, embassies, detention centers and public places, for aircraft cabin covers, lighting equipment, industrial safety baffles and bulletproof glass, etc. With the continuous in-depth development of application fields, the demand for its performance is also increasing, making the current application and development of polycarbonate develop in the direction of high composite, high function, specialization and serialization. Among them, copolymerized polycarbonate materials have flexible improvement directions, strong applicability and excellent characteristics, and have become the focus of research and development in the industry.

[0003] High molecular brominated PC (brominated PC, brominated polycarbonate) is a new type of copolymer PC made from tetrabromobisphenol A. It has excellent flame retardancy, electrical properties and mechanical properties. It is a high-end specialty PC and can be widely used in home appliances, automobiles, and OA office fields. Copolymerized siloxane polycarbonate (silicon PC) has good low temperature resistance and high cantilever beam notch impact strength at low temperatures. Conventional PC is brittle at -10°C, while the silicon-containing copolymerized PC remains tough at -40°C and has good impact resistance. Copolymerized silicon PC has good flame retardancy and can reach V1 grade, and also has good hydrolysis resistance, weather resistance, and corrosion resistance.

[0004] However, in the actual production process of copolymer polycarbonate materials, especially in the final extrusion granulation process, there are still problems such as poor stability. For example, in the extrusion granulation process of brominated PC, the extruder die strip frequently collapses, which greatly reduces the stability of the strip and shortens the operation cycle. In the actual silicon PC extrusion production process, because the silicon PC introduces silicone groups, the rigidity is reduced, the toughness is enhanced, and the fluidity is enhanced compared to ordinary PC. It is difficult to plasticize completely during the extrusion granulation process, which will also cause problems such as vacuum mirror material throwing and die strip collapse, resulting in poor extruder operation stability and shortened operation cycle, which greatly affects the actual production efficiency of copolymer polycarbonate materials and increases the actual production cost.

[0005] Therefore, how to develop a more suitable pelletizing process for copolymerized polycarbonate materials and improve the above-mentioned deficiencies of the existing process has become one of the urgent problems to be solved by R&D-based production companies in the industry. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in the preparation process of copolymerized polycarbonate and a twin-screw extrusion pelletizing process for copolymerized polycarbonate, in particular a twin-screw extrusion pelletizing process for copolymerized polycarbonate with a production capacity of 5 t / h. The present invention adjusts and controls the operating parameters, extrusion formula and screw combination of the silicon PC semi-finished flakes in the twin-screw extruder, thereby achieving stable operation of the twin-screw extruder in the process of producing copolymerized polycarbonate, greatly improving production efficiency and reducing production costs.

[0007] The present invention provides an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in the preparation process of copolymerized polycarbonate;

[0008] The copolycarbonate comprises copolysiloxane polycarbonate or brominated polycarbonate;

[0009] The twin-screw extrusion pelletizing process includes one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder;

[0010] The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw;

[0011] The conveying section screw adopts large lead thread elements, medium lead thread elements and small lead thread elements;

[0012] The melting section screw adopts small lead thread elements and medium lead thread elements;

[0013] The mixing section screw adopts a small lead thread element;

[0014] The exhaust section screw adopts a medium-lead thread element;

[0015] The homogenizing section screw adopts medium lead thread elements and small lead thread elements.

[0016] Preferably, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the conveying section screw adopts a first large lead thread element, a first medium lead thread element and a first small lead thread element, the melting section screw adopts a first small lead thread element and a first medium lead thread element, the mixing section screw adopts a second small lead thread element, the exhaust section screw adopts a first medium lead thread element, and the homogenizing section screw adopts a first medium lead thread element and a second small lead thread element;

[0017] When the copolymerized polycarbonate is brominated polycarbonate, the conveying section screw adopts the second large lead thread element, the second medium lead thread element and the fourth small lead thread element, the melting section screw adopts the third small lead thread element and the fourth small lead thread element, the mixing section screw adopts the second small lead thread element, the exhaust section screw adopts the second medium lead thread element, and the homogenizing section screw adopts the third medium lead thread element and the second small lead thread element;

[0018] The pitch of the first large lead thread element is 1.5D to 1.75D; the pitch of the second large lead thread element is 1.5D to 1.6D;

[0019] The pitch of the first medium lead thread element is 1D to 1.25D; the pitch of the second medium lead thread element is 1.2D to 1.4D; the pitch of the third medium lead thread element is 1D to 1.2D;

[0020] The pitch of the first small lead thread element is 0.75D to 0.85D; the pitch of the second small lead thread element is 0.5D to 0.6D; the pitch of the third small lead thread element is 0.9D to 0.95D; the pitch of the fourth small lead thread element is 0.75D to 0.8D;

[0021] Wherein, D is the unit pitch, D=130mm.

[0022] Preferably, the stable operation includes no material throwing off and / or no strip collapse;

[0023] The non-rejection of material specifically refers to the non-rejection of material at the vacuum sight glass port of the extruder;

[0024] The non-collapse of strips specifically refers to the non-collapse of strips at the die head of the extruder;

[0025] The twin-screw extrusion pelletizing process is specifically a process of extruding and pelletizing copolymerized polycarbonate flakes into copolymerized polycarbonate particles.

[0026] Preferably, the operating parameters of the twin-screw extruder include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure, extruder load and speed ratio;

[0027] The extrusion pelletizing formula includes copolymerized polycarbonate flakes, and pentaerythritol stearate and / or phosphite antioxidant;

[0028] The threaded element is specifically a double helical threaded element;

[0029] The twin-screw extruder is specifically a twin-screw extruder with a production capacity of 5 t / h.

[0030] The present invention provides a twin-screw extrusion pelletizing process for copolymerized polycarbonate, comprising the following steps:

[0031] Copolymer polycarbonate flakes and phosphite antioxidant are used as raw materials, and the twin-screw extrusion pelletizing process parameters are controlled to obtain copolymer polycarbonate pellets after extrusion pelletizing through a twin-screw extruder;

[0032] The copolycarbonate comprises copolysiloxane polycarbonate or brominated polycarbonate;

[0033] When the copolymer polycarbonate is a copolymer silicone polycarbonate, the raw material further comprises pentaerythritol stearate;

[0034] The twin-screw extrusion pelletizing process parameters include one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder;

[0035] The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw;

[0036] The operating parameters of the twin-screw extruder include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure and extruder speed ratio.

[0037] Preferably, the extruder barrel temperature includes the barrel conveying section temperature, the barrel melting section temperature, the barrel mixing section temperature, the barrel exhaust section temperature and the barrel homogenizing section temperature;

[0038] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the barrel conveying section is controlled at 280-290°C; the temperature of the barrel melting section is controlled at 280-290°C; the temperature of the barrel mixing section is controlled at 280-290°C; the temperature of the barrel exhaust section is controlled at 270-280°C; the temperature of the barrel homogenizing section is controlled at 270-280°C;

[0039] When the copolymer polycarbonate is brominated polycarbonate, the temperature of the barrel conveying section is controlled at 250-260°C; the temperature of the barrel melting section is controlled at 250-260°C; the temperature of the barrel mixing section is controlled at 250-260°C; the temperature of the barrel exhaust section is controlled at 250-260°C; and the temperature of the barrel homogenizing section is controlled at 250-260°C.

[0040] Preferably, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the start valve temperature is controlled at 270-280°C;

[0041] When the copolymerized polycarbonate is brominated polycarbonate, the start-up valve temperature is controlled at 245-255° C.;

[0042] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the melt pump is controlled at 270-280° C.;

[0043] When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the melt pump is controlled at 245-255° C.;

[0044] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the screen changer is controlled at 270-280° C.;

[0045] When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the screen changer is controlled at 255-260°C.

[0046] Preferably, the die temperature includes the temperature of die zone 1, the temperature of die zone 2, the temperature of die zone 3 and the temperature of die zone 4;

[0047] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the first zone of the die head is controlled at 250-260° C.;

[0048] When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the first zone of the die is controlled at 240-250° C.;

[0049] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the second die zone, the temperature of the third die zone, and the temperature of the fourth die zone are each controlled at 270-280° C.;

[0050] When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the second die zone, the temperature of the third die zone and the temperature of the fourth die zone are each controlled at 250-260°C.

[0051] Preferably, the melt pump inlet pressure is controlled at 20-25 bar;

[0052] The vacuum degree of the exhaust port is controlled at -45 to -50 kPa;

[0053] The pressure at the screw feed port is controlled at -0.05 to -0.1 kPa;

[0054] When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the rotation speed ratio of the twin-screw extruder is controlled at 16.5 to 17 kg / rpm;

[0055] When the copolymerized polycarbonate is brominated polycarbonate, the speed ratio of the twin-screw extruder is controlled at 15.5 to 16.5 kg / rpm;

[0056] The diameter of the copolymerized polycarbonate flakes is 2.36 to 12.5 mm;

[0057] The particle size of the copolymerized polycarbonate particles is 2.9 to 3.15 mm.

[0058] Preferably, the amount of pentaerythritol stearate added is 500ppm;

[0059] The amount of the phosphite antioxidant added is 300ppm;

[0060] The conveying section screw adopts large lead thread elements, medium lead thread elements and small lead thread elements;

[0061] The melting section screw adopts small lead thread elements and medium lead thread elements;

[0062] The mixing section screw adopts a small lead thread element;

[0063] The exhaust section screw adopts a medium-lead thread element;

[0064] The homogenizing section screw adopts medium lead thread elements and small lead thread elements;

[0065] The twin-screw extruder is specifically a twin-screw extruder with a production capacity of 5 t / h.

[0066] The invention provides an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in a preparation process of copolymerized polycarbonate; the copolymerized polycarbonate comprises copolymerized siloxane polycarbonate or brominated polycarbonate; the twin-screw extrusion pelletizing process comprises one or more of the operating parameters of the twin-screw extruder, the formula of extrusion pelletizing and the screw combination of the twin-screw extruder; the screw combination of the twin-screw extruder comprises a conveying section screw, a melting section screw, a mixing section screw, an exhaust section screw and a homogenizing section screw; the conveying section screw adopts a large lead thread element, a medium lead thread element and a small lead thread element; the melting section screw adopts a small lead thread element and a medium lead thread element; the mixing section screw adopts a small lead thread element; the exhaust section screw adopts a medium lead thread element; the homogenizing section screw adopts a medium lead thread element and a small lead thread element. Compared with the prior art, the present invention applies a specific twin-screw extrusion pelletizing process to the preparation process of copolymerized polycarbonate, which greatly improves the stable operation of the twin-screw extruder, thereby improving the production efficiency of copolymerized polycarbonate particles and reducing production costs.

[0067] The present invention also provides a twin-screw extrusion pelletizing process for copolymerized polycarbonate, which is a twin-screw extrusion pelletizing process for copolymerized polycarbonate with a production capacity of 5 t / h. The present invention adjusts and controls the operating parameters, extrusion formula and screw combination of the copolymerized PC semi-finished flakes in the twin-screw extruder, and the multiple parameters cooperate with each other, thereby achieving stable operation of the twin-screw extruder. By adopting the twin-screw extrusion pelletizing process provided by the present invention, the copolymerized silicone polycarbonate semi-finished flakes are well plasticized inside the barrel, the material throwing phenomenon at the vacuum sight glass port of the extruder is eliminated, and the high vacuum degree and negative pressure are maintained, which reduces the content of water vapor and small molecules, eliminates bubbles in the material strips, and eliminates the phenomenon of material strip collapse at the die head; similarly, the problem of frequent die head material strip collapse in the extrusion granulation process of brominated PC is also eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 A schematic diagram of the screw configuration assembly in the copolysiloxane polycarbonate production process provided by the present invention;

[0069] Figure 2 A schematic diagram of the screw configuration assembly in the brominated polycarbonate production process provided by the present invention;

[0070] Figure 3 The number of cleaning times of the vacuum mirror port before and after the implementation of Example 1 of the present invention;

[0071] Figure 4 The number of times the material strip collapses at the die head before and after the implementation of Example 1 of the present invention;

[0072] Figure 5 It is the number of times the material strip collapses at the die head before and after the implementation of Example 2 of the present invention. DETAILED DESCRIPTION

[0073] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0074] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0075] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses industrially pure materials or materials of conventional purity used in the field of copolymerization of polycarbonate preparation.

[0076] The present invention has no particular limitation on the brands or models of all raw materials, and any conventional brands or models in the field known to those skilled in the art may be used. Those skilled in the art may select manufacturers based on actual production conditions, product requirements or quality requirements.

[0077] The present invention provides an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in the preparation process of copolymerized polycarbonate;

[0078] The copolycarbonate comprises copolysiloxane polycarbonate (silicon PC) or brominated polycarbonate (brominated PC);

[0079] The twin-screw extrusion pelletizing process includes one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder;

[0080] The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw;

[0081] The conveying section screw adopts large lead thread elements, medium lead thread elements and small lead thread elements;

[0082] The melting section screw adopts small lead thread elements and medium lead thread elements;

[0083] The mixing section screw adopts a small lead thread element;

[0084] The exhaust section screw adopts a medium-lead thread element;

[0085] The homogenizing section screw adopts medium lead thread elements and small lead thread elements.

[0086] In the present invention, when the copolymer polycarbonate is a copolymer silicone polycarbonate, the conveying section screw preferably adopts a first large lead thread element, a first medium lead thread element and a first small lead thread element, the melting section screw preferably adopts a first small lead thread element and a first medium lead thread element, the mixing section screw preferably adopts a second small lead thread element, the exhaust section screw preferably adopts a first medium lead thread element, and the homogenizing section screw preferably adopts a first medium lead thread element and a second small lead thread element.

[0087] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the conveying section screw preferably adopts the second large lead thread element, the second medium lead thread element and the fourth small lead thread element, the melting section screw preferably adopts the third small lead thread element and the fourth small lead thread element, the mixing section screw preferably adopts the second small lead thread element, the exhaust section screw preferably adopts the second medium lead thread element, and the homogenizing section screw preferably adopts the third medium lead thread element and the second small lead thread element;

[0088] In the present invention, D is a unit pitch, preferably D=130 mm.

[0089] In the present invention, the pitch of the first large lead thread element is preferably 1.5D to 1.75D, more preferably 1.55D to 1.7D, more preferably 1.6D to 1.65D. The pitch of the second large lead thread element is preferably 1.5D to 1.6D, more preferably 1.52D to 1.58D, more preferably 1.54D to 1.56D.

[0090] In the present invention, the pitch of the first medium lead threaded element is preferably 1D to 1.25D, more preferably 1.05D to 1.2D, and more preferably 1.1D to 1.15D; the pitch of the second medium lead threaded element is preferably 1.2D to 1.4D, more preferably 1.24D to 1.36D, and more preferably 1.28D to 1.32D; the pitch of the third medium lead threaded element is preferably 1D to 1.2D, more preferably 1.04D to 1.16D, and more preferably 1.08D to 1.12D.

[0091] In the present invention, the pitch of the first small lead threaded element is preferably 0.75D to 0.85D, more preferably 0.77D to 0.83D, and more preferably 0.79D to 0.81D; the pitch of the second small lead threaded element is preferably 0.5D to 0.6D, more preferably 0.52D to 0.58D, and more preferably 0.54D to 0.56D; the pitch of the third small lead threaded element is preferably 0.9D to 0.95D, more preferably 0.91D to 0.94D, and more preferably 0.92D to 0.93D; the pitch of the fourth small lead threaded element is preferably 0.75D to 0.8D, more preferably 0.76D to 0.79D, and more preferably 0.77D to 0.78D.

[0092] In the present invention, the stable operation preferably includes no material throwing and / or no strip collapse, more preferably no material throwing or no strip collapse. Specifically, when the copolycarbonate is a copolysiloxane polycarbonate, the stable operation includes no material throwing and / or no strip collapse. When the copolycarbonate is a brominated polycarbonate, the stable operation includes no strip collapse.

[0093] In the present invention, the non-throwing material is preferably non-throwing material at the vacuum sight glass port of the extruder.

[0094] In the present invention, the non-collapsed strip is preferably the non-collapsed strip at the die head of the extruder.

[0095] In the present invention, the twin-screw extrusion pelletizing process is preferably a process of extruding and pelletizing copolymerized polycarbonate flakes into copolymerized polycarbonate particles.

[0096] In the present invention, the operating parameters of the twin-screw extruder preferably include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure, extruder load and speed ratio, and more preferably include extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure, extruder load or speed ratio.

[0097] In the present invention, the extrusion pelletizing formula preferably includes copolymerized polycarbonate flakes, and pentaerythritol stearate and / or phosphite antioxidants.

[0098] In the present invention, the threaded element is preferably a double-helix threaded element.

[0099] In the present invention, the twin-screw extruder is preferably a twin-screw extruder with a production capacity of 5 t / h.

[0100] The present invention provides a twin-screw extrusion pelletizing process for copolymerized polycarbonate, comprising the following steps:

[0101] Copolymer polycarbonate flakes and phosphite antioxidant are used as raw materials, and the twin-screw extrusion pelletizing process parameters are controlled to obtain copolymer polycarbonate pellets after extrusion pelletizing through a twin-screw extruder;

[0102] The copolycarbonate comprises copolysiloxane polycarbonate or brominated polycarbonate;

[0103] When the copolymer polycarbonate is a copolymer silicone polycarbonate, the raw material further comprises pentaerythritol stearate;

[0104] The twin-screw extrusion pelletizing process parameters include one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder;

[0105] The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw;

[0106] The operating parameters of the twin-screw extruder include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure and extruder speed ratio.

[0107] In the present invention, the extruder barrel temperature preferably includes the barrel conveying section temperature, the barrel melting section temperature, the barrel mixing section temperature, the barrel exhaust section temperature and the barrel homogenizing section temperature.

[0108] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the barrel conveying section is preferably controlled at 280-290°C, more preferably 282-288°C, more preferably 284-286°C; the temperature of the barrel melting section is preferably controlled at 280-290°C, more preferably 282-288°C, more preferably 284-286°C; the temperature of the barrel mixing section is controlled at 280-290°C, more preferably 282-288°C, more preferably 284-286°C; the temperature of the barrel exhaust section is preferably controlled at 270-280°C, more preferably 272-278°C, more preferably 274-276°C; the temperature of the barrel homogenizing section is controlled at 270-280°C, more preferably 272-278°C, more preferably 274-276°C.

[0109] In the present invention, when the copolymer polycarbonate is brominated polycarbonate, the temperature of the barrel conveying section is preferably controlled at 250-260°C, more preferably 252-258°C, more preferably 254-256°C; the temperature of the barrel melting section is controlled at 250-260°C, more preferably 252-258°C, more preferably 254-256°C; the temperature of the barrel mixing section is controlled at 250-260°C, more preferably 252-258°C, more preferably 254-256°C; the temperature of the barrel exhaust section is controlled at 250-260°C, more preferably 252-258°C, more preferably 254-256°C; the temperature of the barrel homogenizing section is controlled at 250-260°C, more preferably 252-258°C, more preferably 254-256°C.

[0110] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the valve opening temperature is preferably controlled at 270-280°C, more preferably 272-278°C, and more preferably 274-276°C.

[0111] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the valve opening temperature is preferably controlled at 245-255°C, more preferably 247-253°C, and more preferably 249-251°C.

[0112] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the melt pump is controlled at 270-280°C, more preferably 272-278°C, and more preferably 274-276°C.

[0113] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the temperature of the melt pump is controlled at 245-255°C, more preferably 247-253°C, and more preferably 249-251°C.

[0114] In the present invention, when the copolymerized polycarbonate is copolymerized siloxane polycarbonate, the temperature of the screen changer is controlled at 270-280°C, more preferably 272-278°C, and more preferably 274-276°C.

[0115] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the screen changer temperature is preferably controlled at 255-260°C, more preferably 256-259°C, and more preferably 257-258°C.

[0116] In the present invention, the die temperature preferably includes the temperature of die zone 1, the temperature of die zone 2, the temperature of die zone 3 and the temperature of die zone 4.

[0117] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the first zone of the die is preferably controlled at 250-260°C, more preferably 252-258°C, and more preferably 254-256°C.

[0118] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the temperature of the first zone of the die is preferably controlled at 240-250°C, more preferably 242-248°C, and more preferably 244-246°C.

[0119] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperatures of the second die zone, the third die zone and the fourth die zone are each preferably controlled at 270-280°C, more preferably 272-278°C, and more preferably 274-276°C.

[0120] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the temperature of the second die zone, the temperature of the third die zone and the temperature of the fourth die zone are each preferably controlled at 250-260°C, more preferably 252-258°C, and more preferably 254-256°C.

[0121] In the present invention, the melt pump inlet pressure is preferably controlled at 20 to 25 bar, more preferably 21 to 24 bar, and more preferably 22 to 23 bar.

[0122] In the present invention, the vacuum degree of the exhaust port is preferably controlled at -45 to -50 kPa, more preferably at -46 to -49 kPa, and more preferably at -47 to -48 kPa.

[0123] In the present invention, the pressure at the screw feed port is preferably controlled at -0.05 to -0.1 kPa, more preferably at -0.06 to -0.09 kPa, and more preferably at -0.07 to -0.08 kPa.

[0124] In the present invention, when the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the rotation speed ratio of the twin-screw extruder is preferably controlled at 16.5 to 17 kg / rpm, more preferably 16.6 to 16.9 kg / rpm, and more preferably 16.7 to 16.8 kg / rpm.

[0125] In the present invention, when the copolymerized polycarbonate is brominated polycarbonate, the rotation speed ratio of the twin-screw extruder is preferably controlled at 15.5 to 16.5 kg / rpm, more preferably 15.7 to 16.3 kg / rpm, and more preferably 15.9 to 16.1 kg / rpm.

[0126] In the present invention, the diameter of the copolycarbonate flakes is preferably 2.36-12.5 mm, more preferably 5-10 mm, and more preferably 7-9 mm. Specifically, the diameter distribution of the copolycarbonate flakes may be: ≥12.5 mm mm 0.67%, 9.5 < d < 12.5 mm 49.03%, 6.3 < d < 9.5 mm 48.3%, and 2.36 < d < 6.3 mm 2%.

[0127] In the present invention, the particle size of the copolymerized polycarbonate particles is 2.9-3.15 mm. Specifically, the particle size distribution of the copolymerized polycarbonate particles may be: 2.9<d<3.15 mm 99% and 3.15<d<3.5 mm 1%.

[0128] In the present invention, the addition amount of the pentaerythritol stearate is preferably 500 ppm.

[0129] In the present invention, the added amount of the phosphite antioxidant is preferably 300 ppm.

[0130] In the present invention, the conveying section screw preferably adopts a large lead thread element, a medium lead thread element and a small lead thread element.

[0131] In the present invention, the melting section screw preferably adopts a small lead screw element and a medium lead screw element.

[0132] In the present invention, the mixing section screw preferably adopts a small-pitch screw element.

[0133] In the present invention, the exhaust section screw preferably adopts a medium-lead thread element.

[0134] In the present invention, the homogenizing section screw preferably adopts medium lead thread elements and small lead thread elements.

[0135] In the present invention, the twin-screw extruder is preferably a twin-screw extruder with a production capacity of 5 t / h.

[0136] The present invention is a complete and detailed overall technical solution, which better ensures the structure and performance of copolymerized polycarbonate particles, further improves the stability and operability of the copolymerized polycarbonate particle extrusion pelletizing process, and the application of the twin-screw extrusion pelletizing process in improving the stable operation of the twin-screw extruder in the preparation process of copolymerized polycarbonate and a twin-screw extrusion pelletizing process of copolymerized polycarbonate can specifically include the following contents:

[0137] Operating parameters, extrusion formula and screw combination of silicone PC semi-finished flakes in a twin-screw extruder.

[0138] 1. Screw combination:

[0139] (1) Conveying section: conveying materials and preventing overflow.

[0140] The use of large lead threaded elements is beneficial to material transportation, increasing production and shortening residence time.

[0141] D: Unit pitch (130mm)

[0142] The maximum lead pitch is 1.5D-1.75D, the pitch is 195-227.5mm, and it is a double helix form.

[0143] The medium lead pitch is 1D-1.25D, the pitch is 130-162.5mm, and it is a double helix form.

[0144] The small lead pitch is 0.75D-0.85D, the pitch is 97.5-110.5mm, and it is a double helix form.

[0145] (2) Melting stage: The material is fully melted and homogenized through heat transfer and friction shearing.

[0146] The use of small lead threaded elements is conducive to the shearing and melting of materials.

[0147] D: Unit pitch (130mm)

[0148] The small lead pitch is 0.75D-0.85D, the pitch is 97.5-110.5mm, and it is a double helix form.

[0149] The medium lead pitch is 1D-1.25D, the pitch is 130-162.5mm, and it is a double helix form.

[0150] (3) Mixing section: It makes the material further refined and uniform, and has distribution and dispersion mixing functions.

[0151] The use of small lead thread elements is conducive to uniform dispersion of materials.

[0152] D: Unit pitch (130mm)

[0153] The small lead pitch is 0.5D-0.6D, the pitch is 65-78mm, and it is a double helix form.

[0154] (4) Exhaust section: Exhausts impurities such as water vapor and small molecules.

[0155] Selecting a medium lead is beneficial for exhausting gas.

[0156] D: Unit pitch (130mm)

[0157] The medium lead pitch is 1D-1.25D, the pitch is 130-162.5mm, and it is a double helix form.

[0158] (5) Homogenizing section: conveying and pressurizing, building up a certain pressure to make the die head have a certain density and further mix.

[0159] Selecting a medium lead is beneficial for pressure building and mixing.

[0160] D: Unit pitch (130mm)

[0161] The medium lead pitch is 1D-1.25D, the pitch is 130-162.5mm, and it is a double helix form.

[0162] The small lead pitch is 0.5D-0.6D, the pitch is 65-78mm, and it is a double helix form.

[0163] See also Figure 1 , Figure 1 The present invention provides a schematic diagram of the screw configuration combination in the copolysiloxane polycarbonate production process.

[0164] 2. Twin screw extruder operating parameters:

[0165] (1) Extruder barrel temperature:

[0166] a. The temperature of the barrel conveying section is controlled at 280-290℃.

[0167] b. The temperature of the barrel melting section is controlled at 280-290℃.

[0168] c. The temperature of the mixing section of the barrel is controlled at 280-290℃.

[0169] d. The temperature of the barrel exhaust section is controlled at 270-280℃.

[0170] e. The temperature of the barrel homogenizing section is controlled at 270-280℃.

[0171] (2) Opening valve temperature:

[0172] The start-up valve temperature is controlled at 270-280℃.

[0173] (3) Melt pump temperature:

[0174] The temperature before and after the melt pump and the temperature of the pump body are controlled at 270-280℃.

[0175] (4) Screen changer temperature:

[0176] The start-up valve temperature is controlled at 270-280℃.

[0177] (5) Die head temperature:

[0178] a. The temperature of the first zone of the die is controlled at 250-260℃.

[0179] b. The temperature of the second zone of the die is controlled at 270-280℃.

[0180] c. The temperature of the three zones of the die head is controlled at 270-280℃.

[0181] d. The temperature of the four zones of the die head is controlled at 270-280℃.

[0182] (6) Melt pump inlet pressure:

[0183] The pressure setting value is 20-25bar.

[0184] (7) Vacuum degree of exhaust port:

[0185] The vacuum degree is controlled at -45-50kpa.

[0186] (8) Screw feed port pressure:

[0187] The feed inlet pressure is controlled at -0.05 to -0.1 kPa.

[0188] (9) Extruder load and speed ratio:

[0189] 16.5-17kg / rpm.

[0190] 3. Silicon PC extrusion formula:

[0191] (1) Pentaerythritol stearate: 500ppm;

[0192] (2) Phosphite antioxidant: 300ppm.

[0193] Operating parameters, extrusion formula and screw combination of brominated PC semi-finished flakes in a twin-screw extruder.

[0194] 1. Screw block combination:

[0195] (1) Conveying section: conveying materials and preventing overflow.

[0196] The use of large lead threaded elements is beneficial to material transportation, increasing production and shortening residence time.

[0197] D: Unit pitch (130mm)

[0198] The maximum lead pitch is 1.5D-1.6D, the pitch is 195-208mm, and it is a double helix form.

[0199] The medium lead pitch is 1.2D-1.4D, the pitch is 156-182mm, and it is a double helix form.

[0200] The small lead pitch is 0.75D-0.8D, the pitch is 97.5-104mm, and it is a double helix form.

[0201] (2) Melting stage: The material is fully melted and homogenized through heat transfer and friction shearing.

[0202] The use of small lead threaded elements is conducive to the shearing and melting of materials.

[0203] D: Unit pitch (130mm)

[0204] The small lead pitch is 0.9D-0.95D, the pitch is 117-123.5mm, and it is a double helix form.

[0205] The small lead pitch is 0.75D-0.8D, the pitch is 97.5-104mm, and it is a double helix form.

[0206] (3) Mixing section: It makes the material further refined and uniform, and has distribution and dispersion mixing functions.

[0207] The use of small lead thread elements is conducive to uniform dispersion of materials.

[0208] D: Unit pitch (130mm)

[0209] The small lead pitch is 0.5D-0.6D, the pitch is 65-78mm, and it is a double helix form.

[0210] (4) Exhaust section: Exhausts impurities such as water vapor and small molecules.

[0211] Selecting a medium lead is beneficial for exhausting gas.

[0212] D: Unit pitch (130mm)

[0213] The medium lead pitch is 1.2D-1.4D, the pitch is 156-182mm, and it is a double helix form.

[0214] (5) Homogenizing section: conveying and pressurizing, building up a certain pressure to make the die head have a certain density and further mix.

[0215] Selecting a medium lead is beneficial for pressure building and mixing.

[0216] D: Unit pitch (130mm)

[0217] The medium lead pitch is 1D-1.2D, the pitch is 130-156mm, and it is a double helix form.

[0218] The small lead pitch is 0.5D-0.6D, the pitch is 65-78mm, and it is a double helix form.

[0219] See also Figure 2 , Figure 2 The present invention provides a schematic diagram of the screw configuration assembly in the brominated polycarbonate production process.

[0220] 2. Twin screw extruder operating parameters:

[0221] (1) Extruder barrel temperature:

[0222] a. The temperature of the barrel conveying section is controlled at 250-260℃.

[0223] b. The temperature of the barrel melting section is controlled at 250-260℃.

[0224] c. The temperature of the mixing section of the barrel is controlled at 250-260℃.

[0225] d. The temperature of the barrel exhaust section is controlled at 250-260℃.

[0226] e. The temperature of the barrel homogenizing section is controlled at 250-260℃.

[0227] (2) Opening valve temperature:

[0228] The start-up valve temperature is controlled at 245-255℃.

[0229] (3) Melt pump temperature:

[0230] The temperature before and after the melt pump and the temperature of the pump body are controlled at 245-255℃.

[0231] (4) Screen changer temperature:

[0232] The start-up valve temperature is controlled at 255-260℃.

[0233] (5) Die head temperature:

[0234] a. The temperature of the first zone of the die head is controlled at 240-250℃.

[0235] b. The temperature of the second zone of the die is controlled at 250-260℃.

[0236] c. The temperature of the three zones of the die head is controlled at 250-260℃.

[0237] d. The temperature of the four zones of the die head is controlled at 250-260℃.

[0238] (6) Melt pump inlet pressure:

[0239] The pressure setting value is 20-25bar.

[0240] (7) Vacuum degree of exhaust port:

[0241] The vacuum degree is controlled at -45-50kpa.

[0242] (8) Screw feed port pressure:

[0243] The feed inlet pressure is controlled at -0.05 to -0.1 kPa.

[0244] (9) Extruder load and speed ratio:

[0245] 15.5-16.5kg / rpm.

[0246] 3. Bromine PC extrusion formula:

[0247] (1) Phosphite antioxidant: 300ppm.

[0248] The present invention provides an application of a twin-screw extrusion pelletizing process in improving the stable operation of a twin-screw extruder in the preparation process of copolycarbonate and a twin-screw extrusion pelletizing process for copolycarbonate with a production capacity of 5 t / h. The present invention applies a specific twin-screw extrusion pelletizing process to the preparation process of copolycarbonate, greatly improving the stable operation of the twin-screw extruder, thereby improving the production efficiency of copolycarbonate particles and reducing production costs.

[0249] The present invention also provides a twin-screw extrusion pelletizing process for copolymerized polycarbonate, which is a twin-screw extrusion pelletizing process for copolymerized brominated polycarbonate with a production capacity of 5 t / h. The present invention adjusts and controls the operating parameters, extrusion formula and screw combination of the copolymerized PC semi-finished flakes in the twin-screw extruder, and the multiple parameters cooperate with each other to achieve the stable operation of the twin-screw extruder. By adopting the twin-screw extrusion pelletizing process provided by the present invention, the copolymerized silicone polycarbonate semi-finished flakes are well plasticized inside the barrel, the material throwing phenomenon at the vacuum sight glass port of the extruder is eliminated, and the high vacuum degree and negative pressure are maintained, which reduces the water vapor and small molecule content, eliminates the bubbles in the material strips, and eliminates the material strip collapse phenomenon at the die head; similarly, the problem of frequent die head material strip collapse in the extrusion granulation process of brominated PC is also eliminated.

[0250] To further illustrate the present invention, the application of the twin-screw extrusion pelletizing process provided by the present invention in improving the stable operation of the twin-screw extruder in the preparation process of copolymerized polycarbonate and a twin-screw extrusion pelletizing process of copolymerized polycarbonate are described in detail below in combination with the embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating procedures are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0251] Example 1

[0252] Preparation Example of Copolysiloxane Polycarbonate

[0253] 1. The arrangement and model of the extruder screw block, such as Figure 1 shown.

[0254] 2. Extruder operating parameters

[0255] (1) Barrel temperature setting: conveying section temperature is controlled at 285°C; melting section temperature is controlled at 285°C; mixing section temperature is controlled at 285°C; exhaust section temperature is controlled at 280°C; homogenizing section temperature is controlled at 280°C.

[0256] The start valve temperature is set at 280℃; the melt pump temperature is set at 280℃; the screen changer temperature is set at 280℃; the temperature of the die zone 1 is controlled at 260℃; the temperature of the die zone 2 is controlled at 280℃; the temperature of the die zone 3 is controlled at 280℃.

[0257] The temperature of the four zones of the die was controlled at 280°C.

[0258] (2) The melt pump inlet pressure is set to 20 bar; the vacuum degree is set to -50 kPa; the feed inlet pressure is controlled to -0.05 kPa.

[0259] 3. Formula addition ratio: Pentaerythritol stearate: 500ppm; Phosphite antioxidant: 300ppm.

[0260] The performance of the silicon PC product prepared in Example 1 of the present invention was tested.

[0261] See Table 1, which shows the indicators of silicon PC products.

[0262] Table 1

[0263]

[0264] It can be seen from the above data that the silicon PC produced by the present invention has excellent ductility at low temperature, which is manifested in that the cantilever beam notched impact strength is higher than that of ordinary PC.

[0265] Under the same silicon content, the low-temperature impact performance of the silicon PC produced by the present invention is better than that of similar foreign products.

[0266] Under the same silicon content, the heat resistance of the silicon PC produced by the present invention is higher than that of similar foreign products.

[0267] It can be seen from the production process monitoring of the silicon PC product prepared in Example 1 of the present invention that the material is no longer thrown out at the vacuum sight glass port and the material strip at the extruder die head is no longer collapsed.

[0268] See also Figure 3 , Figure 3 The number of cleaning times of the vacuum mirror port before and after the implementation of Example 1 of the present invention.

[0269] See also Figure 4 , Figure 4 It is the number of times the material strip collapses at the die head before and after the implementation of Example 1 of the present invention.

[0270] Example 2

[0271] Preparation Example of Brominated Polycarbonate

[0272] 1. The arrangement and model of the extruder screw block, such as Figure 2 shown.

[0273] 2. Extruder operating parameters

[0274] (1) Barrel temperature setting: conveying section temperature is controlled at 255°C; melting section temperature is controlled at 255°C; mixing section temperature is controlled at 255°C; exhaust section temperature is controlled at 255°C; homogenizing section temperature is controlled at 255°C.

[0275] The start valve temperature is set at 250℃; the melt pump temperature is set at 250℃; the screen changer temperature is set at 260℃; the temperature of the die zone 1 is controlled at 240℃; the temperature of the die zone 2 is controlled at 250℃; the temperature of the die zone 3 is controlled at 250℃.

[0276] The temperature of the four zones of the die was controlled at 250°C.

[0277] (2) The melt pump inlet pressure is set to 20 bar; the vacuum degree is set to -50 kPa; the feed inlet pressure is controlled to -0.05 kPa.

[0278] 3. Formula addition ratio: Phosphite antioxidant: 300ppm.

[0279] The performance of the brominated PC product prepared in Example 2 of the present invention was tested.

[0280] See Table 2, which shows the indicators of brominated PC products.

[0281] Table 2

[0282] project unit index Melt flow rate g / 10min 9.8 Izod notched impact strength (3mm) <![CDATA[KJ / m 2 ]]> 71 Izod notched impact strength (4mm) <![CDATA[KJ / m 2 ]]> 73 Tensile yield stress Mpa 60 Tensile yield strain ％ 7.2 Tensile stress at break Mpa 71.5 Tensile fracture strain ％ 120 Flexural modulus MPa 2100 Bending Strength MPa 93.5 Light transmittance ％ 89.5 Haze ％ 0.35

[0283] From the above data, it can be seen that the produced brominated PC has excellent mechanical properties, as shown by the higher Izod notched impact strength than ordinary PC.

[0284] From the production process monitoring of the brominated PC product prepared in Example 2 of the present invention, it can be seen that the material strips at the die head of the extruder no longer collapse.

[0285] See also Figure 5 , Figure 5 It is the number of times the material strip collapses at the die head before and after the implementation of Example 2 of the present invention.

[0286] The above is a detailed introduction to the application of the twin-screw extrusion pelletizing process provided by the present invention in improving the stable operation of the twin-screw extruder in the preparation process of copolymerized polycarbonate and a twin-screw extrusion pelletizing process of copolymerized polycarbonate with a capacity of 5 t / h. The principle and implementation mode of the present invention are described in detail using specific examples. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. Application of twin-screw extrusion pelletizing process in improving the stable operation of twin-screw extruder in the preparation process of copolymerized polycarbonate; The copolycarbonate comprises copolysiloxane polycarbonate or brominated polycarbonate; The twin-screw extrusion pelletizing process includes one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder; The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw; The conveying section screw adopts large lead thread elements, medium lead thread elements and small lead thread elements; The melting section screw adopts small lead thread elements and medium lead thread elements; The mixing section screw adopts a small lead thread element; The exhaust section screw adopts a medium-lead thread element; The homogenizing section screw adopts medium lead thread elements and small lead thread elements.

2. The use according to claim 1, characterized in that: When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the conveying section screw adopts a first large lead thread element, a first medium lead thread element and a first small lead thread element, the melting section screw adopts a first small lead thread element and a first medium lead thread element, the mixing section screw adopts a second small lead thread element, the exhaust section screw adopts a first medium lead thread element, and the homogenizing section screw adopts a first medium lead thread element and a second small lead thread element; When the copolymerized polycarbonate is brominated polycarbonate, the conveying section screw adopts the second large lead thread element, the second medium lead thread element and the fourth small lead thread element, the melting section screw adopts the third small lead thread element and the fourth small lead thread element, the mixing section screw adopts the second small lead thread element, the exhaust section screw adopts the second medium lead thread element, and the homogenizing section screw adopts the third medium lead thread element and the second small lead thread element; The pitch of the first large lead thread element is 1.5D to 1.75D; the pitch of the second large lead thread element is 1.5D to 1.6D; The pitch of the first medium lead thread element is 1D to 1.25D; the pitch of the second medium lead thread element is 1.2D to 1.4D; the pitch of the third medium lead thread element is 1D to 1.2D; The pitch of the first small lead thread element is 0.75D to 0.85D; the pitch of the second small lead thread element is 0.5D to 0.6D; the pitch of the third small lead thread element is 0.9D to 0.95D; the pitch of the fourth small lead thread element is 0.75D to 0.8D; Wherein, D is the unit pitch, D=130mm.

3. The use according to claim 1, characterized in that: The stable operation includes no material throwing and / or no strip collapse; The non-rejection of material specifically refers to the non-rejection of material at the vacuum sight glass port of the extruder; The non-collapse of strips specifically refers to the non-collapse of strips at the die head of the extruder; The twin-screw extrusion pelletizing process is specifically a process of extruding and pelletizing copolymerized polycarbonate flakes into copolymerized polycarbonate particles.

4. The use according to claim 3, characterized in that: The operating parameters of the twin-screw extruder include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure, extruder load and speed ratio; The extrusion pelletizing formula includes copolymerized polycarbonate flakes, and pentaerythritol stearate and / or phosphite antioxidant; The threaded element is specifically a double helical threaded element; The twin-screw extruder is specifically a twin-screw extruder with a production capacity of 5 t / h.

5. A twin-screw extrusion pelletizing process for copolymerized polycarbonate, characterized in that: The following steps are involved: Copolymer polycarbonate flakes and phosphite antioxidant are used as raw materials, and the twin-screw extrusion pelletizing process parameters are controlled to obtain copolymer polycarbonate pellets after extrusion pelletizing through a twin-screw extruder; The copolycarbonate comprises copolysiloxane polycarbonate or brominated polycarbonate; When the copolymer polycarbonate is a copolymer silicone polycarbonate, the raw material further comprises pentaerythritol stearate; The twin-screw extrusion pelletizing process parameters include one or more of the operating parameters of the twin-screw extruder, the formula of the extrusion pelletizing, and the screw combination of the twin-screw extruder; The screw assembly of the twin-screw extruder includes a conveying section screw, a melting section screw, a mixing section screw, a venting section screw and a homogenizing section screw; The operating parameters of the twin-screw extruder include one or more of extruder barrel temperature, start-up valve temperature, melt pump temperature, screen changer temperature, die head temperature, melt pump inlet pressure, exhaust port vacuum, screw feed port pressure and extruder speed ratio.

6. The twin-screw extrusion pelletizing process according to claim 5, characterized in that: The extruder barrel temperature includes the barrel conveying section temperature, the barrel melting section temperature, the barrel mixing section temperature, the barrel exhaust section temperature and the barrel homogenizing section temperature; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the barrel conveying section is controlled at 280-290°C; the temperature of the barrel melting section is controlled at 280-290°C; the temperature of the barrel mixing section is controlled at 280-290°C; the temperature of the barrel exhaust section is controlled at 270-280°C; the temperature of the barrel homogenizing section is controlled at 270-280°C; When the copolymer polycarbonate is brominated polycarbonate, the temperature of the barrel conveying section is controlled at 250-260°C; the temperature of the barrel melting section is controlled at 250-260°C; the temperature of the barrel mixing section is controlled at 250-260°C; the temperature of the barrel exhaust section is controlled at 250-260°C; and the temperature of the barrel homogenizing section is controlled at 250-260°C.

7. The twin-screw extrusion pelletizing process according to claim 5, characterized in that: When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the start valve temperature is controlled at 270-280°C; When the copolymerized polycarbonate is brominated polycarbonate, the start-up valve temperature is controlled at 245-255° C.; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the melt pump is controlled at 270-280° C.; When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the melt pump is controlled at 245-255° C.; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the screen changer is controlled at 270-280° C.; When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the screen changer is controlled at 255-260°C.

8. The twin-screw extrusion pelletizing process according to claim 5, characterized in that: The die temperature includes the temperature of die zone 1, the temperature of die zone 2, the temperature of die zone 3 and the temperature of die zone 4; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the first zone of the die head is controlled at 250-260° C.; When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the first zone of the die is controlled at 240-250° C.; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the temperature of the second die zone, the temperature of the third die zone, and the temperature of the fourth die zone are each controlled at 270-280° C.; When the copolymerized polycarbonate is brominated polycarbonate, the temperature of the second die zone, the temperature of the third die zone and the temperature of the fourth die zone are each controlled at 250-260°C.

9. The twin-screw extrusion pelletizing process according to claim 5, characterized in that: The melt pump inlet pressure is controlled at 20-25 bar; The vacuum degree of the exhaust port is controlled at -45 to -50 kPa; The pressure at the screw feed port is controlled at -0.05 to -0.1 kPa; When the copolymerized polycarbonate is a copolymerized siloxane polycarbonate, the rotation speed ratio of the twin-screw extruder is controlled at 16.5 to 17 kg / rpm; When the copolymerized polycarbonate is brominated polycarbonate, the speed ratio of the twin-screw extruder is controlled at 15.5 to 16.5 kg / rpm; The diameter of the copolymerized polycarbonate flakes is 2.36 to 12.5 mm; The particle size of the copolymerized polycarbonate particles is 2.9 to 3.15 mm.

10. The twin-screw extrusion pelletizing process according to claim 5, characterized in that: The added amount of the pentaerythritol stearate is 500ppm; The amount of the phosphite antioxidant added is 300ppm; The conveying section screw adopts large lead thread elements, medium lead thread elements and small lead thread elements; The melting section screw adopts small lead thread elements and medium lead thread elements; The mixing section screw adopts a small lead thread element; The exhaust section screw adopts a medium-lead thread element; The homogenizing section screw adopts medium lead thread elements and small lead thread elements; The twin-screw extruder is specifically a twin-screw extruder with a production capacity of 5 t / h.

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