Halogen-free flame-retardant antibacterial polycarbonate and its preparation process

Abstract

The present invention relates to the field of modified polycarbonates, and more particularly to a process for preparing halogen-free, flame-retardant, and antibacterial polycarbonates. A portion of PC resin, a halogen-free flame retardant, and other additives are mixed to obtain a mixture A. Another portion of PC resin is mixed with an antibacterial agent to obtain a mixture B. Mixture A is fed into a twin-screw extruder for main feeding, and mixture B is fed into a twin-screw extruder for side feeding for melt mixing, followed by extrusion and granulation. The twin-screw extruder is a co-rotating, parallel twin-screw extruder, and the screw assembly is sequentially divided into a feeding section, a plasticizing section, a mixing section, a venting section, and a metering section. By optimizing the existing process for preparing halogen-free, flame-retardant, and antibacterial polycarbonates, the material is fully melted and homogenized in the mixing section, thereby reducing the melt temperature and simultaneously resolving problems such as porous particles and substandard flame retardancy and impact resistance.

Description

Technical Field

[0001] The present invention relates to the field of modified polycarbonate, in particular to a halogen-free flame-retardant and antibacterial polycarbonate and a preparation process thereof. Background Art

[0002] Polycarbonate material (PC material) is a thermoplastic engineering material with the advantages of high transparency, outstanding impact resistance, creep resistance, heat resistance, and non-deformation. Therefore, it is widely used in glass assembly, automobiles, electronics, electrical appliances, medical treatment, protective equipment and other fields. In order to make polycarbonate materials have antibacterial properties, it is often achieved by adding antibacterial agents thereto. Existing antibacterial agents are mainly divided into natural antibacterial agents, organic antibacterial agents and inorganic antibacterial agents. Among them, inorganic antibacterial agents such as silver-based antibacterial agents, zinc-based antibacterial agents, copper-containing antibacterial agents, etc. are commonly used as additives for halogen-free flame retardant and antibacterial polycarbonate materials due to their good durability and heat resistance. However, since metal ions have good thermal conductivity, it is easy to cause the melt temperature of halogen-free flame retardant and antibacterial polycarbonate materials to be high during the preparation process. When the melt temperature is too high, polycarbonate degrades, thereby causing problems such as poor toughness and flame retardant effect of the finished product, honeycomb holes in the particles, and increased water absorption. Summary of the Invention

[0003] In order to solve the problem that the high melt temperature of existing halogen-free flame-retardant and antibacterial polycarbonate materials easily leads to the decomposition of polycarbonate, the present invention provides a preparation process for halogen-free flame-retardant and antibacterial polycarbonate, which comprises mixing a portion of PC resin, a halogen-free flame retardant and other additives to obtain a mixture A, and mixing another portion of PC resin with an antibacterial agent to obtain a mixture B. Mixture A is fed into a twin-screw extruder for main feeding, and mixture B is fed into a twin-screw extruder for side feeding to perform melt mixing, and then extrusion granulation is performed. The twin-screw extruder is a co-rotating parallel twin-screw extruder, and the screw assembly is sequentially divided into a feeding section, a plasticizing section, a mixing section, an exhaust section and a metering section, wherein each section sequentially includes the following threaded elements:

[0004] Feeding section: 48 / 48A, 72 / 72, 72 / 72, 72 / 36, 64 / 64, 64 / 64, 48 / 48;

[0005] Plasticizing section: K45 / 5 / 64, K45 / 5 / 48, K45 / 5 / 48, 64 / 64, K45 / 5 / 48, 48 / 48, 32 / 16L;

[0006] Mixing section: 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, FME48 / 48, 64 / 64, FME48 / 48, 64 / 64, 64 / 64, 48 / 48, 32 / 16L;

[0007] Exhaust section: 64 / 64, 64 / 64, 64 / 64, 64 / 64;

[0008] Metering sections: 48 / 48, 48 / 48, 48 / 48.

[0009] Among them, 72 / 72 means a conveying element with a pitch of 72mm and an element length of 72m, and the others are similar;

[0010] 48 / 48A indicates a conveying element with a pitch of 48 mm and an element length of 48 mm, where "A" indicates that the element is the starting element of the screw;

[0011] 32 / 16L means a left-handed conveying element with a pitch of 32mm and an element length of 16mm;

[0012] The "K" series indicates that the element is a shear element. Taking K45 / 5 / 64 as an example, "45" indicates the kneading disc angle, "5" indicates that the shear element includes 5 kneading discs, and "64" indicates that the total length of the shear element is 64mm. Others are similar.

[0013] The "FME" series indicates that the component is a hybrid component, and FME48 / 48 indicates a hybrid component with a pitch of 48 mm and a component length of 48 mm.

[0014] By optimizing the existing halogen-free flame-retardant and antibacterial polycarbonate preparation process, PC resin and antibacterial agent are pre-dispersed and mixed to enhance the dispersion and distribution of the antibacterial agent in the polycarbonate; a twin-screw extruder with a specific screw combination is used to fully melt and homogenize the material in the mixing section, thereby reducing the melt temperature and solving problems such as porous particles, unqualified flame retardant properties, and impact resistance.

[0015] Furthermore, the halogen-free flame retardant antibacterial polycarbonate comprises, by mass percentage:

[0016]

[0017] It should be noted that the 93%-98% PC resin herein refers to the sum of the mass percentages of the aforementioned “part of PC resin” and “another part of PC resin”.

[0018] Furthermore, the other additives include 0.2%-0.6% antioxidant, 0.2%-0.6% lubricant, 1%-3.6% toughening agent and 0.1%-0.7% anti-dripping agent.

[0019] Furthermore, 80%-90% of the PC resin, 0.1%-0.5% of the halogen-free flame retardant, 0.2%-0.6% of the antioxidant, 0.2%-0.6% of the lubricant, 1%-3.6% of the toughening agent and 0.1%-0.7% of the anti-dripping agent are mixed to obtain a mixture A, and the remaining PC resin and 0.4-1% of the antibacterial agent are mixed to obtain a mixture B. The mixture A is fed into the twin-screw extruder for main feeding, and the mixture B is fed into the twin-screw extruder for side feeding for melt mixing, and extrusion granulation is performed.

[0020] Preferably, 80%-90% PC resin, 0.1%-0.5% halogen-free flame retardant, 0.2%-0.6% antioxidant, 0.2%-0.6% lubricant, 1%-3.6% toughening agent and 0.1%-0.7% anti-dripping agent are stirred in a high-speed mixer at 200 rpm for 120 seconds to obtain a mixture A, the remaining PC resin and 0.4%-1% antibacterial agent are stirred in a powder mixer at 300 rpm for 300 seconds to obtain a mixture B, the mixture A is fed into the twin-screw extruder for main feeding, and the mixture B is fed into the twin-screw extruder for side feeding for melt mixing, and extrusion granulation is performed. It is understood that the sum of the PC resin in the mixture A and the mixture B is 93%-98%.

[0021] Furthermore, the aspect ratio of the screw is 40:1, and the total length of the screw is 1876 mm.

[0022] Furthermore, the temperature of the twin-screw extruder is 180-220°C, and the screw speed is 300-400 rpm. Preferably, the temperature is 180-200°C, and the screw speed is 400 rpm.

[0023] Furthermore, the PC resin is one or more combinations of aliphatic polycarbonate resin, aromatic polycarbonate resin, and aliphatic-aromatic polycarbonate resin.

[0024] Furthermore, the halogen-free flame retardant is one or more combinations of potassium perfluorobutanesulfonate, potassium 3-phenylsulfonylbenzenesulfonate, and polytetrafluoroethylene.

[0025] Furthermore, the antibacterial agent is one or more combinations of silver ion antibacterial agents, copper ion antibacterial agents, zinc ion antibacterial agents, and zinc oxide.

[0026] The present invention also provides a halogen-free flame-retardant antibacterial polycarbonate, which is prepared according to the above-mentioned preparation process of the halogen-free flame-retardant antibacterial polycarbonate.

[0027] Compared with the existing technology, the preparation process of halogen-free flame-retardant and antibacterial polycarbonate provided by the present invention is conducive to the full melting and homogenization of raw materials, reducing the melt temperature of the material to avoid high-temperature degradation of polycarbonate, so that the prepared halogen-free flame-retardant and antibacterial polycarbonate material has good flow properties, mechanical properties and flame retardant properties. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. The "%" below refers to mass percentage.

[0029] Example 1

[0030] A process for preparing halogen-free flame-retardant and antibacterial polycarbonate comprises the following steps: 85.7% PC resin, 0.3% halogen-free flame retardant, 0.4% antioxidant, 0.6% lubricant, 2% toughening agent, and 0.3% anti-drip agent are stirred in a high-speed mixer at 200 rpm for 120 seconds to obtain mixture A. 10% PC resin and 0.7% antibacterial agent are stirred in a powder mixer at 300 rpm for 300 seconds to obtain mixture B. Mixture A is fed into a twin-screw extruder as a main feed, and mixture B is fed into a twin-screw extruder as a side feed for melt mixing, followed by extrusion and pelletization. The twin-screw extruder has an aspect ratio of 40:1, a barrel temperature of 180-200°C, a main engine speed of 400 rpm, and a production capacity of 300 kg / h.

[0031] Among them, PC resin is aromatic polycarbonate resin; the halogen-free flame retardant is potassium perfluorobutanesulfonate; the antioxidant is 1076 (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate); the lubricant is PETS (pentaerythritol stearate); the toughening agent is MBS; the anti-dripping agent is PTFE polytetrafluoroethylene; and the antibacterial agent is a zinc ion antibacterial agent.

[0032] The twin-screw extruder is a co-rotating parallel twin-screw extruder. The screw assembly is divided into a feeding section, a plasticizing section, a mixing section, a venting section and a metering section. The total length of the screw is 1876 mm. Each section includes the following screw elements:

[0033] Feeding section: 48 / 48A, 72 / 72, 72 / 72, 72 / 36, 64 / 64, 64 / 64, 48 / 48;

[0034] Plasticizing section: K45 / 5 / 64, K45 / 5 / 48, K45 / 5 / 48, 64 / 64, K45 / 5 / 48, 48 / 48, 32 / 16L;

[0035] Mixing section: 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, FME48 / 48, 64 / 64, FME48 / 48, 64 / 64, 64 / 64, 48 / 48, 32 / 16L;

[0036] Exhaust section: 64 / 64, 64 / 64, 64 / 64, 64 / 64;

[0037] Metering sections: 48 / 48, 48 / 48, 48 / 48.

[0038] The prepared halogen-free flame-retardant and antibacterial polycarbonate particles have no pores inside.

[0039] Example 2

[0040] A process for preparing halogen-free flame-retardant and antibacterial polycarbonate comprises the following steps: 90% PC resin, 0.5% halogen-free flame retardant, 0.6% antioxidant, 0.6% lubricant, 3% toughening agent, and 0.5% anti-drip agent are stirred in a high-speed mixer at 200 rpm for 120 seconds to obtain mixture A. 3.8% PC resin and 1% antibacterial agent are stirred in a powder mixer at 300 rpm for 300 seconds to obtain mixture B. Mixture A is fed into a twin-screw extruder as a main feed, and mixture B is fed into a twin-screw extruder as a side feed for melt mixing, followed by extrusion and pelletization. The twin-screw extruder has an aspect ratio of 40:1, a barrel temperature of 180-220°C, a main engine speed of 300 rpm, and a production capacity of 300 kg / h.

[0041] Among them, PC resin is aromatic polycarbonate resin; the halogen-free flame retardant is potassium 3-phenylsulfonylbenzenesulfonate; the antioxidant is 1076 (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate); the lubricant is PETS (pentaerythritol stearate); the toughening agent is MBS; the anti-dripping agent is PTFE polytetrafluoroethylene; and the antibacterial agent is a silver ion antibacterial agent.

[0042] The screw assembly of the twin-screw extruder is the same as that in Example 1. The prepared halogen-free flame-retardant and antibacterial polycarbonate particles have no pores inside.

[0043] Example 3

[0044] A process for preparing halogen-free flame-retardant and antibacterial polycarbonate comprises the following steps: 80% PC resin, 0.1% halogen-free flame retardant, 0.3% antioxidant, 0.3% lubricant, 1% toughening agent, and 0.1% anti-drip agent are stirred in a high-speed mixer at 200 rpm for 120 seconds to obtain mixture A. 17.2% PC resin and 1% antibacterial agent are stirred in a powder mixer at 300 rpm for 300 seconds to obtain mixture B. Mixture A is fed into a twin-screw extruder as a main feed, and mixture B is fed into a twin-screw extruder as a side feed for melt mixing, followed by extrusion and pelletization. The twin-screw extruder has an aspect ratio of 40:1, a barrel temperature of 180-200°C, a main engine speed of 350 rpm, and a production capacity of 300 kg / h.

[0045] Among them, PC resin is aliphatic-aromatic polycarbonate resin; the halogen-free flame retardant is potassium 3-phenylsulfonylbenzenesulfonate; the antioxidant is 1076 (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate); the lubricant is PETS (pentaerythritol stearate); the toughening agent is MBS; the anti-dripping agent is PTFE polytetrafluoroethylene; and the antibacterial agent is a copper ion antibacterial agent.

[0046] The screw assembly of the twin-screw extruder is the same as that in Example 1. The prepared halogen-free flame-retardant and antibacterial polycarbonate particles have no pores inside.

[0047] Comparative Example 1

[0048] 95.7% PC powder resin, 0.3% halogen-free flame retardant, 0.4% antioxidant, 0.6% lubricant, 2% toughening agent, 0.7% antibacterial agent, and 0.3% anti-drip agent were placed in a high-speed mixer and stirred at 200 rpm for 120 seconds to obtain a mixture. The mixture was then melt-mixed in a twin-screw extruder for extrusion into pellets. The twin-screw extruder had an aspect ratio of 40:1, a barrel temperature of 180-200°C, a main engine speed of 400 rpm, and a production capacity of 300 kg / h. The twin-screw extruder screw assembly was the same as in Example 1. The resulting halogen-free, flame-retardant, and antibacterial polycarbonate particles were porous.

[0049] Comparative Example 2

[0050] Unlike Example 1, the screw assembly of the twin-screw extruder included the following screw elements in the mixing section: 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, K45 / 5 / 48, 64 / 64, K45 / 5 / 48, 64 / 64, 64 / 64, 48 / 48, and 32 / 16L. Other conditions were the same as in Example 1. The resulting halogen-free, flame-retardant, and antibacterial polycarbonate particles still had a small amount of pores inside.

[0051] According to the extruder panel, the melt temperature of the halogen-free flame retardant and antibacterial polycarbonate in Example 1 is 233°C, the melt temperature of the halogen-free flame retardant and antibacterial polycarbonate in Comparative Example 1 is 273°C, and the melt temperature of the halogen-free flame retardant and antibacterial polycarbonate in Comparative Example 2 is 258°C. It can be seen that the preparation process provided by the present invention can effectively reduce the melt temperature of the halogen-free flame retardant and antibacterial polycarbonate, thereby preventing the degradation of the polycarbonate and affecting the product performance.

[0052] The mechanical properties specimens of halogen-free flame-retardant and antibacterial polycarbonate were prepared using an injection molding machine. The injection molding temperatures are shown in the following table:

[0053] Table 1 Injection molding process conditions of halogen-free flame retardant and antibacterial polycarbonate samples

[0054]

[0055] The halogen-free flame retardant and antibacterial polycarbonate materials prepared in Example 1 and Comparative Examples 1-2 were tested for relevant performance indicators under the same test conditions. The test results are shown in Table 2 below:

[0056] Table 2 Performance test results of halogen-free flame retardant and antibacterial polycarbonate samples

[0057]

[0058]

[0059] Among them, the melt index, that is, the melt flow rate volume method is tested in accordance with GB / T 3682.1-2018 standard;

[0060] The tensile strength is tested according to GB / T 1040.1-2018 standard;

[0061] Flexural strength and flexural modulus are tested in accordance with GB / T 9341-2008 standard;

[0062] Notched impact properties are tested in accordance with GB / T 1043.1-2008;

[0063] Moisture content was tested according to ASTM D6980-17;

[0064] The vertical method for the burning performance of plastics is tested in accordance with IEC60695 and UL94 standards;

[0065] From the test results in Table 2, we can conclude that:

[0066] The halogen-free flame-retardant and antibacterial polycarbonate material produced by the halogen-free flame-retardant and antibacterial polycarbonate preparation process provided by the embodiment of the present invention has superior performance in all aspects to the comparative example. The difference between Comparative Example 1 and Example 1 is that all raw materials are mixed at once; the difference between Comparative Example 2 and Example 1 is that an existing twin-screw extruder is used for melt blending and extrusion granulation. Test results show that the embodiment of the present invention adopts the pre-mixing of part of the PC resin and the antibacterial agent and the specific screw combination to fully disperse the raw materials, reduce the melt temperature of the halogen-free flame-retardant and antibacterial polycarbonate, avoid degradation of the polycarbonate, and solve the problems of porous particles, unqualified flame retardancy and impact resistance.

[0067] In addition, the main equipment and instruments used in the above examples are shown in Table 3

[0068] Table 3

[0069] Instrument name model factory High-speed mixer SHR200 Suzhou Songyuan Co-rotating parallel twin-screw extruder STS-50 Nanjing Coperion Pendulum impact testing machine ZBC8400-C Meters Electronic universal testing machine AGS-X-10KN Shimadzu Melt flow rate meter MFI-2322S Jin Jian Injection molding machine EM80-V Haitian injection molding machine Water quality vertical combustion test machine AUTO-SPA Odyssey powder machine YE2-160M-6 Shanghai Linge Motor

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing halogen-free flame-retardant and antibacterial polycarbonate, characterized by: A portion of PC resin, halogen-free flame retardant and other additives are mixed to obtain a mixture A, and another portion of PC resin is mixed with an antibacterial agent to obtain a mixture B. Mixture A is fed into a twin-screw extruder for main feeding, and mixture B is fed into the twin-screw extruder for side feeding to be melt-mixed, and then extruded into granules. The twin-screw extruder is a co-rotating parallel twin-screw extruder, and the screw assembly is sequentially divided into a feeding section, a plasticizing section, a mixing section, a venting section and a metering section, wherein each section sequentially includes the following screw elements: Feeding section: 48 / 48A, 72 / 72, 72 / 72, 72 / 36, 64 / 64, 64 / 64, 48 / 48; Plasticizing section: K45 / 5 / 64, K45 / 5 / 48, K45 / 5 / 48, 64 / 64, K45 / 5 / 48, 48 / 48, 32 / 16L; Mixing section: 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, 64 / 64, FME48 / 48, 64 / 64, FME48 / 48, 64 / 64, 64 / 64, 48 / 48, 32 / 16L; Exhaust section: 64 / 64, 64 / 64, 64 / 64, 64 / 64; Metering sections: 48 / 48, 48 / 48, 48 / 48.

2. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The halogen-free flame-retardant antibacterial polycarbonate comprises, by mass percentage: PC resin 93%-98% Halogen-free flame retardant 0.1%-0.5% Antimicrobial agent 0.4%-1% Other additives 1.5%-5.5%.

3. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 2, wherein: The other additives include 0.2%-0.6% antioxidant, 0.2%-0.6% lubricant, 1%-3.6% toughening agent and 0.1%-0.7% anti-dripping agent.

4. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 3, wherein: 80%-90% of the PC resin, 0.1%-0.5% of the halogen-free flame retardant, 0.2%-0.6% of the antioxidant, 0.2%-0.6% of the lubricant, 1%-3.6% of the toughening agent and 0.1%-0.7% of the anti-dripping agent are mixed to obtain a mixture A, and the remaining PC resin and 0.4%-1% of the antibacterial agent are mixed to obtain a mixture B. The mixture A is fed into the twin-screw extruder for main feeding, and the mixture B is fed into the twin-screw extruder for side feeding for melt mixing, and extrusion granulation is performed.

5. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The aspect ratio of the screw is 40:1, and the total length of the screw is 1876 mm.

6. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The temperature of the twin-screw extruder is 180-220° C., and the screw speed is 300-400 rpm.

7. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The PC resin is one or more combinations of aliphatic polycarbonate resin, aromatic polycarbonate resin, and aliphatic-aromatic polycarbonate resin.

8. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The halogen-free flame retardant is one or more combinations of potassium perfluorobutanesulfonate and potassium 3-phenylsulfonylbenzenesulfonate.

9. The process for preparing the halogen-free flame-retardant and antibacterial polycarbonate according to claim 1, wherein: The antibacterial agent is one or more combinations of silver ion antibacterial agents, copper ion antibacterial agents, zinc ion antibacterial agents, and zinc oxide.

10. A halogen-free flame-retardant and antibacterial polycarbonate, obtained according to the preparation process of the halogen-free flame-retardant and antibacterial polycarbonate according to any one of claims 1 to 9.

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