Preparation method of flame-retardant PET (Polyethylene Terephthalate)

Abstract

The invention discloses a preparation method of flame-retardant PET (polyethylene terephthalate), which comprises the following steps: mixing 50-70 parts by weight of PET resin, 15-20 parts by weight of a flame retardant, 2-6 parts by weight of polysiloxane, 1-2 parts by weight of a modified carbon agent, 3-5 parts by weight of an anti-dripping agent and 20-40 parts by weight of a reinforcing agent by using a twin-screw extruder, melting and extruding to obtain the flame-retardant PET, wherein the processing temperature of the double-screw extruder is 250 to 285 DEG C; the vacuum degree of the double-screw extruder is (-0.08) to (0.04) MPa; the rotating speed of a main machine of the double-screw extruder is 300 to 600r / min. According to the method provided by the invention, the flame retardant property of the flame-retardant PET material can be improved by adjusting the process conditions for preparing the flame-retardant PET material by a blending method, the mechanical property of the flame-retardant PET material is further improved, and the negative influence of a flame retardant on the mechanical property of PET is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of flame-retardant PET, and belongs to the technical field of PET composite materials. BACKGROUND

[0002] Polyethylene terephthalate (PET) is a thermoplastic engineering plastic. Traditional PET is widely used in the fields of fibers, films, tapes and plastic bottles due to excellent mechanical properties, heat resistance, chemical resistance and dimensional stability. In addition, the PET has good creep resistance, fatigue resistance, friction resistance and dimensional stability, and is particularly excellent in electrical insulation, and even at high temperature and high frequency, the electrical insulation performance is still good, and the PET is also favored in the fields of electrical equipment, mechanical equipment, home and household appliances.

[0003] The main components of PET are C, H and O, and the limiting oxygen index is less than 21%, which belongs to flammable materials and is easy to burn and cause fire. A large amount of smoke generated in the combustion process of PET can cause suffocation of people and animals and cause serious threat to life. Due to the straight-chain structure characteristics of PET, serious melt dripping is generated in the combustion process, and the melt dripping becomes a secondary fire source, causing the fire situation to expand continuously. Therefore, it is of great significance to modify the flame retardant PET.

[0004] The blending method is one of the common methods for developing flame-retardant PET. The PET is blended with a flame retardant, and then granulated through high-temperature blending. Based on this idea, a single flame retardant with multiple functions is prepared into a composite mixed flame retardant, and then the PET is modified through the blending method to develop various multifunctional flame-retardant PET.

[0005] At present, in order to optimize the flame-retardant efficiency of the flame-retardant PET material and improve the material performance, the current research is mainly to improve and optimize the flame retardant, add functional additives to improve the flame-retardant efficiency of the flame-retardant PET material, and reduce the negative influence of the flame retardant on the mechanical properties of the PET. At present, there is no research on optimizing the process parameters to improve the flame-retardant efficiency of the flame-retardant PET material and improve the material performance. SUMMARY

[0006] Therefore, the purpose of the application is to optimize the process parameters of the blending method, improve the dispersion uniformity of the flame retardant in the PET matrix, improve the flame-retardant efficiency and performance of the material, reduce the negative influence of the flame retardant on the mechanical properties of the PET such as impact strength, and ensure that the material meets the flame-retardant requirements while maintaining the necessary physical and mechanical properties.

[0007] One aspect of the application provides a preparation method of flame-retardant PET. The method improves the blending process, optimizes the process parameters of the flame-retardant PET blending method, and prepares the PET material with good flame-retardant performance and meeting the requirements of necessary physical and mechanical properties.

[0008] Optionally, the preparation method comprises: mixing, melting and extruding raw materials of PET resin 50-70 parts by weight, flame retardant 15-20 parts by weight, polysiloxane 2-6 parts by weight, modified carbon agent 1-2 parts by weight, anti-dripping agent 3-5 parts by weight, and reinforcing agent 20-40 parts by weight by using a twin-screw extruder to obtain the flame-retardant PET.

[0009] The processing temperature of the twin-screw extruder is 250-285℃.

[0010] The vacuum degree of the twin-screw extruder is -0.08-0.04MPa.

[0011] The main machine rotating speed of the twin-screw extruder is 300-600r / min.

[0012] Optionally, the processing temperature of the twin-screw extruder is independently selected from any value or a range value between any two values of 250℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃.

[0013] Optionally, the vacuum degree of the twin-screw extruder is independently selected from any value or a range value between any two values of -0.08MPa, -0.06MPa, -0.05MPa, -0.04MPa, -0.02MPa, -0.01MPa, 0.01MPa, 0.02MPa, 0.04MPa.

[0014] Optionally, the main machine rotating speed of the twin-screw extruder is independently selected from any value or a range value between any two values of 300r / min, 400r / min, 500r / min, 600r / min.

[0015] Optionally, the processing temperature of the twin-screw extruder is 260-285℃.

[0016] The vacuum degree of the twin-screw extruder is -0.05-0.02MPa.

[0017] Optionally, the intrinsic viscosity of the PET resin is 0.6-1.5dL / g.

[0018] Optionally, the intrinsic viscosity of the PET resin is independently selected from any value or a range value between any two values of 0.6dL / g, 0.8dL / g, 1.0dL / g, 1.2dL / g, 1.5dL / g.

[0019] Optionally, the flame retardant is composed of ammonium polyphosphate and melamine.

[0020] The mass ratio of the ammonium polyphosphate and the melamine is 1.5-2.5:1.

[0021] Optionally, the mass ratio of the ammonium polyphosphate and melamine is independently selected from any value in 1.5:1, 2:1, 2.5:1 or a range value between any two of the above.

[0022] Optionally, the polysiloxane is selected from at least one of polydimethylsiloxane, polysilsesquioxane;

[0023] The modified carbon agent is selected from at least one of magnesium oxide, magnesium carbonate, magnesium silicate;

[0024] The anti-dripping agent is a coated polytetrafluoroethylene;

[0025] The reinforcing agent is selected from glass fiber.

[0026] Optionally, the anti-dripping agent is a styrene-acrylonitrile coated polytetrafluoroethylene.

[0027] Optionally, before mixing, further comprising drying treatment on the PET resin, the flame retardant;

[0028] The temperature of the drying treatment is 100-120℃, and the time of the drying treatment is 5-8 hours.

[0029] Optionally, the temperature of the drying treatment is independently selected from any value in 100℃, 110℃, 120℃ or a range value between any two of the above.

[0030] Optionally, the time of the drying treatment is independently selected from any value in 5 hours, 6 hours, 7 hours, 8 hours or a range value between any two of the above.

[0031] Optionally, the rotation speed of the mixing is 100-300r / min;

[0032] The time of the mixing is 4-6min;

[0033] The temperature of the mixing is 50-70℃.

[0034] Optionally, the rotation speed of the mixing is independently selected from any value in 100r / min, 200r / min, 300r / min or a range value between any two of the above.

[0035] Optionally, the time of the mixing is independently selected from any value in 4min, 5min, 6min or a range value between any two of the above.

[0036] Optionally, the temperature of the mixing is independently selected from any value in 50℃, 60℃, 70℃ or a range value between any two of the above.

[0037] Optionally, the processing temperature of the twin-screw extruder comprises: a zone temperature of 250-265 DEG C, a second zone of 255-265 DEG C, a third zone of 260-275 DEG C, a fourth zone of 275-285 DEG C; a fifth zone of 270-280 DEG C; a sixth zone of 265-275 DEG C.

[0038] Optionally, the ratio L / D of the length L of the screw of the twin-screw extruder to the diameter D is 40-60:1.

[0039] Optionally, the ratio L / D of the length L of the screw of the twin-screw extruder to the diameter D is independently selected from any value in 40:1, 45:1, 50:1, 55:1, 60:1 or a range value between any two of the above.

[0040] The beneficial effects that can be produced by the present application include:

[0041] The method provided by the present application can improve the flame retardant performance of the flame-retardant PET material while further improving the mechanical properties of the flame-retardant PET material by adjusting the process conditions of the blending method for preparing the flame-retardant PET material, and reducing the negative impact of the flame retardant on the mechanical properties of the PET. DETAILED DESCRIPTION

[0042] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples.

[0043] Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0044] Example 1

[0045] The present embodiment provides a flame-retardant PET material comprising the following components by weight:

[0046] 50 parts of PET resin (intrinsic viscosity of 0.6 dL / g), 15 parts of flame retardant (polyammonium phosphate and melamine compounded according to a mass ratio of 1.5:1), 2 parts of polydimethylsiloxane, 1 part of magnesium silicate, 3 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 20 parts of glass fiber.

[0047] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0048] (1) The PET resin and the flame retardant are respectively subjected to 100 DEG C drying treatment for 8 hours;

[0049] (2) The PET resin and the flame retardant after drying treatment, polydimethylsiloxane, magnesium silicate, styrene-acrylonitrile coated polytetrafluoroethylene, and glass fiber are added into a twin-screw extruder (length-diameter ratio L / D of 40:1) to be mixed at 60 DEG C for 6 min at 150 r / min, melted, and extruded to obtain a flame-retardant PET material A;

[0050] The vacuum degree in the twin-screw extruder is-0.08 MPa, the main machine rotating speed of the twin-screw extruder is 300 r / min, and the processing temperature of the twin-screw extruder includes: the temperature of the first zone is 250 DEG C, the temperature of the second zone is 255 DEG C, the temperature of the third zone is 260 DEG C, the temperature of the fourth zone is 275 DEG C, the temperature of the fifth zone is 270 DEG C, and the temperature of the sixth zone is 265 DEG C.

[0051] Example 2

[0052] The example provides a flame-retardant PET material, which comprises the following components by weight:

[0053] 50 parts of PET resin (intrinsic viscosity is 0.6 dL / g), 15 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 1.5:1), 2 parts of polydimethylsiloxane, 1 part of magnesium silicate, 3 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 20 parts of glass fiber.

[0054] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0055] (1) The PET resin and the flame retardant are respectively subjected to 110 DEG C drying treatment for 8 hours;

[0056] (2) The PET resin and the flame retardant after drying treatment, polydimethylsiloxane, magnesium silicate, styrene-acrylonitrile coated polytetrafluoroethylene, and glass fiber are added into a twin-screw extruder (length-diameter ratio L / D is 40:1), mixed at 60 DEG C for 6 min at 200 r / min, melted, extruded, and a flame-retardant PET material B is obtained;

[0057] The vacuum degree in the twin-screw extruder is-0.06 MPa, the main machine rotating speed of the twin-screw extruder is 300 r / min, and the processing temperature of the twin-screw extruder includes: the temperature of the first zone is 255 DEG C, the temperature of the second zone is 260 DEG C, the temperature of the third zone is 265 DEG C, the temperature of the fourth zone is 275 DEG C, the temperature of the fifth zone is 270 DEG C, and the temperature of the sixth zone is 265 DEG C.

[0058] Example 3

[0059] The example provides a flame-retardant PET material, which comprises the following components by weight:

[0060] 60 parts of PET resin (intrinsic viscosity is 0.8 dL / g), 15 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 2:1), 4 parts of polydimethylsiloxane, 2 parts of magnesium silicate, 3 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 30 parts of glass fiber.

[0061] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0062] (1) The PET resin and the flame retardant are respectively subjected to 110℃ drying treatment for 8 hours;

[0063] (2) The PET resin and the flame retardant after drying treatment, and the polysilicic, the magnesium carbonate, the styrene-acrylonitrile coated polytetrafluoroethylene, and the glass fiber are added into a double screw extruder (the length-diameter ratio L / D is 50:1) to be mixed at 60℃ and 200r / min for 6min, melted, extruded, and a flame-retardant PET material C is obtained;

[0064] The vacuum degree in the double screw extruder is -0.05MPa, the main machine rotating speed of the double screw extruder is 400r / min, and the processing temperature of the double screw extruder includes: the temperature of the first zone is 260℃, the temperature of the second zone is 265℃, the temperature of the third zone is 270℃, the temperature of the fourth zone is 280℃, the temperature of the fifth zone is 275℃, and the temperature of the sixth zone is 270℃.

[0065] Example 4

[0066] The example provides a flame-retardant PET material, which includes the following components by weight:

[0067] 60 parts of PET resin (the intrinsic viscosity is 0.8dL / g), 18 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 2:1), 4 parts of polysilicic, 2 parts of magnesium carbonate, 3 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 30 parts of glass fiber.

[0068] The above raw material formula is used to prepare a flame-retardant PET material according to the following steps.

[0069] (1) The PET resin and the flame retardant are respectively subjected to 120℃ drying treatment for 5 hours;

[0070] (2) The PET resin and the flame retardant after drying treatment, and the polysilicic, the magnesium carbonate, the styrene-acrylonitrile coated polytetrafluoroethylene, and the glass fiber are added into a double screw extruder (the length-diameter ratio L / D is 50:1) to be mixed at 70℃ and 200r / min for 5min, melted, extruded, and a flame-retardant PET material D is obtained;

[0071] The vacuum degree in the double screw extruder is -0.02MPa, the main machine rotating speed of the double screw extruder is 400r / min, and the processing temperature of the double screw extruder includes: the temperature of the first zone is 260℃, the temperature of the second zone is 262℃, the temperature of the third zone is 275℃, the temperature of the fourth zone is 280℃, the temperature of the fifth zone is 270℃, and the temperature of the sixth zone is 265℃.

[0072] Example 5

[0073] The example provides a flame-retardant PET material, which includes the following components by weight:

[0074] 70 parts of PET resin (intrinsic viscosity of 1.5 dL / g), 20 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 2.5:1), 4 parts of polydimethylsiloxane, 2 parts of magnesium oxide, 4 parts of styrene-acrylonitrile coated polytetrafluoroethylene, 40 parts of glass fiber.

[0075] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0076] (1) The PET resin and the flame retardant are respectively subjected to drying treatment at 110 DEG C for 8 hours;

[0077] (2) The PET resin and the flame retardant after drying treatment are mixed with polydimethylsiloxane, magnesium oxide, styrene-acrylonitrile coated polytetrafluoroethylene and glass fiber in a double-screw extruder (length-diameter ratio L / D of 55:1) at 70 DEG C and 300 r / min for 6 min, melted, extruded, and a flame-retardant PET material E is obtained;

[0078] The vacuum degree in the double-screw extruder is 0.02 MPa, the main machine rotating speed of the double-screw extruder is 500 r / min, and the processing temperature of the double-screw extruder includes: the temperature of the first zone is 260 DEG C, the second zone is 265 DEG C, the third zone is 275 DEG C, the fourth zone is 285 DEG C, the fifth zone is 275 DEG C, and the sixth zone is 270 DEG C.

[0079] Example 6

[0080] The example provides a flame-retardant PET material, which comprises the following components by weight:

[0081] 70 parts of PET resin (intrinsic viscosity of 1.2 dL / g), 20 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 2.5:1), 4 parts of polydimethylsiloxane, 2 parts of magnesium oxide, 4 parts of styrene-acrylonitrile coated polytetrafluoroethylene, 40 parts of glass fiber.

[0082] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0083] (1) The PET resin and the flame retardant are respectively subjected to drying treatment at 110 DEG C for 8 hours;

[0084] (2) The PET resin and the flame retardant after drying treatment are mixed with polydimethylsiloxane, magnesium oxide, styrene-acrylonitrile coated polytetrafluoroethylene and glass fiber in a double-screw extruder (length-diameter ratio L / D of 55:1) at 70 DEG C and 300 r / min for 6 min, melted, extruded, and a flame-retardant PET material E is obtained;

[0085] The vacuum degree in the twin-screw extruder is 0.04 MPa, the main machine rotating speed of the twin-screw extruder is 600 r / min, and the processing temperature of the twin-screw extruder includes: the temperature of the first zone is 260 DEG C, the second zone is 265 DEG C, the third zone is 275 DEG C, the fourth zone is 285 DEG C, the fifth zone is 278 DEG C, and the sixth zone is 275 DEG C.

[0086] Comparative Example 1

[0087] The present comparative example provides a flame-retardant PET material, which comprises the following components by weight:

[0088] 50 parts of PET resin (the intrinsic viscosity is 0.6 dL / g), 15 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 1.5:1), 2 parts of polydimethylsiloxane, 1 part of magnesium silicate, 3 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 20 parts of glass fiber.

[0089] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0090] (1) The PET resin and the flame retardant are respectively subjected to 130 DEG C drying treatment for 4 hours;

[0091] (2) The PET resin and the flame retardant after drying treatment, polydimethylsiloxane, magnesium silicate, styrene-acrylonitrile coated polytetrafluoroethylene, and glass fiber are added into a twin-screw extruder (the length-diameter ratio L / D is 40:1), mixed at 40 DEG C for 10 min at 80 r / min, melted, extruded, and a flame-retardant PET material F is obtained.

[0092] The vacuum degree in the twin-screw extruder is -0.1 MPa, the main machine rotating speed of the twin-screw extruder is 250 r / min, and the processing temperature of the twin-screw extruder includes: the temperature of the first zone is 220 DEG C, the second zone is 225 DEG C, the third zone is 230 DEG C, the fourth zone is 245 DEG C, the fifth zone is 240 DEG C, and the sixth zone is 235 DEG C.

[0093] Comparative Example 2

[0094] The present comparative example provides a flame-retardant PET material, which comprises the following components by weight:

[0095] 70 parts of PET resin (the intrinsic viscosity is 1.2 dL / g), 20 parts of flame retardant (polyammonium phosphate and melamine are compounded according to the mass ratio of 2.5:1), 4 parts of polyphenylsiloxane, 2 parts of magnesium oxide, 5 parts of styrene-acrylonitrile coated polytetrafluoroethylene, and 40 parts of glass fiber.

[0096] The above raw material formula is used to prepare the flame-retardant PET material according to the following steps.

[0097] (1) The PET resin and the flame retardant are respectively subjected to 90 DEG C drying treatment for 10 hours;

[0098] (2) The PET resin after drying treatment, flame retardant, and polysilicane, magnesium oxide, styrene-acrylonitrile coated polytetrafluoroethylene, and glass fiber are added into a double screw extruder (length-diameter ratio L / D is 60:1) and mixed at 80℃ for 8min at 400r / min, melted, extruded, and a flame retardant PET material E is obtained;

[0099] The vacuum degree in the double screw extruder is 0.05MPa, the main machine rotation speed of the double screw extruder is 700r / min, and the processing temperature of the double screw extruder includes: the temperature of the first zone is 270℃, the temperature of the second zone is 275℃, the temperature of the third zone is 280℃, the temperature of the fourth zone is 290℃, the temperature of the fifth zone is 285℃, and the temperature of the sixth zone is 278℃.

[0100] Test Example 1

[0101] Performance test:

[0102] The performance of the flame retardant PET material obtained in the above examples and comparative examples is characterized, and the specific test items, test methods, and results are shown in Table 1.

[0103] Tensile strength: tested according to GB / T1040-2006 standard, the tensile rate is 50mm / min, and the tensile temperature is 25℃;

[0104] Bending strength: tested according to GB / T9341-2008 standard, wherein the specific test conditions are: the sample size is 80×10×4mm, and the pressing speed is 2mm / min;

[0105] Charpy notched impact strength: tested according to GB / T1843-2008 standard, wherein the specific test conditions are: the rectangular sample with a V-shaped notch (0.8mm deep) with a specification of 80×10×4mm is selected as the characterization sample, and the pendulum energy is 25J;

[0106] Flame retardant performance: tested according to UL 94 standard, thickness is 1.6mm;

[0107] Oxygen index measurement: tested according to GB / T2406-2009 standard, wherein the specific test conditions are: the sample size is 120×6.5×3mm, and under the specified test conditions, the sample maintains stable combustion (i.e. the required minimum oxygen concentration in the mixed gas required to maintain combustion for 50mm or 3min) in the oxygen-nitrogen mixed gas stream;

[0108] Table 1 Performance test results of the flame retardant PET obtained in the examples and comparative examples

[0109]

[0110]

[0111] From the above results, it can be seen that by adjusting the preparation process parameters, the prepared flame-retardant PET material has good flame-retardant performance and also can improve the mechanical properties of the flame-retardant PET material. In the examples of the present application, the flame-retardant performance of the flame-retardant PET material can reach V0 level, the oxygen index is above 29%, the tensile strength is above 57.97 MPa, the bending strength is above 55.84 MPa, and the toughness can reach 5.4 KJ / m 2 Compared with the comparative examples, the above examples have obvious improvement.

[0112] From the present application, it can be seen that by adjusting the preparation parameters, under the condition of the same formula, selecting appropriate process parameters can also improve the performance of the flame-retardant PET.

[0113] The above is only a few examples of the present application, and does not limit the present application in any form. Although the present application discloses the above preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. A method for preparing flame-retardant PET, characterized in that: By weight, 50-70 parts of PET resin, 15-20 parts of flame retardant, 2-6 parts of polysiloxane, 1-2 parts of modified carbon agent, 3-5 parts of anti-dripping agent, and 20-40 parts of reinforcing agent are mixed, melted, and extruded using a twin-screw extruder to obtain the flame-retardant PET; Wherein, the processing temperature of the twin-screw extruder is 250-285°C; The vacuum degree of the twin-screw extruder is -0.08 to 0.04 MPa; The main engine speed of the twin-screw extruder is 300-600 r / min.

2. The preparation method according to claim 1, characterized in that The processing temperature of the twin-screw extruder is 260-285°C; The vacuum degree of the twin-screw extruder is -0.05 to 0.02 MPa.

3. The preparation method according to claim 1, characterized in that The intrinsic viscosity of the PET resin is 0.6 to 1.5 dL / g.

4. The preparation method according to claim 1, characterized in that The flame retardant consists of ammonium polyphosphate and melamine; The mass ratio of the ammonium polyphosphate to melamine is 1.5-2.5:

1.

5. The preparation method according to claim 1, characterized in that The polysiloxane is selected from at least one of polydimethylsiloxane and polysilsesquioxane; The modified carbon agent is selected from at least one of magnesium oxide, magnesium carbonate, and magnesium silicate; The anti-dripping agent is coated polytetrafluoroethylene; The reinforcing agent is selected from glass fibers.

6. The preparation method according to claim 4, characterized in that The anti-dripping agent is styrene-acrylonitrile coated polytetrafluoroethylene.

7. The preparation method according to claim 1, characterized in that Before mixing, the PET resin and the flame retardant are dried; The temperature of the drying treatment is 100-120° C., and the time of the drying treatment is 5-8 hours.

8. The preparation method according to claim 1, characterized in that The mixing speed is 100-300 r / min; The mixing time is 4 to 6 minutes; The mixing temperature is 50-70°C.

9. The preparation method according to claim 1, characterized in that The processing temperatures of the twin-screw extruder include: zone 1 temperature of 250-265°C, zone 2 of 255-265°C, zone 3 of 260-275°C, zone 4 of 275-285°C, zone 5 of 270-280°C, and zone 6 of 265-275°C.

10. The preparation method according to claim 1, characterized in that The ratio L / D of the screw length L to the diameter D of the twin-screw extruder is 40 to 60:1.

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