Hot and cold impact resistant PBT (polybutylene terephthalate) composition as well as preparation method and application thereof

Abstract

The invention discloses a hot and cold impact resistant PBT (polybutylene terephthalate) composition as well as a preparation method and application thereof. The PBT composition is prepared from 40 to 60 parts of PBT resin, 10 to 20 parts of PCT resin, 10 to 15 parts of brominated flame retardant, 2 to 6 parts of synergistic flame retardant and 0.2 to 0.6 part of ester exchange inhibitor, the brominated flame retardant is a 2, 4, 6-tribromophenoxy terminated tetrabromobisphenol-A carbonic ester oligomer, and the flame retardant is a 2, 4, 6-tribromophenoxy terminated tetrabromobisphenol-A carbonic ester oligomer. The PBT composition has excellent cold and hot impact resistance, good flame retardance and weather resistance, and is not easy to crack when being used for coating metal inserts.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and more specifically, to a PBT composition, a preparation method and an application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) is a fast-crystallizing polyester engineering plastic, which has excellent mechanical properties, electrical properties, heat resistance, solvent resistance, fatigue resistance and creep resistance, etc., and is widely used in the fields of electronics and electrical engineering, automobiles, household appliances, etc. However, in the application scenario of plastic coating metal inserts, the PBT material often cracks. One of the reasons is that the toughness of the material is insufficient, and the second is the difference in the linear expansion coefficient between the plastic and the metal insert. The linear expansion coefficient of the PBT plastic is nearly 10 times higher than that of the metal insert. During the cooling and shrinking process of the material, the shrinkage degree of the plastic is much larger than that of the metal insert, so that the interface between the plastic and the metal is extruded and cracks appear. Therefore, it is necessary to study and improve the thermal shock resistance of the PBT material. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects and deficiencies of the existing PBT materials, and provide a PBT composition, which can improve the thermal shock resistance, and at the same time has good flame retardancy and weather resistance.

[0004] Another purpose of the present invention is to provide a preparation method of a PBT composition.

[0005] Another purpose of the present invention is to provide an application of a PBT composition in the preparation of a metal insert coating material.

[0006] The above objects of the present invention are achieved by the following technical solutions:

[0007] The present invention protects a PBT composition, which comprises the following components in parts by mass:

[0008] 40-60 parts of PBT resin,

[0009] 10-20 parts of PCT resin,

[0010] 10-15 parts of brominated flame retardant,

[0011] 2-6 parts of synergistic flame retardant,

[0012] 0.2-0.6 part of transesterification inhibitor;

[0013] The brominated flame retardant is 2,4,6-tribromophenoxy-terminated tetrabromobisphenol-A carbonate oligomer.

[0014] In the PBT composition of the present invention, PBT resin is used as the matrix resin, and a specific amount of PCT (poly(1,4-cyclohexanedimethylene terephthalate)) resin is added, which can improve the cold and heat shock resistance of the material; an ester exchange inhibitor is added to inhibit the ester exchange reaction between PBT resin and PCT resin and improve the overall toughness of the material; at the same time, a specific brominated flame retardant is added to endow the material with good flame retardant performance, and it has a synergistic effect with the composite system of PBT resin and PCT resin to control the cold and heat shrinkage degree of the material, so that the material has good cold and heat shock resistance and is not prone to cracking when applied to coat metal inserts.

[0015] In some of these embodiments, the end-capping rate of the 2,4,6-tribromophenoxy-terminated tetrabromobisphenol-A carbonate oligomer is above 90%; preferably, the end-capping rate is above 98%.

[0016] Preferably, the molecular weight of the 2,4,6-tribromophenoxy-terminated tetrabromobisphenol-A carbonate oligomer is 3000 - 8000; more preferably, its molecular weight is 4000 - 6000; the test method for the molecular weight is gel permeation chromatography.

[0017] In some of these embodiments, the PBT resin content capable of achieving the object of the present invention can be 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts or any range between 50 parts or more and two values.

[0018] In some of these embodiments, the PCT resin content capable of achieving the object of the present invention can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or any range between 20 parts or more and two values.

[0019] It should be noted that controlling the PCT resin content in the present invention has a great influence on the toughness of the PBT composition. When the PCT content is too low, the toughening effect on the PBT composition is limited; when the PCT content is too high, a relatively serious ester exchange reaction is likely to occur between it and PBT, which will make the heat resistance and toughness of the system poor.

[0020] In some of these embodiments, the mass ratio of the PBT resin to the PCT resin is (1.5 - 6):1, preferably (2 - 5):1.

[0021] Preferably, the mass ratio of the PBT resin and the PCT resin capable of achieving the object of the present invention can be 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1 or any range between the above two ratios.

[0022] In some embodiments, the intrinsic viscosity of the PBT resin is 0.70-1.4 dL / g; the intrinsic viscosity is measured according to the ISO 1628 standard method. The PBT resin with low intrinsic viscosity can further improve the mechanical properties and processing properties of the PBT composition.

[0023] In some embodiments, the intrinsic viscosity of the PCT resin is 0.5-0.8 dL / g. Preferably, the intrinsic viscosity of the PCT resin is 0.6-0.75 dL / g.

[0024] In the present invention, the mass content of CHDM in the PCT resin is not particularly limited. Preferably, the molar ratio of CHDM and PTA in the PCT resin is (1-1.5):1, more preferably (1.1-1.3):1.

[0025] In some embodiments, the synergistic flame retardant is antimony trioxide and / or sodium antimonate.

[0026] In some embodiments, the transesterification inhibitor is sodium dihydrogen pyrophosphate and / or sodium dihydrogen phosphate.

[0027] In some embodiments, it further includes: 15-25 parts of glass fiber.

[0028] Preferably, the glass fiber content capable of achieving the object of the present invention can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts or any range between the above two values.

[0029] In some embodiments, the diameter of the glass fiber is 7 μm-15 μm and the length is 3 mm-5 mm.

[0030] In some embodiments, it further includes: 3-6 parts of toughening agent.

[0031] Preferably, the toughening agent content capable of achieving the object of the present invention can be 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts or any range between the above two values.

[0032] In some embodiments, the toughening agent is ethylene-acrylate and / or ethylene-acrylate-glycidyl ester.

[0033] Specifically, the ethylene-acrylate is ethylene-methyl acrylate and / or ethylene-butyl acrylate; the ethylene-acrylate-glycidyl ester is ethylene-methyl acrylate-glycidyl methacrylate.

[0034] In some embodiments, it further includes: 0.5 - 1 part of a lubricant.

[0035] Preferably, the content of the lubricant capable of achieving the object of the present invention can be 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part or any range between the above two values.

[0036] The lubricant can be selected from the lubricants commonly used in the art, including but not limited to at least one of ester lubricants, amide lubricants, polyethylene lubricants or stearic acid lubricants.

[0037] Preferably, the lubricant is an ester lubricant. Specifically, the ester lubricant is at least one of lower alcohol esters, higher alcohol esters, polyol esters or polyethylene glycol esters of fatty acids.

[0038] In some embodiments, it further includes: 0.1 - 0.3 part of an antioxidant.

[0039] Preferably, the content of the antioxidant capable of achieving the object of the present invention can be 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part or any range between the above two values.

[0040] The antioxidant can be selected from the antioxidants commonly used in the art, including but not limited to at least one of hindered phenol antioxidants, thioether antioxidants, hindered phenol antioxidants or diphenylamine antioxidants.

[0041] In a specific embodiment, the phosphite antioxidant is at least one of tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36) or 627A;

[0042] The thioether antioxidant is at least one of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol tetrakis(3-laurylthiopropionate);

[0043] The hindered phenol antioxidant is at least one of N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), n-octadecyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate (Irganox 1076), or 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acryloyl]-1,1-dimethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADK AO-80);

[0044] The diphenylamine antioxidant is at least one of butyl / octyldiphenylamine and dioctyldiphenylamine.

[0045] In some embodiments, it further includes: 15-25 parts of glass fiber, 3-6 parts of toughening agent, 0.5-1 part of lubricant, and 0.1-0.3 part of antioxidant.

[0046] The present invention protects a preparation method of a PBT composition, which includes the following steps: mixing the raw material components in formula amounts evenly and performing melt blending and extrusion to obtain the PBT composition.

[0047] In some embodiments, the preparation method of the PBT composition includes the following steps:

[0048] 1) Mix the brominated flame retardant and the synergistic flame retardant evenly;

[0049] 2) Mix the PBT resin, PCT resin, toughening agent, transesterification inhibitor, lubricant, and antioxidant evenly;

[0050] 3) Mix the mixture obtained in step 1), the mixture obtained in step 2), and the glass fiber evenly, perform melt extrusion and granulation to obtain the PBT composition.

[0051] In some embodiments, the melt extrusion is processed by a twin-screw extruder. The temperature of the first zone of the twin-screw extruder from the feeding port to the head is 220-240 °C, the temperature of the second zone is 240-260 °C, the temperature of the third zone is 255-275 °C, the temperature of the fourth zone is 255-275 °C, the temperature of the fifth zone is 255-275 °C, the temperature of the sixth zone is 240-260 °C, the temperature of the seventh zone is 240-260 °C, the temperature of the eighth zone is 240-260 °C, the temperature of the ninth zone is 240-260 °C, the temperature of the tenth zone is 240-260 °C, and the screw speed of the twin-screw extruder is 200-450 revolutions per minute.

[0052] The present invention protects the application of a PBT composition in the preparation of a metal insert coating material; specifically, it includes the application in the preparation of motor stators and rotors, high-voltage distribution boxes or cooling fans of new energy batteries.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] The present invention provides a PBT composition, which uses PBT resin as the matrix resin and adds a specific amount of PCT resin, a specific brominated flame retardant and an ester exchange inhibitor, so that the material has good cold and heat shock resistance and is not prone to cracking when applied to coat metal inserts. Detailed implementation manners

[0055] The following further describes the present invention in conjunction with specific implementation manners, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0056] The raw materials used in the following examples and comparative examples are as follows:

[0057] Polybutylene terephthalate (PBT):

[0058] PBT 1#: The intrinsic viscosity at 25 °C is 0.82 dL / g; PBT GX112, Jiangsu Yizheng Chemical Fiber Co., Ltd.

[0059] PBT 2#: The intrinsic viscosity at 25 °C is 1.0 dL / g; PBT GX121, Jiangsu Yizheng Chemical Fiber Co., Ltd.

[0060] PBT 3#: The intrinsic viscosity at 25 °C is 1.28 dL / g; PBT GL236, Jiangsu Yizheng Chemical Fiber Co., Ltd.

[0061] Poly(1,4-cyclohexanedimethylene terephthalate) (PCT):

[0062] PCT 1#: The intrinsic viscosity at 25 °C is 0.62 dL / g; PCT 0302, SK Chemical Co., Ltd.

[0063] PCT 2#: The intrinsic viscosity at 25 °C is 0.74 dL / g; PCT 0502, SK Chemical Co., Ltd.

[0064] PC resin: The melt index (ISO 1133) at 300 °C and 1.2 kg is 34 cm 3 / 10 min; PC 2350, Wanhua Chemical (Yantai) Sales Co., Ltd.

[0065] PCTG Resin: PCTG JN200, SK Chemical Co., Ltd.

[0066] Brominated Flame Retardant 1#: 2,4,6-Tribromophenoxy-Terminated Tetrabromobisphenol-A Carbonate Oligomer, FG-8500, Teijin Limited, Japan.

[0067] Brominated Flame Retardant 2#: 2,4,6-Tribromophenoxy-Terminated Tetrabromobisphenol-A Carbonate Oligomer, BC-58, purchased from LANXESS Deutschland GmbH.

[0068] Brominated Flame Retardant 3#: Brominated Epoxy Resin, F-2100, ICL-IP.

[0069] Synergistic Flame Retardant: Antimony Trioxide, S-05N, purchased from Foshan Chen Antimony Economy & Trade Co., Ltd.

[0070] Glass Fiber: Alkali-Free Chopped E Glass Fiber, with an average length of 4.5 mm and an average diameter of 11 μm; Glass Fiber ECS11-4.5-534A, China National Bluestar (Group) Co., Ltd.

[0071] Toughening Agent: EMA-GMA Triblock Copolymer, DuPont PTW.

[0072] Transesterification Inhibitor 1#: Disodium Dihydrogen Pyrophosphate, DHPP, TaiPing Chemical Industry Co., Ltd.

[0073] Transesterification Inhibitor 2#: Sodium Dihydrogen Phosphate, MSP2040, Lianyungang Xidu Biochemical Co., Ltd.

[0074] Lubricant: Ester Lubricant, PETS, Far East Additives S.p.A., Italy.

[0075] Antioxidant: RIANOX 1076, Tianjin Lionon New Materials Co., Ltd.

[0076] The preparation method of the PBT compositions in the following examples and comparative examples includes the following steps:

[0077] 1) Put the brominated flame retardant and the synergistic flame retardant into a high-speed mixer and dry mix for 2 - 4 minutes at a rotational speed of 700 - 900 revolutions per minute;

[0078] 2) Put the PBT resin, PCT resin, toughening agent, transesterification inhibitor, lubricant and antioxidant into a high-speed mixer and dry mix for 2 - 4 minutes at a rotational speed of 600 - 800 revolutions per minute;

[0079] 3) Add the mixture obtained in step 1), the mixture obtained in step 2) and the glass fiber into a twin-screw extruder through a feeder respectively, and conduct mixing, dispersion, melt extrusion and pelletizing;

[0080] The temperature of the first zone of the twin-screw extruder from the feeding port to the head is 220 - 240 °C, the temperature of the second zone is 240 - 260 °C, the temperature of the third zone is 255 - 275 °C, the temperature of the fourth zone is 255 - 275 °C, the temperature of the fifth zone is 255 - 275 °C, the temperature of the sixth zone is 240 - 260 °C, the temperature of the seventh zone is 240 - 260 °C, the temperature of the eighth zone is 240 - 260 °C, the temperature of the ninth zone is 240 - 260 °C, the temperature of the tenth zone is 240 - 260 °C, and the screw speed of the twin-screw extruder is 200 - 450 revolutions per minute.

[0081] Examples 1 - 12

[0082] This example provides a series of PBT compositions, and the raw material components (in parts by mass) are shown in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] Comparative Examples 1 - 7

[0087] This comparative example provides a series of PBT compositions, and the raw material components (in parts by mass) are shown in Table 2.

[0088] Table 2

[0089]

[0090] Performance Testing

[0091] Take the PBT compositions of the above examples and comparative examples for the following tests:

[0092] 1. Tensile strength: Refer to the test standard ISO 527.

[0093] 2. Izod notched impact strength: Refer to the test standard ISO 180.

[0094] 3. Flame retardancy performance: Test according to the UL94 vertical burning standard, with a test thickness of 0.8 mm V-0.

[0095] 4. Thermal shock test conditions:

[0096] Test sample: The test sample is a sensor component of a new energy battery. Each part is composed of 6 iron cores and a PBT composition to form a coating structure. Through in-mold insert injection molding, the plastic material is used to wrap and mold the metal insert. Among them, the iron core size is 30 mm × 20 mm × 5 mm, which is a right-angle structure. The thinnest wall thickness of the plastic is 1.0 mm, and the PBT composition plays the role of fixing the iron core and insulating against voltage.

[0097] Test temperature requirements: Each extreme temperature of -40°C and 85°C lasts for 30 minutes, the environmental change time ≤ 5 minutes, one cycle consists of the low-temperature extreme environment + the high-temperature extreme environment, and 800 cycles are performed.

[0098] By observing the cracking phenomenon of the workpiece, corresponding test result evaluations are given. The evaluation results include: no cracking, slight cracks, and a large number of cracks.

[0099] Table 3

[0100]

[0101] Table 4

[0102]

[0103]

[0104] The results show that the tensile strength of the PBT composition of the present invention is above 108 MPa, the notched impact strength is above 11.2 kJ / m 2 above, the flame retardancy reaches V-0 level or above, its coated metal inserts do not crack under impact at -40°C and 85°C, and the thermal shock resistance is excellent. Compared with Example 1, in Comparative Example 1, the brominated epoxy resin is used as the brominated flame retardant, and the thermal shock resistance significantly decreases, proving that the specific brominated flame retardant adopted in the present invention not only endows the material with good flame retardant properties, but also has a synergistic effect with the composite system of PBT resin and PCT resin, enabling the material to have good thermal shock resistance and not easily crack when applied to coated metal inserts.

[0105] In Comparative Example 2, without PCT resin, the tensile strength and notched impact strength significantly decrease, and a large number of cracks appear in the thermal shock test, indicating poor toughness and thermal shock resistance. In Comparative Example 3, with excessive PCT resin, the melt flow rate significantly decreases, and at the same time, the degree of transesterification reaction between PCT and PBT is relatively large, and the thermal shock result is slight cracks.

[0106] In Comparative Examples 4-5, the PCT resin is replaced with PC resin or PCTG resin respectively, and their notched impact strengths significantly decrease, and a large number of cracks appear in the thermal shock results.

[0107] In Comparative Example 6, without adding the transesterification inhibitor, there is an obvious transesterification reaction between PCT and PBT, resulting in a decrease in tensile strength and notched impact strength and poor thermal shock resistance;

[0108] In Comparative Example 7, with excessive transesterification inhibitor, the thermal shock resistance is reduced to a certain extent.

[0109] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A PBT composition, characterized in that, Comprising the following components by mass parts: The brominated flame retardant is 2,4,6-tribromophenoxy-terminated tetrabromobisphenol-A carbonate oligomer.

2. The PBT composition according to claim 1, characterized in that, The end-capping rate of the 2,4,6-tribromophenoxy-terminated tetrabromobisphenol-A carbonate oligomer is above 90%.

3. The PBT composition according to claim 1, wherein The mass ratio of the PBT resin to the PCT resin is (2 - 5):

1.

4. The PBT composition according to claim 1, wherein The intrinsic viscosity of the PBT resin is 0.7 - 1.4 dL / g.

5. The PBT composition according to claim 1, wherein The intrinsic viscosity of the PCT resin is 0.5 - 0.8 dL / g.

6. The PBT composition according to claim 1, characterized in that, The synergistic flame retardant is antimony trioxide and / or sodium antimonate.

7. The PBT composition according to claim 1, characterized in that, The transesterification inhibitor is sodium dihydrogen pyrophosphate and / or sodium dihydrogen phosphate.

8. The PBT composition according to claim 1, wherein It further comprises: 15 - 25 parts of glass fiber, 3 - 6 parts of toughening agent, 0.5 - 1 part of lubricant, 0.1 - 0.3 part of antioxidant.

9. A method for preparing the PBT composition according to any one of claims 1-8, characterized in that, Comprising the following steps: mixing the raw material components in formula amounts evenly, and melt-blending and extruding to obtain the PBT composition.

10. Use of the PBT composition according to any one of claims 1 - 8 in the preparation of a metal insert coating material.

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