A thin-wall flame-retardant PBT composition with high toughness and high fluidity, and its preparation method and application

Abstract

The present invention discloses a thin-walled flame-retardant PBT composition with high toughness and high fluidity. The thin-walled flame-retardant PBT composition comprises the following components calculated in parts by weight: 55-70 parts of medium-viscosity polybutylene terephthalate, 5-20 parts of high-viscosity polybutylene terephthalate, 3-8 parts of toughening agent; 12-20 parts of flame retardant; 3-5 parts of flame retardant synergist; 1-2 parts of lubricant; 0.1-1 parts of other additives; the toughening agent is a glycidyl methacrylate toughening agent, wherein the mass fraction of glycidyl methacrylate is not less than 6%. In the present invention, two types of polybutylene terephthalate with different viscosities are compounded, and a toughening agent containing a specific content of glycidyl methacrylate is added to obtain a thin-walled flame-retardant PBT composition having a melt flow rate of 10.8-20.9 g / 10 min and an unnotched impact strength of not less than 109 kJ / m 2 The number of times of notch-free breaking is not less than 3 times, and it meets the V-0 flame retardancy of 0.8mm, and the comprehensive performance is better.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and more specifically to a thin-wall flame-retardant PBT composition with high toughness and high fluidity, and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT), one of the five general engineering plastics, is widely used in the fields of electronics, household appliances, motors and coil skeletons due to its good heat resistance, mechanical properties, aging resistance, solvent resistance and weather resistance, as well as its advantages of short molding cycle, low water absorption and fast crystallization speed. However, the defects of flame-retardant non-reinforced PBT compositions are also obvious. PBT materials have poor toughness and are sensitive to notches, which greatly limits the application of PBT compositions in various fields. In order to improve the toughness of PBT compositions, toughening agents are added to improve it, but the addition of toughening agents will have a negative impact on the fluidity and flame retardant properties of the product; when the fluidity of the composition is improved, its toughness will be affected, that is, the toughness, fluidity and flame retardant properties of the PBT composition are mutually restrictive.

[0003] When the fluidity is too high, it is easy to produce casting phenomenon during the injection molding process and cause flash on the parts; when the fluidity is too low, there will be glue shortage during the injection molding process, affecting its processing performance; when the fluidity of the PBT composition is too large and the melt flow rate is higher than 30g / 10min, it is easy to produce casting phenomenon during the injection molding process and cause flash on the parts. Generally, the flame-retardant PBT composition has better processing performance when the melt flow rate is in the range of 10 to 30g / 10min. It is found in the application process that the toughness of the material is proportional to the unnotched impact strength and the number of unnotched break times.

[0004] Prior art CN 111073233A discloses a high-toughness PBT composite material and a preparation method thereof, wherein PBT is compounded with a certain content of TPU and a small amount of toughening agent is added for compounding, and the resulting composition has excellent low-temperature toughness; Prior art CN 106147153A discloses a high-fluidity low-melting-point glass fiber reinforced PBT composition, which improves and adjusts the fluidity of the PBT composition by adding a low-melting-point PET resin into the PBT resin.

[0005] However, there is little research in the prior art on thin-wall flame-retardant PBT compositions with both high toughness and high fluidity. Therefore, there is a need in the art to develop a thin-wall flame-retardant PBT composition with high toughness and high fluidity, which has good toughness and fluidity. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects in the above-mentioned prior art and provide a thin-wall flame-retardant PBT composition with high toughness and high fluidity, wherein the PBT composition has good toughness and fluidity and meets the flame retardant requirement of 0.8mm V-0.

[0007] Another object of the present invention is to provide a method for preparing a thin-walled flame-retardant PBT composition with high toughness and high fluidity.

[0008] Another object of the present invention is to provide a thin-wall flame-retardant PBT composition with high toughness and high fluidity for use in electronic components, motors and coil skeletons, and household appliances.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A high-toughness, high-fluidity thin-wall flame-retardant PBT composition, comprising the following components calculated in parts by weight:

[0011]

[0012] The toughening agent is a glycidyl methacrylate toughening agent, wherein the mass fraction of glycidyl methacrylate is not less than 6%; the intrinsic viscosity of the medium-viscosity polybutylene terephthalate is 0.95-1.05 dL / g; and the intrinsic viscosity of the high-viscosity polybutylene terephthalate is 1.1-1.3 dL / g.

[0013] In the above scheme, medium-viscosity polybutylene terephthalate and high-viscosity polybutylene terephthalate are compounded to obtain a resin system with better fluidity, and a toughening agent containing a specific content of glycidyl methacrylate is added to the system. The glycidyl methacrylate in the toughening agent can react with the terminal groups of the polybutylene terephthalate molecular chain, and the high-viscosity polybutylene terephthalate and the toughening agent have good compatibility, so that the toughening agent is evenly distributed in the matrix resin, the distribution uniformity of the toughening agent in the system is improved, and thus the toughness of the composition is improved.

[0014] In the present invention, the mass fraction of glycidyl methacrylate is not less than 6%, and can be specifically 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., all of which can realize the present invention.

[0015] Furthermore, the mass ratio of the medium-viscosity polybutylene terephthalate to the high-viscosity polybutylene terephthalate is (12-13):(2-3).

[0016] Furthermore, the thin-wall flame-retardant PBT composition comprises the following components calculated in parts by weight:

[0017]

[0018] Furthermore, the flame retardant is 14 to 16 parts.

[0019] Furthermore, the intrinsic viscosity of the medium-viscosity polybutylene terephthalate and the high-viscosity polybutylene terephthalate is tested according to the ISO 1628-5-2015 standard method.

[0020] Furthermore, the intrinsic viscosity of the medium-viscosity polybutylene terephthalate and the high-viscosity polybutylene terephthalate is measured at a temperature of 25°C.

[0021] Furthermore, the toughening agent is ethylene octene copolymer grafted with glycidyl methacrylate and / or ethylene-methyl acrylate-glycidyl methacrylate.

[0022] Furthermore, the toughening agent is ethylene-methyl acrylate-glycidyl methacrylate.

[0023] Furthermore, the flame retardant is one or more of brominated epoxy resin, decabromodiphenyl ethane, tetrabromobisphenol A, imine bromide, decabromodiphenyl ether, brominated polyphenylene, decabromodiphenyl ethane or octabromosulfide.

[0024] Furthermore, the flame retardant is brominated epoxy resin.

[0025] Furthermore, the flame retardant synergist is antimony oxide or antimonate.

[0026] In the present invention, commonly used lubricants can be selected according to the prior art. Further, the lubricant includes ester grease, amide lubricant, polyethylene lubricant or stearic acid lubricant. Preferably, the lubricant is an ester lubricant.

[0027] Specifically, the ester lubricant is one or more of lower alcohol esters of fatty acids, higher alcohol esters of fatty acids, polyol esters or polyethylene glycol esters.

[0028] Furthermore, the other auxiliary agent is one or more of an anti-dripping agent, an antioxidant or a nucleating agent.

[0029] In the present invention, commonly used anti-dripping agents can be selected according to the prior art, including but not limited to at least one of SAN-coated polytetrafluoroethylene micropowder, acrylate-coated polytetrafluoroethylene micropowder or siloxane-coated polytetrafluoroethylene micropowder.

[0030] In the present invention, commonly used nucleating agents can be selected according to the prior art, including but not limited to at least one of metal salt nucleating agents, organic phosphate salt nucleating agents or sorbitol nucleating agents.

[0031] Specifically, the metal salt nucleating agent is one or more of sodium benzoate, sodium stearate, calcium stearate, sodium p-phenolsulfonate, calcium p-phenolsulfonate or sodium phenolate.

[0032] Specifically, the organic phosphate salt nucleating agent is 2,2'-methylenebis(4,6-di-tert-butylphenyl) sodium phosphate or / and 2,2'-methylenebis(4,6-di-tert-butylphenyl) aluminum phosphate.

[0033] Specifically, the sorbitol nucleating agent is one or more of dibenzylidene alcohol, di(p-chlorophenyl)sorbitol, p-methylbenzylidene sorbitol or di(p-ethylbenzylidene sorbitol).

[0034] In the present invention, commonly used antioxidants can be selected according to the prior art, including hindered phenol antioxidants, phosphite antioxidants, diphenylamine antioxidants, copper salt antioxidants or thioether antioxidants. Preferably, the antioxidant is a hindered phenol antioxidant.

[0035] Specifically, the hindered phenol antioxidant is one or more of β(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester or 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, tetrakis[β(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester or diethylene glycol bis[methyl 3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].

[0036] The present invention provides a method for preparing the above-mentioned thin-wall flame-retardant PBT composition with high toughness and high fluidity, comprising the following steps:

[0037] S1. The flame retardant and the flame retardant synergist are mixed to obtain a first mixture;

[0038] S2. The medium viscosity polybutylene terephthalate, the high viscosity polybutylene terephthalate, the toughening agent, the lubricant and other additives are mixed to obtain a second mixture;

[0039] S3. The first mixed material and the second mixed material are melt-blended and extruded into granules to obtain a thin-wall flame-retardant PBT composition.

[0040] Furthermore, in step S1., the mixing speed is 700 to 900 rpm.

[0041] Furthermore, in step S1., the mixing time is 2 to 4 minutes.

[0042] Furthermore, in step S2, the mixing speed is 600 to 800 rpm.

[0043] Furthermore, in step S2., the mixing time is 2 to 4 minutes.

[0044] Furthermore, the extrusion granulation is carried out in a twin-screw extruder.

[0045] Furthermore, the temperature of zone one of the twin-screw extruder is 200-230°C, the temperature of zone two is 240-260°C, the temperature of zone three is 235-255°C, the temperature of zone four is 235-255°C, the temperature of zone five is 235-255°C, the temperature of zone six is ​​240-260°C, the temperature of zone seven is 240-260°C, the temperature of zone eight is 220-240°C, the temperature of zone nine is 220-240°C, the temperature of zone ten is 240-260°C, and the screw speed of the twin-screw extruder is 200-450 rpm.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention provides a thin-wall flame-retardant PBT composition with high toughness and high fluidity. The thin-wall flame-retardant PBT composition is compounded with medium-viscosity polybutylene terephthalate and high-viscosity polybutylene terephthalate, and a glycidyl methacrylate toughening agent is added. The melt flow rate of the thin-wall flame-retardant PBT composition obtained by the combination is 10.8-20.9 g / 10 min, and the unnotched impact strength is not less than 109 kJ / m 2 , the number of times of notch-free breaking is not less than 3 times, and meets the V-0 flame retardancy of 0.8mm. DETAILED DESCRIPTION

[0048] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0049] The raw materials used in each embodiment and comparative example are:

[0050] PBT resin 1: medium viscosity polybutylene terephthalate, intrinsic viscosity 0.98 dL / g, Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0051] PBT resin 2: high viscosity polybutylene terephthalate, intrinsic viscosity 1.28 dL / g, Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0052] PBT resin 3: medium viscosity polybutylene terephthalate, intrinsic viscosity 1.02dL / g, Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0053] PBT resin 4: high viscosity polybutylene terephthalate, intrinsic viscosity 1.12 dL / g, Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0054] Toughener 1: ethylene-methyl acrylate-glycidyl methacrylate block copolymer, Arkema AX8900, glycidyl methacrylate mass fraction is 8%;

[0055] Toughener 2: ethylene-methyl acrylate-glycidyl methacrylate block copolymer, DuPont PTW, glycidyl methacrylate mass fraction is 5%;

[0056] Toughener 3: ethylene-methyl acrylate-glycidyl methacrylate block copolymer, Ketong KT-33, the mass fraction of the glycidyl methacrylate is 3%;

[0057] Flame retardant 1: brominated epoxy resin, F-2100, Shanghai Kain Chemical Co., Ltd.;

[0058] Flame retardant 2: brominated polyphenylene flame retardant, SAYTEX 621, Albemarle, USA;

[0059] Flame retardant synergist: antimony trioxide, Foshan Chenti Economic and Trade Co., Ltd.

[0060] Lubricant: ester lubricant, fatty acid ester lubricant; other additives: antioxidant: hindered phenol antioxidant β (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester; anti-drip agent, polytetrafluoroethylene anti-drip agent; lubricants, antioxidants and anti-drip agents are all commercially available, and the parallel tests of Examples 1 to 14 and Comparative Examples 1 to 6 all use the same lubricant and antioxidant.

[0061] Examples 1 to 14 and Comparative Examples 1 to 6

[0062] According to the formula in Tables 1-2, a high-toughness, high-fluidity thin-wall flame-retardant PBT composition was prepared according to the following preparation method:

[0063] S1. The flame retardant and the flame retardant synergist are placed in a high-speed mixer and mixed at a speed of 700 to 900 rpm for 2 to 4 minutes to obtain a first mixture;

[0064] S2. The medium viscosity polybutylene terephthalate, high viscosity polybutylene terephthalate, toughening agent, lubricant and other additives are mixed at a speed of 600 to 800 rpm for 2 to 4 minutes to obtain a second mixture;

[0065] S3. The first mixture and the second mixture are placed in a twin-screw extruder and melt blended and extruded to obtain a thin-wall flame-retardant PBT composition;

[0066] The temperature of zone one of the twin-screw extruder is 200-230°C, the temperature of zone two is 240-260°C, the temperature of zone three is 235-255°C, the temperature of zone four is 235-255°C, the temperature of zone five is 235-255°C, the temperature of zone six is ​​240-260°C, the temperature of zone seven is 240-260°C, the temperature of zone eight is 220-240°C, the temperature of zone nine is 220-240°C, the temperature of zone ten is 240-260°C, and the screw speed of the twin-screw extruder is 200-450 rpm.

[0067] Table 1 Amount of each component in the high toughness, high fluidity thin-wall flame-retardant PBT composition of Examples 1 to 14 (parts by weight) Table 2 Amount of each component in the high toughness, high fluidity thin-wall flame-retardant PBT composition of Comparative Examples 1 to 6 (parts by weight)

[0068]

[0069]

[0070] Performance Testing

[0071] 1. Test methods

[0072] The performance of the high-toughness, high-flow thin-wall flame-retardant PBT composition prepared above was tested:

[0073] (1) Unnotched impact strength: The high toughness, high flowability thin-wall flame retardant PBT composition prepared above was tested according to standard ISO 180-2000

[0074] (2) Number of unnotched impact fractures: The high-toughness, high-flowability thin-walled flame-retardant PBT composition prepared above was tested according to standard ISO 180-2000, with a pendulum energy of 2.75 J, and the number of times the unnotched impact specimen was broken by the pendulum was tested;

[0075] (3) Melt flow rate test: The high toughness and high fluidity thin-wall flame retardant PBT composition prepared above was tested according to standard ISO 1133-2011, wherein the test conditions were 250°C / 2.16kg;

[0076] (4) Flame retardant performance test: The high toughness and high fluidity thin-wall flame retardant PBT composition prepared above was tested according to the UL94 vertical burning standard;

[0077] 2. Test results

[0078] The performance test results of the high-toughness, high-fluidity thin-wall flame-retardant PBT composition prepared above are shown in Table 3.

[0079] Table 3 Performance test results of various embodiments and comparative examples

[0080]

[0081]

[0082] It can be seen from Table 3 that the thin-wall flame-retardant PBT compositions with high toughness and high fluidity prepared by the present invention all meet the 0.8 mm flame-retardant V-0 grade, and the melt flow rate is 10.8 to 20.9 g / 10 min, and the unnotched impact strength is not less than 109 kJ / m 2 , the number of times of breaking without gap is not less than 3 times.

[0083] It can be seen from Examples 1 to 4 that when the medium viscosity polybutylene terephthalate is adjusted to 60 to 65 parts, the high viscosity polybutylene terephthalate is adjusted to 10 to 15 parts, and the mass ratio of the medium viscosity polybutylene terephthalate to the high viscosity polybutylene terephthalate is (12 to 13): (2 to 3), the obtained thin-wall flame-retardant PBT composition has better processing performance, a melt flow rate of 15.7 to 18.3 g / 10 min, and the higher the melt flow rate is when it meets 10 to 30 g / 10 min, the better, the unnotched impact performance is better, and the unnotched impact strength is not less than 137 kJ / m 2 , the number of times of breaking without gap is not less than 5 times.

[0084] It can be seen from Examples 1 and 7 to 9 that when the flame retardant is adjusted to 14 to 16 parts, the obtained thin-wall flame retardant PBT composition has better processing performance and better toughness, and the unnotched impact strength is not less than 137 kJ / m 2 , excellent flame retardant stability and relatively suitable cost, more suitable for mass production.

[0085] It can be seen from Comparative Example 1 that when only medium-viscosity polybutylene terephthalate is used to prepare a thin-wall flame-retardant PBT composition, the unnotched impact performance of the prepared PBT composition is significantly reduced, and the unnotched impact strength is only 89 kJ / m 2 , the number of times of no-gap breaking is only 2 times.

[0086] It can be seen from Comparative Example 2 that when the medium-viscosity polybutylene terephthalate is too little and the high-viscosity polybutylene terephthalate is too much, the obtained thin-wall flame-retardant PBT composition has good unnotched impact performance, but the melt flow rate is only 8.3 g / 10 min. The fluidity is too low and the glue shortage phenomenon is easy to occur during the injection molding process.

[0087] It can be seen from Comparative Examples 3 to 4 that when the amount of toughening agent in the system is too small, the unnotched impact performance of the obtained thin-wall flame-retardant PBT composition is poor, and the unnotched impact strength is only 50 kJ / m 2 , the number of unnotched breakages is only 1 and the fluidity is too high, which will cause flash on the product; when the amount of toughening agent is too much, although the obtained thin-wall flame-retardant PBT composition has good unnotched impact performance, the melt flow rate is only 4.5g / 10min, and the flame retardant performance is reduced, which can only meet the 0.8mm V-1 flame retardant level.

[0088] It can be seen from Comparative Examples 5 to 6 that when the mass fraction of glycidyl methacrylate in the toughening agent is too low, the unnotched impact strength of the obtained thin-wall flame-retardant PBT composition is not higher than 95 kJ / m 2 , the number of times of no-gap breaking is only 2 times.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled 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 list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A thin-wall flame-retardant PBT composition with high toughness and high fluidity, characterized in that: The composition comprises the following components calculated by weight: 55-70 parts of medium viscosity polybutylene terephthalate; 5-20 parts of high viscosity polybutylene terephthalate; 3 to 8 parts of toughening agent; 14-16 parts of flame retardant; 3-5 parts of flame retardant synergist; 1-2 parts of lubricant; Other additives 0.1-1 part; The toughening agent is ethylene octene copolymer grafted with glycidyl methacrylate and / or ethylene-methyl acrylate-glycidyl methacrylate, wherein the mass fraction of glycidyl methacrylate is not less than 6%; the intrinsic viscosity of the medium viscosity polybutylene terephthalate is 0.95-1.05 dL / g; the intrinsic viscosity of the high viscosity polybutylene terephthalate is 1.1-1.3 dL / g; The mass ratio of the medium viscosity polybutylene terephthalate to the high viscosity polybutylene terephthalate is (12-13): (2-3); The flame retardant is one or more of brominated epoxy resin, decabromodiphenyl ethane, tetrabromobisphenol A, imine bromide, decabromodiphenyl ether, brominated polyphenyl or octabromosulfide.

2. The high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to claim 1, characterized in that: The composition comprises the following components calculated by weight: 60-65 parts of medium viscosity polybutylene terephthalate; 10-15 parts of high viscosity polybutylene terephthalate; 3 to 8 parts of toughening agent; 14-16 parts of flame retardant; 3-5 parts of flame retardant synergist; 1-2 parts of lubricant; Other additives 0.1 to 1 part.

3. The high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to claim 1, characterized in that: The flame retardant synergist is antimony oxide or antimonate.

4. The high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to claim 1, characterized in that: The lubricant is one or more of ester grease, amide lubricant, polyethylene lubricant or stearic acid lubricant.

5. The high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to claim 1, characterized in that: The other auxiliary agents are one or more of an anti-dripping agent, an antioxidant or a nucleating agent.

6. A method for preparing a thin-wall flame-retardant PBT composition with high toughness and high fluidity according to any one of claims 1 to 5, comprising the following steps: S1. The flame retardant and the flame retardant synergist are mixed to obtain a first mixture; S2. The medium viscosity polybutylene terephthalate, the high viscosity polybutylene terephthalate, the toughening agent, the lubricant and other additives are mixed to obtain a second mixture; S3. The first mixed material and the second mixed material are melt-blended and extruded into granules to obtain a thin-wall flame-retardant PBT composition.

7. Use of the high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to any one of claims 1 to 5 in electronic components and household appliances.

8. Use of the high-toughness, high-fluidity thin-wall flame-retardant PBT composition according to any one of claims 1 to 5 in motors and coil skeletons.

Images