A halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging, its preparation method and application

Abstract

The present invention discloses a halogen-free flame-retardant reinforced PBT composition and its preparation method and application. The halogen-free flame-retardant reinforced PBT composition comprises the following components calculated by weight: 45-55 parts of polybutylene terephthalate; 12-18 parts of organic phosphorus-based flame retardant; 2-4 parts of nitrogen-based flame retardant; 25-35 parts of glass fiber; 1-5 parts of toughening agent; 0.3-1 part of metal deactivator; 0-1 part of processing aid; the metal deactivator contains hindered phenolic hydroxyl and hydrazide groups, or contains hindered phenolic hydroxyl and oxamide groups; the glass fiber is glass fiber surface-treated with an epoxy sizing agent. The PBT composition of the present invention has good flame retardancy and resistance to damp heat aging. After the PBT composition is aged for 1000 h in an environment of 85 °C and 85% humidity, the retention rate of the mechanical properties of the material is not less than 80.0%, and at the same time, the PBT composition meets the V-0 flame retardancy.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and more specifically, to a halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging, and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) has the advantages of fast crystallization speed, short molding cycle, good fluidity, good dimensional stability, etc., and is widely used in the fields of home appliances, automobiles, new energy, electronic and electrical appliances, etc. due to its excellent mechanical properties, heat resistance and solvent resistance. However, the PBT composition is prone to hydrolysis reaction under high temperature and high humidity conditions, resulting in a significant decline in the overall mechanical properties of the material, which limits its application.

[0003] The prior art CN 102838850A provides a preparation method of a hydrolysis-resistant PBT composition, which improves the hydrolysis resistance of the PBT composition by the reaction of specific groups in polycarbodiimide with the PBT resin. The addition of a halogen-free flame retardant will exhibit a certain acidity under high temperature and high humidity conditions, which will cause the molecular chain of the PBT resin to age and degrade rapidly, and then the mechanical properties will be reduced to less than 80% of the initial properties in a short period of time, that is, it is difficult for the halogen-free flame-retardant PBT composition in the prior art to have good high-temperature hydrolysis resistance at the same time. Therefore, there is still a need in the art to develop a PBT composition resistant to damp heat aging, which has both good flame retardant performance and damp heat aging resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide a halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging to overcome the defects and deficiencies in the prior art, and the PBT composition has good flame retardant performance and damp heat aging resistance.

[0005] Another object of the present invention is to provide a preparation method of the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging.

[0006] Another object of the present invention is to provide the application of the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging in the preparation of connectors, new energy batteries, automobiles, and home appliance materials.

[0007] In order to achieve the above object, the present invention is realized by adopting the following technical solutions:

[0008] A halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging, comprising the following components calculated by weight:

[0009]

[0010]

[0011] The metal deactivator contains hindered phenolic hydroxyl groups and hydrazide groups or oxamide groups; the glass fiber is a glass fiber surface-treated with an epoxy sizing agent.

[0012] The present invention provides a halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging. By adding a metal deactivator containing hindered phenolic hydroxyl groups and hydrazide groups / oxamide groups to the PBT composition, on the one hand, due to the steric hindrance, the hydrogen atom of the hindered phenolic hydroxyl group is easily detached from the original molecular structure, acting as a proton donor and combining with peroxy radicals, alkyl radicals, hydroxyl radicals, etc., causing them to lose their original activity, thus terminating the oxygen aging reaction; on the other hand, the hydrazide groups / oxamide groups can passivate the residual metal ions in the system, which can not only reduce the generation of initial alkyl radicals but also reduce the degradation caused by metal-catalyzed transesterification. The combined action of the two improves the damp heat aging resistance of the material.

[0013] The epoxy groups of the glass fiber surface-treated with an epoxy sizing agent are evenly distributed in the interface layer between the glass fiber and the matrix resin. As chemical cross-linking points, they can enable the PBT composition to obtain better and more stable mechanical properties; in addition, the epoxy groups can react with the terminal carboxyl groups of the PBT resin, thereby reducing the content of terminal carboxyl groups in the system and making the PBT composition have better hydrolysis resistance; supplemented with a suitable proportion of flame retardant, the PBT composition has good flame retardant properties and excellent damp heat aging effects at the same time.

[0014] It should be noted that the metal deactivator contains hindered phenolic hydroxyl groups and hydrazide groups or oxamide groups means that the metal deactivator contains hindered phenolic hydroxyl groups and hydrazide groups or the metal deactivator contains hindered phenolic hydroxyl groups and oxamide groups.

[0015] Further, the metal deactivator is bis(3,5-di-tert-butyl-4-hydroxy-benzoyl) hydrazide and / or 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)] propionate.

[0016] Further, in the PBT composition, the content of polybutylene terephthalate is not less than 40%, and the content of polybutylene terephthalate accounts for more than 70% of the resin component content in the PBT composition.

[0017] Further, the intrinsic viscosity of the polybutylene terephthalate is 0.6 - 1.2 dL / g.

[0018] Furthermore, the intrinsic viscosity of the polybutylene terephthalate is 0.70 - 0.85 dL / g. The intrinsic viscosity of polybutylene terephthalate can further improve the mechanical properties and processing properties of the flame-retardant PBT composition.

[0019] Further, the intrinsic viscosity of the polybutylene terephthalate is measured according to the standard method of ISO 1628-5-2015.

[0020] Furthermore, the measuring temperature of the intrinsic viscosity of the polybutylene terephthalate is 25 °C, and the solvent is phenol / 1,1,2,2-tetrachloroethane (mass ratio 50:50).

[0021] Further, the organophosphorus flame retardant is aluminum diethyl phosphinate.

[0022] Further, the nitrogen-based flame retardant is melamine cyanurate and / or melamine polyphosphate.

[0023] Further, the weight ratio of the organophosphorus flame retardant to the nitrogen-based flame retardant is (3.5 - 9):1.

[0024] Further, the toughening agent is one or more of ethylene-acrylate, ethylene-acrylate-glycidyl methacrylate, ethylene-octene copolymer, ethylene-octene copolymer-glycidyl methacrylate, ethylene-vinyl acetate copolymer.

[0025] Specifically, the ethylene-acrylate is one or more of ethylene-methyl acrylate or ethylene-butyl acrylate.

[0026] The ethylene-acrylate-glycidyl methacrylate is ethylene-methyl acrylate-glycidyl methacrylate.

[0027] Further, the average diameter of the glass fiber is 9 - 17 μm.

[0028] Furthermore, the average length of the glass fiber is 3 - 5 mm.

[0029] Further, the processing aid is an antioxidant and / or a lubricant.

[0030] In the present invention, common lubricants can be selected according to the prior art, including but not limited to ester-based greases, amide-based lubricants, polyethylene-based lubricants or stearic acid-based lubricants.

[0031] Further, the lubricant is an ester-based lubricant.

[0032] Specifically, the ester-based lubricant is one or more of lower alcohol esters of fatty acids, higher alcohol esters of fatty acids, polyol esters or polyethylene glycol esters.

[0033] In the present invention, common antioxidants can be selected according to the prior art, including but not limited to hindered phenol antioxidants, phosphite antioxidants, diphenylamine antioxidants, copper salt antioxidants or thioether antioxidants.

[0034] Furthermore, the antioxidant is a hindered phenol antioxidant.

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

[0036] The present invention also protects a method for preparing the above-mentioned halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging, which includes the following steps:

[0037] S1. Mix an organic phosphorus-based flame retardant and a nitrogen-based flame retardant to obtain a first mixture;

[0038] S2. Mix polybutylene terephthalate, a toughening agent, a metal deactivator, and a processing aid to obtain a second mixture;

[0039] S3. Melt-blend and extrude pelletize the first mixture, the second mixture, and glass fiber to obtain the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging.

[0040] Furthermore, in step S1, the rotation speed of the mixing is 700-900 revolutions per minute.

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

[0042] Furthermore, in step S2, the rotation speed of the mixing is 600-800 revolutions per minute.

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

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

[0045] Furthermore, the temperature of the first zone of the twin-screw extruder is 200-230°C, the temperature of the second zone is 240-260°C, the temperature of the third zone is 235-255°C, the temperature of the fourth zone is 235-255°C, the temperature of the fifth zone is 235-255°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 220-240°C, the temperature of the ninth zone is 220-240°C, the temperature of the tenth zone is 240-260°C, and the screw rotation speed of the twin-screw extruder is 200-450 revolutions per minute.

[0046] The present invention protects the application of the above-mentioned halogen-free flame-retardant reinforced PBT composition with resistance to damp heat aging in connectors, new energy batteries, automobiles, and household appliance materials.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] The present invention provides a halogen-free flame-retardant reinforced PBT composition with resistance to damp heat aging. The PBT composition selects hydrolysis-resistant glass fiber, and the glass fiber can react with the PBT resin to increase the bonding force between the PBT resin and the glass fiber. Moreover, a metal deactivator is added. The metal deactivator contains a hindered phenolic hydroxyl group and a hydrazide group / oxamide group. The hindered phenolic hydroxyl group can play a role in proton donation, combine with peroxyl radicals, etc. to make them deactivated, and terminate the oxygen aging. The hydrazide group / oxamide group can reduce the generation of initial alkyl radicals, so as to reduce the degradation caused by metal-catalyzed transesterification. Therefore, the PBT composition has good flame-retardant performance and resistance to damp heat aging. After the PBT composition is aged for 1000 h in an environment of 85°C and 85% humidity, the retention rate of the mechanical properties of the material is not less than 80.0%. At the same time, the PBT composition meets the V-0 flame retardancy. Detailed implementation manners

[0049] The following further illustrates 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.

[0050] Raw materials used in the embodiments and comparative examples of the present invention:

[0051] PBT resin:

[0052] PBT resin 1: PBT GX111, intrinsic viscosity is 0.73 dL / g; Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0053] PBT resin 2: PBT GX112, intrinsic viscosity is 0.82 dL / g; Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0054] PBT resin 3: PBT GX110, intrinsic viscosity is 0.67 dL / g; Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0055] PBT resin 4: PBT GX121, intrinsic viscosity is 1.0 dL / g; Jiangsu Yizheng Chemical Fiber Co., Ltd.;

[0056] Glass fiber:

[0057] Glass fiber 1: Glass fiber surface-treated with an epoxy-based sizing agent, ECS10-3.0-T436HK, Taishan Fiberglass Co., Ltd.;

[0058] Glass fiber 2: Glass fiber surface-treated with epoxy sizing agent, ECS10-03-534AYF03, Jushi Group Co., Ltd.;

[0059] Glass fiber 3: Glass fiber surface-treated with epoxy sizing agent, ECS303HR-3-H, Chongqing International Composite Materials Co., Ltd.;

[0060] Glass fiber 4: Ordinary cylindrical glass fiber, HMG436S-10-4.0, Taishan Fiberglass Inc.;

[0061] Toughening agent: Ethylene-methyl acrylate-glycidyl methacrylate block copolymer, DuPont PTW;

[0062] Organophosphorus flame retardant:

[0063] Organophosphorus flame retardant: Aluminum diethylphosphinate, BEP-22H, Zhuhai Wantong Chemical Co., Ltd.;

[0064] Nitrogen-based flame retardant:

[0065] Nitrogen-based flame retardant 1: Melamine polyphosphate, BUDIT 3141, purchased from Budenheim;

[0066] Nitrogen-based flame retardant 2: Melamine cyanurate, MCA, purchased from Sichuan Institute of Fine Chemical Industry Research and Design;

[0067] Metal deactivator:

[0068] Metal deactivator 1: Bis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamoyl) hydrazine, MD-1024, Tianjin Li'anlong New Materials Co., Ltd.;

[0069] Metal deactivator 2: 2,2'-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)] propionate, SONOX 1027, Shandong Linyi Sanfeng Chemical Industry Co., Ltd.;

[0070] Metal deactivator 3: Sebacic dihydrazide, Wuhan Rongcan Biotechnology Co., Ltd.;

[0071] Toughening agent: Ethylene-methyl acrylate-glycidyl methacrylate block copolymer, DuPont PTW;

[0072] Lubricant: Pentaerythritol stearate; Antioxidant: Hindered phenolic antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid octadecyl ester. Both the lubricant and the antioxidant are commercially available, and the same lubricant and antioxidant are used in the parallel tests of the examples and comparative examples.

[0073] Examples 1 to 13 and Comparative Examples 1 to 6

[0074] According to the formulations in Tables 1 to 3, prepare a halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to the following preparation method:

[0075] S1. Add the organic phosphorous-based flame retardant and the nitrogen-based flame retardant into a high-speed mixer and mix for 3 minutes at a rotation speed of 800 revolutions per minute to obtain a first mixture;

[0076] S2. Put polybutylene terephthalate, toughening agent, metal deactivator and processing aid into a high-speed mixer and mix for 2 - 4 minutes at a rotation speed of 700 revolutions per minute to obtain a second mixture;

[0077] S3. Melt-blend the first mixture, the second mixture and glass fiber, and then extrude and pelletize to obtain a halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging; the temperature of the first zone of the twin-screw extruder is 220°C, the temperature of the second zone is 250°C, the temperature of the third zone is 245°C, the temperature of the fourth zone is 245°C, the temperature of the fifth zone is 245°C, the temperature of the sixth zone is 250°C, the temperature of the seventh zone is 250°C, the temperature of the eighth zone is 230°C, the temperature of the ninth zone is 230°C, the temperature of the tenth zone is 250°C, and the screw rotation speed of the twin-screw extruder is 350 revolutions per minute.

[0078] Table 1 Dosages of each component in the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging in Examples 1 - 6 (unit: parts by weight)

[0079]

[0080] Table 2 Dosages of each component in the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging in Examples 7 - 13 (unit: parts by weight)

[0081]

[0082]

[0083] Table 3 Dosages of each component in the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging in Comparative Examples 1 - 6 (unit: parts by weight)

[0084]

[0085] Performance testing

[0086] 1. Test method

[0087] Perform performance testing on the halogen-free flame-retardant reinforced PBT compositions prepared in the above examples and comparative examples:

[0088] (1) Tensile strength test: Test the halogen-free flame-retardant reinforced PBT compositions prepared in the above examples and comparative examples according to standard ISO 527 - 2012, and record it as the initial tensile strength;

[0089] (2) Flame retardancy test: The moisture and heat resistant halogen-free reinforced PBT compositions prepared in the above-mentioned examples and comparative examples were tested according to the UL94-2009 vertical burning standard, and the thickness of the specimen was 0.75 mm;

[0090] (3) Moisture and heat aging resistance test: The ISO mechanical specimens of the moisture and heat resistant halogen-free reinforced PBT compositions prepared in the above-mentioned examples and comparative examples were respectively placed in a moisture and heat aging chamber at 85 °C and 85% humidity. After aging for 1000 h, the tensile strength was tested according to the standard ISO527-2012 and recorded as the double 85 tensile strength. The tensile strength retention rate = double 85 tensile strength / initial tensile strength * 100%.

[0091] 2. Test results

[0092] The performance test results of the moisture and heat resistant halogen-free reinforced PBT compositions prepared by the above method are shown in Table 4.

[0093] Table 4 Performance test results of each example and comparative example

[0094]

[0095] As can be seen from Table 4, the moisture and heat resistant halogen-free reinforced PBT compositions prepared in each example of the present invention have good moisture and heat aging resistance and good flame retardancy. Specifically: after moisture and heat aging treatment, the tensile strength retention rate is not less than 80.0%, and the flame retardant grade can reach V-0 level.

[0096] As can be seen from Example 1 and Example 2, when the metal deactivator is bis(3,5-di-tert-butyl-4-hydroxy-benzoyl) hydrazide, the comprehensive performance of the halogen-free reinforced PBT prepared is better.

[0097] As can be seen from Example 1 and Examples 3-4, with the increase of the glass fiber content, the initial tensile strength of the halogen-free reinforced PBT composition gradually increases, and the tensile strength retention rate gradually increases.

[0098] As can be seen from Example 1 and Examples 12-13, when the intrinsic viscosity of the selected PBT resin is 0.70-0.85 dL / g, the comprehensive performance of the halogen-free reinforced PBT composition is better, and its retention rate is higher under the condition of comparable or higher initial tensile strength.

[0099] As can be seen from Comparative Example 1, if the metal deactivator is not added, even if the amount of the hindered phenol antioxidant is increased, the moisture and heat aging resistance of the prepared halogen-free reinforced PBT composition is significantly decreased, and the tensile strength retention rate is only 60.4%.

[0100] It can be seen from Comparative Example 2 that even if a metal passivator is added, the moisture and heat aging resistance of the halogen-free reinforced PBT composition prepared with ordinary round glass fibers is significantly poor, and the tensile strength retention rate is only 67.0%, which is significantly worse than that of the examples.

[0101] It can be seen from Comparative Example 3 that only using ordinary round glass fibers, the moisture and heat aging resistance of the halogen-free reinforced PBT composition prepared is poor, and the tensile strength retention rate is only 50.1%.

[0102] It can be seen from Comparative Example 4 that when the mass ratio of the organophosphorus-based flame retardant to the nitrogen-based flame retardant is too large, the flame retardant system of the halogen-free reinforced PBT composition prepared is unstable and cannot achieve V-0 flame retardancy.

[0103] It can be seen from Comparative Example 5 that when the mass ratio of the organophosphorus-based flame retardant to the nitrogen-based flame retardant is too small, since the nitrogen-based flame retardant makes the system acidic during the moisture and heat aging process, catalytic degradation leads to poor moisture and heat aging resistance of the halogen-free reinforced PBT composition prepared, and the tensile strength retention rate is only 64.9%.

[0104] It can be seen from Comparative Example 6 that when the metal passivator used contains a hydrazide group but does not contain a hindered phenolic hydroxyl group, even when combined with hydrolysis-resistant glass fibers, the hydrolysis resistance of the PBT composition cannot be significantly improved, and the tensile strength retention rate is only 58.8%.

[0105] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not 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 on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging, characterized in that, It comprises the following components by weight: 45 - 55 parts of polybutylene terephthalate; 12 - 18 parts of organophosphorus flame retardant; 2 - 4 parts of nitrogen - based flame retardant; 25 - 35 parts of glass fiber; 0 - 5 parts of toughening agent; 0.3 - 1 part of metal deactivator; 0 - 5 parts of processing aid; The metal deactivator contains hindered phenolic hydroxyl group and hydrazide group or the metal deactivator contains hindered phenolic hydroxyl group and oxamide group; The glass fiber is glass fiber surface - treated with epoxy sizing agent.

2. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The organophosphorus flame retardant is aluminum diethyl phosphinate.

3. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The metal deactivator is bis(3,5 - di - tert - butyl - 4 - hydroxyphenylpropionyl) hydrazine and / or 2,2 - oxamido - bis[ethyl - 3 - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate].

4. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The nitrogen - based flame retardant is melamine cyanurate and / or melamine polyphosphate.

5. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The mass ratio of the organophosphorus flame retardant to the nitrogen - based flame retardant is (3.5 - 9):

1.

6. The halogen-free flame retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein, The intrinsic viscosity of the polybutylene terephthalate is 0.6 - 1.2 dL / g; The intrinsic viscosity of the polybutylene terephthalate is tested according to the ISO 1628 - 5 - 2015 standard method, the test temperature is 25 °C, and the solvent is a mixture of phenol and 1,1,2,2 - tetrachloroethane with a mass ratio of 50:

50.

7. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The toughening agent is one or more of ethylene - acrylate, ethylene - acrylate - glycidyl ester, ethylene - octene copolymer, ethylene - octene copolymer - glycidyl ester, ethylene - vinyl acetate copolymer.

8. The halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to claim 1, wherein The processing aid includes antioxidant and / or lubricant.

9. The preparation method of the halogen-free flame-retardant reinforced PBT composition resistant to damp heat aging according to any one of claims 1 to 8, characterized in that, It includes the following steps: S1. Mix the organophosphorus flame retardant and the nitrogen - based flame retardant to obtain a first mixture; S2. Mix the polybutylene terephthalate, the toughening agent, the metal deactivator and the processing aid to obtain a second mixture; S3. Melt - blend the first mixture, the second mixture and the glass fiber, and extrude and pelletize to obtain a halogen - free flame - retardant reinforced PBT composition with resistance to damp - heat aging.

10. Use of the halogen - free flame - retardant reinforced PBT composition with resistance to damp - heat aging according to any one of claims 1 - 8 in the preparation of connectors, new energy batteries, automotive, and household appliance materials.

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