A polybutylene terephthalate composition, a method for preparing the same and use thereof

Abstract

The application relates to the technical field of high polymer materials, and particularly discloses a polybutylene terephthalate composition, a preparation method and application thereof. The polybutylene terephthalate composition comprises the following components in parts by weight: 44-80 parts of PBT resin, 18-42 parts of glass fiber, 1-3 parts of a toughening agent, 1-15 parts of a nano-modifier, 0.2-0.5 parts of an antioxidant and 0.2-0.5 parts of a lubricant; the nano-modifier is nano-silica particles with an organosiloxane containing an epoxy group on the surface. The polybutylene terephthalate composition has better hydrolysis resistance and heat resistance, and is not easy to be extracted or migrated to the surface of a product during production, processing and injection molding, so that the application range of the polybutylene terephthalate composition can be expanded.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to a polybutylene terephthalate composition, its preparation method and application. Background Technology

[0002] Polybutylene terephthalate (PBT) is a high molecular weight polymer formed by esterification and dehydration of terephthalic acid and butylene glycol ester. It possesses excellent dimensional stability, good electrical insulation, and high mechanical properties, making it widely used in automotive electronics, home appliances, and other fields. However, due to the large number of ester groups in its molecular structure, it is susceptible to degradation (hydrolysis) under certain high-temperature and high-humidity conditions, leading to molecular chain breakage and a significant decrease in mechanical properties due to the reduction in molecular weight. Furthermore, the high content of terminal carboxyl groups during PBT resin synthesis exacerbates the hydrolysis reaction of the ester groups. Therefore, the application of PBT resin in automotive underbody protection panels, engines, and other similar applications is limited.

[0003] Currently, methods to improve the hydrolysis resistance of PBT mainly include: ① adding chemical auxiliaries, such as carbodiimide and epoxy compound hydrolysis-resistant auxiliaries; ② increasing the molecular weight of PBT by introducing chain extenders. For example, patent CN 114231006A improves the hydrolysis resistance of PBT by adding carbodiimide and phenyl glycidyl ether auxiliaries to the system, but it suffers from problems such as small molecular weight, high addition amount, and insufficient long-term hydrolysis efficiency; patents CN 109294177A and CN 112029244A improve the long-term hydrolysis resistance of PBT by introducing chain extenders or barrier agents on the basis of traditional hydrolysis resistance, respectively. While increasing production costs, they still cannot avoid the environmental risks and health hazards of small carbodiimide molecules being easily extracted or precipitated. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the prior art and provide a polybutylene terephthalate composition, its preparation method, and its application. The polybutylene terephthalate composition of this application possesses both excellent hydrolysis resistance and heat resistance, and is not easily migrated to the surface of the product during production, processing, and injection molding, thereby expanding its application range.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a polybutylene terephthalate composition comprising the following components in parts by weight:

[0007] 44-80 parts PBT resin, 18-42 parts glass fiber, 1-3 parts toughening agent, 1-15 parts nano-modifier, 0.2-0.5 parts antioxidant and 0.2-0.5 parts lubricant;

[0008] The nano-modifier is a nano-silica particle with an organosiloxane containing epoxy groups on its surface.

[0009] In the technical solution of this application, an organosiloxane containing epoxy groups is used to modify nano-silica to obtain the nano-modifier of this application. This nano-modifier is added to the polybutylene terephthalate composition, and the nano-modifier can enhance the performance of the polybutylene terephthalate composition. The organosiloxane containing epoxy groups of this application can simultaneously reduce the end carboxyl group content of PBT resin and can also combine multiple PBT molecular chains through chemical bonds, thereby extending the PBT molecular chains and increasing the molecular weight, further improving the heat resistance and hydrolysis resistance of the PBT composition.

[0010] Preferably, the content of PBT resin in the polybutylene terephthalate composition is not less than 44%.

[0011] Preferably, the epoxy equivalent of the organosiloxane containing epoxy groups in this application is 160-250 g / mol, and more preferably 160-200 g / mol.

[0012] In a preferred embodiment of the polybutylene terephthalate composition described in this application, the organosiloxane is a cage-type polysilsesquioxane or a cyclic tetrasiloxane.

[0013] The structural formula of the cage-type polysilsesquioxane is shown in Formula I; the structural formula of the cyclic tetrasiloxane is shown in Formula II.

[0014]

[0015] Wherein, R1 = one of epoxycyclohexylethyl, glycidyl etheroxypropyl, glycidyl etheroxyethyl, epoxy ethyl, and propylene oxide isobutyl; preferably, R1 = glycidyl etheroxypropyl or glycidyl etheroxyethyl.

[0016] Wherein, R2 = one of hydrogen, methyl, ethyl, methoxy, ethoxy, epoxycyclohexylethyl, glycidyl etheroxypropyl, glycidyl etheroxyethyl, epoxyethyl, epoxypropane isobutyl, and epoxybutyl, preferably, R2 = hydrogen, methyl, or methoxy.

[0017] This application utilizes cage-like polysilsesquioxanes or cyclic tetrasiloxanes containing epoxy groups, which can simultaneously reduce the end carboxyl group content of PBT and bind multiple PBT molecular chains together through chemical bonds, thereby elongating the PBT molecular chains and increasing the molecular weight, thus better improving the heat resistance and hydrolysis resistance of the PBT composition. Furthermore, the cage-like polysilsesquioxanes or cyclic tetrasiloxanes, due to their unique spatial structure and large molecular weight, prevent the nano-modifiers from migrating to the surface of the prepared polybutylene terephthalate composition during production, processing, and injection molding, thereby expanding its application range.

[0018] As a preferred embodiment of the polybutylene terephthalate composition described in this application, the method for preparing the nano-modifier includes the following steps: taking dried inorganic nano-silica particles, adding an organosiloxane containing an epoxy group and mixing to obtain the nano-modifier.

[0019] This application modifies inorganic nano-silica particles by using cage-like polysilsesquioxanes or cyclic tetrasiloxanes containing epoxy groups, so that the cage-like polysilsesquioxanes or cyclic tetrasiloxanes containing epoxy groups cover the surface of the inorganic nanoparticles, and then adds them to the polybutylene terephthalate composition to improve the heat resistance and hydrolysis resistance of the polybutylene terephthalate composition.

[0020] The D of the nano-modifier 50 The average particle size is 10–500 nm.

[0021] The D of the nano-modifier 50 The average particle size was measured using the laser particle size distribution method according to GB / T 19077-2016.

[0022] In a preferred embodiment of the polybutylene terephthalate composition described in this application, the mass ratio of the inorganic nano-silica particles to the organosiloxane is 100:(3-10).

[0023] As a preferred embodiment of the polybutylene terephthalate composition described in this application, the PBT resin has a terminal carboxyl group content of 10-22 mol / t, preferably 10-15 mol / t, and the test method for the terminal carboxyl group content is GB / T14190-2017.

[0024] As a preferred embodiment of the polybutylene terephthalate composition described in this application, the glass fiber is a short-cut filament glass fiber with an average diameter of 8-13 μm and an average length of 3-6 mm.

[0025] As a preferred embodiment of the polybutylene terephthalate composition described in this application, the toughening agent is one or more of ethylene-methyl acrylate copolymer, ethylene-methyl acrylate-methyl methacrylate glycidyl ester; and the lubricant is at least one of esters, polyethylene waxes, stearic acid, and ethylene bis-stearamides.

[0026] In a preferred embodiment of the polybutylene terephthalate composition described in this application, the antioxidant is a hindered phenolic antioxidant and / or a phosphorus-containing antioxidant; the hindered phenolic antioxidant is at least one of antioxidant 1010, antioxidant 1098 and antioxidant 3114; the phosphorus-containing antioxidant is at least one of antioxidant 168, antioxidant PEP-36 and antioxidant 608.

[0027] Secondly, this application provides a method for preparing the aforementioned polybutylene terephthalate composition, comprising the following steps:

[0028] 1) Add PBT resin, nano-modifier, lubricant, antioxidant and toughening agent into a premixer and mix to obtain a mixture;

[0029] 2) The mixture is fed into the twin-screw extruder from the main feed port, and the glass fiber is side-fed into the twin-screw extruder. The mixture is melted, extruded and granulated to obtain a polybutylene terephthalate composition.

[0030] Preferably, the temperature of the twin-screw extruder is set to 220–250°C, and the screw speed is 250–400 r / min.

[0031] Thirdly, this application provides the application of the above-described polybutylene terephthalate composition in automotive parts. Preferably, the automotive part includes a domain controller housing for automotive brakes.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] This application provides a polybutylene terephthalate (PBT) composition, its preparation method, and its application. The invention modifies inorganic nano-silica particles using a cage-like polysilsesquioxane or a cyclic tetrasiloxane containing epoxy groups, causing the epoxy-containing cage-like polysilsesquioxane or cyclic tetrasiloxane to coat the surface of the inorganic nanoparticles. When added to the PBT composition, the epoxy-containing cage-like polysilsesquioxane or cyclic tetrasiloxane simultaneously reduces the end carboxyl group content of PBT. Furthermore, multiple PBT molecular chains can be linked together through chemical bonds, thereby extending the PBT molecular chains and increasing the molecular weight, which in turn improves the heat resistance and hydrolysis resistance of the polybutylene terephthalate composition. In addition, the introduced cage-like polysilsesquioxane or cyclic tetrasiloxane, due to their unique spatial structure and large molecular weight, makes it difficult for the nano-modifier to migrate to the surface of the product during production, processing and injection molding, thus expanding its application range. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of this application, the following will provide further explanation of this application in conjunction with specific embodiments.

[0035] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0036] PBT resin 1: terminal carboxyl group content 10mol / t (test method for terminal carboxyl group content GB / T 14190-2017), PBTGX112J, Yizheng Chemical Fiber, China;

[0037] PBT resin 2: terminal carboxyl group content 15mol / t (test method for terminal carboxyl group content GB / T 14190-2017), PBTTH6082, Tunhe, Lanshan, Xinjiang;

[0038] PBT resin 3: terminal carboxyl group content 22mol / t (test method for terminal carboxyl group content GB / T 14190-2017), PBTGX112, Yizheng Chemical Fiber, China;

[0039] Fiberglass: ECS10-3.0-T436HK, average diameter 10μm, average length 3mm, Taishan Fiberglass;

[0040] Organosiloxanes containing epoxy groups 1: epoxy equivalent 175, glycidyl etheroxypropylcyclotetrasiloxane (Ecotion CTS101), wherein R1 is glycidyl etheroxypropyl and R2 is methyl, Guangzhou Yixin Technology Co., Ltd.

[0041] Organosiloxanes containing epoxy groups 2: epoxy equivalent 167, glycidyl etheroxypropyl cage-like polysilsesquioxane (Ecotion POSS101), wherein R1 is glycidyl etheroxypropyl, Guangzhou Yixin Technology Co., Ltd.

[0042] 3. Organosiloxanes containing epoxy groups: epoxy equivalent 177, octaepoxycyclohexylethyl cage-like polysilsesquioxane (Ecotion POSS1010), wherein R1 is epoxycyclohexylethyl, Guangzhou Yixin Technology Co., Ltd.

[0043] Organosiloxanes containing epoxy groups 4: Epoxy equivalent 188, tetramethyltetraepoxycyclohexylethylcyclotetrasiloxane (ChangFu EXC4), where R1 is epoxycyclohexylethyl and R2 is methyl, Changfu Chemical.

[0044] Organosiloxanes containing epoxy groups 5: Epoxy equivalent 236, (3-glycidyloxypropyl)trimethoxysilane, Sigma-Aldrich;

[0045] Organosiloxane 6: Dimethylsiloxy cage-like polysilsesquioxane (POSS1015), Guangzhou Yixin Technology Co., Ltd.

[0046] The epoxy equivalent of the above-mentioned organosiloxanes containing epoxy groups was tested according to ISO 3001-1978.

[0047] Inorganic silica nanoparticles: particle size 200nm (measured by laser particle size distribution according to GB / T 19077-2016), SM, Nanjing Dongna Biotechnology Co., Ltd.

[0048] Toughening agent: Ethylene-acrylic acid copolymer elastomer (LUCOFIN 1400PN), Shanghai Zhuangjing Chemical Co., Ltd.;

[0049] Lubricant: Oxidized polyethylene wax, commercially available;

[0050] Antioxidant: Antioxidant 1010 and Antioxidant 608 are compounded in a 1:1 mass ratio and are commercially available;

[0051] In all the embodiments and comparative examples, the toughening agent, lubricant and antioxidant are the same commercially available products.

[0052] Examples 1-12 and Comparative Examples 1-4

[0053] Examples 1-12 and Comparative Examples 1-4 provide a polybutylene terephthalate composition, the weight parts of which are shown in Tables 1-2, and the preparation method is as follows:

[0054] 1) Weigh a certain amount of inorganic nano-silica particles and dry them in an oven at 80℃ for 24 hours. Then, add the dried inorganic nanoparticles into a beaker under mechanical stirring at 200 r / min. Add an organosilica containing epoxy groups (or an organosilica without epoxy groups) to the beaker at a mass ratio of inorganic nano-silica particles to organosiloxane of 100:5. Stir for 10 minutes under mechanical stirring at 4000 r / min. Dry and grind the mixture in an oven at 80℃ to obtain nano-modifiers 1-6.

[0055] 1) PBT resin, nano-modifier, toughening agent, lubricant, and antioxidant are premixed according to the weight ratio to obtain a mixture;

[0056] 3) The mixture is fed into the twin-screw extruder through the main feed port, and glass fiber is added to the twin-screw extruder through side feeding. After traction, cooling, pelleting, and drying at 120℃ for 2 hours, a polybutylene terephthalate (PBT) composition is obtained. The temperature of each section of the twin-screw extruder from the feed port to the extrusion die is 60-220-220-240-240-250-250-240-240-250℃, and the screw speed is 250~400 r / min.

[0057] Table 1

[0058]

[0059]

[0060] Table 2

[0061]

[0062]

[0063] The polybutylene terephthalate (PBT) compositions prepared in Examples 1-12 and Comparative Examples 1-4 were subjected to performance tests. The test methods for each performance are as follows:

[0064] 1. Tensile strength: The sample was injection molded into a dumbbell shape of 150*10*4mm and tested according to ISO 527-93-1 method, with a tensile rate of 5mm / min;

[0065] 2. Maximum rate of thermal weight loss temperature: TG test, air atmosphere, temperature rise from room temperature to 750℃ at a rate of 20℃ / min.

[0066] 3. Hydrolysis resistance: A dumbbell-shaped tensile specimen of 150*10*4mm was placed at 85℃ and 85%RH for 1000 hours and then at 23℃ and 50%RH for 24 hours. The tensile strength was tested at a tensile rate of 5mm / min according to ISO 527-93-1. The performance retention rate was calculated by comparing it with the original tensile strength.

[0067] Performance retention rate calculation method: P x / P0×100%, where P0 is the initial tensile strength property and Px is the tensile strength property tested after being placed at 85℃ and 85%RH for 1000 hours and then at 23℃ and 50%RH for 24 hours.

[0068] The test results of the polybutylene terephthalate (PBT) compositions prepared in Examples 1-12 and Comparative Examples 1-4 are shown in Table 3.

[0069] Table 3

[0070]

[0071]

[0072] The results are shown in Table 3. The maximum thermal decomposition temperature of the PBT composition prepared in the embodiments of this application is greater than 387°C, and the tensile strength retention rate after being placed at 85°C and 85%RH for 1000 hours is greater than 71%. The maximum thermal decomposition rate is between 387.8 and 427.5°C, and the hydrolysis resistance retention rate is between 71% and 95%.

[0073] Example 5 uses a PBT composition modified with a common epoxy siloxane nanomodifier containing epoxy groups. The maximum thermal weight loss rate temperature and the retention rate of hydrolysis resistance are both lower than those of Examples 1, 2, 3 and 4.

[0074] The PBT compositions prepared in Examples 6-10 also exhibit good heat resistance and hydrolysis resistance.

[0075] The PBT compositions prepared in Examples 1, 11 and 12 show that the lower the content of terminal carboxyl groups in the PBT raw materials, the better their hydrolysis resistance.

[0076] Compared with Example 1, Comparative Examples 1 and 2 showed that the tensile properties, maximum thermal weight loss temperature, and hydrolysis resistance of the siloxane nanoparticles modified with epoxy groups were significantly higher than those of the PBT compositions modified with organosiloxanes containing only inorganic nanoparticles or only epoxy groups.

[0077] In Comparative Example 3, without the addition of the nano-modifier, the maximum thermal weight loss rate temperature and the retention rate of hydrolysis resistance of the PBT composition were significantly lower than those in Examples 1 and 2. This demonstrates that the combination of PBT resin and the nano-modifier described in this application can significantly improve the heat resistance and hydrolysis resistance of the material.

[0078] Comparative Example 4 shows that the PBT composition using a siloxane-modified nano-modifier without epoxy groups has poor retention of maximum thermal weight loss rate temperature and hydrolysis resistance.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A polybutylene terephthalate composition, characterized in that, The components include the following parts by weight: 44-80 parts PBT resin, 18-42 parts glass fiber, 1-3 parts toughening agent, 1-15 parts nano-modifier, 0.2-0.5 parts antioxidant and 0.2-0.5 parts lubricant; The nano-modifier is a nano-silica particle with an organosiloxane containing epoxy groups on its surface; the epoxy equivalent of the organosiloxane is 160~200 g / mol. The PBT resin has a terminal carboxyl group content of 10~22 mol / t; The organosiloxane is a cage-type polysilsesquioxane or a cyclic tetrasiloxane; The structural formula of the cage-type polysilsesquioxane is shown in Formula I; the structural formula of the cyclic tetrasiloxane is shown in Formula II. Formula I Formula II Wherein, R1 = one of epoxycyclohexylethyl, glycidyl etheroxypropyl, glycidyl etheroxyethyl, epoxyethyl, and propylene oxide isobutyl; Wherein, R2 = one of hydrogen, methyl, ethyl, methoxy, ethoxy, epoxycyclohexylethyl, glycidyl etheroxypropyl, glycidyl etheroxyethyl, epoxyethyl, epoxypropane isobutyl, and epoxybutyl.

2. The polybutylene terephthalate composition according to claim 1, characterized in that, R1 = glycidyl etheroxypropyl or glycidyl etheroxyethyl.

3. The polybutylene terephthalate composition according to claim 1, characterized in that, The preparation method of the nano-modifier includes the following steps: taking dry inorganic nano-silica particles, adding them to an organosiloxane containing epoxy groups and mixing to obtain the nano-modifier.

4. The polybutylene terephthalate composition according to claim 3, characterized in that, The mass ratio of the inorganic nano-silica particles to the organosiloxane is 100:(3~10).

5. The polybutylene terephthalate composition according to claim 1, characterized in that, The average diameter of the glass fiber is 8~13μm.

6. The polybutylene terephthalate composition according to claim 1, characterized in that, The toughening agent is one or more of ethylene-methyl acrylate copolymer, ethylene-methyl acrylate-methyl methacrylate glycidyl ester; the lubricant is at least one of esters, polyethylene waxes, stearic acid, and ethylene bis-stearamide.

7. The polybutylene terephthalate composition according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant and / or a phosphorus-containing antioxidant; the hindered phenolic antioxidant is at least one of antioxidant 1010, antioxidant 1098 and antioxidant 3114; the phosphorus-containing antioxidant is at least one of antioxidant 168, antioxidant PEP-36 and antioxidant 608.

8. A method for preparing the polybutylene terephthalate composition according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Add PBT resin, nano-modifier, lubricant, antioxidant, and toughening agent into a premixer and mix to obtain a mixture; 2) The mixture is fed into the twin-screw extruder from the main feed port, and the glass fiber is side-fed into the twin-screw extruder. The mixture is melted, extruded and granulated to obtain a polybutylene terephthalate composition.

9. The use of the polybutylene terephthalate composition according to any one of claims 1 to 7 in an automotive component, said automotive component comprising a domain controller housing for an automotive brake.

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