PBT composite material, preparation method and application thereof

Abstract

The application discloses a PBT composite material and a preparation method and application thereof. The PBT composite material comprises the following components: PBT resin, alkali-free glass fiber, epoxy resin, antioxidant and lubricant, wherein the intrinsic viscosity of the PBT resin is 0.88dL / g-1.16dL / g. The preparation method of the PBT composite material comprises the following steps: 1) mixing the PBT resin, the epoxy resin, the antioxidant and the lubricant according to mass fractions to obtain premix; and 2) mixing the premix and the alkali-free glass fiber according to mass fractions to obtain the PBT composite material. The PBT composite material is prepared by taking the PBT resin as a main material, the content of the lubricant, the epoxy resin, the antioxidant and other additives is small, a toughening agent is not needed, the PBT composite material has the advantages of high mechanical strength, good water resistance and alkali resistance, convenient processing and simple preparation, and is suitable for actual production and application.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a PBT composite material, its preparation method, and its applications. Background Technology

[0002] Polybutylene terephthalate (PBT) is a polyester produced by the condensation polymerization of terephthalic acid and 1,4-butanediol. It is an important thermoplastic polyester and one of the five major engineering plastics. PBT possesses advantages such as high crystallinity, rapid molding capability, low coefficient of friction, high heat distortion temperature, excellent electrical properties, and ultrasonic welding capability. Therefore, it is widely used in industrial fields such as home appliances, automobiles, electronics, aircraft manufacturing, communication equipment, and transportation. It is particularly suitable for manufacturing electronic or electrical components, such as integrated circuit sockets, printed circuit boards, computer keyboards, electrical switches, fuses, temperature control switches, and protective devices. However, PBT material suffers from poor water and alkali resistance.

[0003] Because PBT molecules contain a large number of ester groups, they are prone to degradation under high temperature, high humidity, acidic, and alkaline environments. This leads to chain breakage and shortening, resulting in a decline in some of its excellent properties and limiting the promotion and application of PBT composites. Currently, existing technologies use PBT materials mixed with various other resins and additives to create composites that effectively improve water resistance. However, increasing the content of other resins and additives significantly impacts the performance of PBT materials, making it difficult for them to fully realize their advantages.

[0004] Meanwhile, PBT materials are less resistant to alkalis than to hydrolysis because alkalis accelerate their degradation. In practical applications, PBT materials are often directly exposed to alkaline substances or in alkaline environments. For example, when used in electronic and electrical appliances, PBT materials come into contact with detergents used in automobiles and kitchen appliances. Also, in winter, de-icing agents (sodium chloride) and water can easily adhere to PBT automotive trim parts or wiring containing PBT materials. Under the influence of electric current, these agents and water can produce alkaline substances, affecting the performance of the PBT material and potentially creating safety hazards.

[0005] Therefore, there is an urgent need to develop a PBT composite material with PBT resin as the main material, which has high mechanical strength, good water and alkali resistance, is easy to process, and is simple to prepare. Summary of the Invention

[0006] In order to expand the application of PBT materials in alkaline environments and overcome other problems existing in the prior art, the present invention aims to provide a PBT composite material, its preparation method and application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a PBT composite material comprising the following components in parts by mass:

[0009] PBT resin: 50 to 90 parts;

[0010] Fiberglass: 5 parts to 45 parts;

[0011] Epoxy resin: 1 part to 9 parts;

[0012] Antioxidant: 0.4 to 0.6 parts;

[0013] Lubricant: 0.4 parts to 0.6 parts;

[0014] The intrinsic viscosity of the PBT resin is 0.88 dL / g to 1.16 dL / g; the glass fiber is alkali-free glass fiber.

[0015] Preferably, the PBT composite material comprises the following components in parts by weight:

[0016] PBT resin: 55 parts to 85 parts;

[0017] Fiberglass: 10 to 40 parts;

[0018] Epoxy resin: 2 to 8 parts;

[0019] Antioxidant: 0.4 to 0.6 parts;

[0020] Lubricant: 0.4 parts to 0.6 parts;

[0021] The intrinsic viscosity of the PBT resin is 0.88 dL / g to 1.16 dL / g; the glass fiber is alkali-free glass fiber.

[0022] More preferably, the PBT composite material comprises the following components in parts by weight:

[0023] PBT resin: 58 to 65 parts;

[0024] Fiberglass: 25-35 parts;

[0025] Epoxy resin: 6 to 8 parts;

[0026] Antioxidant: 0.4 to 0.6 parts;

[0027] Lubricant: 0.4 to 0.5 parts;

[0028] The intrinsic viscosity of the PBT resin is 0.88 dL / g to 1.16 dL / g; the glass fiber is alkali-free glass fiber.

[0029] Preferably, the intrinsic viscosity of the PBT resin is 0.95 dL / g to 1.15 dL / g.

[0030] More preferably, the intrinsic viscosity of the PBT resin is 1.05 to 1.13 dL / g.

[0031] Preferably, the PBT resin is polybutylene terephthalate.

[0032] More preferably, the PBT resin is polybutylene terephthalate chips.

[0033] Specifically, the polybutylene terephthalate chips are medium-viscosity Taiwan Changchun PBT1100-211M.

[0034] Preferably, the alkali-free glass fiber is chopped alkali-free glass fiber.

[0035] Preferably, the chopped alkali-free glass fiber has a monofilament diameter of 7μm to 11μm and a chopped length of 3mm to 5mm.

[0036] Specifically, selecting alkali-free glass fibers with appropriate monofilament diameter and chopped length can help achieve a balance between high mechanical properties and excellent appearance in the overall PBT composite material.

[0037] Preferably, the antioxidant is a compound antioxidant system composed of antioxidant 1010 and antioxidant S-9228 in any proportion.

[0038] Specifically, antioxidant 1010 is BASF Irganox 1010, a hindered phenolic antioxidant, chemically named pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF (Germany); antioxidant S-9228 is a phosphite antioxidant, chemically named bis(2,4-dimethyl)pentaerythritol diphosphite, manufactured by Dover (USA).

[0039] Preferably, the ratio of antioxidant 1010 to antioxidant S-9228 is 1:2 to 2:1.

[0040] Preferably, the lubricant is one or more of pentaerythritol stearate, zinc stearate, barium stearate, and calcium stearate.

[0041] More preferably, the lubricant is pentaerythritol stearate.

[0042] Preferably, the epoxy resin is a bisphenol A type epoxy resin, and the epoxy equivalent of the bisphenol A type epoxy resin is 1 Eq / kg to 2 Eq / kg.

[0043] More preferably, the epoxy resin is a bisphenol A type epoxy resin, and the epoxy resin of the bisphenol A type epoxy resin has an epoxy equivalent of 1.68 Eq / kg to 1.75 Eq / kg.

[0044] More preferably, the epoxy resin is a bisphenol A type epoxy resin, and the bisphenol A type epoxy resin is Huntsman's GT-7072.

[0045] In a second aspect, the present invention provides a method for preparing the PBT composite material described in the first aspect, comprising the following steps:

[0046] 1) PBT resin, epoxy resin, antioxidant and lubricant are mixed in the proportions by weight as described in the first aspect to obtain a premix;

[0047] 2) The premix and glass fiber are mixed according to the mass fractions described in the first aspect to obtain the PBT composite material.

[0048] Preferably, the preparation method of the PBT composite material includes the following steps:

[0049] 1) PBT resin, epoxy resin, antioxidant and lubricant are mixed in the proportions by weight as described in the first aspect to obtain a premix;

[0050] 2) The premixed material is fed into the main feed hopper of the twin-screw extruder, and the glass fiber of the mass fraction mentioned in the first aspect is added into the side feed hopper of the twin-screw extruder. The mixture is then mixed and extruded to obtain the PBT composite material.

[0051] Preferably, the mixing in step 1) is performed using a high-speed mixer, and the stirring rate is 300 r / min to 700 r / min.

[0052] Preferably, the mixing time in step 1) is 3 min to 10 min.

[0053] Preferably, the mixing and extrusion temperature in step 2) is 200℃~250℃.

[0054] Preferably, the screw speed of the twin-screw extruder in step 2) is 400 r / min to 800 r / min.

[0055] Preferably, the length-to-diameter ratio of the screw in the twin-screw extruder described in step 2) is 40:1.

[0056] Thirdly, the present invention also provides the application of the PBT composite material described in the first aspect in the production of electronic and electrical, mechanical manufacturing or chemical materials.

[0057] Preferably, the electronic and electrical materials include at least one of automobiles, electrical appliances, and electronic components.

[0058] The beneficial effects of this invention are: the PBT composite material of this invention uses PBT resin as the main material, which not only has low content of lubricants, epoxy resins, antioxidants and other additives, eliminating the need for toughening agents, but also has the advantages of high mechanical strength, good water resistance and alkali resistance, convenient processing, and simple preparation, making it suitable for practical production and application. Specifically:

[0059] (1) The PBT composite material in this invention has good mechanical properties and alkali resistance. After 300 hours of alkali treatment, its mechanical properties can be retained at a rate of over 90%.

[0060] (2) The PBT composite material in this invention uses less additives, but has good compatibility and the raw material components can play a synergistic role.

[0061] (3) The PBT composite material in this invention also has relatively good processing fluidity, which facilitates practical promotion and application;

[0062] (4) The PBT composite material in this invention has the characteristics of not involving complex synthesis reactions, simple preparation, high efficiency, and large-scale production, making it suitable for industrial production and application.

[0063] (5) The PBT composite material in this invention is suitable for use in the fields of home appliances, automobiles, electronics, electrical engineering, and machinery and chemical engineering. Detailed Implementation

[0064] The present invention will be further described in detail below through specific embodiments.

[0065] It should be noted that "wt%" in this invention refers to mass fraction;

[0066] The raw materials used in the embodiments and comparative examples of this invention are as follows:

[0067] PBT resin: Polybutylene terephthalate chips, PBT1100-211M (intrinsic viscosity: 1.0 dL / g) from Chang Chun Pharmaceutical Co., Ltd., Taiwan; PBT1200-211M (intrinsic viscosity: 0.8 dL / g) from Chang Chun Pharmaceutical Co., Ltd., Taiwan; PBT1100-211S (intrinsic viscosity: 1.2 dL / g) from Chang Chun Pharmaceutical Co., Ltd., Taiwan.

[0068] Glass fiber: chopped alkali-free glass fiber, grade ECS11-4.5-534A, manufactured by Jushi Co., Ltd., with a single filament diameter of 11μm and a chopped length of 4.5mm;

[0069] Antioxidant: Antioxidant 1010 is BASF Irganox 1010, a hindered phenolic antioxidant, chemically named pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF, Germany.

[0070] Antioxidant S-9228 is a phosphite antioxidant with the chemical name bis(2,4-dimethyl)pentaerythritol diphosphite, manufactured by Dover Corporation, USA.

[0071] Lubricant: Its chemical name is pentaerythritol tetrastearate (PETS), manufactured by LONZA (USA), and is referred to as lubricant PETS;

[0072] Epoxy resin: Solid bisphenol A type epoxy resin, brand name Araldite GT-7072, with an epoxy value of 1.68~1.75Eq / kg, manufactured by Huntsman Corporation, USA;

[0073] Toughening agent: ethylene-methyl acrylate-glycidyl methacrylate random terpolymer, ARKEMA (France) product AX-8900.

[0074] Example 1

[0075] This embodiment provides a method for preparing PBT composite material, including the following steps:

[0076] 1) Weigh 85 parts of PBT resin (i.e., PBT 1100-211M), 0.2 parts of antioxidant 1010, 0.2 parts of antioxidant S-9228, 0.6 parts of lubricant PETS, and 4 parts of solid bisphenol A epoxy resin (brand name: Araldite GT-7072) according to the following weight proportions. Add these raw materials to a high-speed mixer (i.e., high-speed mixer, speed: 300r / min~700r / min) and stir for 5 minutes to obtain a premixed material.

[0077] 2) The premixed material from step 1) is fed into the main feed hopper of the twin-screw extruder using a loss-in-weight weighing system;

[0078] Ten parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder (screw length-to-diameter ratio of 40:1), cooled, and pelletized to obtain the PBT composite material.

[0079] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0080] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 9:1.

[0081] It should be noted that the present invention also provides Examples 2 to 5. The difference between Examples 2 to 5 and Example 1 is only that the raw materials used are different. For the specific types and amounts of raw materials used in Examples 2 to 5, please refer to Table 1.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a PBT composite material. The main difference between this comparative example and Example 4 is that this comparative example does not add solid bisphenol A type epoxy resin. The purpose of this addition is to highlight the alkali resistance of epoxy resin in glass fiber reinforced PBT materials. Specifically, it includes the following steps:

[0084] 1) Weigh 69 parts of PBT resin (i.e. PBT 1100-211M), 0.2 parts of antioxidant 1010, 0.2 parts of antioxidant S-9228 and 0.6 parts of lubricant PETS according to the mass ratio, and add these raw materials into a high-speed mixer and stir for 5 minutes to obtain a premixed material;

[0085] 2) The premixed material from step 1) is fed into the main feed hopper of the twin-screw extruder using a loss-in-weight weighing system;

[0086] Thirty parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder (screw length-to-diameter ratio of 40:1), cooled, and pelletized to obtain the PBT composite material.

[0087] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0088] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 7:3.

[0089] Comparative Example 2

[0090] This comparative example provides a method for preparing a PBT composite material. The main difference between this comparative example and Example 4 is the amount of solid bisphenol A epoxy resin added. The purpose of this method is to highlight the alkali resistance of the epoxy resin in glass fiber reinforced PBT materials. The specific steps include:

[0091] 1) Weigh 59 parts of PBT resin (i.e., PBT 1100-211M), 0.2 parts of antioxidant 1010, 0.4 parts of antioxidant S-9228, 0.4 parts of lubricant PETS, and 10 parts of solid bisphenol A epoxy resin (brand name: Araldite GT-7072) according to the following weight proportions, and add these raw materials into a high-speed mixer and stir for 5 minutes to obtain a premixed material;

[0092] 2) The premixed material from step 1) is fed into the main feed hopper of a twin-screw extruder (screw length-to-diameter ratio of 40:1) using a loss-in-weight weighing system;

[0093] Thirty parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder, cooled, and pelletized to obtain the PBT composite material.

[0094] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0095] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 7:3.

[0096] Comparative Example 3

[0097] This comparative example provides a method for preparing a PBT composite material. The main difference between this comparative example and Example 1 is that this comparative example does not add epoxy resin, but instead adds 6 parts by weight of toughening agent AX-8900 (ethylene-methyl acrylate-glycidyl methacrylate random terpolymer). The purpose of setting up this comparative example is to compare the effects of toughening agent and epoxy resin on the alkali hydrolysis resistance of the material, thereby confirming the outstanding contribution of epoxy resin to the alkali hydrolysis resistance. The specific steps include:

[0098] 1) Weigh 81 parts of PBT resin (i.e., PBT 1100-211M), 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant S-9228, 0.4 parts of lubricant PETS, and 6 parts of ethylene-methyl acrylate-glycidyl methacrylate random terpolymer (i.e. toughening agent AX-8900) according to the following weight proportions, and add these raw materials to a high-speed mixer and stir for 5 minutes to obtain a premixed material;

[0099] 2) The premixed material from step 1) is fed into the main feed hopper of a twin-screw extruder (screw length-to-diameter ratio of 40:1) using a loss-in-weight weighing system;

[0100] Ten parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder, cooled, and pelletized to obtain the PBT composite material.

[0101] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0102] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 9:1.

[0103] Comparative Example 4

[0104] This comparative example provides a method for preparing a PBT composite material. The difference between this comparative example and Example 5 is that the intrinsic viscosity of the PBT resin is different. The intrinsic viscosity of the PBT resin in this comparative example is 0.8 dL / g, so its flowability is higher than that of the PBT resin in Example 5 (intrinsic viscosity 1.0 dL / g). The purpose of setting up this comparative example is to study the effect of the molecular chain length of the resin on the alkali resistance. Specifically, it includes the following steps:

[0105] 1) Weigh 55 parts of PBT resin (i.e., PBT 1200-211M), 0.25 parts of antioxidant 1010, 0.25 parts of antioxidant S-9228, 0.5 parts of lubricant PETS, and 4 parts of solid bisphenol A epoxy resin (brand name: Araldite GT-7072) according to the following weight proportions, and add these raw materials into a high-speed mixer and stir for 5 minutes to obtain a premixed material;

[0106] 2) The premixed material from step 1) is fed into the main feed hopper of a twin-screw extruder (screw length-to-diameter ratio of 40:1) using a loss-in-weight weighing system;

[0107] Forty parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder, cooled, and pelletized to obtain the PBT composite material.

[0108] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0109] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 6:4.

[0110] Comparative Example 5

[0111] This comparative example provides a method for preparing a PBT composite material. The difference between this comparative example and Example 5 is that the intrinsic viscosity of the PBT resin is different. The intrinsic viscosity of PBT in this comparative example is 1.2 dL / g, and its flowability is lower than that of Example 5 (PBT intrinsic viscosity 1.0 dL / g). The purpose of setting up this comparative example is to study the effect of the molecular chain length of the resin on the resistance to alkali hydrolysis. The specific steps include:

[0112] 1) Weigh 55 parts of PBT resin (i.e., PBT 1100-211S), 0.3 parts of antioxidant 1010, 0.3 parts of antioxidant S-9228, 0.6 parts of lubricant PETS, and 4 parts of solid bisphenol A epoxy resin (brand name: Araldite GT-7072) according to the following weight proportions, and add these raw materials into a high-speed mixer and stir for 5 minutes to obtain a premixed material;

[0113] 2) The premixed material from step 1) is fed into the main feed hopper of the twin-screw extruder using a loss-in-weight weighing system;

[0114] Thirty parts of chopped glass fiber were added to the side feed hopper using a loss-in-weight weighing system, which dispersed the chopped glass fiber in the molten premix. The mixture was then extruded through a twin-screw extruder (screw length-to-diameter ratio of 40:1), cooled, and pelletized to obtain the PBT composite material.

[0115] In step 2), the main screw speed of the twin-screw extruder is 400 r / min-800 r / min, and the temperature of the twin-screw extruder is 200℃-250℃.

[0116] In step 2), the mass ratio of the feed from the main feed hopper to the feed from the side feed hopper is 6:4.

[0117] The preparation steps of the PBT composite materials provided in Examples 2-5 are the same as those in Example 1. The differences between them and Example 1 are: the content of the raw material components used is different, and the mass ratio of the feed from the main feed hopper and the side feed hopper is different (this mass ratio is determined according to the amount of raw material added to the main feed hopper and the side feed hopper); the preparation steps of the PBT composite materials provided in Comparative Examples 2-5 are the same as those in Comparative Example 1. The differences between them and Comparative Example 1 are: the content of the raw material components used is different, and the mass ratio of the feed from the main feed hopper and the side feed hopper of the twin-screw extruder is different; the specific raw material component contents are shown in Table 1.

[0118] Table 1. Raw material composition of PBT composite materials in Examples 1-5 and Comparative Examples 1-5

[0119]

[0120]

[0121] Note: The position of mass fraction in Table 1 is recorded as "-", which means that no mass fraction was added.

[0122] Performance Tests and Results

[0123] 1. Melt index test:

[0124] The plastic granules of the PBT composite materials in Examples 1-5 and Comparative Examples 1-5 were dried at 120°C for 3 hours. The melt flow rate (i.e., melt flow rate) of the PBT composite materials was tested according to the method in GB / T 3682.1-2018 Determination of Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastic Plastics. The test results are shown in Table 2. The test conditions for melt flow rate were 250°C / 2.16KG, where the test temperature was 250°C and 2.16KG indicated that the test was conducted under the condition of applying a 2.16kg weight.

[0125] Table 2 Melt flow index of PBT composite materials in Examples 1-5 and Comparative Examples 1-5

[0126]

[0127] Note: The melt flow index in Table 2 is the melt flow rate. The higher the melt flow index, the better the processing fluidity of the PBT composite material.

[0128] As shown in Tables 2 and 3, the melt flow indexes of Examples 1 to 5 range from 19.7 g / 10 min to 36.3 g / 10 min. Compared with Example 1 (melt flow index: 36.3 g / 10 min), although the PBT composite material of Comparative Example 1 contains a toughening agent, its melt flow index is only 26.2 g / 10 min.

[0129] Compared with Example 4, the PBT composite material of Comparative Example 1 has a lower melt index and relatively poor processing fluidity; while the PBT composite material of Comparative Example 2 has a slightly higher melt index. However, the mechanical properties and alkali resistance of the PBT composite material of Example 4 are better than those of Comparative Example 1 and Comparative Example 2.

[0130] Compared to Example 5, the PBT composite material of Comparative Example 5 has a very low melt index and poor processing fluidity; while the PBT composite material of Comparative Example 4 has a slightly higher melt index. Although the intrinsic viscosity values ​​of the PBT raw materials are relatively similar, the mechanical properties and alkali resistance of the PBT composite material of Example 4 are better than those of Comparative Example 4 and Comparative Example 5.

[0131] 2. Testing of mechanical properties and alkali resistance

[0132] In the embodiments and comparative examples of this invention, the PBT composite materials were injection molded into standard test specimens according to relevant standard requirements and tested. The comprehensive mechanical properties of the materials were characterized by tensile strength and flexural strength, and the alkali resistance of the materials was measured by the tensile and flexural properties before and after alkali treatment.

[0133] The test methods for mechanical properties and alkali resistance are as follows:

[0134] 1) The PBT composite materials in Examples 1-5 and Comparative Examples 1-5 were made into specimens, and the tensile strength and flexural strength of each group of specimens without treatment were tested. The tensile strength and flexural strength were recorded as the tensile strength and flexural strength when the alkali treatment time was 0 hours.

[0135] 2) The PBT composite materials in Examples 1-5 and Comparative Examples 1-5 were made into specimens and immersed in 10wt% NaOH solution (i.e., alkaline solution, the solute of the alkaline solution is sodium hydroxide and the solvent is water). After a certain period of time (i.e. 300 hours), they were taken out and placed at room temperature (20-25℃) for 24 hours. Then, the tensile strength and flexural strength of the specimens were tested and the retention rate was calculated. The statistical test data and calculation results are shown in Table 3.

[0136] Tensile strength was tested according to the method in GB / T 1040.2-2006 Determination of Tensile Properties of Plastics, and flexural strength was tested according to the method in GB / T9341-2008 Determination of Flexural Properties of Plastics.

[0137] Table 3 shows the mechanical strength and alkali resistance of the PBT composite materials in Examples 1-5 and Comparative Examples 1-5.

[0138]

[0139]

[0140] Note: The tensile strength and flexural strength in Table 3 reflect the mechanical properties of the PBT composite material itself; the tensile strength, flexural strength, and retention rate after 300 hours of alkali treatment reflect the alkali resistance of the PBT composite material; the tensile strength and flexural strength after 0 hours of alkali treatment are the initial tensile strength and initial flexural strength, respectively; the retention rate in Table 3 includes the tensile property retention rate and the flexural property retention rate, and the relevant calculation formulas are as follows:

[0141] Tensile property retention rate (%) = Tensile strength after 300 hours of alkali treatment / Initial tensile strength × 100%;

[0142] Bending performance retention rate (%) = Bending strength after 300 hours of alkali treatment / Initial bending strength × 100%.

[0143] Analysis of Tables 1, 2, and 3 shows that:

[0144] Compared to Comparative Example 1, Examples 1-5 incorporated 2wt% to 8wt% epoxy resin. After immersion in 10% NaOH solution for 300 hours, the tensile and flexural strength retention rates of the test specimens from Examples 1-5 were both above 90%. In contrast, the mechanical properties of the PBT composite material from Comparative Example 1 decreased sharply after alkali resistance testing; its tensile strength after 300 hours of alkali treatment was only 27.5% of the initial value, and its flexural strength was only 29.3% of the initial value. This indicates that the amount of bisphenol A type epoxy resin added is crucial in the formulation of this invention. An appropriate amount can synergistically work with other components to obtain a PBT composite material with good alkali resistance.

[0145] Epoxy resin can improve the bonding between glass fiber and resin, but if too little epoxy resin is added, it will affect the bonding between glass fiber and PBT resin. If too much epoxy resin is added, the unreacted free epoxy resin will affect the mechanical properties of the PBT composite material. Compared with Comparative Example 2, Examples 2-4 of the present invention can obtain PBT composite materials with high tensile strength and flexural strength while reducing the amount of bisphenol A epoxy resin, using less lubricant, and without using toughening agents. Further analysis shows that compared with Comparative Example 2, the PBT composite materials in Examples 3-4 not only have higher tensile strength and flexural strength, but also better alkali resistance, creating conditions for broadening the application of PBT composite materials.

[0146] Furthermore, as can be seen from Examples 2-4, under the condition that the glass fiber addition amount is 30 wt%, the PBT composite material (i.e., Example 2) prepared when the epoxy resin addition amount is 2 wt% exhibits a tensile strength retention rate of 94.3% and a flexural strength retention rate of 91.6% in the alkali resistance test. With the increase of the bisphenol A type epoxy resin content in the formulation, the retention rates of tensile strength and flexural strength of the PBT composite material can be further improved. When the bisphenol A type epoxy resin content in the formulation is 8 wt%, the tensile strength retention rate measured after the alkali resistance test is 99.4%, and the flexural strength retention rate is 96.2%. However, by comparing Example 4 and Comparative Example 2, it can be seen that when the epoxy resin content exceeds 8 wt%, the retention rates of tensile strength and flexural strength of the PBT composite material decrease after the alkali resistance test. Therefore, the optimal addition amount of epoxy resin in the overall formulation of this invention is 2 wt%-8 wt%.

[0147] Compared with Comparative Example 3, Example 1 did not add toughening agent and the amount of lubricant was only 0.6 wt%. Although Comparative Example 3 added 6 wt% toughening agent AX-8900, the performance retention rate of its test specimens after alkaline treatment was improved, with a tensile strength retention rate of 82.3% and a flexural strength retention rate of 78.5%. However, the mechanical properties, alkaline resistance, and flowability of the PBT composite material containing toughening agent were worse than those of the PBT composite material containing bisphenol A epoxy resin in Example 1 (tensile property retention rate: 96.2%, flexural property retention rate: 95.2%).

[0148] Comparing Examples 5, 4, and 5, the PBT composite material prepared using PBT resin with an intrinsic viscosity of 0.8 dL / g exhibits slightly higher initial tensile and flexural strengths. However, after alkali resistance testing, the retention rates of tensile and flexural strengths are relatively low, at 91.8% and 90.4%, respectively. In contrast, the PBT composite material prepared using PBT resin with an intrinsic viscosity of 1.0 dL / g in Example 5 shows higher retention rates of tensile and flexural properties, at 95.8% and 94.1%, respectively. The PBT composite material prepared using PBT resin with an intrinsic viscosity of 1.2 in Comparative Example 5 shows similar alkali resistance to Example 5, but its mechanical properties and processing fluidity are poorer. Therefore, in the formulation of the invention, the PBT composite material prepared using PBT resin with an intrinsic viscosity of 1.0 dL / g combines the advantages of good processing fluidity, strong mechanical properties, and excellent alkali resistance of PBT composite materials.

[0149] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A PBT composite material, characterized in that, It consists of the following components in parts by mass: PBT resin: 55 parts to 85 parts; Fiberglass: 10 to 40 parts; Epoxy resin: 2 to 8 parts; Antioxidant: 0.4 to 0.6 parts; Lubricant: 0.4 parts to 0.6 parts; The intrinsic viscosity of the PBT resin is 0.95 dL / g to 1.15 dL / g; the glass fiber is chopped alkali-free glass fiber with a single filament diameter of 7 μm to 11 μm and a chopped length of 3 mm to 5 mm.

2. The PBT composite material according to claim 1, characterized in that: The antioxidant is a compound antioxidant system composed of antioxidant 1010 and antioxidant S-9228 in any proportion.

3. The PBT composite material according to claim 1, characterized in that: The lubricant is one or more of pentaerythritol stearate, zinc stearate, barium stearate, and calcium stearate.

4. The PBT composite material according to claim 1, characterized in that: The epoxy resin is a bisphenol A type epoxy resin, and the epoxy equivalent of the bisphenol A type epoxy resin is 1 Eq / kg to 2 Eq / kg.

5. A method for preparing the PBT composite material according to any one of claims 1 to 4, characterized in that, Includes the following steps: 1) PBT resin, epoxy resin, antioxidant and lubricant are mixed in the proportions of mass described in claim 1 to obtain a premix; 2) The premix and glass fiber are mixed according to the mass fractions described in claim 1 to obtain the PBT composite material.

6. The method for preparing the PBT composite material according to claim 5, characterized in that, Step 2) The mixing and extrusion temperature is 200℃~250℃.

7. The application of the PBT composite material as described in any one of claims 1 to 4 in the production of electronic and electrical, mechanical, or chemical materials.

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