A pbt composition, its preparation and use

Abstract

The application discloses a PBT composition and a preparation method and application thereof, and belongs to the technical field of high polymer materials. The product is prepared by compounding two PBT matrix resins with different melting points, and is prepared by compounding an organic solid phosphate ester and a sub-organic halogen-free flame retardant as a flame-retardant component, and is prepared by introducing an ultrasonic welding modifier with a specific composition for cooperation, so that the flame retardance, processable fluidity and excellent ultrasonic welding effect of an ultrathin size can be realized.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a PBT composition, its preparation method, and its application. Background Technology

[0002] In addition to needing sufficient flame retardancy and processing performance to meet production and usage requirements, plastic parts used in the electronics and electrical industry also need to have ultrasonic welding performance because they are often processed by ultrasonic welding.

[0003] Ultrasonic welding is a process that fuses plastic products using ultrasound. It is commonly used in the production of small electrical components such as charger housings, USB connectors, and low-voltage electrical appliance housings. One of the factors affecting welding quality is the type of plastic being welded. For example, PBT (polybutylene terephthalate), a material frequently used in the electrical industry, has good mechanical strength and processing properties, but it is a fast-crystallizing material. In its solid state, the weld surface is difficult to melt, requiring additional welding time or pressure. On the other hand, due to the significant difference in shrinkage rates between the injection molding flow direction and the vertical direction of PBT material, some thin and lightweight products may experience significant warping, which seriously affects the ultrasonic welding process.

[0004] In addition, inorganic materials present in PBT materials can also reduce their ultrasonic welding performance. Summary of the Invention

[0005] Based on the deficiencies of existing technologies, the present invention aims to provide a PBT composition. This product is made by compounding two PBT matrix resins with different melting points, and uses organic solid phosphate esters combined with a secondary organic halogen-free flame retardant as a flame retardant component. A specific ultrasonic welding modifier is introduced for synergistic effect, which can achieve flame retardancy, processability and fluidity in ultra-thin dimensions, and excellent ultrasonic welding effect.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A PBT composition comprising the following components in parts by weight:

[0008] PBT resin 1 30-45 parts, PBT resin 2 8-15 parts, organic halogen-free flame retardant 8-16 parts, phosphate ester 3-7 parts, ultrasonic welding modifier 1-4 parts, glass fiber 20-35 parts.

[0009] The melting point of PBT resin 1 is 220-235℃, and the melting point of PBT resin 2 is ≤200℃;

[0010] The phosphate ester has a melting point ≥90℃;

[0011] The ultrasonic welding modifier includes a polyether block amide elastomer;

[0012] The length of the glass fiber is ≤100μm.

[0013] Preferably, the mass ratio of PBT resin 1 to PBT resin 2 is (2.1 to 4.9): 1.

[0014] Preferably, the mass ratio of PBT resin 1 to PBT resin 2 is one or any two of the following: 2.1:1, 2.3:1, 2.5:1, 2.8:1, 2.9:1, 3:1, 3.5:1, 3.7:1, 4:1, 4.5:1, 4.9:1.

[0015] More preferably, the mass ratio of PBT resin 1 to PBT resin 2 is (2.9 to 3.7):1.

[0016] More preferably, the PBT resin 1 is in the form of 35 to 27 parts by weight, and the PBT resin 2 is in the form of 10 to 12 parts by weight.

[0017] More preferably, the ultrasonic welding modifier is present in 2 to 3 parts by weight.

[0018] Preferably, in the PBT composition, the total mass content of PBT resin 1 and PBT resin 2 is ≥50wt%.

[0019] PBT resin has a high melting point, fast crystallization rate, and high degree of crystallization, resulting in good heat resistance, but it is difficult to process effectively using conventional ultrasonic welding techniques. On the other hand, to meet basic usage requirements, PBT materials are often compounded with functional additives such as fillers and flame retardants during processing. If these additives contain a high proportion of inorganic components, it will also reduce the ultrasonic welding efficiency of the product. Based on this, in the technical solution of this invention, PBT resins with different melting points are compounded. The high-melting-point PBT resin 1 maintains the basic mechanical strength requirements, while the low-melting-point PBT resin effectively reduces the melting energy consumption of the overall matrix resin, widens the process window for ultrasonic welding, increases the fluidity of the product, and ultimately improves the ultrasonic welding performance of the product. On the other hand, the technical solution of this invention uses pure organic flame retardants and glass fibers of specific lengths as functional additives. On the one hand, the phosphate esters of specific melting points are solid at room temperature, but can be melted and plasticized in the processing temperature range. Without affecting the fluidity and flame retardancy, the ultrasonic welding performance is far superior to other inorganic or organic flame retardant synergists. On the other hand, the ultra-short glass fibers have better dispersion performance and thermal conductivity in the product, and lower anisotropy, which can fully guarantee the ultrasonic welding performance of the product and basically does not affect the mechanical properties of the product. After optimizing the design of the main resin and functional additives, the technical solution of this invention also uses a PA elastomer with polyamide as the hard segment and polyether as the soft segment as an ultrasonic welding modifier for synergistic compounding. This component has high compatibility with PBT resin and can further improve the toughness of the product. At the same time, it can effectively combine with the resin after the resin melts and improve its ultrasonic welding performance, so that the product has sufficient pull-out force during the welding process.

[0020] Through the synergistic use of these components, the product not only achieves high flame retardancy in a thin and light size, but also has good flowability, good ultrasonic welding effect, and excellent overall performance. If other types or conventional similar components are used as substitutes, the product performance will be significantly reduced. In addition, the product ratio of each component is also the key to achieving the expected performance. For example, if the proportion of PBT resin 2 added is too small, the product will have poor flowability and poor ultrasonic welding effect. However, if it is added too much, the crystallinity of the product will be significantly reduced, the mechanical strength of the product will be poor, and the injection molding effect will be poor.

[0021] Preferably, the intrinsic viscosity of the PBT resin 1 at 25°C is 0.8 to 0.9 dL / g.

[0022] More preferably, the melting point of the PBT resin 1 is a range of one or any two of 220°C, 222°C, 223°C, 225°C, and 228°C.

[0023] Preferably, the intrinsic viscosity of the PBT resin 2 at 25°C is 0.8 to 0.95 dL / g.

[0024] More preferably, the melting point of the PBT resin 2 is 160-200°C, more preferably 175-195°C, and even more preferably, the melting point of the PBT resin 2 is one or any two of the following: 175°C, 185°C, 190°C, 192°C, 195°C, 198°C, and 200°C.

[0025] Preferably, the organic halogen-free flame retardant is a hypophosphite flame retardant.

[0026] Preferably, the phosphate ester is at least one of 1,3-phenylene phosphate tetra(2,6-dimethylphenyl) ester and hydroquinone bis(diphenyl phosphate), with a melting point of 92-110°C.

[0027] The high-melting-point phosphate ester described in this invention contains phosphorus-oxygen double bonds, which can improve the stability of hypophosphite flame retardants in the resin matrix to a certain extent, allowing them to fully exert their flame retardant properties, while also improving the overall product's component uniformity and flame retardancy in a lightweight and thin design.

[0028] Preferably, the average diameter of the glass fiber is 10–15 μm.

[0029] Preferably, the average length of the glass fiber is 50–80 μm.

[0030] The average diameter and average length of the glass fiber described in this invention are tested using a two-dimensional microscope. The specific method is as follows: the glass fiber is ultrasonically dispersed in anhydrous ethanol, and then at least 200 glass fiber monofilaments are screened under a two-dimensional microscope. The diameter and length are confirmed using image mapping software, and the average value is calculated, which is the average diameter and average length of the glass fiber.

[0031] Preferably, the ultrasonic welding modifier is a nylon 6 elastomer.

[0032] Preferably, the density of the ultrasonic welding modifier is 1.0–1.2 g / cm³. 3 .

[0033] Preferably, the Shore hardness of the ultrasonic welding modifier is 40D to 55D.

[0034] Preferably, the PBT composition further comprises 2 to 4 parts of toughening agent.

[0035] More preferably, the toughening agent is at least one of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and ethylene-butyl acrylate-glycidyl methacrylate terpolymer.

[0036] Introducing a specific amount of toughening agent into the product can further enhance its mechanical strength, making it exhibit stronger pull-out force during ultrasonic welding.

[0037] Preferably, the PBT composition further comprises 0.5 to 1.5 parts of lubricant.

[0038] More preferably, the lubricant is at least one of ester-based lubricants, amide-based lubricants, and oxidized polyethylene-based lubricants.

[0039] More preferably, the lubricant is an oxidized polyethylene lubricant, and the oxidized polyethylene lubricant has a melting point of 90-110°C.

[0040] When oxidized polyethylene lubricants are used in the PBT composition described in this invention, on the one hand, their lubricating effect can improve the overall external lubricity of the components, reduce the system viscosity of the product during processing, increase the compatibility between the components and the resin, and further improve the ultrasonic welding effect of the product. On the other hand, the components can also have a synergistic effect with polyether block amide elastomers, strengthen the adhesion effect of the compounded resin, and ultimately improve the ultrasonic welding performance of the product.

[0041] Preferably, the PBT composition further includes 0.1 to 0.3 parts of a chain extender.

[0042] More preferably, the chain extender is at least one of bisphenol A diglycidyl ether and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate.

[0043] Introducing a chain extender into the components of the PBT composition of the present invention can accelerate the binding of small molecules during product processing, reduce the degree of degradation of components, and at the same time improve the degree of molecular chain fusion of each component during ultrasonic welding, thereby improving the welding effect.

[0044] Preferably, the PBT composition further comprises 0.1 to 0.3 parts of antioxidant.

[0045] More preferably, the antioxidant is a hindered phenolic antioxidant, and even more preferably, at least one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

[0046] More preferably, the components of the PBT composition may include, but are not limited to, antistatic agents, light stabilizers, solvent resistant agents, etc. Based on the processing or actual use needs of those skilled in the art, other types of functional additives may be added without affecting the expected performance of the product. For example, the above-mentioned additives can improve the antistatic ability, anti-photoaging ability and solvent resistance of the product without affecting the flame retardancy, flowability and ultrasonic welding performance of the product. In order to give the product color, those skilled in the art may also add a certain amount of colorant to the product. That is, the description of the components of the PBT composition in the technical solution of the present invention is not a limitation on its types.

[0047] Another object of the present invention is to provide a method for preparing the PBT composition, comprising the following steps:

[0048] The components are added to a screw extruder for melt extrusion granulation to obtain the PBT composition.

[0049] Preferably, the temperature zones of the screw extruder are set as follows: Zone 1 200-230℃, Zone 2 240-260℃, Zone 3 235-255℃, Zone 4 235-255℃, Zone 5 235-255℃, Zone 6 240-260℃, Zone 7 240-260℃, Zone 8 220-240℃, Zone 9 220-240℃, and Zone 10 240-260℃, and the screw speed is 200-450 rpm.

[0050] Another object of the present invention is to provide the application of the PBT composition in the manufacture of electronic and electrical components.

[0051] Preferably, the electronic and electrical components include at least one of a charger housing, a USB connector, and a low-voltage electrical appliance housing.

[0052] The PBT composition of this invention is based on its compounded dual-melting-point matrix resin, and at the same time introduces specific types of fillers, flame retardant system additives and ultrasonic welding modifiers to achieve synergistic effects. It can not only achieve high flow while maintaining the flame retardancy of the product and designing a thinner (0.4mm) product, but also significantly improve its ultrasonic welding performance compared with traditional PBT composite materials. When applied to the production of electronic and electrical components with corresponding requirements, the production efficiency and production quality are significantly improved, and the ultrasonic welding pull-out force reaches more than 170N.

[0053] The beneficial effects of this invention are that it provides a PBT composition, which is made by compounding two PBT matrix resins with different melting points, and using organic solid phosphate esters combined with a secondary organic halogen-free flame retardant as a flame retardant component, and introducing an ultrasonic welding modifier of a specific composition for synergistic effect, which can achieve flame retardancy, processability and fluidity in ultra-thin dimensions, and excellent ultrasonic welding effect. Detailed Implementation

[0054] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0055] Examples 1-16

[0056] An embodiment of the PBT composition, its preparation method and application described in this invention, wherein the composition of the PBT composition is shown in Table 1.

[0057] The method for preparing the PBT composition includes the following steps:

[0058] The components are mixed evenly, and then melt-extruded and granulated in a twin-screw extruder to obtain the PBT composition.

[0059] During melt extrusion of the component, the temperature zones of the twin-screw extruder are set as follows: Zone 1 210℃, Zone 2 245℃, Zone 3 250℃, Zone 4 250℃, Zone 5 255℃, Zone 6 250℃, Zone 7 245℃, Zone 8 240℃, Zone 9 235℃, Zone 10 240℃, and the screw speed is 300 rpm.

[0060] Comparative Examples 1-9

[0061] The only difference between each comparative example and the embodiment is the type and ratio of components, as shown in Table 2.

[0062] In the components described in each embodiment and comparative example,

[0063] The PBT resin a is PBT GX112 produced by Yizheng Chemical Fiber, with a melting point of 233℃ and an intrinsic viscosity of 0.82 dL / g at 25℃.

[0064] The PBT resin b is PBT GX112J produced by Yizheng Chemical Fiber, with a melting point of 223.2℃ and an intrinsic viscosity of 0.85 dL / g at 25℃.

[0065] The PBT resin c is PBT DR905 produced by Yizheng Chemical Fiber, with a melting point of 190℃ and an intrinsic viscosity of 0.894 dL / g at 25℃.

[0066] The PBT resin d is a self-made product, prepared according to the method described in Example 2 of CN109575252A, with a melting point of 186℃ and an intrinsic viscosity of 0.838dL / g at 25℃.

[0067] The organic halogen-free flame retardant is Clariant's Exolit OP1230, a hypophosphite flame retardant.

[0068] Phosphate ester 1 is PX200, 1,3-phenylene phosphate tetratetra(2,6-dimethylphenyl) ester, produced by Daihachi Chemical Industry Co., Ltd., with a melting point of 95°C.

[0069] Phosphate ester 2 is WSFR-PX-220 produced by Zhejiang Wansheng, hydroquinone bis(diphenyl phosphate), with a melting point of 92℃;

[0070] Phosphate 3 is triphenyl phosphate produced by Shanghai Zhuhui New Materials Co., Ltd., with a melting point of 49.9℃;

[0071] The melamine polyphosphate mentioned is melamine cyanurate produced by Sichuan Fine Chemical Research and Design Institute.

[0072] The ultrasonic welding modifier 1 is produced by Arkema, France. MH 2030, a polyether block amide elastomer with a density of 1.14 g / cm³. 3 Shore hardness 40D;

[0073] The ultrasonic welding modifier 2 is produced by Arkema, France. 55R53SP 01, polyether block amide elastomer, density 1.03 g / cm³ 3 Shore hardness 52D;

[0074] The ultrasonic welding modifier 3 is NEUSoft manufactured by Arkema, France. TM UR842A Natural, polyether block polyurethane elastomer, density 0.948 g / cm³ 3 Shore hardness 42A;

[0075] The glass fiber 1 is MF 7904 manufactured by Lanxess in Germany, with a length ≤100μm, an average length of 50μm, and an average diameter of 14μm;

[0076] The glass fiber 2 is EPH 80M-01N manufactured by Nippon Electric Glass Co., Ltd., with a length ≤100μm, an average length of 80μm, and an average diameter of 10.5μm;

[0077] The glass fiber 3 is MF 7980 manufactured by Lanxess in Germany, with a length >100μm, an average length of 190μm, and an average diameter of 14μm;

[0078] The glass fiber 4 is MF 7982 manufactured by Lanxess in Germany, with a length >100μm, an average length of 210μm, and an average diameter of 14μm;

[0079] The toughening agent is Arkema AX8900, a terpolymer of ethylene-methyl acrylate-glycidyl methacrylate produced in France.

[0080] The lubricant 1 is PED 521, an oxidized polyethylene wax lubricant manufactured by Clariant, with a melting point of 103°C;

[0081] The lubricant 2 is PETS-AP, an ester-based lubricant produced by Italian company Fagi, with a melting point of 60°C.

[0082] The lubricant 3 is EBS B50, an amide-based lubricant produced by Guangzhou Runfeng Chemical Co., Ltd., with a melting point of 142℃.

[0083] The chain extender is commercially available bisphenol A diglycidyl ether;

[0084] The antioxidant is a commercially available 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

[0085] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0086] Table 1

[0087]

[0088]

[0089] Table 2

[0090]

[0091] To verify the performance of the PBT composition described in this invention, the products prepared in each embodiment and comparative example were subjected to the following performance tests, with the specific steps as follows:

[0092] (1) Flame retardant performance test: The products of each embodiment and comparative example were injection molded into thin vertical strips of 127*13*0.8mm and 127*13*0.4mm, and the flame retardant rating was tested according to UL94-2020 standard;

[0093] (2) Flowability test: The spiral length of each product was measured under the conditions of 260℃ and 80MPa pressure. After 51 consecutive injection moldings, the spiral length of the last molded product was tested. The longer the spiral length, the better the product's molding flowability.

[0094] (3) Ultrasonic welding performance test: Each product was injection molded into a sample of 80*10*4mm and ultrasonically welded. The welding area was 10*10mm, the pressure was 20MPa, the welding time was 0.5s, and the pressure was held for 1s. Then, the tensile strength of the ultrasonic welding was tested by a tensile tester. The greater the tensile strength, the better the ultrasonic welding performance.

[0095] The test results are shown in Tables 3 and 4.

[0096] Table 3

[0097]

[0098] Table 4

[0099]

[0100] As can be seen from Tables 3 and 4, the PBT composition of the present invention has ideal comprehensive performance. The flame retardant rating of the product can reach V0 level at a thickness of 0.8 mm, and V2 level at a thinner thickness of 0.4 mm, demonstrating excellent flame retardant performance. At the same time, the spiral length of the product can reach more than 290 mm, which fully demonstrates that the product has considerable fluidity and excellent processing performance. In terms of ultrasonic welding performance, the pull-out force of the product after welding using conventional ultrasonic welding process can reach 170 N or more.

[0101] Based on Comparative Examples 1-2 and Examples 1, 4-6, and 10-11, it can be seen that blending two PBT resins with different melting points significantly improves the flowability and ultrasonic welding performance. With the total PBT resin content remaining constant, if low-melting-point PBT resin is not used in the blend, as shown in Comparative Example 1, although the flame retardant performance of the product is not affected, the helix length and pull-out force are substandard. As the amount of low-melting-point PBT resin increases, the flowability and ultrasonic welding performance of the product gradually improve. However, after reaching a certain level, the crystallinity of the product decreases, affecting not only the ultrasonic welding performance but also the flame retardancy due to molding issues, as shown in Comparative Example 2. When the ratio of the two resins is within the range of (2.9-3.7):1, the products of Examples 1 and 5 exhibit superior overall performance.

[0102] On the other hand, the use of ultrasonic welding modifier in the product of this invention is also key to achieving ideal ultrasonic welding performance. As can be seen from Examples 1, 12, and Comparative Example 7, when selecting its type, if other commercially available types of non-polyether block amide elastomers are chosen, the product will not achieve the expected improvement effect, and the pull-out force after ultrasonic welding will be low. Furthermore, as can be seen from Examples 1, 7-9, and Comparative Examples 5-6, with a small amount added, the product not only has low mechanical strength, but also the compatibility and dispersibility of the components are not ideal, making effective ultrasonic welding impossible. As shown in Comparative Example 5, although it has high fluidity, it has low pull-out force and even exhibits a low level in terms of flame retardancy. As the amount of ultrasonic welding modifier added increases, the fluidity of the product gradually decreases. As a result, the flame retardancy and pull-out force after ultrasonic welding of the product are significantly improved. When the amount added is 1 to 4 parts, the product can achieve high flame retardancy and high ultrasonic weldability while ensuring sufficient fluidity. However, if the amount added is too much, as shown in Comparative Example 6, the fluidity of the product is poor, which affects the uniformity of the product components. The flame retardancy of the product decreases, and the pull-out force is also reduced to a level similar to that of Comparative Example 5.

[0103] Besides key additives, the selection of flame retardant synergists and fillers also has a decisive impact on the performance of the product. As shown in Examples 1, 12, and Comparative Examples 3-4, there are many types of phosphate-based synergists used as flame retardant synergists. However, in the product system described in this invention, if non-phosphate ester phosphate synergists or low-melting-point phosphate ester synergists are used, they cannot work together with the ultrasonic welding modifier and low-melting-point PBT resin to improve the product's flowability and ultrasonic welding effect. Furthermore, as can be seen from the comparison of Examples 1, 13, and Comparative Examples 8-9, in the product described in this invention, if longer glass fibers are used, the high degree of anisotropy reduces their dispersibility in the product, and the product cannot achieve ideal flowability and ultrasonic welding performance.

[0104] As can be seen from Examples 1 and 14-15, the performance of the product varies when different lubricants are used. When an oxidized polyethylene lubricant is used in combination, it can have a synergistic effect with the ultrasonic welding modifier, increasing the adhesion of the resin components and further improving the pull-out force of the product.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention 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 the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PBT composition, characterized in that, The components include the following parts by weight: 30-45 parts of PBT resin 1, 8-15 parts of PBT resin 2, 8-16 parts of organic halogen-free flame retardant, 3-7 parts of phosphate ester, 1-4 parts of ultrasonic welding modifier, and 20-35 parts of glass fiber. The melting point of PBT resin 1 is 220~235℃, and the melting point of PBT resin 2 is ≤200℃; The phosphate ester has a melting point ≥90℃; The ultrasonic welding modifier is a polyether block amide elastomer; The length of the glass fiber is ≤100μm.

2. The PBT composition according to claim 1, characterized in that, The mass ratio of PBT resin 1 to PBT resin 2 is (2.1~4.9):

1.

3. The PBT composition according to claim 1, characterized in that, The PBT composition also includes 2 to 4 parts toughening agent.

4. The PBT composition according to claim 3, characterized in that, The toughening agent is at least one of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and ethylene-butyl acrylate-glycidyl methacrylate terpolymer.

5. The PBT composition according to claim 1, characterized in that, The PBT composition also includes 0.5 to 1.5 parts of lubricant.

6. The PBT composition according to claim 5, characterized in that, The lubricant is at least one of ester-based lubricants, amide-based lubricants, and oxidized polyethylene-based lubricants.

7. The PBT composition according to claim 1, characterized in that, The PBT composition further includes 0.1 to 0.3 parts of chain extender and / or 0.1 to 0.3 parts of antioxidant.

8. The PBT composition according to claim 7, characterized in that, The chain extender is at least one of bisphenol A diglycidyl ether and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate; the antioxidant is a hindered phenolic antioxidant.

9. A method for preparing the PBT composition according to any one of claims 1 to 8, characterized in that, Includes the following steps: The components are added to a screw extruder for melt extrusion granulation to obtain the PBT composition.

10. The use of the PBT composition according to any one of claims 1 to 8 in the manufacture of electronic and electrical components.

11. The application as described in claim 10, characterized in that, The electronic components include one of the following: charger housing, USB connector, and low-voltage electrical appliance housing.

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