PBT (polybutylene terephthalate) composite material as well as preparation method and application thereof

Abstract

The invention discloses a PBT (polybutylene terephthalate) composite material and a preparation method and application thereof, and belongs to the technical field of high polymer materials, according to the product, PBT with low carboxyl content is compounded with high-flowability PP (polypropylene) to serve as an organic resin system, and meanwhile, nano-zirconia particles are introduced to serve as a stability regulator, so that the hydrolysis resistance of the product in a humid and hot environment can be effectively improved, and the service life of the product is prolonged. The alkali resistance is good, the comprehensive stability is good, and the application scene is wide.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a PBT composite material and a preparation method and application thereof. BACKGROUND

[0002] Glass fiber reinforced PBT (polybutylene terephthalate) is a kind of high polymer composite material with high processability, high insulation and high mechanical properties, which is widely used in fields such as electronic and electrical parts, automobile parts and the like. However, PBT has high density due to a large number of benzene rings in its molecular structure, and also contains a large number of ester groups in its molecular structure, which leads to decomposition of the product in a humid environment, low alkali resistance, continuous attenuation of mechanical properties (such as tensile strength) in actual application, poor durability, and can only be applied in some scenes with relatively single environmental composition. SUMMARY

[0003] Based on the defects of the prior art, the purpose of the present application is to provide a PBT composite material, which uses PBT with low carboxyl content and high flowability PP (polypropylene) as an organic resin system, and introduces nano zirconium oxide particles as a stability regulator, which can effectively improve the hydrolysis resistance of the product in a humid environment, has good alkali resistance, good comprehensive stability, and wide application scenarios.

[0004] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: A PBT composite material comprises the following components by weight: PBT resin 52-71 parts, PP resin 10-20 parts, glass fiber 15-35 parts, stability regulator 0.5-3 parts, and compatibility agent 3-10 parts. The carboxyl content of the PBT resin is ≤30 mol / t. The melt flow rate of the PP resin is ≥30 g / 10 min at 230℃ and 2.16 kg according to ISO 1133-2011. The stability regulator comprises nano zirconium oxide particles.

[0005] In order to improve the product's resistance to hydrolysis and alkali resistance, in the technical scheme of the present application, low carboxyl content PBT resin and high flow PP resin are compounded to form an organic resin matrix, which can effectively improve the chemical stability of PBT resin, reduce the polarity difference between PBT resin and PP resin, and improve the compatibility of the overall matrix resin. On the other hand, PP resin itself does not absorb water, which can reduce the probability of direct contact between external water and PBT resin in a humid environment, and can also reduce the ester content per unit volume of the overall product through reaction. The high flow can effectively disperse on the surface of PBT resin to form a protective barrier, thereby improving the product's resistance to hydrolysis and alkali resistance. However, there is still a large polarity difference between PBT resin and PP resin after blending, and the PP resin at the two-phase interface is prone to spherulite growth and size increase. Even with the help of a compatibilizer, it is still difficult to achieve uniform compatibility of the two phases, and the stability is low, so it is difficult to achieve long-term resistance to hydrolysis and alkali resistance. Therefore, in the product of the present application, nano-sized zirconium oxide is further introduced as a stability regulator. Zirconium is a transition metal, which has high charge density and empty d orbital characteristics, and is easy to coordinate with carboxyl or hydroxyl in PBT resin to form a complex. It can not only disperse uniformly in the resin to improve the crystallinity of PBT resin, but also inhibit the spherulite growth of PP resin in the two-phase region, thereby ensuring the long-term compatibility of the resin matrix composition. If the zirconium oxide used is not nano-sized, or other types of inorganic or organic stability regulators are used, the same effect cannot be achieved.

[0006] In some embodiments, the weight fraction of the PBT resin is one or any range value of 52 parts, 54 parts, 55 parts, 58 parts, 60 parts, 65 parts, 70 parts, 71 parts, the weight fraction of the PP resin is one or any range value of 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, the weight fraction of the glass fiber is one or any range value of 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, the weight fraction of the compatibilizer is one or any range value of 3 parts, 5 parts, 6 parts, 8 parts, 10 parts, and the weight fraction of the stability regulator is one or any range value of 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts.

[0007] More preferably, the mass content of the PBT resin in the PBT composite material is ≥40wt%.

[0008] More preferably, the PBT composite material comprises the following components by weight: PBT resin 55-70 parts, PP resin 12-18 parts, glass fiber 20-30 parts, stability regulator 1-2 parts, compatibilizer 5-8 parts.

[0009] In some embodiments, the PBT resin has a carboxyl content of 10-30 mol / t.

[0010] In some embodiments, the PBT resin has a carboxyl content of one or a range value of any two of 10 mol / t, 12 mol / t, 15 mol / t, 18 mol / t, 20 mol / t, 22 mol / t, 25 mol / t, 30 mol / t.

[0011] Further preferably, the PBT resin has a carboxyl content of 15-22 mol / t.

[0012] The carboxyl content of the PBT resin, as described above, needs to be controlled in a lower range, and if further preferred in the above range, the relative viscosity of the PBT resin can be maintained at a suitable level, and the reactivity with the compatibilizer can also be maintained at a more optimal level, and the product performance is more optimal.

[0013] The carboxyl content of the PBT resin is the terminal carboxyl content of the PBT, which can be determined by, but not limited to, the method A in chapter 5.4 of GB / T14190-2017.

[0014] In some embodiments, the PBT resin has a melt flow rate of 15-50 g / 10 min at 250°C under a load of 1.2 kg according to ISO 1133-1-2011.

[0015] Preferably, the PP resin comprises at least one of a homopolymer PP resin, a copolymer PP resin.

[0016] More preferably, the PP resin is a copolymer PP resin.

[0017] Preferably, the PP resin has a melt flow rate of 20-80 g / 10 min at 230°C under a load of 2.16 kg. More preferably, the PP resin has a melt flow rate of 30-60 g / 10 min at 230°C under a load of 2.16 kg.

[0018] When the melt flow rate of the PP resin is preferably in the above range, not only the thermal stability of the product during processing can be ensured, but also the uniformity of the dispersion of the components can be ensured, and the functional additives can have more optimal effect.

[0019] In some embodiments, the glass fiber has an average diameter of 8-13 μm and an average length of 3-6 mm.

[0020] More preferably, the glass fiber is a silane coupling agent modified glass fiber.

[0021] The type of the glass fiber is not particularly limited, and any type of glass fiber commonly used in the existing PBT system reinforced by glass fiber can be used, which can be commercially available or self-made. For example, a person skilled in the art can select glass fibers of different sizes based on actual mechanical performance requirements, as long as the effects of the key components, i.e., the PP resin and the stability regulator, are not affected, and the product can achieve acceptable moisture and heat hydrolysis resistance and alkali resistance.

[0022] Preferably, the average particle size of the nano zirconium oxide particles is 10-1000 nm.

[0023] Preferably, the average particle size of the nano zirconium oxide particles is one of 10 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm or a range value of any two thereof.

[0024] Further preferably, the average particle size of the nano zirconium oxide particles is 50-800 nm. Further preferably, the average particle size of the nano zirconium oxide particles is ≥100 nm.

[0025] Further preferably, the average particle size of the nano zirconium oxide particles is 100-200 μm.

[0026] When the nano-sized zirconium oxide particles in the above range are preferably used, the uniformity when the particles are complexed and dispersed with the PBT resin is better, the degree of agglomeration is lower, and the compatibility of the two-phase interface of the PBT and PP resins is more improved, and the overall environmental performance of the product is more optimal.

[0027] The average particle size of the nano zirconium oxide particles is directly tested and confirmed by a laser particle size analyzer (non-sedimentation method), and the tested particle Dv50 is the average particle size of the nano zirconium oxide particles.

[0028] More preferably, the nano zirconium oxide particles are silane coupling agent surface modified nano zirconium oxide particles.

[0029] More preferably, the content of the silane coupling agent and the nano zirconium oxide particles in the silane coupling agent surface modified nano zirconium oxide particles is (3-10): 100.

[0030] More preferably, the silane coupling agent includes at least one of an epoxy silane, an alkyl silane, and an amino silane.

[0031] More preferably, the silane coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, methyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, chloropropylmethyldiethoxysilane, and dodecylmethyldimethoxysilane.

[0032] More preferably, the silane coupling agent surface modified nano-zirconium oxide particles can be a commercially available product or a self-made product. When preparing, the nano-zirconium oxide particles and the silane coupling agent D can be mixed according to a set mass ratio, then stirred at 60-80°C for 12-24h, and vacuum dried to obtain the material.

[0033] The surface modification by the silane coupling agent can ensure that the nano-zirconium oxide particles can achieve good processing dispersibility after entering the matrix resin, and achieve the expected stability regulation effect.

[0034] Preferably, the compatilizer includes at least one of maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted polyolefin elastomer, ethylene-methyl acrylate-methyl methacrylate glycidyl ester.

[0035] More preferably, the maleic anhydride grafting rate of the maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, and maleic anhydride grafted polyolefin elastomer is 1-3%.

[0036] In the product, the type of compatilizer is not particularly required, and any common type suitable for glass fiber reinforced PBT resin is acceptable. The compatilizer has different effects from the stability regulator and the PP resin in the present application, and therefore, as long as the effects of the two are not affected when used, the product can have the expected resistance to hydrolysis and resistance to alkali.

[0037] Preferably, the components of the PBT composite material can include, but are not limited to, antistatic agents, lubricants, flame retardants, antioxidants, etc. Based on the processing or actual use of the product by those skilled in the art, other types of functional additives can be added without affecting the expected performance of the product, for example, the above-mentioned additives can improve the antistatic ability, processing ability, flame retardance and antioxidant property of the product without affecting the characteristic performance of the product. That is, the component description of the present application is not a limitation on the type of product.

[0038] More preferably, the PBT composite material includes 0.2-0.5 parts of an antioxidant and / or 0.2-0.5 parts of a lubricant.

[0039] More preferably, the antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant.

[0040] Further, the hindered phenolic antioxidant includes at least one of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and the phosphite antioxidant includes at least one of tris[2.4-di-tert-butylphenyl]phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, and triisooctyl phosphite.

[0041] More preferably, the antioxidant is a mixture of the hindered phenolic antioxidant and the phosphite antioxidant, and the mass ratio of the two is (0.5~1.5):(0.5~1.5).

[0042] More preferably, the lubricant includes at least one of an organosilane lubricant, a wax lubricant, and an alcohol ester lubricant.

[0043] Another object of the present application is to provide a preparation method of the PBT composite material, including the following steps: Each component is added to a screw extruder for melt extrusion granulation, and the PBT composite material is obtained.

[0044] Preferably, the temperature zones of the screw extruder are set as follows: the first zone is 130~150℃, the second zone is 220~240℃, the third zone is 230~250℃, the fourth zone is 190~210℃, the fifth zone is 190~210℃, the sixth zone is 190~210℃, the seventh zone is 190~210℃, and the eighth zone is 190~210℃, the screw rotation speed is 250~400rpm, and the length-diameter ratio is (25~30):1.

[0045] Another object of the present application is to provide the application of the PBT composite material in the preparation of an outer packaging material.

[0046] Specifically, the outer packaging material includes automobile packaging parts, such as automobile interior packaging parts, automobile outer packaging parts, etc., or includes electrical packaging devices, such as electrical housings, electrical separation layers, etc.

[0047] Another object of the present application is to provide an outer packaging material including the PBT composite material.

[0048] The PBT composite material can not only realize long-time resistance to hydrolysis in wet heat and resistance to alkali, so that the product can maintain effective usability in such an environment and does not appear mechanical property attenuation, but also is very suitable for application scenarios such as automobile packaging parts or electrical packaging devices which have certain requirements for insulation, environmental resistance, and mechanical strength.

[0049] The PBT composite material provided by the application has the advantages that the product is prepared by using PBT with low carboxyl content and high-fluidity PP as the organic resin system, and nano-zirconium oxide particles are introduced as a stability regulator, so that the hydrolysis resistance of the product in a humid and hot environment can be effectively improved, the product has good alkali resistance and good comprehensive stability, and the application scenarios are wide. DETAILED DESCRIPTION

[0050] In order to better illustrate the purposes, technical solutions and advantages of the application, the application will be further described below in combination with specific examples and comparative examples, and the purpose is to understand the content of the application in detail, rather than to limit the application. All other examples obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of the application are common ordinary reagents and instruments.

[0051] Examples 1-12 The composition of the PBT composite material in the examples of the application is shown in Table 1.

[0052] The preparation method of the PBT composite material comprises the following steps: The components are uniformly mixed, and then granulated by melt extrusion in a twin-screw extruder, to obtain the PBT composite material.

[0053] When the components are melt-extruded, the temperature zones of the screw extruder are set as 140 DEG C for the first zone, 230 DEG C for the second zone, 240 DEG C for the third zone, 200 DEG C for the fourth zone, 200 DEG C for the fifth zone, 200 DEG C for the sixth zone, 200 DEG C for the seventh zone, 200 DEG C for the eighth zone, the screw rotation speed is 300 rpm, and the length-diameter ratio is 28:1.

[0054] Comparative Examples 1-8 The difference between each comparative example and Example 1 is only in the types and proportions of the components, as shown in Table 2.

[0055] In the components of each example and comparative example, The PBT resin 1 is PBT GX112J produced by Yizheng Chemical Fibre, has a carboxyl end group content of 10 mol / t, and a melt flow rate of 34 g / 10 min (250 DEG C, 1.2 kg) ; The PBT resin 2 is PBT GX121J produced by Yizheng Chemical Fibre, has a carboxyl end group content of 15 mol / t, and a melt flow rate of 28 g / 10 min (250 DEG C, 1.2 kg) ; The PBT resin 3 is PBT GX121 produced by Yizheng Chemical Fibre, has a carboxyl end group content of 22 mol / t, and a melt flow rate of 28 g / 10 min (250 DEG C, 1.2 kg) ; The PBT resin 4 is PBT GX112 produced by Yizheng Chemical Fibre, with a carboxyl end group content of 30 mol / t and a melt flow rate of 35 g / 10 min (250℃, 1.2 kg); The PBT resin 5 is PBT GX111 produced by Yizheng Chemical Fibre, with a carboxyl end group content of 35 mol / t and a melt flow rate of 45 g / 10 min (250℃, 1.2 kg); The PP resin 1 is PP Z30S produced by Sinopec, which is a copolymer PP with a melt flow rate of 30 g / 10 min under a load of 2.16 kg at 230℃; The PP resin 2 is PP M60T produced by Sinopec, which is a copolymer PP with a melt flow rate of 57 g / 10 min under a load of 2.16 kg at 230℃; The PP resin 3 is PP EP640V produced by Sinopec, which is a copolymer PP with a melt flow rate of 80 g / 10 min under a load of 2.16 kg at 230℃; The PP resin 4 is PP N-Z30S produced by Sinopec, which is a copolymer PP with a melt flow rate of 20 g / 10 min under a load of 2.16 kg at 230℃; The zirconium oxide particles 1-5 are self-made products, and the specific method is as follows: commercially available zirconium oxide particle raw materials are mixed with commercially available γ-glycidyl ether propyltrimethoxysilane (KH-560) according to a mass ratio of 100:5, and stirred at 60℃ for 12 h, so that the particles are completely dispersed, and then dried at 80℃ under vacuum for 2 h to obtain the material; The average particle size of the raw material of the zirconium oxide particle 1 is 50 nm; The average particle size of the raw material of the zirconium oxide particle 2 is 100 nm; The average particle size of the raw material of the zirconium oxide particle 3 is 200 nm; The average particle size of the raw material of the zirconium oxide particle 4 is 800 nm; The average particle size of the raw material of the zirconium oxide particle 5 is 2 μm; It is measured that the average particle size difference between the raw material and the final product of each particle is within 10 nm, so the average particle size of the raw material can be considered as the average particle size of the final product.

[0056] The nano-titanium dioxide particles are prepared by the same method as the zirconium oxide particles, and the only difference is that the raw material is titanium dioxide with an average particle size of 200 nm.

[0057] The nano-aluminum oxide particles are commercially available, and are prepared by the same method as the zirconium oxide particles, and the only difference is that the raw material is aluminum oxide with an average particle size of 200 nm.

[0058] The compatibilizer 1 is DuPont's FUSABONDN493, a maleic anhydride-grafted ethylene-vinyl acetate copolymer with a grafting rate of approximately 2.0%. The compatibilizer 2 is SOG-03 produced by Jia Yi Rong, which is maleic anhydride grafted with POE, with a grafting rate of approximately 2.0%. The glass fiber is ECS10-3.0-T436HK produced by Taishan Fiberglass, with an average diameter of 10μm and an average length of 3mm; The lubricant is commercially available pentaerythritol stearate; The antioxidant is a mixture of commercially available pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite in a mass ratio of 1:1; 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.

[0059] Table 1 Table 2 To verify the performance of the PBT composite material 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: (1) Initial tensile strength test: The products obtained from each embodiment and comparative example were injection molded into dumbbell-shaped strips of 150*10*4mm, and then the initial tensile strength A0 was tested according to ISO 527-93-1-2019 at a tensile rate of 5mm / min. (2) Place each parallel sample of each sample in step (1) in a heat preservation box at 85℃ and 85% relative humidity for 1000h. Then adjust the temperature of the heat preservation box to 23℃ and the relative humidity to 50%, and continue to place it for 24h. Use the same method as in step (1) to test the tensile strength A1 of the product after wet heat treatment. Calculate the tensile strength retention rate of the product after wet heat treatment = 100% × A1 / A0.

[0060] (3) Immerse each parallel sample from step (1) in a 10wt% sodium hydroxide solution at 23℃ for 200h, then remove and wash with deionized water, let stand and dry for 24h, and test the tensile strength A2 of the product after alkaline treatment using the same method as in step (1). Calculate the tensile strength retention rate of the product after alkaline treatment = 100% × A2 / A0 The test results are shown in Tables 3 and 4.

[0061] Table 3 Table 4 As can be seen from Tables 3 and 4, the PBT composite material of the present invention has ideal stability. The tensile strength retention rate can reach more than 74% after damp heat treatment, and the tensile strength retention rate can reach more than 60% after alkaline treatment. This indicates that the product has sufficient resistance to damp heat aging and alkali resistance. This is mainly due to the synergistic compounding of the organic resin matrix constructed by the low carboxyl content PBT resin and the high flowability PP resin with nano-sized zirconium oxide.

[0062] In contrast, the product described in Comparative Example 1 did not incorporate nano-zirconia particles. Due to the significant polarity difference between PBT and PP resins after blending, PP resin at the interface is prone to spherulite growth, leading to an increase in phase size. Even with the aid of a compatibilizer, it is difficult to achieve uniform compatibility between the two phases, resulting in low stability and difficulty in achieving long-term resistance to wet hydrolysis and alkali resistance. Comparative Example 2, by further increasing the amount of compatibilizer compared to Comparative Example 1, showed almost no improvement in performance. However, excessive introduction of these particles is also problematic. As shown in Comparative Example 8, since it remains an inorganic powder, excessive introduction in a glass fiber reinforced system can still lead to significant agglomeration, resulting in poor component uniformity and suboptimal performance.

[0063] In Comparative Examples 3 and 4-5, inorganic particles were introduced into the matrix resin. However, the zirconium oxide in Comparative Example 3 was at the micron level and could not effectively disperse the particles. In contrast, the nanoparticles introduced in Comparative Examples 4 and 5 were titanium dioxide and aluminum oxide, which do not form complexes with PBT resin to improve the crystallinity of PBT and inhibit the growth of spherulites in PP resin. Therefore, although the performance was improved to some extent compared to the product of Comparative Example 1, it still did not reach the level of the product of the examples.

[0064] The PBT resin used in Comparative Examples 6 and 7 had an excessively high carboxyl content or the PP had too low fluidity, so the two resins could not complement each other, and the PP resin could not be used as a protective barrier for the PBT resin. The products failed to meet the requirements for resistance to wet hot water hydrolysis and alkali resistance.

[0065] As can be seen from the products in Examples 1 and 4-6, when the carboxyl content of PBT resin is controlled within 30 mol / t, and further optimized to 15-22 mol / t, the relative viscosity of the product is more moderate, the reactivity with the compatibilizer is higher, and the environmental resistance of the product is better.

[0066] Furthermore, as can be seen from Examples 1 and 9-11, when the average particle size of nano-sized zirconia particles reaches 100 μm or above, the particle dispersibility is better, which is more conducive to improving the interfacial compatibility of the two resins and making the product have better environmental resistance.

[0067] 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 composite material, characterized by, The PBT composite material comprises the following components by weight: PBT resin 52~71 parts, PP resin 10~20 parts, glass fiber 15~35 parts, stability regulator 0.5~3 parts, and compatibility agent 3~10 parts; The carboxyl content of the PBT resin is ≤30 mol / t. The melt flow rate of the PP resin is ≥30 g / 10 min under 230℃ and 2.16 kg according to ISO 1133-2011. The stability regulator comprises nano zirconium oxide particles.

2. The PBT composite of claim 1, wherein, The carboxyl content of the PBT resin is 10~30 mol / t.

3. The PBT composite of claim 1, wherein, The melt flow rate of the PP resin is 30~80 g / 10 min under 230℃ and 2.16 kg.

4. The PBT composite of claim 1, wherein, The average particle size of the nano zirconium oxide particles is 10~1000 nm.

5. The PBT composite of claim 4, wherein the PBT is a PBT homopolymer. The average particle size of the nano zirconium oxide particles is ≥100 nm.

6. The PBT composite of claim 1, wherein, The compatibility agent comprises at least one of maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, and ethylene-methyl acrylate-methyl methacrylate glycidyl ester.

7. The PBT composite of claim 1, wherein, The PBT composite material comprises 0.2~0.5 parts of antioxidant and / or 0.2~0.5 parts of lubricant.

8. The method for preparing the PBT composite material according to any one of claims 1 to 7, characterized in that, The PBT composite material comprises the following steps: Each component is added into a screw extruder for melt extrusion granulation, and the PBT composite material is obtained.

9. Use of the PBT composite material according to any one of claims 1~7 in the preparation of an outer packaging material.

10. An overpack material characterized by, The outer packaging material comprises automobile packaging parts or electrical packaging devices, and the outer packaging material comprises the PBT composite material according to any one of claims 1~7.

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