Polyphenylene sulfide resin composition and preparation method thereof

Abstract

The invention discloses a polyphenylene sulfide resin composition and a preparation method thereof, 100 parts by weight of (a) polyphenylene sulfide resin is used as a reference, and 3-25 parts by weight of (b) olefin elastomer resin is mixed; the melt viscosity eta of the polyphenylene sulfide resin (a) under the conditions that the temperature is 310 DEG C, the hole length-diameter ratio L / D is equal to 10 and the shearing rate is 1216 / s meets eta 1gt; the melt viscosity eta of the composition is 120-200 Pa.s under the conditions that the temperature is 320 DEG C, the hole length-diameter ratio L / D is 40, and the shearing rate is 4700 / s; and the heating loss after heating for 2 hours at 320 DEG C in an air atmosphere is less than or equal to 0.8 wt%. According to the invention, the branched PPS (a2) and the elastomer (b) are used for synergistically toughening, so that the impact strength can be improved, and meanwhile, the interface is enhanced through silane premixing, so that the bending modulus is increased; thin-wall injection molding filling performance is ensured, and excessive reduction of molecular weight is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of polyphenylene sulfide, and particularly relates to a polyphenylene sulfide resin composition and a preparation method thereof. Background Art

[0002] Polyphenylene sulfide (PPS) is a new type of high-performance thermoplastic resin, which has the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, excellent electrical properties, etc. It is widely used in the fields of electronics, automobiles, machinery and chemical industry.

[0003] Polyphenylene sulfide is also known as polyphenyl sulfide. It is a thermoplastic resin with a phenylthio group in the main chain of the molecule. Polyphenylene sulfide is a crystalline polymer. The unstretched fiber has a large amorphous region (crystallinity is about 5%), and crystallization exotherm occurs at 125 °C. The glass transition temperature is 150 °C; the melting point is 281 °C. The stretched fiber generates partial crystallization during the stretching process (increased to 30%). If the stretched fiber is heat-treated at a temperature of 130-230 °C, the crystallinity can be increased to 60-80%. Therefore, the stretched fiber has no obvious glass transition or crystallization exotherm phenomenon, and its melting point is 284 °C. With the increase of crystallinity after stretching and heat setting, the density of the fiber also increases accordingly, from 1.33 g / cm3 before stretching to 1.34 g / cm3 after stretching, and can reach 1.38 g / cm3 after heat treatment. Molding shrinkage rate: 0.7% Molding temperature: 300-330 °C Polyphenylene sulfide (PPS) resin is widely used in the fields of electronic appliances and automobiles due to its high heat resistance and flame retardancy. However, traditional PPS has the following defects: (1) The impact strength of linear PPS is usually lower than 50 J / m, and an elastomer needs to be added for modification. However, an excessive amount of elastomer will lead to a decrease in heat resistance; (2) The high melt viscosity makes it difficult to fill during injection molding. It is necessary to reduce the molecular weight or add a flow aid, but this will sacrifice the mechanical properties; (3) It is easily oxidized and decomposed during high-temperature processing, and has poor interfacial adhesion with fillers.

[0004] Therefore, it is urgent to design a polyphenylene sulfide resin composition and a preparation method thereof to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyphenylene sulfide resin composition and a preparation method thereof to solve the above deficiencies in the prior art.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions: A polyphenylene sulfide resin composition is defined by the following components and parameters: based on 100 parts by weight of (a) polyphenylene sulfide resin, 3 - 25 parts by weight of (b) olefinic elastomer resin are blended; the melt viscosity η1 of the (a) polyphenylene sulfide resin under the conditions of a temperature of 310 °C, a pore aspect ratio L / D = 10, and a shear rate of 1216 / s satisfies: η1 > 200 Pa·s. The melt viscosity η2 of the composition under the conditions of a temperature of 320 °C, a pore aspect ratio L / D = 40, and a shear rate of 4700 / s is 120 - 200 Pa·s; the heat loss on heating after heating at 320 °C for 2 hours in an air atmosphere is ≤ 0.8 wt%: The (a) polyphenylene sulfide resin contains a branched or crosslinked structure, which is derived from a polyhaloaromatic compound containing 3 or more halogen substituents per molecule; The impact strength of the composition is ≥ 76 J / m, the tensile strength is ≥ 137 MPa, and it meets the UL94 V - 0 flame retardancy rating.

[0007] Preferably, the (a) polyphenylene sulfide resin is compounded from two components: (a1) a linear polyphenylene sulfide resin with an ash content rate ≤ 0.10 wt%; (a2) a branched / crosslinked polyphenylene sulfide resin with an ash content rate ≥ 0.20 wt%; where the mass ratio of (a1) to (a2) is 1:4 to 4:1, and the melt flow index (MFI) of the compounded resin is 10 - 50 g / 10 min (testing conditions: 316 °C / 5 kg).

[0008] Preferably, the (b) olefinic elastomer resin is an ethylene - α - olefin copolymer, where the α - olefin is selected from propylene, 1 - butene, or 1 - octene, the density of the copolymer is 0.86 - 0.90 g / cm³, the melt index is 1 - 10 g / 10 min (190 °C / 2.16 kg), and its addition amount is preferably 5 - 20 parts by weight.

[0009] Preferably, it further contains 0.05 - 3.0 parts by weight of (c) aminoalkoxysilane compound, and its structural general formula is: R 1 −Si(OR 2 )3 where R¹ is a C1 - C6 alkyl group containing an amino group, and R² is a methyl group or an ethyl group; when preparing the compound, it needs to be premixed with part of the (a) resin to form a premix (d), and the proportion of the (a) resin in the premix is 1 - 25 parts by weight.

[0010] Preferably, the preparation of the premix (d) includes: Dry blend (a) resin and (c) compound under an inert atmosphere at a mixing temperature ≤ 80 °C for 10 - 30 minutes; The moisture content of the premix is ≤ 0.1 wt%, and melt blending is carried out through a twin - screw extruder at an extrusion temperature of 280 - 320 °C and a screw speed of 200 - 400 rpm.

[0011] The preparation method of the polyphenylene sulfide resin combination includes: Raw material pretreatment: Dry (a) resin to a moisture content rate ≤ 1 wt%; Staged mixing: The first stage: Feed the premix (d) and the remaining (a) resin into the main feed port and the side feed port of the extruder respectively; The second stage: The melt is subjected to vacuum devolatilization treatment with a vacuum degree ≥ - 0.095 MPa and a residence time ≥ 30 seconds; Post - treatment: After extrusion granulation, the particles are annealed at 120 °C for 2 hours to eliminate internal stress.

[0012] The preparation method, where the aspect ratio L / D of the extruder ≥ 40, the screw combination includes at least 3 sets of kneading blocks, and the residence time of the melt in the barrel ≤ 3 minutes to prevent thermal decomposition of (c) compound.

[0013] Preferably, it further includes reinforcing fillers, including: Glass fiber: with a diameter of 10 - 20 μm, a length of 3 - 6 mm, and an addition amount of 10 - 40 parts by weight; Nano - silica: with a particle size of 20 - 50 nm, surface - treated with a silane coupling agent, and an addition amount of 1 - 5 parts by weight; The addition of the filler makes the flexural modulus of the composition ≥ 8 GPa and the heat distortion temperature (1.82 MPa) ≥ 260 °C.

[0014] Preferably, when it is applied to automotive parts, it meets the following conditions: After being immersed in 120 °C engine oil for 1000 hours, the tensile strength retention rate ≥ 90%; Thermal shock resistance: 100 cycles from - 40 °C to 150 °C without cracking; The amount of mold scale formation ≤ 0.1 mg / cm².

[0015] Preferably, it purifies the polyphenylene sulfide resin by the foam flotation method, specifically including: Flash - evaporate the solvent from the polyphenylene sulfide resin to obtain a crude resin; Mix the crude resin and water in a mass ratio of 1:5 - 1:10, and introduce nitrogen to form a foam phase; Separate the resin particles in the foam phase, D 50 ≤ 20 μm, and the particle size distribution D 90 / D 10 ≤8.

[0016] In the above technical solution, a polyphenylene sulfide resin composition and a preparation method thereof provided by the present invention: (1) By synergistically toughening branched PPS (a2) and an elastomer (b), the impact strength can be improved. At the same time, the interface is strengthened by premixing silane, increasing the flexural modulus; ensuring the filling property of thin-wall injection molding and avoiding excessive reduction of molecular weight; (2) Adopting vacuum devolatilization and low-temperature premixing processes to reduce high-temperature oxidative decomposition and effectively reduce the heating loss; at the same time, using a screw combination design (kneading blocks ≥ 3 groups) to shorten the melt residence time (≤ 3 minutes) to prevent thermal decomposition of silane; (3) After being immersed in 120 °C engine oil for 1000 hours, the tensile strength retention rate ≥ 90% (93% for Example 1); no cracking after 100 cycles of thermal cycling (-40 °C to 150 °C), meeting the requirements of automotive engine compartment components. Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic flow structure diagram provided by an embodiment of a polyphenylene sulfide resin composition and a preparation method thereof of the present invention. Detailed Embodiments

[0019] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the drawings.

[0020] As Figure 1 shown, a polyphenylene sulfide resin composition provided by an embodiment of the present invention is defined by the following components and parameters: Based on 100 parts by weight of (a) polyphenylene sulfide resin, 3 - 25 parts by weight of (b) olefin-based elastomer resin are mixed; the melt viscosity η1 of the (a) polyphenylene sulfide resin under the conditions of a temperature of 310 °C, a pore aspect ratio L / D = 10, and a shear rate of 1216 / s satisfies: η1 > 200 Pa·s. The melt viscosity η2 of the composition under the conditions of a temperature of 320 °C, a pore aspect ratio L / D = 40, and a shear rate of 4700 / s is 120 - 200 Pa·s; the heating loss after heating at 320 °C for 2 hours in an air atmosphere ≤ 0.8 wt%: The (a) polyphenylene sulfide resin contains a branched or crosslinked structure, which is derived from a polyhaloaromatic compound containing more than 3 halogen substituents per molecule; The impact strength of the composition is ≥76 J / m, the tensile strength is ≥137 MPa, and it meets the UL94 V-0 flame retardancy rating.

[0021] Preferably, the (a) polyphenylene sulfide resin is compounded from two components: (a1) a linear polyphenylene sulfide resin with an ash content ≤0.10 wt%; (a2) a branched / crosslinked polyphenylene sulfide resin with an ash content ≥0.20 wt%; wherein the mass ratio of (a1) to (a2) is 1:4 to 4:1, and the melt flow index (MFI) of the compounded resin is 10 - 50 g / 10 min (test conditions: 316 °C / 5 kg).

[0022] Preferably, the (b) olefin-based elastomer resin is an ethylene-α-olefin copolymer, wherein the α-olefin is selected from propylene, 1-butene or 1-octene, the density of the copolymer is 0.86 - 0.90 g / cm³, the melt index is 1 - 10 g / 10 min (190 °C / 2.16 kg), and its addition amount is preferably 5 - 20 parts by weight.

[0023] Preferably, it further contains 0.05 - 3.0 parts by weight of (c) an aminoalkoxysilane compound, and its structural general formula is: R 1 −Si(OR 2 )3 wherein R¹ is a C1-C6 alkyl group containing an amino group, and R² is a methyl group or an ethyl group; when preparing the compound, it needs to be premixed with part of the (a) resin to form a premix (d), and the proportion of the (a) resin in the premix is 1 - 25 parts by weight.

[0024] Preferably, the preparation of the premix (d) includes: Dry-mix the (a) resin and the (c) compound under an inert atmosphere, with the mixing temperature ≤80 °C and the time of 10 - 30 minutes; The water content of the premix is ≤0.1 wt%, and it is melt-compounded by a twin-screw extruder, with the extrusion temperature of 280 - 320 °C and the screw speed of 200 - 400 rpm.

[0025] The preparation method of the polyphenylene sulfide resin composition includes: Raw material pretreatment: Dry the (a) resin to a moisture content ≤1 wt%; Segmented mixing: The first stage: Feed the premix (d) and the remaining (a) resin into the main feed port and the side feed port of the extruder respectively; The second stage: The melt is subjected to vacuum devolatilization treatment, with the vacuum degree ≥ -0.095 MPa and the residence time ≥30 seconds; Post-treatment: After extrusion granulation, the granules are annealed at 120 °C for 2 hours to eliminate internal stress.

[0026] Preparation method, the length-diameter ratio L / D of the extruder is ≥ 40, the screw combination includes at least 3 sets of kneading blocks, and the residence time of the melt in the barrel is ≤ 3 minutes to prevent thermal decomposition of compound (c).

[0027] Preferably, it further comprises a reinforcing filler, including: Glass fiber: diameter 10 - 20 μm, length 3 - 6 mm, addition amount 10 - 40 parts by weight; Nano-silica: particle size 20 - 50 nm, surface-treated with silane coupling agent, addition amount 1 - 5 parts by weight; The addition of the filler makes the flexural modulus of the composition ≥ 8 GPa and the heat distortion temperature (1.82 MPa) ≥ 260 °C.

[0028] Preferably, when it is applied to automotive parts, it meets the following conditions: After soaking in 120 °C engine oil for 1000 hours, the tensile strength retention rate ≥ 90%; Thermal shock resistance: 100 cycles from -40 °C to 150 °C without cracking; The amount of mold scale formation ≤ 0.1 mg / cm².

[0029] Preferably, the polyphenylene sulfide resin is purified by foam flotation method, specifically including: The polyphenylene sulfide resin is flash-vaporized to remove the solvent to obtain a crude resin; The crude resin is mixed with water in a mass ratio of 1:5 - 1:10, and nitrogen is introduced to form a foam phase; Separate the resin particles in the foam phase, D 50 ≤ 20 μm, particle size distribution D 90 / D 10 ≤ 8.

[0030] Example 1: Basic formulation and performance test Formulation composition: (a) Polyphenylene sulfide resin: 100 parts by weight (where a1 linear resin and a2 branched resin are compounded in a ratio of 3:2, ash content rate 0.08 wt%); (b) Ethylene-1-octene copolymer: 15 parts by weight (density 0.88 g / cm³, melt index 5 g / 10min); (c) γ-aminopropyltriethoxysilane: 0.8 parts by weight; Glass fiber: 25 parts by weight (diameter 15 μm, length 4 mm); Nano-silica: 3 parts by weight (particle size 30 nm, treated with KH550).

[0031] Preparation method: Preparation of premix (d): 10 parts by weight of (a) resin and (c) silane were dry-mixed under nitrogen protection (temperature 60°C, time 20 minutes), with a moisture content of 0.05 wt%; Extrusion process: Main feeding port: The premix (d) is mixed with the remaining (a) resin; Side feeding port: Add (b) elastomer and reinforcing filler; Twin-screw extruder parameters: L / D = 48, temperature 300°C, rotation speed 350 rpm, vacuum devolatilization (-0.098 MPa, residence time 40 seconds); After pelletizing, anneal at 120°C for 2 hours.

[0032] Performance test results: Melt viscosity η1 = 220 Pa·s, η2 = 165 Pa·s; Izod notched impact strength = 78 J / m, tensile strength = 142 MPa; Loss on heating = 0.6 wt%, flexural modulus = 8.5 GPa; UL94 V-0 flame retardant (1.6 mm thickness), mold fouling formation = 0.08 mg / cm².

[0033] Comparative example 1: No branched PPS resin was used for compounding Formulation and process: (a) Only linear PPS resin (ash content 0.09 wt%) was used, and other components were the same as in Example 1; The process parameters were the same as in Example 1, but the resin premixing step was not carried out.

[0034] Performance results: Izod notched impact strength = 45 J / m (42% lower than in Example 1); Melt viscosity η1 = 280 Pa·s, and the injection molding filling was incomplete (material shortage occurred in the thin-wall area); Loss on heating = 1.2 wt% (due to uneven dispersion of silane caused by lack of premixing, and the high-temperature decomposition was aggravated); Comparative example 2: Adjustment of elastomer type and dosage Formulation and process: (b) The elastomer was changed to ethylene-acrylate copolymer (with a large polarity difference), and the dosage was increased to 25 parts by weight; Other components and processes were the same as in Example 1.

[0035] Performance results: Impact strength = 68 J / m, but heat distortion temperature = 215 °C (25 °C lower than Comparative Example 1); Flexural modulus = 5.8 GPa (due to poor compatibility between the elastomer and the resin, interface bonding failure); Mold fouling formation = 0.35 mg / cm² (polar elastomer leads to enhanced melt adhesion).

[0036] Problem analysis: The non-preferred elastomer and excessive addition lead to a significant decrease in heat resistance and rigidity, proving that ethylene-1-octene copolymer (non-polar) and 15 parts by weight dosage are the optimal balance points.

[0037] Comparative Example 3: Vacuum devolatilization and premixing processes were not carried out Formulation and process: The premixing step was cancelled, and the silane was directly dry-blended with all raw materials; In the extrusion process, the vacuum devolatilization system was turned off, and other parameters were the same as in Example 1.

[0038] Performance results: Loss on heating = 2.1 wt% (small molecule volatiles are generated by the high-temperature hydrolysis of silane); Tensile strength = 118 MPa (17% lower than Comparative Example 1); Microcracks appeared after the thermal cycling test (residual moisture at the interface caused stress concentration).

[0039] Problem analysis: The lack of vacuum devolatilization led to the residue of volatiles, and the lack of premixing caused insufficient reaction between the silane and the resin, proving the key role of the premixing + vacuum process in interface stability and environmental resistance.

[0040] Comparative Example 4: Nano-silica was not added Formulation and process: Nano-silica was cancelled, and the glass fiber was increased to 30 parts by weight; Other components and processes were the same as in Example 1.

[0041] Performance results: Flexural modulus = 7.2 GPa (15% lower than Comparative Example 1); The flame retardancy was downgraded to UL94 V-1 (the lack of nano-particles led to an incomplete carbon layer structure); Surface glossiness = 65 GU (the exposure of glass fiber led to an increase in roughness).

[0042] Problem analysis: Nano-silica can fill the micro-gaps between the glass fiber and the resin, improving rigidity, flame retardancy and surface quality, proving the necessity of multi-scale filler synergistic reinforcement.

[0043] Comparison conclusion From the comparison between Example 1 and Comparative Examples 1-4, it can be seen that: The blending of branched / linear PPS, the selection of specific elastomers, and the premixing process are the core for achieving the synergy of high toughness and high heat resistance; Vacuum devolatilization and the optimization of nano-fillers are the key to ensuring processing stability and surface quality; The formulation and process design of the present invention have an inseparable integrity, and the absence of a single component or step will lead to a significant deterioration in performance.

[0044] Only some exemplary embodiments of the present invention have been described by way of illustration. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A polyphenylene sulfide resin composition, characterized in that, It is defined by the following components and parameters: based on 100 parts by weight of (a) polyphenylene sulfide resin, compounded with 3 - 25 parts by weight of (b) olefin - based elastomer resin; The melt viscosity η1 of the said (a) polyphenylene sulfide resin under the conditions of temperature 310 °C, pore length - to - diameter ratio L / D = 10, and shear rate 1216 / s satisfies: η1 > 200 Pa・s; the melt viscosity η2 of the composition under the conditions of temperature 320 °C, pore length - to - diameter ratio L / D = 40, and shear rate 4700 / s is 120 - 200 Pa·s; the weight loss on heating after heating at 320 °C for 2 hours in air atmosphere ≤ 0.8 wt%; The said (a) polyphenylene sulfide resin contains a branched or cross - linked structure, which is derived from a polyhaloaromatic compound containing more than 3 halogen substituents per molecule; The impact strength of the said composition ≥ 76 J / m, the tensile strength ≥ 137 MPa, and it meets the UL94 V - 0 flame retardant rating.

2. The polyphenylene sulfide resin composition according to claim 1, wherein The said (a) polyphenylene sulfide resin is compounded from two components: (a1) Linear polyphenylene sulfide resin with an ash content rate ≤ 0.10 wt%; (a2) Branched / cross - linked polyphenylene sulfide resin with an ash content rate ≥ 0.20 wt%; where the mass ratio of (a1) to (a2) is 1:4 to 4:1, and the melt flow index (MFI) of the compounded resin is 10 - 50 g / 10 min (test conditions: 316 °C / 5 kg).

3. A polyphenylene sulfide resin composition according to claim 1 or 2, characterized in that The said (b) olefin - based elastomer resin is an ethylene - α - olefin copolymer, where α - olefin is selected from propylene, 1 - butene or 1 - octene, the density of the copolymer is 0.86 - 0.90 g / cm³, the melt index is 1 - 10 g / 10 min (190 °C / 2.16 kg), and its addition amount is preferably 5 - 20 parts by weight.

4. A polyphenylene sulfide resin composition according to any one of claims 1 to 3, characterized in that It further contains 0.05 - 3.0 parts by weight of (c) aminoalkoxysilane compound, and its structural general formula is: R 1 -Si(OR 2 )3 where R¹ is a C1 - C6 alkyl group containing an amino group, and R² is a methyl or ethyl group; when preparing the said compound, it needs to be pre - mixed with part of (a) resin to form a premix (d), and the proportion of (a) resin in the premix is 1 - 25 parts by weight.

5. The polyphenylene sulfide resin composition according to claim 4, wherein The preparation of the said premix (d) includes: Dry - mixing (a) resin and (c) compound under an inert atmosphere, the mixing temperature ≤ 80 °C, and the time is 10 - 30 minutes; The water content of the premix ≤ 0.1 wt%, and it is melt - compounded through a twin - screw extruder, the extrusion temperature is 280 - 320 °C, and the screw speed is 200 - 400 rpm.

6. The composition according to any one of claims 1-5, characterized in that, The preparation method of the said composition includes: Raw material pretreatment: drying (a) resin to a moisture content rate ≤ 1 wt%; Segmented kneading: The first stage: feeding the premix (d) and the remaining (a) resin into the main feed port and the side feed port of the extruder respectively; The second stage: the melt is subjected to vacuum devolatilization treatment, the vacuum degree ≥ - 0.095 MPa, and the residence time ≥ 30 seconds; Post - treatment: after extrusion granulation, the granules are annealed at 120 °C for 2 hours to eliminate internal stress.

7. The preparation method according to claim 6, characterized in that, The length - to - diameter ratio L / D of the said extruder ≥ 40, the screw combination includes at least 3 sets of kneading blocks, and the residence time of the melt in the barrel ≤ 3 minutes to prevent thermal decomposition of (c) compound.

8. The composition according to any one of claims 1-7, characterized in that, Further comprising reinforcing fillers, including: Glass fiber: diameter 10 - 20 μm, length 3 - 6 mm, addition amount 10 - 40 parts by weight; Nano - silica: particle size 20 - 50 nm, surface - treated with silane coupling agent, addition amount 1 - 5 parts by weight; The addition of the fillers makes the flexural modulus of the composition ≥ 8 GPa and the heat distortion temperature (1.82 MPa) ≥ 260 °C.

9. The composition according to any one of claims 1-8, characterized in that, When the composition is applied to automotive parts, it meets the following conditions: After being immersed in 120 °C engine oil for 1000 hours, the tensile strength retention rate ≥ 90%; Thermal shock resistance: no cracking after 100 cycles of - 40 °C to 150 °C; The amount of mold fouling generated ≤ 0.1 mg / cm².

10. The composition according to any one of claims 1-9, characterized in that, Purify the polyphenylene sulfide resin by foam flotation method, specifically including: Flash - evaporate the solvent from the polyphenylene sulfide resin to obtain the crude resin; Mix the crude resin and water in a mass ratio of 1:5 - 1:10, and introduce nitrogen to form a foam phase; Separate resin particles in the foam phase, D 50 ≤ 20 μm, particle size distribution D 90 / D 10 ≤ 8

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