A polyphenylene ether composition which can be repeatedly injection molded and a method for producing the same

Abstract

The application discloses a kind of repeatedly injection moulding polyphenyl ether compositions and preparation method thereof, repeatedly injection moulding polyphenyl ether compositions include matrix resin, crosslinking agent and toughening agent;Matrix resin is the mixture of polyphenyl ether and polystyrene;Crosslinking agent is the mixture of low molecular weight oxazoline and polystyrene graft oxazoline;Toughening agent is SEBS-g-MAH;The mass fraction ratio of low molecular weight oxazoline and polystyrene graft oxazoline is 0.5-1.5:2-5, the mass fraction ratio of SEBS-g-MAH and polystyrene graft oxazoline is 5-10:2-5;Preparation method is melt blending method.The preparation method of the application is simple, and the polyphenyl ether composition prepared can be repeatedly injection moulding, which makes up for the shortcomings of prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and relates to a polyphenyl ether composition capable of repeated injection molding and a preparation method thereof. BACKGROUND

[0002] Polyphenylene ether (PPO) is a high-performance thermoplastic engineering plastic with good mechanical properties, chemical stability, dielectric properties, heat resistance and flame retardance. However, the polyphenylene ether molecular chain is relatively rigid, and the notched impact is very sensitive. The relatively high melt viscosity of the polyphenylene ether makes it unable to be injection molded. In addition, the polyphenylene ether also has the disadvantages of poor oil resistance, easy high-temperature degradation and easy yellowing, which greatly limits its application. Usually, the polyphenylene ether is used as a composition with other high polymer materials, and common compositions include a polyphenylene ether / polystyrene composition and a polyphenylene ether / polyamide composition. The structural characteristics of the polyphenylene ether lead to the fact that the polyphenylene ether is easily yellowed under the action of high temperature and shearing in the process of extrusion and injection molding.

[0003] A large amount of pouring system condensate, i.e. the molded material of the sprue and runner outside the injection molding product, is generated in the injection molding process of thermoplastic plastic, which is also called a nozzle material. Generally, the nozzle material is directly injection molded after being crushed. Because the thermoplastic plastic is affected by high temperature and shearing again, the performance of the material is greatly deteriorated, and the injection molded product is prone to quality problems, so the nozzle material cannot be used for multiple cycle injection molding and can only be discarded, causing great resource waste.

[0004] In the prior art, the nozzle material is usually recycled by blending new and old materials, that is, the nozzle material in the injection molding process of plastic is mixed into the plastic raw material that has not been injection molded at a certain proportion to make up for the performance decline of the thermoplastic plastic under multiple injection molding. The nozzle material in this way cannot be directly used, and the recycling efficiency is low, and the performance decline of the thermoplastic plastic caused by multiple cycle injection molding cannot be completely solved. More importantly, for the plastic such as polyphenylene ether which is prone to discoloration, multiple cycle injection molding not only causes the performance decline, but also causes the material to seriously discolor, and even color instability fluctuation occurs in the injection molding process. In the prior art, patent CN102432990 produces color-stable polyphenylene ether by using a molecular sieve, patent CN201010191661.9 proposes to use HP136 antioxidant to improve the color stability of PPE, and US5210119 improves the color stability of PPE by adding a hindered amine and an epoxy. The above patents only solve the change of the color of the polyphenylene ether under the condition of one-time injection molding, and do not solve the change of the color of the polyphenylene ether under the condition of multiple injection molding. Under the current attention to carbon cycle and PCR materials at home and abroad, it is of great significance to research a polyphenylene ether composition capable of repeated injection molding. SUMMARY

[0005] The present application aims at solving the problems existing in the prior art and providing a polyphenyl ether composition capable of repeated injection molding and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A polyphenyl ether composition capable of repeated injection molding, comprising a base resin, a crosslinking agent and a toughening agent.

[0008] The base resin is a mixture of polyphenyl ether and polystyrene.

[0009] The crosslinking agent is a mixture of low molecular weight oxazoline and polystyrene grafted oxazoline, the weight average molecular weight (Mw) of the low molecular weight oxazoline is 3×10 4 -8×10 4 , the oxazoline group content is 4.5 mmol / g, the weight average molecular weight of the polystyrene grafted oxazoline is 1×10 5 -2×10 5 , and the oxazoline group content is 0.27 mmol / g, and the structural formula is as follows:

[0010]

[0011] Both the low molecular weight oxazoline and the polystyrene grafted oxazoline can provide intermolecular crosslinking promotion under the conditions of heat, light or irradiation.

[0012] The toughening agent is SEBS-g-MAH.

[0013] The mass ratio of the low molecular weight oxazoline to the polystyrene grafted oxazoline is 0.5-1.5:2-5, and the mass ratio of the SEBS-g-MAH to the polystyrene grafted oxazoline is 5-10:2-5.

[0014] During the repeated injection molding of the polyphenyl ether composition, the mechanical properties decrease due to the breakage of the polyphenyl ether molecular chain. When the phenoxy bond in the polyphenyl ether molecular chain breaks, phenoxy free radicals are formed. Once the phenoxy free radicals are oxidized into benzoquinone groups, the accumulation of the benzoquinone groups and the coupling reaction between the accumulated benzoquinone groups and free radicals will cause the color change of the polyphenyl ether composition.

[0015] The inventors have found that the oxazoline added to the polyphenyl ether composition system of the present application can provide good molecular chain protection for the polyphenyl ether material. The high reactivity of the oxazoline enables linear polyphenyl ether molecules to be connected to each other to form a network structure. This network structure enables the phenoxy bond of the polyphenyl ether to be highly protected during processing, and the probability of chain segment breakage is greatly reduced. In addition, the oxazoline can quickly capture and cap free radicals generated by high temperature and shear action during injection molding, thereby preventing phenoxy free radicals from being oxidized into benzoquinone and preventing coupling reactions between benzoquinone and free radicals, and preventing the accumulation of benzoquinone and benzoquinone coupling products, thereby improving the yellowing of the material during repeated extrusion.

[0016] The oxazoline selected in the present application is a mixture of low molecular weight oxazoline and polystyrene grafted oxazoline. The addition of low molecular weight oxazoline takes advantage of its low molecular weight and high reactivity to avoid the consumption of the reaction functional groups of macromolecular polystyrene grafted oxazoline, and provides sufficient reaction group support for the protection of the polyphenyl ether molecular chain and color during subsequent repeated injection molding. The reactivity of polystyrene grafted oxazoline is lower than that of low molecular weight oxazoline, and it will not be consumed in large quantities during extrusion or first injection molding, thereby playing a crucial role in the protection of the polyphenyl ether molecular chain and color during subsequent repeated molding.

[0017] The present application controls the molecular weight of low molecular weight oxazoline. If the molecular weight of low molecular weight oxazoline is too high, the low molecular weight oxazoline is not sufficient to protect the polystyrene grafted oxazoline, resulting in a large amount of consumption of polystyrene grafted oxazoline before secondary or tertiary injection molding, and a decrease in material performance and a change in color. If the molecular weight of low molecular weight oxazoline is too low, the low molecular weight oxazoline is excessively reactive, resulting in a large number of crosslinking groups, and the material processing performance is significantly reduced, making it difficult to be injection molded.

[0018] The present application controls the molecular weight and oxazoline grafting rate of polystyrene grafted oxazoline. If the molecular weight of polystyrene grafted oxazoline is too high, the oxazoline in the polystyrene grafted oxazoline cannot fully react with the groups generated by chain scission in the polyphenyl ether, resulting in insufficient protection of the material performance and color during secondary or tertiary injection molding. If the molecular weight of polystyrene grafted oxazoline is too low, the polystyrene molecular weight is not sufficient to protect the grafted oxazoline, resulting in a large amount of consumption of grafted oxazoline groups before secondary or tertiary injection molding, a decrease in material performance, and a change in color. If the oxazoline grafting rate of polystyrene grafted oxazoline is too high, the oxazoline groups are consumed in large quantities during extrusion or first injection molding, resulting in excessive crosslinking points and making it difficult to be injection molded. If the oxazoline grafting rate of polystyrene grafted oxazoline is too low, the polystyrene grafted oxazoline cannot protect the polyphenyl ether composition during secondary or tertiary injection molding, resulting in a large decrease in material performance and a significant change in color.

[0019] In the case of the determination of the molecular weight of the low molecular weight oxazoline, the molecular weight of the polystyrene grafted oxazoline and the oxazoline grafting rate, the present application controls the mass fraction ratio of the low molecular weight oxazoline to the polystyrene grafted oxazoline to be 0.5-1.5:2-5, if the proportion of the low molecular weight oxazoline is too high, over-crosslinking condition is easily formed, resulting in the decrease of the material processing performance, and it is difficult to injection molding, if the proportion of the low molecular weight oxazoline is too low, the low molecular weight oxazoline is consumed in large quantities during extrusion or primary injection molding, the protection of the polystyrene grafted oxazoline is insufficient, resulting in the lack of protection of the polyphenylene ether composition by the oxazoline group during secondary or tertiary injection molding, and the performance of the composition is decreased, and the color is changed.

[0020] The prior art usually selects SEBS as the toughening agent of the polyphenylene ether, and the present application is different from the prior art, and selects SEBS-g-MAH as the toughening agent of the polyphenylene ether, the addition of SEBS-g-MAH not only improves the initial toughness of the polyphenylene ether composition, and SEBS-g-MAH has excellent synergistic effect with the polystyrene grafted oxazoline. Due to the presence of the polystyrene grafted oxazoline, after repeated injection molding, SEBS-g-MAH not only plays a role in toughening the polyphenylene ether composition, but more importantly, the maleic anhydride groups present in it and the oxazoline segments in the polystyrene grafted oxazoline gradually and fully react during repeated injection molding, so that the phase interface between the resin and the rubber can be better maintained, thereby greatly improving the toughness retention rate after repeated injection molding.

[0021] The present application controls the mass fraction ratio of SEBS-g-MAH to the polystyrene grafted oxazoline to be 5-10:2-5, if the proportion of SEBS-g-MAH is too high, the toughness of the composition is significantly increased, the material strength is decreased, in addition, the maleic anhydride groups will also consume oxazoline, and the material performance is decreased and the color is changed during the secondary or tertiary injection process, if the proportion of SEBS-g-MAH is too low, the toughness of the composition is significantly decreased, and a certain brittleness is presented, in addition, the reaction of the maleic anhydride groups and the oxazoline segments in the polystyrene grafted oxazoline is insufficient during repeated injection molding, the interface between the resin and the rubber phase cannot be well maintained, and the toughness cannot be sufficiently maintained.

[0022] As a preferred technical solution:

[0023] The polyphenylene ether composition capable of repeated injection molding as described above, the intrinsic viscosity of the polyphenylene ether in chloroform at 25℃ is 0.35-0.45dL / g.

[0024] The polyphenylene ether composition capable of repeated injection molding as described above, the polystyrene is high-impact polystyrene, and the melt flow rate at 200℃ under a load of 5kg is 4.5-6g / 10min.

[0025] The repeatedly injection-moldable polyphenyl ether composition according to any one of the above, further comprising glass fiber and antioxidant.

[0026] The repeatedly injection-moldable polyphenyl ether composition according to the above, wherein the components and contents are as follows: polyphenyl ether 20-50 parts, polystyrene 20-50 parts, low-molecular-weight oxazoline 0.5-1.5 parts, polystyrene grafted oxazoline 2-5 parts, SEBS-g-MAH 5-10 parts, glass fiber 10-40 parts, and antioxidant 1-3 parts.

[0027] The repeatedly injection-moldable polyphenyl ether composition according to the above, wherein the tensile strength retention rate after twice injection molding is >96%, the notched impact strength retention rate is >96%, and the ΔE is <1; and the tensile strength retention rate after thrice injection molding is >90%, the notched impact strength retention rate is >90%, and the ΔE is <1.5.

[0028] The application further provides a method for preparing the repeatedly injection-moldable polyphenyl ether composition according to any one of the above, comprising the following steps:

[0029] (1) adding all the components into a double-screw extruder, wherein the glass fiber is added from a side feeding port, and the other components are mixed and added from a main feeding port;

[0030] (2) extruding and granulating through the double-screw extruder to obtain the repeatedly injection-moldable polyphenyl ether composition.

[0031] As a preferred technical solution:

[0032] The method according to the above, wherein in step (1), the mixing time is 2-5 min.

[0033] The method according to the above, wherein in step (2), the rotating speed of the double-screw extruder is 180-600 rpm, and the temperature is 235-275℃.

[0034] Beneficial effects:

[0035] (1) The application effectively improves the mechanical property retention rate of the repeatedly injection-moldable polyphenyl ether composition after repeated injection molding through the synergistic effect of low-molecular-weight oxazoline, polystyrene grafted oxazoline and SEBS-g-MAH.

[0036] (2) The SEBS-g-MAH used in the present application not only plays a role of toughening the polyphenyl ether composition, but more importantly, the maleic anhydride groups present in the SEBS-g-MAH gradually and fully react with the oxazoline segments in the polystyrene grafted oxazoline in multiple repeated injection molding processes, so that the phase interface between the resin and the rubber can be better maintained, thereby greatly improving the toughness retention rate after multiple repeated injection molding.

[0037] (3) The polyphenyl ether composition of the present application has a mechanical property retention rate >96% and ΔE <1 after secondary injection molding, and a mechanical property retention rate >90% and ΔE <1.5 after tertiary injection molding, and is suitable for multiple repeated injection molding. DETAILED DESCRIPTION

[0038] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0039] The following are the test methods for the properties in the examples:

[0040] Intrinsic viscosity: determined in accordance with GB / T 1632.1-2008.

[0041] Melt flow rate under a load of 5 kg at 200℃: determined in accordance with ISO 1133-1:2011.

[0042] Weight average molecular weight: tested in accordance with GPC.

[0043] First injection molding: The polyphenyl ether composition pellets after extrusion granulation were dried in a 120℃ air blast drying oven for 6h, and then ISO standard mechanical bars were injected by an injection molding machine, i.e. the first injection molding mechanical bars, and 80×80×2(mm) square plates were injected by an injection molding machine, and color data was determined, wherein the temperature during injection was 280℃, the holding pressure time was 4 seconds, and the cooling time was 10 seconds.

[0044] Second injection molding: The first injection molding mechanical bars were crushed using a crusher, and the crushed particles were dried in a 120℃ air blast drying oven for 6h, and then ISO standard mechanical bars were injected by an injection molding machine, i.e. the second injection molding mechanical bars, and 80×80×2(mm) square plates were injected by an injection molding machine, and color data was determined, wherein the temperature during injection was 280℃, the holding pressure time was 4 seconds, and the cooling time was 10 seconds.

[0045] Third injection molding: the mechanical sample obtained by the second injection molding was crushed by a crusher, the crushed particles were dried in a 120℃ air drying oven for 6h, and then ISO standard mechanical sample was obtained by injection molding machine, that is, the third injection molding mechanical sample, and the color data was measured by injection molding machine to form a square plate with a size of 80x80x2(mm), wherein the temperature during injection molding was 280℃, the holding time was 4s, and the cooling time was 10s.

[0046] The first / second / third injection molding mechanical sample was respectively subjected to mechanical property test and color difference test, and the specific method of the mechanical property test and color difference test was as follows:

[0047] Tensile strength: detected according to the standard method of ISO527-2:2012.

[0048] Notched impact strength: detected according to the standard method of ISO179-1:2010.

[0049] The calculation method of performance retention rate was: (the performance value of the second or third injection molding / the performance value of the first injection molding) x 100%.

[0050] ΔE: the color difference value of the second injection molding sample, the third injection molding sample and the first injection molding sample measured according to the standard of GBT16422.3.

[0051] Example 1

[0052] A preparation method of a polyphenyl ether composition capable of repeated injection molding, the specific steps were as follows:

[0053] (1) Preparation of raw materials;

[0054] Polyphenyl ether: the manufacturer was Nantong Xingchen Synthetic Material Co., Ltd., the brand was PPO LXN040, and the intrinsic viscosity in chloroform at 25℃ was 0.4dL / g;

[0055] Polystyrene: the manufacturer was Shanghai Sike Petroleum Chemical Co., Ltd., the brand was 622P, and the melt flow rate under a load of 5kg at 200℃ was 4.5g / 10min;

[0056] Low molecular weight oxazoline: the manufacturer was Japan Catalyst Co., Ltd., the brand was WS-500, the weight average molecular weight was 7x10 4 , and the oxazoline group content was 4.5mmol / g;

[0057] Polystyrene grafted oxazoline: the manufacturer was Japan Catalyst Co., Ltd., the brand was RPS-1005, the weight average molecular weight was 1.6x10 5 , and the oxazoline group content was 0.27mmol / g;

[0058] Toughening agent: SEBS-g-MAH, manufacturer: American Kraton Corporation, brand: FG1901;

[0059] Antioxidant: manufacturer: American Dover Corporation, brand: S9228;

[0060] Glass fiber: manufacturer: China Jushi Co., Ltd., brand: 540H;

[0061] (2) 50 parts of polyphenyl ether, 20 parts of polystyrene, 0.5 parts of low molecular weight oxazoline, 4 parts of polystyrene grafted oxazoline, 5 parts of toughening agent and 0.5 parts of antioxidant were mixed and then added into the twin-screw extruder from the main feeding port, while 10 parts of glass fiber was added into the twin-screw extruder from the side feeding port; wherein the mixing time was 2 min;

[0062] (3) extruded and granulated by the twin-screw extruder to obtain the polyphenyl ether composition capable of multiple repeated injection molding; wherein the rotating speed of the twin-screw extruder was 180 rpm and the temperature was 235-275℃.

[0063] The final polyphenyl ether composition capable of multiple repeated injection molding had a tensile strength of 78.5 MPa, a notched impact strength of 8.3 KJ / m 2 After the second injection molding, the tensile strength was 76.2 MPa, the tensile strength retention rate was 97.1%, the notched impact strength was 8.1 KJ / m 2 , the notched impact strength retention rate was 97.6%, the ΔE was 0.5, and after the third injection molding, the tensile strength was 71.3 MPa, the tensile strength retention rate was 90.8%, the notched impact strength was 7.8 KJ / m 2 , the notched impact strength retention rate was 94%, and the ΔE was 1.3.

[0064] Example 2

[0065] A method for preparing a polyphenyl ether composition capable of multiple repeated injection molding, the specific steps are as follows:

[0066] (1) Preparation of raw materials;

[0067] Polyphenyl ether: manufacturer: Nantong Xingchen Synthetic Material Co., Ltd., brand: PPO LXN040, intrinsic viscosity in chloroform at 25℃ is 0.4 dL / g;

[0068] Polystyrene: manufacturer: Shanghai Sike Petroleum Chemical Co., Ltd., brand: 622P, melt flow rate under a load of 5 kg at 200℃ is 4.5 g / 10 min;

[0069] Low molecular weight oxazoline: manufacturer: Japan Catalyst Co., Ltd., brand: WS-500, weight average molecular weight is 7 x 104 oxazoline group content is 4.5 mmol / g;

[0070] Polystyrene grafted oxazoline: manufacturer is Japan Catalyst Co., Ltd., brand is RPS-1005, weight average molecular weight is 1.6 x 104 5 oxazoline group content is 0.27 mmol / g;

[0071] Toughening agent: SEBS-g-MAH, manufacturer is American Kraton Co., Ltd., brand is FG1901;

[0072] Antioxidant: manufacturer is American Dover Co., Ltd., brand is S9228;

[0073] Glass fiber: manufacturer is China Jushi Co., Ltd., brand is 540H;

[0074] (2) 40 parts of polyphenyl ether, 30 parts of polystyrene, 0.8 parts of low molecular weight oxazoline, 2 parts of polystyrene grafted oxazoline, 6 parts of toughening agent and 0.8 parts of antioxidant are mixed and then added into the twin-screw extruder from the main feeding port, and 20 parts of glass fiber is added into the twin-screw extruder from the side feeding port; wherein the mixing time is 3 min;

[0075] (3) extruded and granulated by the twin-screw extruder to obtain the polyphenyl ether composition which can be repeatedly injection molded; wherein the rotating speed of the twin-screw extruder is 550 rpm, and the temperature is 235-275°C.

[0076] After the first injection molding, the tensile strength of the finally prepared polyphenyl ether composition which can be repeatedly injection molded is 105 MPa, the notched impact strength is 10.8 KJ / m 2 After the second injection molding, the tensile strength is 101 MPa, the tensile strength retention rate is 96.2%, the notched impact strength is 10.4 KJ / m 2 The notched impact strength retention rate is 96.3%, the ΔE is 0.4, and after the third injection molding, the tensile strength is 96.2 MPa, the tensile strength retention rate is 91.6%, the notched impact strength is 9.8 KJ / m 2 The notched impact strength retention rate is 90.7%, and the ΔE is 1.4.

[0077] Comparative Example 1

[0078] A preparation method of a polyphenyl ether composition is basically the same as that of Example 2, except that no toughening agent is prepared in step (1), and no toughening agent is added in step (2).

[0079] After the first injection molding, the tensile strength of the finally prepared polyphenyl ether composition which can be repeatedly injection molded is 105 MPa, the notched impact strength is 10.8 KJ / m 2After two injection molding processes, the tensile strength is 94.3 MPa, the tensile strength retention rate is 95.3%, and the notched impact strength is 6.1 KJ / m. 2 The notched impact strength retention rate was 95.3%, ΔE was 0.8, and the tensile strength after three injection molding cycles was 86.0 MPa, with a tensile strength retention rate of 87.0%. The notched impact strength was 5.6 KJ / m. 2 The notched impact strength retention rate was 87.5%, and ΔE was 1.5.

[0080] Comparing Comparative Example 1 and Example 2, it can be seen that the impact performance of the polyphenylene ether composition in Comparative Example 1 is significantly reduced. This is because the toughening agent lacks the protective effect of the resin-rubber interface. Meanwhile, the retention rate of the polyphenylene ether composition in Example 2, which can be repeatedly injection molded, is significantly higher than that of the polyphenylene ether composition in Comparative Example 1. This is because the maleic anhydride group of the toughening agent and the azoline segment in the oxazoline grafted onto the polystyrene gradually and fully react during repeated injection molding, so that the interface between the resin and rubber can be better maintained, thereby greatly improving the toughness retention rate after repeated injection molding.

[0081] Example 3

[0082] A method for preparing a polyphenylene ether composition that can be repeatedly injection molded includes the following steps:

[0083] (1) Preparation of raw materials;

[0084] Polyphenylene oxide (PPO): The manufacturer is Ruicheng Branch of Bluestar New Materials Co., Ltd., and the grade is PPO LXR035. The intrinsic viscosity in chloroform at 25°C is 0.35 dL / g.

[0085] Polystyrene: Manufacturer is Formosa Plastics (Ningbo) Co., Ltd., grade HP8250, melt flow rate at 200℃ and 5kg load is 5.5g / 10min;

[0086] Low molecular weight oxazoline: Manufacturer: Nippon Shokubai Co., Ltd., Brand name: WS-700, Weight average molecular weight: 4×10 4 The oxazoline content is 4.5 mmol / g;

[0087] Polystyrene grafted with oxazoline: Manufacturer: Nippon Shokubai Co., Ltd., Brand: RPS-1005, Weight-average molecular weight: 1.6 × 10⁻⁶ 5 The oxazoline content is 0.27 mmol / g;

[0088] Toughening agent: SEBS-g-MAH, manufactured by Kraton Pharmaceuticals, USA, brand name FG1901;

[0089] Antioxidant: Manufacturer is Dover Corporation, USA, brand name is S9228;

[0090] Glass fiber: manufacturer Chongqing International Composite Material Co., Ltd., trade designation 306;

[0091] (2) 35 parts of polyphenylene ether, 35 parts of polystyrene, 1 part of low molecular weight oxazoline, 3 parts of polystyrene grafted oxazoline, 8 parts of toughening agent and 0.8 parts of antioxidant were mixed according to parts by weight, and then added into the twin-screw extruder from the main feeding port, while 20 parts of glass fiber was added into the twin-screw extruder from the side feeding port; wherein the mixing time was 4 min;

[0092] (3) extruded and granulated by the twin-screw extruder, to obtain the polyphenylene ether composition capable of repeated injection molding; wherein the rotating speed of the twin-screw extruder was 600 rpm, and the temperature was 235-275°C.

[0093] The final polyphenylene ether composition capable of repeated injection molding had a tensile strength of 102 MPa, a notched impact strength of 11.3 KJ / m 2 After the first injection molding, a tensile strength of 98.4 MPa, a tensile strength retention rate of 96.5%, a notched impact strength of 10.9 KJ / m 2 After the second injection molding, a notched impact strength retention rate of 96.5%, a ΔE of 0.2, a tensile strength of 93.4 MPa, a tensile strength retention rate of 91.6%, a notched impact strength of 10.5 KJ / m 2 After the third injection molding, a notched impact strength retention rate of 92.9%, and a ΔE of 1.3.

[0094] Comparative Example 2

[0095] A method for preparing a polyphenylene ether composition, which was basically the same as Example 3, except that no low molecular weight oxazoline was prepared in step (1), and no low molecular weight oxazoline was added in step (2).

[0096] The final polyphenylene ether composition had a tensile strength of 100.5 MPa, a notched impact strength of 10.2 KJ / m 2 After the first injection molding, a tensile strength of 97.2 MPa, a tensile strength retention rate of 96.7%, a notched impact strength of 9.8 KJ / m 2 After the second injection molding, a notched impact strength retention rate of 96.1%, a ΔE of 1.0, a tensile strength of 89.2 MPa, a tensile strength retention rate of 88.8%, a notched impact strength of 8.9 KJ / m 2 After the third injection molding, a notched impact strength retention rate of 87.3%, and a ΔE of 1.8.

[0097] Comparing Example 3 with Comparative Example 2, it can be seen that the three times injection molding performance retention and color performance of the repeatedly injection molding polyphenyl ether composition of Example 3 are obviously superior to those of the polyphenyl ether composition of Comparative Example 2, because the reaction activity of polystyrene grafted oxazoline is not as good as that of low molecular weight oxazoline, and the protection of molecular chain is insufficient.

[0098] Example 4

[0099] A preparation method of a repeatedly injection molding polyphenyl ether composition, the specific steps are as follows:

[0100] (1) Preparation of raw materials;

[0101] Polyphenyl ether: the manufacturer is Lantian New Material Co., Ltd. Ruicheng Branch, the brand is PPO LXR035, and the intrinsic viscosity in chloroform at 25°C is 0.35 dL / g;

[0102] Polystyrene: the manufacturer is Taizhu Plastics (Ningbo) Co., Ltd., the brand is HP8250, and the melt flow rate under a load of 5 kg at 200°C is 5.5 g / 10 min;

[0103] Low molecular weight oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is WS-700, the weight average molecular weight is 4×10 4 , and the oxazoline group content is 4.5 mmol / g;

[0104] Polystyrene grafted oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is RPS-1005, the weight average molecular weight is 1.6×10 5 , and the oxazoline group content is 0.27 mmol / g;

[0105] Toughening agent: SEBS-g-MAH, the manufacturer is Kraton Corporation, the brand is FG1901;

[0106] Antioxidant: the manufacturer is Dover Corporation, the brand is S9228;

[0107] Glass fiber: the manufacturer is Chongqing International Composite Material Co., Ltd., the brand is 306;

[0108] (2) 30 parts of polyphenyl ether, 40 parts of polystyrene, 1.2 parts of low molecular weight oxazoline, 5 parts of polystyrene grafted oxazoline, 10 parts of toughening agent and 0.5 parts of antioxidant are mixed and then added into the twin-screw extruder from the main feeding port, and 30 parts of glass fiber is added into the twin-screw extruder from the side feeding port; wherein, the mixing time is 5 min;

[0109] (3) extruding and granulating by a twin-screw extruder, to obtain the polyphenyl ether composition capable of repeated injection molding; wherein the rotating speed of the twin-screw extruder is 300 rpm, and the temperature is 235-275℃.

[0110] The polyphenyl ether composition capable of repeated injection molding finally prepared has a tensile strength of 95.8 MPa, a notched impact strength of 13.5 KJ / m 2 After the second injection molding, the tensile strength is 94.3 MPa, the tensile strength retention rate is 98.4%, the notched impact strength is 13.3 KJ / m 2 The notched impact strength retention rate is 98.5%, the ΔE is 0.3, after the third injection molding, the tensile strength is 90.1 MPa, the tensile strength retention rate is 94.1%, the notched impact strength is 12.8 KJ / m 2 The notched impact strength retention rate is 94.8%, and the ΔE is 1.1.

[0111] Example 5

[0112] A preparation method of a polyphenyl ether composition capable of repeated injection molding, and the specific steps are as follows:

[0113] (1) Preparation of raw materials;

[0114] Polyphenyl ether: the manufacturer is Lantian New Material Co., Ltd. Ruicheng Branch, the brand is PPO LXR045, and the intrinsic viscosity in chloroform at 25℃ is 0.45 dL / g;

[0115] Polystyrene: the manufacturer is Zhenjiang Qimei Chemical Co., Ltd., the brand is PH-88, and the melt flow rate under a load of 5 kg at 200℃ is 6 g / 10 min;

[0116] Low molecular weight oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is WS-700, the weight average molecular weight is 4×10 4 , and the oxazoline group content is 4.5 mmol / g;

[0117] Polystyrene grafted oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is RPS-1005, the weight average molecular weight is 1.6×10 5 , and the oxazoline group content is 0.27 mmol / g;

[0118] Toughening agent: SEBS-g-MAH, the manufacturer is Kraton Corporation, USA, and the brand is FG1901;

[0119] Antioxidant: the manufacturer is Dover Corporation, USA, and the brand is S9228;

[0120] Glass fiber: the manufacturer is Chongqing International Composite Material Co., Ltd., and the brand is 306;

[0121] (2) 20 parts of polyphenylene ether, 50 parts of polystyrene, 1.5 parts of low molecular weight oxazoline, 4 parts of polystyrene grafted oxazoline, 6 parts of toughening agent and 1 part of antioxidant are mixed according to weight parts, and then fed into the twin-screw extruder from the main feeding port, while 30 parts of glass fiber are fed into the twin-screw extruder from the side feeding port; wherein the mixing time is 4 min;

[0122] (3) extruding and granulating through the twin-screw extruder to obtain the polyphenylene ether composition capable of repeated injection molding; wherein the rotating speed of the twin-screw extruder is 400 rpm, and the temperature is 235-275°C.

[0123] The final polyphenylene ether composition capable of repeated injection molding has a tensile strength of 101.5 MPa, a notched impact strength of 10.8 KJ / m 2 After the first injection molding, a tensile strength of 98.8 MPa, a tensile strength retention rate of 97.3%, a notched impact strength of 10.5 KJ / m 2 After the second injection molding, a notched impact strength retention rate of 97.2%, a ΔE of 0.5, a tensile strength of 94.1 MPa, a tensile strength retention rate of 92.7%, a notched impact strength of 9.8 KJ / m 2 After the third injection molding, a notched impact strength retention rate of 90.7%, and a ΔE of 1.3.

[0124] Comparative Example 3

[0125] A method for preparing a polyphenylene ether composition is substantially the same as that of Example 5, except that no polystyrene grafted oxazoline is prepared in step (1), and no polystyrene grafted oxazoline is added in step (2).

[0126] The final polyphenylene ether composition has a tensile strength of 103.5 MPa, a notched impact strength of 10.4 KJ / m 2 After the first injection molding, a tensile strength of 97.4 MPa, a tensile strength retention rate of 94.1%, a notched impact strength of 9.6 KJ / m 2 After the second injection molding, a notched impact strength retention rate of 92.3%, a ΔE of 1.2, a tensile strength of 87.0 MPa, a tensile strength retention rate of 84.1%, a notched impact strength of 8.5 KJ / m 2 After the third injection molding, a notched impact strength retention rate of 81.7%, and a ΔE of 2.1.

[0127] Comparing Comparative Example 3 and Example 5, it can be seen that although the secondary injection molding performance retention and color performance of the polyphenyl ether composition of Comparative Example 3 are excellent, the material performance retention and color after tertiary injection molding are far inferior to the repeatedly injection molding polyphenyl ether composition of Example 5, because the effective functional groups of the polyphenyl ether composition of Comparative Example 3 are largely consumed in the extrusion or first and second injection molding processes, resulting in insufficient protection for the tertiary injection molding.

[0128] Example 6

[0129] A method for preparing a repeatedly injection molding polyphenyl ether composition, the specific steps are as follows:

[0130] (1) Preparation of raw materials;

[0131] Polyphenyl ether: The manufacturer is Lantian New Material Co., Ltd. Ruicheng Branch, the brand is PPO LXR045, and the intrinsic viscosity in chloroform at 25°C is 0.45 dL / g;

[0132] Polystyrene: The manufacturer is Zhenjiang Qimei Chemical Co., Ltd., the brand is PH-88, and the melt flow rate under a load of 5 kg at 200°C is 6 g / 10 min;

[0133] Low molecular weight oxazoline: The manufacturer is Japan Catalyst Co., Ltd., the brand is WS-700, the weight average molecular weight is 4×10 4 , and the oxazoline group content is 4.5 mmol / g;

[0134] Polystyrene grafted oxazoline: The manufacturer is Japan Catalyst Co., Ltd., the brand is RPS-1005, the weight average molecular weight is 1.6×10 5 , and the oxazoline group content is 0.27 mmol / g;

[0135] Toughening agent: SEBS-g-MAH, the manufacturer is Kraton Corporation, the brand is FG1901;

[0136] Antioxidant: The manufacturer is Dover Corporation, the brand is S9228;

[0137] Glass fiber: The manufacturer is Taishan Glass Fiber Co., Ltd., the brand is T551R;

[0138] (2) 30 parts of polyphenyl ether, 35 parts of polystyrene, 1 part of low molecular weight oxazoline, 3 parts of polystyrene grafted oxazoline, 5 parts of toughening agent and 1 part of antioxidant are mixed and then added to the twin-screw extruder from the main feeding port, and 40 parts of glass fiber are added to the twin-screw extruder from the side feeding port; wherein the mixing time is 5 min;

[0139] (3) extruding and granulating through a twin-screw extruder, i.e. to obtain the polyphenyl ether composition capable of repeated injection molding; wherein the rotating speed of the twin-screw extruder is 450 rpm and the temperature is 235-275°C.

[0140] The final polyphenyl ether composition capable of repeated injection molding has a tensile strength of 110.3 MPa, a notched impact strength of 8.2 KJ / m 2 After the first injection, a tensile strength of 106.3 MPa, a tensile strength retention rate of 96.4%, a notched impact strength of 7.9 KJ / m 2 After the second injection, a notched impact strength retention rate of 96.3%, a ΔE of 0.8, a tensile strength of 102 MPa, a tensile strength retention rate of 92.5%, a notched impact strength of 7.4 KJ / m 2 After the third injection, a notched impact strength retention rate of 90.2%, and a ΔE of 1.2.

[0141] Comparative Example 4

[0142] A method for preparing a polyphenyl ether composition, which is basically the same as that of Example 6, except that in step (1) no low molecular weight oxazoline and polystyrene grafted oxazoline is prepared, and in step (2) no low molecular weight oxazoline and polystyrene grafted oxazoline is added.

[0143] The final polyphenyl ether composition has a tensile strength of 108.3 MPa, a notched impact strength of 8.1 KJ / m 2 After the first injection, a tensile strength of 100.2 MPa, a tensile strength retention rate of 92.5%, a notched impact strength of 7.4 KJ / m 2 After the second injection, a notched impact strength retention rate of 91.4%, a ΔE of 1.6, a tensile strength of 89.3 MPa, a tensile strength retention rate of 82.5%, a notched impact strength of 6.5 KJ / m 2 After the third injection, a notched impact strength retention rate of 80.2%, and a ΔE of 2.5.

[0144] Comparing Comparative Example 4 with Example 6, it can be seen that in Comparative Example 4, no low molecular weight oxazoline and polystyrene grafted oxazoline is added, and although the toughening agent has a significant toughening effect, the retention rate of the final polyphenyl ether composition will drop significantly, and the color change is also significant, which has no obvious help for the second or third injection.

[0145] From the comparative example 2, comparative example 3 and comparative example 4, the high reactivity of oxazoline makes the linear polyphenyl ether molecules connect with each other to form a network structure. This network structure protects the phenoxy bond of polyphenyl ether in the processing process, greatly reduces the probability of chain segment breakage. At the same time, oxazoline can quickly capture and cap the free radicals generated by high temperature and shear action in the injection molding process, thereby preventing the oxidation of phenoxy free radicals into benzoquinone and the coupling reaction between benzoquinone and free radicals, preventing the accumulation of benzoquinone and benzoquinone coupling products, thereby improving the yellowing of the material in the repeated extrusion process. More importantly, the use of high and low molecular weight oxazoline plays a crucial role in protecting the polyphenyl ether molecular chain and color in subsequent repeated molding.

[0146] Example 7

[0147] A method for preparing a polyphenyl ether composition that can be repeatedly injection molded, the specific steps are as follows:

[0148] (1) Preparation of raw materials;

[0149] Polyphenyl ether: the manufacturer is Lantian New Material Co., Ltd. Ruicheng Branch, the brand is PPO LXR045, and the intrinsic viscosity in chloroform at 25°C is 0.45 dL / g;

[0150] Polystyrene: the manufacturer is Zhenjiang Qimei Chemical Industry Co., Ltd., the brand is PH-88, and the melt flow rate under a load of 5 kg at 200°C is 6 g / 10 min;

[0151] Low molecular weight oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is WS-500, and the weight average molecular weight is 7 x 10 4 , and the oxazoline group content is 4.5 mmol / g;

[0152] Polystyrene grafted oxazoline: the manufacturer is Japan Catalyst Co., Ltd., the brand is RPS-1005, and the weight average molecular weight is 1.6 x 10 5 , and the oxazoline group content is 0.27 mmol / g;

[0153] Toughening agent: SEBS-g-MAH, the manufacturer is Kraton Corporation, USA, and the brand is FG1901;

[0154] Antioxidant: the manufacturer is Dover Corporation, USA, and the brand is S9228;

[0155] Glass fiber: the manufacturer is Taishan Glass Fiber Co., Ltd., and the brand is T551R;

[0156] (2) 35 parts of polyphenylene ether, 40 parts of polystyrene, 1.5 parts of low molecular weight oxazoline, 2 parts of polystyrene grafted oxazoline, 7 parts of toughening agent and 0.5 part of antioxidant are mixed according to parts by weight and then fed into the twin-screw extruder from the main feeding port, while 40 parts of glass fiber are fed into the twin-screw extruder from the side feeding port; the mixing time is 4 minutes;

[0157] (3) The twin-screw extruder is extruded and granulated to obtain the polyphenylene ether composition capable of repeated injection molding; the rotating speed of the twin-screw extruder is 200 rpm and the temperature is 235-275°C.

[0158] The final polyphenylene ether composition capable of repeated injection molding has a tensile strength of 114.3 MPa, a notched impact strength of 8.1 KJ / m 2 After the first injection, a tensile strength of 109.8 MPa, a tensile strength retention rate of 96.1%, a notched impact strength of 7.8 KJ / m 2 After the second injection, a notched impact strength retention rate of 96.3%, a ΔE of 0.9, a tensile strength of 104 MPa, a tensile strength retention rate of 91%, a notched impact strength of 7.4 KJ / m 2 After the third injection, a notched impact strength retention rate of 91.4%, and a ΔE of 1.4.

[0159] Comparative Example 5

[0160] A method for preparing a polyphenylene ether composition is substantially the same as that of Example 7, except that no toughening agent, low molecular weight oxazoline and polystyrene grafted oxazoline are prepared in step (1).

[0161] The final polyphenylene ether composition has a tensile strength of 108.2 MPa, a notched impact strength of 6.2 KJ / m 2 After the first injection, a tensile strength of 94.3 MPa, a tensile strength retention rate of 87.2%, a notched impact strength of 5.3 KJ / m 2 After the second injection, a notched impact strength retention rate of 85.5%, a ΔE of 2.4, a tensile strength of 84.3 MPa, a tensile strength retention rate of 77.9%, a notched impact strength of 4.9 KJ / m 2 After the third injection, a notched impact strength retention rate of 79.0%, and a ΔE of 4.3.

[0162] Comparing Comparative Example 5 with Example 7, it can be seen that the polyphenylene ether composition of Comparative Example 5 not only has insufficient toughness, but also has a sharp decrease in performance retention rate and a very significant change in color.

Claims

1. A polyphenylene ether composition capable of repeated injection molding, characterized in that, Includes matrix resin, crosslinking agent, and toughening agent; The matrix resin is a mixture of polyphenylene ether and polystyrene; The crosslinking agent is a mixture of low molecular weight oxazoline and polystyrene-grafted oxazoline, with the low molecular weight oxazoline having a weight-average molecular weight of 3 × 10⁻⁶. 4 -8×10 4 The oxazoline content is 4.5 mmol / g, and the weight-average molecular weight of polystyrene-grafted oxazoline is 1 × 10⁻⁶. 5 -2×10 5 The oxazoline content is 0.27 mmol / g; The toughening agent is SEBS-g-MAH; The mass ratio of low molecular weight oxazoline to polystyrene-grafted oxazoline is 0.5-1.5:2-5, and the mass ratio of SEBS-g-MAH to polystyrene-grafted oxazoline is 5-10:2-5. The polyphenylene ether composition that can be repeatedly injection molded has a tensile strength retention rate of >96% and a notched impact strength retention rate of >96% after two injection moldings, with ΔE<1; and a tensile strength retention rate of >90% and a notched impact strength retention rate of >90% after three injection moldings, with ΔE<1.5; where ΔE is the color difference value between the second or third injection molding sample and the first injection molding sample measured according to GBT16422.3 standard.

2. The polyphenylene ether composition capable of repeated injection molding according to claim 1, characterized in that, The intrinsic viscosity of polyphenylene ether in chloroform at 25°C is 0.35-0.45 dL / g.

3. The polyphenylene ether composition capable of repeated injection molding according to claim 1, characterized in that, The polystyrene is a high-impact polystyrene with a melt flow rate of 4.5-6 g / 10 min at 200℃ and 5 kg load.

4. A polyphenylene ether composition capable of repeated injection molding according to any one of claims 1 to 3, characterized in that, It also includes glass fiber and antioxidants.

5. The polyphenylene ether composition capable of repeated injection molding according to claim 4, characterized in that, By mass, the components and their contents are as follows: 20-50 parts polyphenylene ether, 20-50 parts polystyrene, 0.5-1.5 parts low molecular weight oxazoline, 2-5 parts polystyrene grafted oxazoline, 5-10 parts SEBS-g-MAH, 10-40 parts glass fiber, and 1-3 parts antioxidant.

6. A method for preparing a polyphenylene ether composition capable of repeated injection molding as described in any one of claims 4-5, characterized in that, Includes the following steps: (1) Add all components to the twin-screw extruder, wherein glass fiber is added from the side feed port, and other components are added from the main feed port after mixing; (2) The polyphenylene ether composition that can be repeatedly injection molded is obtained by extruding and granulating the polyphenylene ether through a twin-screw extruder.

7. The method according to claim 6, characterized in that, In step (1), the mixing time is 2-5 minutes.

8. The method according to claim 6, characterized in that, In step (2), the rotation speed of the twin-screw extruder is 180-600 rpm and the temperature is 235-275℃.

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