A modified polyphenylene ether material, and foamed beads and foamed molded bodies thereof

Abstract

The application discloses a modified polyphenyl ether material and foamed beads and foamed molded bodies thereof, and belongs to the technical field of chemical industry.The modified polyphenyl ether material comprises the following components: polyphenyl ether, a crosslinking agent containing a carbonyl group, and a crosslinking aid containing a divalent metal ion; the carbonyl oxygen atom in the crosslinking agent is connected with the metal atom in the crosslinking aid to form a reversible crosslinking structure.The reversible crosslinking structure enables the modified polyphenyl ether material to have good mechanical properties at normal temperature and below the heat distortion temperature (HDT); during the preparation process at high temperature, the reversible crosslinking structure is destroyed, so that the flow performance and processing performance of the modified polyphenyl ether material are significantly improved.This is of great significance to solve the problems of poor melt flowability and difficult processing of the polyphenyl ether material, and provides a new idea for improving the foaming performance of the polyphenyl ether foamed material.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a modified polyphenylene ether material and its foamed beads and foamed molded bodies. Background Technology

[0002] Polyphenylene oxide resin is a new type of high-performance thermoplastic resin with a strength of up to 70 MPa, which is about three times that of polyethylene. Its elastic modulus is greater than 2000 MPa, its impact resistance is greater than 430 J / m, and its heat distortion temperature is as high as 120℃. The product has good dimensional stability, and its creep resistance is the best among the five major engineering plastics. It has high reliability for long-term use, and it also has intrinsic flame retardancy. It is a low-smoke, halogen-free, environmentally friendly flame retardant material.

[0003] Through foaming, polyphenylene ether (PPE) resin can achieve both lightweighting and unique functionalities, such as heat insulation, sound insulation, cushioning, and low dielectric properties. PPE foam beads can expand and bond together during heating, forming foamed products of various shapes and structures, widely used in cushioning packaging, building insulation, cold chain logistics, toys, and other fields. Furthermore, due to the excellent heat resistance and dimensional stability of PPE foam beads, they have broad application prospects in the automotive, new energy battery, and precision instrument industries.

[0004] However, high-performance polyphenylene sulfide or polyphenylene ether resin molecules have disadvantages such as high rigidity, high glass transition temperature, difficulty in orientation, high residual internal stress in the product, poor melt flowability, and difficult processing. These shortcomings undoubtedly limit the application of polyphenylene ether resin materials.

[0005] To obtain polyphenylene ether foam materials with excellent heat resistance and dimensional stability, it is essential to modify the polyphenylene ether resin to make it suitable as a foam material.

[0006] CN100587803C states that "in the modified polyphenylene ether resin constituting the modified polyphenylene ether resin foam sheet, the polyphenylene ether content is 15-60% by weight, and the styrene content is 40-85% by weight." This is because if the polyphenylene ether content in the modified polyphenylene ether resin is too low, the heat resistance of the foam sheet will decrease; if the polyphenylene ether content is too high, a good foam sheet cannot be obtained, and the polyphenylene ether content cannot be greater than 60% by weight.

[0007] CN102471517B states that "the base resin comprises 40wt% to 94wt% polyphenylene ether resin, 5wt% to 20wt% flame retardant, and 0.3wt% to 10wt% rubber component, with the remainder being composed of polystyrene resin." Although the polyphenylene ether content in the claims can be greater than 60%, the provided examples show a maximum polyphenylene ether content of 70%. The comparative examples with contents of 96wt% and 85wt% show poor foaming performance. To improve foaming properties, 0.3wt% to 10wt% rubber component needs to be added.

[0008] CN109054337A discloses a formulation, preparation method, and application of modified polyphenylene ether foamed beads. CN110591331A discloses a similar technical solution using "PP-g-MAH, SEBS-g-MAH, PE-g-MAH, EPDM, and POE-g-GMA" as compatibilizers. However, although these polymers are frequently used as compatibilizers, they are incompatible with polyphenylene ether within the system, significantly weakening the compatibilizer's effect and leading to deterioration of material properties.

[0009] CN103910966A also provides a method for preparing a foamed polyphenylene ether / polystyrene blended gold material, which is prepared by using a chemical foaming agent and an extrusion foaming method.

[0010] CN114736505A discloses a method for preparing foamed polyphenylene ether polypropylene composite beads and wafer packaging boxes. "The composite beads consist of a core layer and a skin layer covering the outside of the core layer, wherein the skin layer is polypropylene." While coating the surface with a layer of polypropylene improves the material's performance, the preparation of composite beads is relatively complicated and requires specialized equipment.

[0011] CN113136098A discloses a modified polyphenylene ether (PPE) microfoam material and its preparation method. The method utilizes maleic anhydride-modified PPE and PPE microspheres containing alloy powder for blending modification, improving the flowability of PPE and making it easier to process and mold, while ensuring its mechanical properties. In particular, gamma-ray irradiation causes the PPE backbone to break, improving its backbone rigidity and thus improving melt flowability. However, the maleic anhydride and PPE are only physically mixed.

[0012] CN114230845A discloses a high-strength polyphenylene sulfide foam and its preparation and molding method. It uses high-temperature resistant and high melt viscosity PPO to improve the viscoelasticity of PPS. Based on the excellent flexibility of HIPS, a functionalized HIPS compatibilizer is prepared by grafting active functional groups such as epoxy groups and acid anhydrides onto its molecules through a simple and efficient reactive melt processing method. The good compatibility between HIPS and PPO, as well as the ring-opening reaction between the grafted active functional groups and the thiol groups of PPS molecules, forms chemical bonds between the components of the blend system, thereby improving its interfacial compatibility and molecular flexibility. Summary of the Invention

[0013] In view of this, the technical problem to be solved by the present invention is to provide a modified polyphenylene ether material, its foamed beads, and foamed molded articles. The modified polyphenylene ether material has good flow properties and processing properties, and possesses excellent mechanical properties and foaming properties.

[0014] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0015] This invention provides a modified polyphenylene ether material comprising the following components: polyphenylene ether, a carbonyl crosslinking agent, and a crosslinking aid containing divalent metal ions.

[0016] The carbonyl oxygen atom in the aforementioned carbonyl-containing crosslinking agent is linked with the metal atom in the crosslinking aid containing divalent metal ions to form a reversible crosslinking structure.

[0017] In this invention, the carbonyl-containing crosslinking agent and the divalent metal ion-containing crosslinking aid form a temperature-responsive reversible crosslinking structure, which greatly improves the processing performance of the modified polyphenylene ether material at high temperatures and the mechanical properties of the modified polyphenylene ether material at room temperature and below the heat distortion temperature (HDT).

[0018] During high-temperature processing, the aforementioned cross-linked structure is disrupted, thereby improving the flowability and processability of the modified polyphenylene ether material. Simultaneously, low-molecular-weight cross-linking agents are preferred, as their plasticizing effect can significantly increase the polyphenylene ether content in the material.

[0019] At room temperature and below HDT, the above cross-linked structure is stable, which allows the modified polyphenylene ether material to maintain good mechanical properties.

[0020] The HDT temperature range of the modified polyphenylene ether material described in this invention is 80℃-120℃.

[0021] In this invention, the above-mentioned room temperature is 10℃-30℃.

[0022] Preferably, the reversible cross-linked structure is destroyed at a temperature ≥200°C.

[0023] Preferably, the mass ratio of the polyphenylene ether to the carbonyl crosslinking agent is (50-90):(3-40).

[0024] Preferably, the mass ratio of the carbonyl-containing crosslinking agent to the divalent metal ion-containing crosslinking aid is (3-40):(0.01-5).

[0025] Preferably, the carbonyl-containing crosslinking agent of the present invention is selected from one or more of styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, styrene-N-phenylmaleimide copolymer, styrene-methacrylic acid copolymer, and styrene-methyl acrylate copolymer. More preferably, it is selected from one or more of styrene-maleic anhydride copolymer, styrene-maleimide copolymer, and styrene-methacrylic acid copolymer.

[0026] Preferably, the crosslinking aid containing divalent metal ions is selected from one or more of zinc oxide, calcium chloride, zinc chloride, zinc borate, zinc sulfate, calcium sulfate, and magnesium sulfate. More preferably, the crosslinking aid containing divalent metal ions is selected from one or more of zinc oxide, zinc chloride, and zinc borate.

[0027] Preferably, the modified polyphenylene ether material further includes a flame retardant.

[0028] The addition of flame retardants can improve the flame retardant properties of modified polyphenylene ether materials, so that the flame retardancy measured in the vertical burning test is V0 or V1.

[0029] Preferably, the mass ratio of the flame retardant to polyphenylene ether is (5-20):(50-90).

[0030] Preferably, the flame retardant of the present invention is selected from non-halogen flame retardants.

[0031] Preferably, the non-halogenated flame retardant is selected from one or more of tricresyl phosphate, triphenyl phosphate, trimethyl phosphate, resorcinol-diphenyl bisphosphate, liquid tetraphenylbisphenol A diphosphate, and solid tetraphenylbisphenol A diphosphate; more preferably, the non-halogenated flame retardant is selected from one or more of tricresyl phosphate, resorcinol-diphenyl bisphosphate, and solid tetraphenylbisphenol A diphosphate.

[0032] Preferably, the modified polyphenylene ether material further includes polystyrene. Its function is that polystyrene has good compatibility with polyphenylene ether resin and a low melt viscosity, which can reduce the melt viscosity of polyphenylene ether and improve its processability.

[0033] The polystyrene is preferably ordinary polystyrene or high-impact polystyrene.

[0034] In this invention, the low molecular weight carbonyl crosslinking agent in the modified polyphenylene ether material has good compatibility with polyphenylene ether. Furthermore, the addition of a crosslinking aid containing divalent metal ions improves the flowability of polyphenylene ether and reduces the processing difficulty of polyphenylene ether, thereby resulting in a higher polyphenylene ether content in the modified polyphenylene ether material.

[0035] In some specific embodiments of the present invention, the modified polyphenylene ether material preferably comprises the following components by mass percentage:

[0036] Polyphenylene oxide: 50%–90%;

[0037] Crosslinking agents containing carbonyl groups: 3%–40%;

[0038] Flame retardant: 5%–20%;

[0039] Crosslinking aids containing divalent metal ions: 0.01%–5%;

[0040] Polystyrene is replenished to 100%.

[0041] Furthermore, in the above components, the carbonyl oxygen atom in the carbonyl-containing crosslinking agent connects with the metal atom in the divalent metal ion-containing crosslinking aid to form a reversible crosslinking structure. The polyphenylene ether content in the modified polyphenylene ether material is significantly increased, reaching up to 90 wt%.

[0042] Inorganic nanomaterials and compatibilizers can also be added to the above-mentioned modified polyphenylene ether materials.

[0043] The inorganic nanomaterial is preferably one or more of the following: talc, SiO2, calcium carbonate, wollastonite, sepiolite, and nano-calcium silicate.

[0044] The compatibilizer is preferably one or more of zinc stearate, calcium stearate, pentaerythritol stearate, stearamide, glyceryl monostearate, erucamide, ethylene bis-stearamide, and polytetrafluoroethylene.

[0045] The present invention also provides a modified polyphenylene ether foamed beads, which are prepared by melt extrusion, granulation and foaming of the above-mentioned modified polyphenylene ether material.

[0046] The reversible cross-linking structure formed by the cross-linking agent and cross-linking aid in the modified polyphenylene ether material is only partially destroyed at the foaming temperature (greater than HDT, less than the processing temperature). The remaining cross-linking structure provides excellent viscoelasticity to the foaming material, greatly improving the foaming properties of the material.

[0047] The preparation method of the above-mentioned modified polyphenylene ether foam beads can be specifically as follows:

[0048] 1) After mixing the above components evenly according to the formula, add them into the screw extruder and heat them. Then melt and extrude them to obtain modified polyphenylene ether material particles.

[0049] 2) The modified polyphenylene ether material particles obtained in step 1) are melt-extruded again and underwater pelletized to obtain uniform foaming particles.

[0050] 3) Add the particles obtained in step 2) into a high-pressure reactor, mix with supercritical fluid, and foam under constant temperature and pressure to prepare modified polyphenylene ether foamed beads.

[0051] The preparation method described in this invention can achieve uniform mixing of all components of the modified polyphenylene ether material through multiple extrusions.

[0052] In the above preparation method, the temperature of the two melt extrusions is preferably 200℃-260℃.

[0053] The particle size of the particles in step 2) is preferably 0.3 to 3 mm.

[0054] The foaming ratio of the particles in step 2) is preferably 2 to 20 times.

[0055] The above preparation method utilizes the diffusivity and solubility of supercritical fluids to dissolve modified polyphenylene ether material particles through gas permeation, followed by pressure release and cooling to obtain modified polyphenylene ether foamed beads.

[0056] In some specific embodiments of the present invention, the supercritical fluid in step 3) is preferably carbon dioxide or nitrogen.

[0057] The preferred temperature for gas permeation and dissolution is 130℃~190℃;

[0058] The preferred pressure for gas permeation and dissolution is 5–15 MPa.

[0059] The foaming process in the above preparation method can be repeated multiple times to obtain modified polyphenylene ether foam beads with a larger foaming ratio.

[0060] After foaming, the modified polyphenylene ether foamed beads prepared above are shaped to obtain a foamed molded body. Specifically, the modified polyphenylene ether foamed beads prepared above are placed in a mold, and the foamed molded body is obtained by heating and in-mold molding.

[0061] The foamed molded body can be a foamed material such as sheet or profile.

[0062] Between the foaming and molding processes described above, a pressurization process can be performed. Specifically, the foamed beads are pressurized in an inorganic gas atmosphere, so that the air bubbles inside the foamed beads are given a certain gas pressure, making it easier to foam and form more uniformly.

[0063] The reversible cross-linking structure described above significantly improves the foaming properties of the modified polyphenylene ether material and increases the polyphenylene ether content in the foaming material.

[0064] The modified polyphenylene ether foam material of the present invention has a higher HDT than ordinary foamed polyphenylene ether material and has good molding performance.

[0065] Compared with existing technologies, the modified polyphenylene ether material provided by this invention comprises the following components: polyphenylene ether, a carbonyl-containing crosslinking agent, and a crosslinking aid containing divalent metal ions. The carbonyl oxygen atoms in the crosslinking agent connect with the metal atoms in the crosslinking aid to form a reversible crosslinking structure. This reversible crosslinking structure enables the polyphenylene ether material to exhibit good mechanical properties at room temperature and below its heat distortion temperature (HDT). During high-temperature preparation, the reversible crosslinking structure is disrupted, significantly improving the flowability and processing performance of the polyphenylene ether in the material. This is of great significance in solving the problems of poor melt flowability and processing difficulties of polyphenylene ether materials, and provides a new approach to improving the foaming performance of polyphenylene ether foamed materials. Detailed Implementation

[0066] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a modified polyphenylene ether material, its foamed beads, and its foamed molded articles provided by the present invention.

[0067] Examples 1-8

[0068] Step 1: Material Modification

[0069] Prepare the raw materials according to Table 1. Using polyphenylene ether (LXR045, intrinsic viscosity 43-47 dL / g, Lanxing Ruicheng New Materials Co., Ltd.) as the base material, add modified polymer (styrene-based polymer), compatibilizer, inorganic nanomaterials and related additives (crosslinking agent, flame retardant, crosslinking aid), mix and heat, and extrude to obtain modified polyphenylene ether material.

[0070] Step 2: Underwater pelletizing

[0071] The modified polyphenylene ether material obtained above is added to a high-speed mixer and mixed evenly. It is then fed into a twin or triple screw extrusion mixer, where the material is melted and extruded at high temperature. The material is then combined with an underwater pelletizing device for underwater pelletizing, resulting in uniform particle size (1 mm), high sphericity, and smooth surface of the pellets.

[0072] Step 3: Foaming

[0073] Supercritical fluids (carbon dioxide, nitrogen), water, etc. are added to a high-pressure autoclave. The underwater-cut particles are heated to a certain temperature, kept at a constant temperature and pressure, dissolved through gas permeation, and the pressure is released to obtain the corresponding foamed beads.

[0074] Step 4: Preparation of foamed molded body

[0075] The modified polyphenylene ether foam beads were placed in a mold and in-mold formed to obtain a foamed molded body. Test strips were prepared according to the test standard requirements. The HDT test results are shown in Table 1.

[0076] Modified polyphenylene ether foam was prepared according to the above steps, and its foam particle density, molding performance and HDT of the foam were recorded in Table 1.

[0077] Measurement of load heat distortion temperature (HDT): According to method B in GB / T 1634, a sample with a size of 80mm×10mm×4mm is prepared, a load of 0.45MPa is applied, and the temperature is increased from 30℃ at a heating rate of 2℃ / min. The temperature at which the deflection reaches 0.34mm is evaluated as HDT.

[0078] Molding performance: A 300mm×300mm×17mm flat plate was formed using a K-68 molding machine. Samples with no gaps on the surface, tightly fused foam beads, and a plate-like shape were rated as "o"; samples with gaps on the surface or unable to be molded into a plate-like shape were rated as "X".

[0079] Comparative Example 1

[0080] Compared with Example 1, without the addition of crosslinking agent and crosslinking aid, the melt viscoelasticity during foaming is poor, the density of the obtained foam beads is low, some perforations are generated, resulting in poor molding performance. In addition, the HDT of the molded body is low at 70°C. Specific data are shown in Table 1.

[0081] Comparative Example 2

[0082] Compared with Example 1, the addition of only a crosslinking agent without the addition of a crosslinking aid also resulted in poor melt viscoelasticity during foaming, causing partial perforation and poor molding performance. In addition, the HDT of the molded body was low, at 75°C. Specific data are shown in Table 1.

[0083] Comparative Example 3

[0084] Compared with Example 1, the addition of a crosslinking aid without the addition of a crosslinking agent resulted in poor processing performance and difficulty in foaming due to the high polyphenylene ether content of 70%. Specific data are shown in Table 1.

[0085] Comparative Example 4

[0086] Compared with Example 1, without the addition of crosslinking agent and crosslinking aid, it is difficult to obtain good foamed beads due to the high polyphenylene ether content of 90%. Specific data are shown in Table 1.

[0087] Table 1. Specific experimental data of Examples 1-8 and Comparative Examples 1-4

[0088]

[0089]

[0090] In summary, the modified polyphenylene ether material of the present invention has a reversible cross-linking structure formed by the carbonyl oxygen atom in the cross-linking agent and the metal atom in the cross-linking aid. This results in good mechanical properties of the polyphenylene ether material at room temperature or below HDT. During the high-temperature preparation process, the reversible cross-linking structure is destroyed, which significantly improves the flow properties and processing performance of the polyphenylene ether in the material.

[0091] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A modified polyphenylene ether material, characterized in that, It includes the following components: polyphenylene ether, a carbonyl-containing crosslinking agent, and a crosslinking aid containing divalent metal ions; The carbonyl oxygen atom in the carbonyl-containing crosslinking agent is linked with the metal atom in the crosslinking aid containing divalent metal ions to form a reversible crosslinking structure. The mass ratio of the polyphenylene ether to the carbonyl-containing crosslinking agent is (50~90):(3~40); The mass ratio of the carbonyl-containing crosslinking agent to the divalent metal ion-containing crosslinking aid is (3~40):(0.01~5). The carbonyl-containing crosslinking agent is selected from one or more of the following: styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, styrene-N-phenylmaleimide copolymer, styrene-methacrylic acid copolymer, and styrene-methyl acrylate copolymer. The crosslinking aid containing divalent metal ions is selected from one or more of zinc oxide, calcium chloride, zinc chloride, zinc borate, zinc sulfate, calcium sulfate, and magnesium sulfate.

2. The modified polyphenylene ether material according to claim 1, characterized in that, The modified polyphenylene ether material also includes a flame retardant; The mass ratio of the flame retardant to polyphenylene ether is (5~20):(50~90).

3. The modified polyphenylene ether material according to claim 2, characterized in that, The flame retardant is selected from non-halogen flame retardants.

4. The modified polyphenylene ether material according to claim 3, characterized in that, The non-halogenated flame retardant is selected from one or more of tricresyl phosphate, triphenyl phosphate, trimethyl phosphate, resorcinol-diphenyl bisphosphate, liquid tetraphenylbisphenol A diphosphate, and solid tetraphenylbisphenol A diphosphate.

5. The modified polyphenylene ether material according to claim 1, characterized in that, The modified polyphenylene ether material also includes polystyrene.

6. A type of polyphenylene ether foamed beads, characterized in that, It is prepared by melt extrusion, granulation and foaming of the modified polyphenylene ether material according to any one of claims 1 to 5.

7. A polyphenylene ether foamed molded article, characterized in that, The polyphenylene ether foamed beads as described in claim 6 are placed in a mold, and a foamed molded body is obtained by heating and in-mold molding.

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