A polymer foam and a method for its production and use

Abstract

The application discloses a kind of polyphenylene sulfide foam material and its preparation method and application, belong to the field of high polymer materials.The present application uses existing commercial polyphenylene sulfide as raw material, after modification treatment, using supercritical carbon dioxide foaming process, the preparation of high-ratio PPS foam is realized, and the foam density (0.07-0.25g / cm 3 ) Controllable, the maximum foaming ratio can reach more than 15 times.Polyphenylene sulfide foam has excellent mechanical properties, self-retardant, has broad application prospect in the field of transportation, new energy vehicle.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a polyphenylene sulfide foam material, its preparation method, and its application. Background Technology

[0002] Polyphenylene sulfide (PPS) is the sixth largest special engineering plastic. It has the characteristics of high temperature resistance, radiation resistance, flame retardancy and chemical corrosion resistance. It has important applications in defense, aerospace, automotive, electronics and petrochemical industries.

[0003] Polyphenylene sulfide (PPS) is a highly crystalline polymer with low melt strength in its molten state, making it difficult to obtain high-expansion foam materials. To improve the melt strength of PPS and thus its foaming properties, researchers have conducted a series of attempts. For example, references (J. Supercrit. Fluid., 2018, 140:116-128) show PPS blended with PEEK, references (J. Appl. Polym. Sci., 2015, 132:42634) show PPS blended with polyethersulfone, and references (J. Supercrit. Fluid., 2022, 189:105731) show PPS blended with other PPS. However, due to compatibility issues, these blends are prone to phase separation and do not significantly improve the foaming properties of PPS. The resulting foam materials all have an expansion ratio of no more than 6 times, and the adjustable range of the expansion ratio is narrow. Patent (202211613817.7) uses polyphenylene sulfide with an isophenyl structure in the main chain as the matrix resin. The crystallinity of polyphenylene sulfide is controlled by adjusting the content of the isophenyl structure. Then, high-ratio polyphenylene sulfide foam is obtained by supercritical foaming technology. However, the introduction of the isophenyl structure will significantly reduce the melting point of polyphenylene sulfide (about 30-60℃), affecting the service temperature of polyphenylene sulfide foam. Furthermore, the introduction of the isophenyl structure will increase the cost of polyphenylene sulfide. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a polyphenylene sulfide foam, its preparation method and application, which is a high-expansion polyphenylene sulfide foam prepared based on commercial polyphenylene sulfide.

[0005] A polyphenylene sulfide (PPS) foam, wherein the PPS foam has a closed-cell structure, the pore diameter is adjustable from 20 to 300 μm, and the density is 0.07-0.25 g / cm³. 3 Controllable.

[0006] Based on the above technical solution, furthermore, the main molecular chain of the polyphenylene sulfide contains a p-phenylene structure but does not contain a m-phenylene structure, and can be easily obtained through commercial means.

[0007] Based on the above technical solutions, the polyphenylene sulfide can be either a linear structure or a cross-linked structure.

[0008] Based on the above technical solution, the melt flow index (MFR) of the polyphenylene sulfide is further specified as 5-500 g / 10 min (316 °C), preferably 10-300 g / 10 min (316 °C).

[0009] The present invention also provides a method for preparing the above-mentioned polyphenylene sulfide foam, the method comprising the following steps:

[0010] (1) Mix polyphenylene sulfide raw materials, additives and accelerators in a certain proportion, then place the mixture in a dryer for pretreatment, and then process the treated sample to obtain a pre-foamed blank.

[0011] (2) Place the pre-foamed blank in a closed mold cavity and introduce carbon dioxide or nitrogen into the mold cavity as a foaming agent to maintain a certain temperature and pressure in the mold cavity. After a period of time, quickly release the pressure in the mold cavity to obtain polyphenylene sulfide foam material.

[0012] Based on the above technical solution, further, in step (1), the additive is selected from one or more combinations of nano-sized alumina, boron nitride, talc, montmorillonite, silica, calcium carbonate, diatomaceous earth, carbon nanotubes, graphene, and MXenes.

[0013] Based on the above technical solution, further, in step (1), the total mass of the additives and the mass ratio of polyphenylene sulfide are 0-5:100.

[0014] Based on the above technical solution, further, in step (1), the accelerator is selected from one or more combinations of chromium oxide, manganese dioxide, calcium hypochlorite, anthraquinone, tetrachloroquinone, sulfur, and melamine.

[0015] Based on the above technical solution, further, in step (1), the total mass ratio of the accelerator to the mass ratio of polyphenylene sulfide is 0-10:100, preferably 0-5:100.

[0016] Based on the above technical solution, further, in step (1), the pretreatment temperature is 200℃-275℃ and the time is 1-24h, preferably 5-18h.

[0017] Based on the above technical solution, further, in step (1), the pre-foamed preform can be formed by compression molding or extrusion molding. The conditions for compression molding are: temperature 290-320℃, pressure 3-10MPa, and time 15-45min.

[0018] Based on the above technical solution, further, in step (2), the temperature inside the mold cavity is 260-300℃, the pressure is 5-30MPa, preferably 5-15MPa; the holding time is 60-150min, preferably 60-90min.

[0019] The present invention also provides a radar radome with the above-mentioned polyphenylene sulfide foam material as the core material.

[0020] Beneficial Effects: This invention, based on existing commercially available polyphenylene sulfide (PPS), significantly improves its foaming performance through modification treatment. High-expansion PPS foam is then obtained using supercritical foaming technology, with controllable foam density. The expansion ratio of PPS foam can reach over 10 times, and when using supercritical carbon dioxide foaming, the expansion ratio can reach over 15 times. PPS foam possesses excellent mechanical properties, with a room temperature compressive strength greater than 1 MPa, self-flame retardancy, and meets UL 94V-0 standards, showing broad application prospects in transportation and new energy vehicles. Compared with existing technologies, this technology does not significantly lower the melting point of PPS, maintaining it above 280℃. Furthermore, using readily available commercial PPS as raw material offers a lower cost advantage. Attached Figure Description

[0021] Figure 1 This is a SEM image of the polyphenylene sulfide foam in Example 1. Detailed Implementation

[0022] The embodiments described below are merely some embodiments of the present invention, and not all embodiments. Other embodiments obtained by those skilled in the art based on the invention and its embodiments without creative effort are all within the scope of protection of the present invention.

[0023] Example 1

[0024] Take 100g of polyphenylene sulfide (MFR = 150g / 10min @ 316℃), 1.2g of 200-mesh talc powder, and 3g of chromium oxide. Mix them evenly using a high-speed mixer. Place the mixture in a 230℃ forced-air drying oven for 6 hours for pretreatment. Then, use a hot press to mold pre-foamed blanks with dimensions of 8cm × 10cm × 0.6cm. The molding conditions are 300℃, 5MPa, and holding pressure for 30 minutes. Place the blanks in a sealed mold cavity, introduce carbon dioxide, and maintain conditions of 10MPa and 287℃ for 1.5 hours. Then, quickly release the pressure and open the mold cavity to obtain a density of 0.08g / cm³. 3 The polyphenylene sulfide foam material has a foaming ratio of 17 times, a melting point of 283℃, an average cell diameter of 90μm, a compressive strength of 1.15MPa, and a flammability rating of UL94 V-0.

[0025] Example 2

[0026] Take 100g of polyphenylene sulfide (MFR = 230g / 10min@316℃), 0.9g of 200-mesh montmorillonite, and 3g of anthraquinone. Mix them evenly using a high-speed mixer. Place the mixture in a 240℃ forced-air drying oven for 5 hours for pretreatment. Then, use a hot press to mold a pre-foamed preform with dimensions of 8cm×10cm×0.6cm. The molding conditions are 300℃, 5MPa, and pressure holding for 30 minutes. Place the preform in a sealed mold cavity, introduce carbon dioxide, and maintain conditions of 10MPa and 283℃ for 1.5 hours. Then, quickly depressurize and open the mold cavity to obtain polyphenylene sulfide foam material with a density of 0.091g / cm3, a foaming ratio of 14.9 times, a melting point of 285℃, an average cell diameter of 120μm, a compressive strength of 1.33MPa, and a flammability rating of UL94 V-0.

[0027] Example 3

[0028] Take 100g of polyphenylene sulfide (MFR = 70g / 10min @ 316℃), 0.4g of 150-mesh boron nitride, and 4g of calcium hypochlorite. Mix them evenly using a high-speed mixer. Place the mixture in a 250℃ forced-air drying oven for 8 hours for pretreatment. Then, use a hot press to mold pre-foamed blanks with dimensions of 8cm × 10cm × 0.6cm. The molding conditions are 300℃, 5MPa, and holding pressure for 40min. Place the blanks in a sealed mold cavity, introduce carbon dioxide, and maintain conditions of 10MPa and 295℃ for 1.5 hours. Then, quickly release the pressure and open the mold cavity to obtain a density of 0.073g / cm³. 3 The polyphenylene sulfide foam material has a foaming ratio of 18.6 times, an average cell diameter of 150μm, a compressive strength of 1.05MPa, and a flammability rating of UL94 V-0.

[0029] Example 4

[0030] Take 100g of polyphenylene sulfide (MFR = 350g / 10min @ 316℃), 1.1g of 200-mesh diatomaceous earth, and 3g of manganese dioxide. Mix them evenly using a high-speed mixer. Place the mixture in a 260℃ forced-air drying oven for 5 hours for pretreatment. Then, use a hot press to mold a pre-foamed green body with dimensions of 8cm × 10cm × 0.6cm. The molding conditions are 300℃, 5MPa, and holding pressure for 30 minutes. Place the green body in a sealed mold cavity, introduce nitrogen gas, and maintain conditions of 8MPa and 273℃ for 1.5 hours. Then, quickly release the pressure and open the mold cavity to obtain a density of 0.13g / cm³. 3 The polyphenylene sulfide foam material has a foaming ratio of 10.4 times, a melting point of 282℃, an average cell diameter of 120μm, a compressive strength of 1.67MPa, and a flammability rating of UL94 V-0.

Claims

1. A polyphenylene sulfide foam, characterized in that, The polyphenylene sulfide foam has a closed-cell structure with a pore diameter of 20-300 μm and a density of 0.07-0.25 g / cm³. 3 .

2. The polyphenylene sulfide foam according to claim 1, characterized in that, The polyphenylene sulfide described herein has a linear structure or a cross-linked structure.

3. The polyphenylene sulfide foam according to claim 1, characterized in that, The polyphenylene sulfide has a melt index of 5-500 g / 10 min at 316 °C.

4. The method for preparing polyphenylene sulfide foam according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix the polyphenylene sulfide raw material, additives and accelerators evenly, and then place the mixture in a dryer for pretreatment. The pre-foamed blank is obtained by processing and molding the treated sample. (2) Place the pre-foamed blank in a closed mold cavity and introduce carbon dioxide or nitrogen into the mold cavity as a foaming agent to maintain a certain temperature and pressure in the mold cavity. After a period of time, release the pressure in the mold cavity to obtain polyphenylene sulfide foam material.

5. The method for preparing polyphenylene sulfide foam according to claim 4, characterized in that, In step (1), the additive is selected from one or more combinations of nano-sized alumina, boron nitride, talc, montmorillonite, silica, calcium carbonate, diatomaceous earth, carbon nanotubes, graphene, and MXenes, and the mass ratio of the additive to polyphenylene sulfide is 0-5:

100.

6. The method for preparing polyphenylene sulfide foam according to claim 4, characterized in that, In step (1), the accelerator is selected from one or more combinations of chromium oxide, manganese dioxide, calcium hypochlorite, anthraquinone, tetrachloroquinone, sulfur, and melamine, and the mass ratio of the accelerator to the polyphenylene sulfide raw material is 0-10:

100.

7. The method for preparing polyphenylene sulfide foam according to claim 4, characterized in that, In step (1), the pretreatment temperature is 200℃-275℃ and the time is 1-24h.

8. The method for preparing polyphenylene sulfide foam according to claim 4, characterized in that, In step (1), the pre-foamed preform is formed by compression molding or extrusion molding.

9. The method for preparing polyphenylene sulfide foam according to claim 4, characterized in that, In step (2), the temperature inside the mold cavity is 260-300℃, the pressure is 5-30Mpa, and the holding time is 60-150min.

10. A radar radome, characterized in that, The polyphenylene sulfide foam according to any one of claims 1-3 is used as the core material.

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