Flame-retardant foamed polypropylene material and preparation method thereof

Abstract

The invention relates to the technical field of polypropylene composite materials, in particular to a flame-retardant foamed polypropylene material and a preparation method thereof, and the flame-retardant foamed polypropylene material is prepared from the following raw materials in parts by mass: 100-120 parts of polypropylene resin, 10-15 parts of modified flame-retardant polyacrylate resin, 10-30 parts of filler, 1-3 parts of a foaming agent, 0.1-0.5 part of a flame retardant and 0.5-1 part of a nucleating agent. The iron oxide is grafted on the surface of the glass fiber, the formed compound can effectively catalyze the carbonization process of a polymer in a high-temperature environment, a condensed phase can be promoted to form a compact carbon layer more completely and efficiently, and an excellent flame-retardant effect is achieved; meanwhile, through free radical polymerization, the glass fiber-ferric oxide compound reacts with acrylate to form modified flame-retardant polyacrylate resin, so that the compatibility of the modified flame-retardant polyacrylate resin and polypropylene resin is enhanced, and the flame-retardant effect and the mechanical property of the modified flame-retardant polyacrylate resin are further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene composite materials, in particular to a flame retardant foamed polypropylene material and a preparation method thereof. Background Art

[0002] Glass fiber reinforced polypropylene (PP / GF) composite materials have excellent corrosion resistance, heat resistance and mechanical properties, and are widely used in various industries. However, polypropylene molecules contain a large number of methyl and methylene groups, which are very flammable. After adding glass fiber, due to the capillary action of the glass fiber, the heat-absorbing molten polypropylene will be sucked into the pores and channels of the glass fiber, further intensifying its combustion process. This highly flammable characteristic makes PP / GF composite materials have certain safety risks and limits their application space.

[0003] In view of the flammability of PP / GF composite materials, the current treatment strategy is to add high-efficiency flame retardants, compound flame retardants or flame retardant fillers to the composite materials to achieve the effect of improving the flame retardant ability. However, in PP / GF composite materials, due to the characteristics of glass fiber that intensifies the combustion process, even if flame retardants or flame retardant fillers exceeding the conventional amount are added, it is still difficult to obtain a satisfactory flame retardant effect. At the same time, the addition of a large amount of flame retardants and flame retardant fillers will inevitably cause problems such as poor compatibility of components, uneven mixing, and decreased mechanical properties, which will in turn affect its performance under high temperature conditions. Therefore, this type of material has been difficult to meet market demand today when various industries have increasingly higher requirements for the performance of composite materials.

[0004] In summary, it is urgent to develop a new technical solution to solve the problems existing in the prior art. Summary of the invention

[0005] Based on this, the present invention has developed a flame-retardant foamed polypropylene material. The present invention grafts iron oxide on the surface of glass fiber to form a composite that can effectively catalyze the carbonization process of the polymer under high temperature environment, and can promote the condensed phase to form a dense carbon layer more completely and efficiently, thereby achieving excellent flame retardant effect; at the same time, the present invention reacts the glass fiber-iron oxide composite with acrylic ester through free radical polymerization to form a modified flame retardant polyacrylate resin, thereby enhancing the compatibility of the modified flame retardant polyacrylate resin with the polypropylene resin, enhancing the dispersibility and stability of the system, and further enhancing its flame retardant effect and mechanical properties under high temperature conditions, thereby achieving efficient flame retardant effect and excellent mechanical properties under the condition of low flame retardant content, achieving multiple performance improvements, and having good application prospects.

[0006] One object of the present invention is to provide a flame retardant foamed polypropylene material, which is prepared from the following raw materials in parts by weight: Polypropylene resin 100-120 parts Modified flame retardant polyacrylate resin 10-15 parts Filler 10-30 parts 1-3 parts of foaming agent Flame retardant 0.1-0.5 parts Nucleating agent 0.5-1 part in, The modified flame-retardant polyacrylate resin is a polypropylene resin grafted with glass fiber-iron oxide.

[0007] Furthermore, the filler is selected from one or more of talc powder, ceramic powder, diatomaceous earth, mica powder, borax, sulfate, carbonate, metal oxide, and metal hydroxide.

[0008] Furthermore, the foaming agent is selected from one or more of N,N-dinitrosopentamethylenetetramine or sodium bicarbonate.

[0009] Furthermore, the flame retardant is selected from one or more of phosphates, phosphites, phosphonates, organic phosphorus salts, phosphate polymers, melamine hydrobromide, tris(2,3-dibromopropyl)isocyanurate, epoxy bromide, decabromodiphenylethane, and dicyanoacrylate.

[0010] Furthermore, the nucleating agent is selected from one or more of inorganic nucleating agents or organic nucleating agents.

[0011] Another object of the present invention is to provide a method for preparing the flame retardant foamed polypropylene material, comprising the following steps: S1, soaking the glass fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, washing and drying, to obtain pretreated glass fiber; S2, adding the pretreated glass fiber into a high-pressure reactor, then adding a solution of ferric nitrate hydrate and urea thereto, heating for reaction, and calcining to obtain a glass fiber-iron oxide composite; S3, subjecting the glass fiber-iron oxide composite to plasma treatment to obtain a hydroxylated glass fiber-iron oxide composite; S4, immersing the hydroxylated glass fiber-iron oxide composite in an acrylic acid solution, heating and ultrasonicating, to obtain an intermediate product; S5, subjecting the intermediate product and acrylic acid ester to free radical polymerization under an inert gas atmosphere with BPO as a catalyst to obtain a modified flame retardant polyacrylate resin; S6, mixing the polypropylene resin, the modified flame-retardant polyacrylate resin and the filler, heating and stirring, then adding the foaming agent, the flame retardant and the nucleating agent, mixing evenly, drying, and adding to a twin-screw extruder for melt extrusion and granulation to obtain the flame-retardant foamed polypropylene material.

[0012] Furthermore, in step S2, the heating temperature is 100-120°C.

[0013] Furthermore, in step S4, the heating temperature is 60-80°C.

[0014] Furthermore, in step S6, the heating temperature is 40-60°C.

[0015] Furthermore, in step S6, the granulation temperature is 160-200°C.

[0016] The present invention has the following beneficial effects: The flame-retardant foamed polypropylene material provided by the present invention contains a modified flame-retardant polyacrylate resin, which is a polypropylene resin grafted with a glass fiber-iron oxide composite, and has a highly efficient flame-retardant effect and excellent mechanical properties. On the one hand, the present invention grafts iron oxide on the surface of the glass fiber, and the composite formed can effectively catalyze the carbonization process of the polymer under a high temperature environment, and can promote the condensed phase to form a dense carbon layer more completely and efficiently, thereby achieving an excellent flame-retardant effect; at the same time, the composite can also effectively improve the mechanical properties of the polypropylene material. On the other hand, the present invention reacts the glass fiber-iron oxide composite with acrylic ester through free radical polymerization to form a modified flame-retardant polyacrylate resin, which enhances the compatibility of the modified flame-retardant polyacrylate resin with the polypropylene resin, enhances the dispersibility and stability of the system, and further enhances its flame-retardant effect and mechanical properties under high temperature conditions, thereby achieving a highly efficient flame-retardant effect and excellent mechanical properties under the condition of a low flame retardant content, achieving improvements in multiple performances, and having good application prospects. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0018] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0019] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0020] The following materials are used in the embodiments and comparative examples of the present invention: Polypropylene resin, brand BX3800, was purchased from SK Chemicals of South Korea.

[0021] The filler is borax with an average particle size of 30 μm.

[0022] The blowing agent is composed of N,N-dinitrosopentamethylenetetramine and sodium bicarbonate (1:2, m / m).

[0023] The flame retardant is a mixture of triphenyl phosphate, melamine hydrobromide and dicyandiamide (1:1:1, m / m / m).

[0024] The nucleating agent is a compound of an inorganic nucleating agent and an organic nucleating agent (3:1, m / m), wherein the inorganic nucleating agent is silicon dioxide with a particle size of 0.01 μm, and the organic nucleating agent is a sorbitol nucleating agent.

[0025] The method for preparing an aqueous solution of iron nitrate nonahydrate and urea comprises the following steps: 0.008 mol of ferric nitrate nonahydrate and 0.036 mol of urea were added into 60 ml of deionized water and stirred until dissolved to obtain an aqueous solution of ferric nitrate nonahydrate and urea.

[0026] Example 1 A flame retardant foamed polypropylene material is prepared from the following raw materials in parts by weight: Polypropylene resin 110 parts Modified flame retardant polyacrylate resin 13 parts 20 parts of filler 2 parts of foaming agent Flame retardant 0.3 parts 0.7 parts of nucleating agent.

[0027] The preparation method of the flame retardant foamed polypropylene material comprises the following steps: S1. Soaking the glass fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide (concentrated sulfuric acid: hydrogen peroxide = 7:3, v / v; the mass fraction of hydrogen peroxide is 30%) for 1 h, washing and drying to obtain pretreated glass fiber; S2, adding the pretreated glass fiber into a high-pressure reactor, and then adding an aqueous solution of iron nitrate nonahydrate and urea (the mass of iron nitrate nonahydrate is 2.5% of the mass of the pretreated glass fiber), reacting at 120° C. for 4 h, cooling, washing, drying, and then calcining at 350° C. for 2 h to obtain a glass fiber-iron oxide composite; S3, placing the glass fiber-iron oxide composite into a low-temperature plasma cleaning machine, setting the plasma treatment time to 60 s, the power to 100 W, and the air flow rate to 400 ml / min, and obtaining a hydroxylated glass fiber-iron oxide composite after the treatment; S4, immersing the hydroxylated glass fiber-iron oxide composite in an acrylic acid aqueous solution (with a concentration of 10%), and subjecting the mixture to ultrasonic reaction at 70° C. for 12 h to obtain an intermediate product; S5, using water as solvent, subjecting the intermediate product and acrylate (intermediate product: acrylate = 5:1, m / m) to ultrasonic reaction at 80° C. for 12 h in a nitrogen atmosphere with BPO as a catalyst (1% by mass of the reactants) to free radical polymerization to obtain a modified flame-retardant polyacrylate resin; S6. Mix the polypropylene resin, the modified flame-retardant polyacrylate resin and the filler according to the above-mentioned mass fractions, stir at 50°C for 1 h, then add the foaming agent, flame retardant and nucleating agent, mix well, dry, and add to a twin-screw extruder for melt extrusion and granulation at 180-200°C to obtain the flame-retardant foamed polypropylene material.

[0028] Example 2 A flame retardant foamed polypropylene material is prepared from the following raw materials in parts by weight: Polypropylene resin 103 parts Modified flame retardant polyacrylate resin 11 parts 15 parts of filler 1 part foaming agent Flame retardant 0.2 parts 0.5 parts of nucleating agent.

[0029] The preparation method of the flame retardant foamed polypropylene material is the same as that of Example 1.

[0030] Example 3 A flame retardant foamed polypropylene material is prepared from the following raw materials in parts by weight: Polypropylene resin 118 parts 14 parts of modified flame retardant polyacrylate resin Filling 27 parts 3 parts of foaming agent Flame retardant 0.4 parts 1 part of nucleating agent.

[0031] The preparation method of the flame retardant foamed polypropylene material is the same as that of Example 1.

[0032] Comparative Example 1 A flame-retardant polypropylene material. The difference between this comparative example and Example 1 is that step S2-3 is not performed, and in step S4, the hydroxylated glass fiber-iron oxide composite is replaced by pretreated glass fiber in equal parts by mass, and other components and preparation methods are the same as those in Example 1.

[0033] Comparative Example 2 A flame retardant polypropylene material. The difference between this comparative example and Example 1 is that: Step S1-5 is not performed, and in Step S6, the modified flame retardant polyacrylate resin is replaced by a mixture of glass fiber and polypropylene resin (glass fiber: polyacrylic resin = 5:1, m / m) in equal parts by mass, and the other ingredients and preparation method are the same as those in Example 1.

[0034] Test Case Test method: The flame retardant foamed polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the flame retardant properties and mechanical properties were measured according to standards such as UL-94 and GB / T5169.12-2006; High temperature resistance: The flame retardant foamed polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2 were placed in an environment of 80° C. for 30 days, and their mechanical properties were tested again.

[0035] The test results are shown in Table 1.

[0036] Table 1 Performance test results According to Table 1, it can be concluded that the flame-retardant foamed polypropylene materials prepared in Examples 1-3 exhibit good flame retardancy, indicating that the iron oxide grafted in the glass fiber has a good effect on improving the flame retardancy of the polypropylene material, while the flame retardancy of Comparative Examples 1-2 is relatively poor without grafting iron oxide; in terms of mechanical properties, Examples 1-3 are equivalent to Comparative Example 1, both of which have ideal values, while the polypropylene resin in Comparative Example 2 has poor compatibility of components due to the lack of grafting with glass fibers, and thus the tensile strength is slightly poor; in addition, after being placed at high temperature for a long time, the mechanical properties exhibited by Examples 1-3 and Comparative Example 1 still remain at a relatively stable level, with a small decline, further illustrating that grafting of polypropylene resin with glass fibers can enhance the compatibility between components, while Comparative Example 2 shows a relatively large decline. In summary, the flame-retardant foamed polypropylene material prepared by grafting iron oxide in glass fibers and then polymerizing with acrylate in the present invention achieves excellent flame retardancy, high temperature resistance and mechanical properties with only a small amount of flame retardant added, and has good application prospects.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A flame retardant foamed polypropylene material, characterized in that: It is prepared from the following raw materials in parts by weight: Polypropylene resin 100-120 parts Modified flame retardant polyacrylate resin 10-15 parts Filler 10-30 parts 1-3 parts of foaming agent Flame retardant 0.1-0.5 parts Nucleating agent 0.5-1 part in, The modified flame-retardant polyacrylate resin is a polypropylene resin grafted with glass fiber-iron oxide.

2. The flame retardant foamed polypropylene material according to claim 1, characterized in that: The filler is selected from one or more of talc powder, ceramic powder, diatomaceous earth, mica powder, borax, sulfate, carbonate, metal oxide, and metal hydroxide.

3. The flame retardant foamed polypropylene material according to claim 1, characterized in that: The foaming agent is selected from one or more of N,N-dinitrosopentamethylenetetramine and sodium bicarbonate.

4. The flame retardant foamed polypropylene material according to claim 1, characterized in that: The flame retardant is selected from one or more of phosphates, phosphites, phosphonates, organic phosphorus salts, phosphate polymers, melamine hydrobromide, tris(2,3-dibromopropyl)isocyanurate, epoxy bromide, decabromodiphenylethane, and dicyanoacrylate.

5. The flame retardant foamed polypropylene material according to claim 1, characterized in that: The nucleating agent is selected from one or more of inorganic nucleating agents or organic nucleating agents.

6. The method for preparing the flame retardant foamed polypropylene material according to any one of claims 1 to 5, characterized in that: The steps include: S1, soaking the glass fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, washing and drying, to obtain pretreated glass fiber; S2, adding the pretreated glass fiber into a high-pressure reactor, then adding a solution of ferric nitrate hydrate and urea thereto, heating for reaction, and calcining to obtain a glass fiber-iron oxide composite; S3, subjecting the glass fiber-iron oxide composite to plasma treatment to obtain a hydroxylated glass fiber-iron oxide composite; S4, immersing the hydroxylated glass fiber-iron oxide composite in an acrylic acid solution, heating and ultrasonicating, to obtain an intermediate product; S5, subjecting the intermediate product and acrylic acid ester to free radical polymerization under an inert gas atmosphere with BPO as a catalyst to obtain a modified flame retardant polyacrylate resin; S6, mixing the polypropylene resin, the modified flame-retardant polyacrylate resin and the filler, heating and stirring, then adding the foaming agent, the flame retardant and the nucleating agent, mixing evenly, drying, and adding to a twin-screw extruder for melt extrusion and granulation to obtain the flame-retardant foamed polypropylene material.

7. The method for preparing the flame retardant foamed polypropylene material according to claim 6, characterized in that: In step S2, the heating temperature is 100-120°C.

8. The method for preparing the flame retardant foamed polypropylene material according to claim 6, characterized in that: In step S4, the heating temperature is 60-80°C.

9. The method for preparing the flame retardant foamed polypropylene material according to claim 6, characterized in that: In step S6, the heating temperature is 40-60°C.

10. The method for preparing the flame retardant foamed polypropylene material according to claim 6, characterized in that: In step S6, the granulation temperature is 160-200°C.

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