A kind of anti-aging flame-retardant polypropylene composite material and preparation method thereof

Abstract

The present invention provides an aging-resistant flame-retardant polypropylene composite material and a preparation method thereof, comprising the following raw materials in parts by weight: 100 parts of polypropylene, 20-40 parts of microcapsule flame retardant, the core material of the microcapsule flame retardant is flame-retardant particles modified by aminosilane coupling agent, the flame-retardant particles are selected from one or a combination of two or more of aluminum hydroxide, magnesium hydroxide, silicone resin micropowder, and montmorillonite; the wall material of the microcapsule flame retardant is obtained by cross-linking reaction of a polymer containing hydroxyl groups in the side chain and a dialdehyde. A microcapsule flame retardant having good compatibility with polypropylene is prepared by a suspension cross-linking method using flame-retardant particles modified by aminosilane coupling agent as core material, a polymer containing hydroxyl groups in the side chain as wall material, and a dialdehyde as a cross-linking agent. The polypropylene composite material using this flame retardant not only has good flame retardant properties, but also can maintain good flame retardant properties after aging under high temperature and high humidity.

Description

Technical Field

[0001] The invention belongs to the technical field of flame-retardant polypropylene, and in particular relates to an aging-resistant flame-retardant polypropylene composite material and a preparation method thereof. Background Art

[0002] Plastic furniture has played an important role in people's daily life, especially outdoor furniture, such as tables, chairs, beach chairs, etc. Polypropylene (PP) is a thermoplastic with excellent performance and one of the five general engineering plastics. It is an excellent material for making plastic furniture due to its good mechanical properties, physical properties and chemical corrosion resistance, low price, easy processing, environmental protection and non-toxicity to the human body. However, PP has a low limiting oxygen index and is very easy to burn. The combustion process will generate a lot of heat and is accompanied by molten droplets, which leads to rapid flame propagation, greatly limiting the application of PP. Therefore, PP needs to be flame-retardant.

[0003] The flame retardants widely used in PP include melamine, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide, etc. For example, patent CN101293984B discloses an expanded carbon-forming flame-retardant polypropylene composition and a preparation method thereof, wherein the composition comprises the following components: polypropylene, 100 parts by weight; ammonium polyphosphate, 10-30 parts by weight; pentaerythritol, 2.8-8.3 parts by weight; melamine cyanurate, 2.8-8.3 parts by weight; montmorillonite, 0.5-5 parts by weight; the total amount of the ammonium polyphosphate, pentaerythritol and melamine cyanurate added is at least 31 parts by weight. The preparation method comprises melt-blending, extruding and granulating the components including the polypropylene, ammonium polyphosphate, pentaerythritol, melamine cyanurate and montmorillonite according to the component proportions. Patent CN115304860B discloses a flame-retardant polypropylene composite material, a preparation method and an application thereof, comprising: a matrix selected from polypropylene; a flame retardant system dispersed in the matrix, the flame retardant system comprising piperazine pyrophosphate and melamine polyphosphate, wherein the mass ratio of piperazine pyrophosphate to melamine polyphosphate is 1:0.3-0.5; and modified nano-kaolin. Patent CN110903546B discloses a flame-retardant polymer material, a preparation method and an application thereof, comprising the following components: 80-120 parts of polypropylene, 10-15 parts of polyacrylamide, 10-40 parts of polysiloxane, 15-25 parts of ammonium polyphosphate, 7-9 parts of melamine, 1-5 parts of chlorinated paraffin, 9-13 parts of graphene, 12-16 parts of nano magnesium hydroxide, 4-9 parts of nano aluminum hydroxide, 2-8 parts of antimony trioxide, 10-20 parts of plasticizer, and 3-5 parts of stabilizer. The above-mentioned flame retardant treatment of PP with organic or inorganic or their combined flame retardants such as melamine, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide, etc. has achieved good flame retardant effect. However, since polypropylene is non-polar and has low surface energy, it has poor compatibility with polar flame retardants such as melamine, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide, etc. or flame retardants with polar groups on the surface, resulting in easy migration and precipitation of flame retardants. Especially in summer, the flame retardant properties of outdoor furniture made of polypropylene decrease after experiencing high temperature and high humidity weather, which is easy to cause fire.

[0004] Therefore, in summary, it is necessary to develop a polypropylene composite material that still has good flame retardant properties after high temperature and high humidity aging. Summary of the invention

[0005] In order to solve the technical problem that the flame retardancy of flame-retardant polypropylene materials decreases after high-temperature and high-humidity aging, the present invention provides an aging-resistant flame-retardant polypropylene composite material and a preparation method thereof. The present invention uses flame-retardant particles modified with aminosilane coupling agents as core materials, polymers containing hydroxyl groups in side chains as wall materials, and dialdehydes as cross-linking agents to prepare a microcapsule flame retardant with good compatibility with polypropylene. The polypropylene composite material using the flame retardant not only has good flame retardant properties, but can also maintain good flame retardant properties after high-temperature and high-humidity aging.

[0006] In order to achieve the above purpose, the following technical solutions are adopted:

[0007] An aging-resistant flame-retardant polypropylene composite material comprises the following raw materials in parts by weight: 100 parts of polypropylene, 20-40 parts of microcapsule flame retardant, the core material of the microcapsule flame retardant is flame-retardant particles modified by an aminosilane coupling agent, the flame-retardant particles are selected from one or a combination of two or more of aluminum hydroxide, magnesium hydroxide, silicone resin micropowder, and montmorillonite; the wall material of the microcapsule flame retardant is obtained by cross-linking a polymer containing hydroxyl groups in the side chain and a dialdehyde.

[0008] Further, the polymer containing hydroxyl groups in the side chain has a hydroxyl value of 200-280 mg KOH / g; further, the polymer containing hydroxyl groups in the side chain is poly(styrene-co-propylene alcohol); preferably, the weight average molecular weight of the poly(styrene-co-propylene alcohol) is 2000-3000 g / mol, and the hydroxyl value is 210-255 mg KOH / g.

[0009] Furthermore, the mass ratio of the core material, the polymer containing hydroxyl groups in the side chain, and the dialdehyde is 3-4:4-5:0.5, and the amount of the aminosilane coupling agent is 1-2wt% of the flame retardant particles.

[0010] The aminosilane coupling agent is selected from one or a combination of two or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0011] The average particle size of the flame retardant particles is 1-5 μm.

[0012] The core material is prepared by a method comprising the following steps:

[0013] Prepare an ethanol-water mixed solution, add an aminosilane coupling agent to the mixed solution, stir to hydrolyze, then add flame retardant particles, stir evenly to react, filter, wash, and dry to obtain the core material.

[0014] Furthermore, the mass concentration of ethanol in the ethanol-water mixed solution is 90-95%, the weight ratio of the aminosilane coupling agent to the ethanol-water mixed solution is 1-2:100, the hydrolysis time is 5-15 minutes, the reaction time after adding the flame retardant particles is 1-5 minutes, the washing is 1-3 times with ethanol, and the drying is drying at 100-120°C for 5-10 minutes.

[0015] Furthermore, the core material is a complex of aluminum hydroxide modified with an aminosilane coupling agent and silicone resin micropowder modified with an aminosilane coupling agent in a weight ratio of 5-9:1.

[0016] Silicone resin micropowder is a kind of micron-sized solid powder with true spherical shape and very narrow particle size distribution. Its chemical structure is an insoluble and infusible trifunctional component densely cross-linked polyorganosiliconesquioxane. It is a kind of silicon-based flame retardant and has the function of reducing smoke generation, heat release, and CO release. The inventors found that when the core material is a complex of aluminum hydroxide modified with an aminosilane coupling agent and silicone resin micropowder modified with an aminosilane coupling agent, the aging-resistant flame-retardant polypropylene composite material can obtain V0-level flame retardant performance, and the two have the function of synergistically improving the flame retardant performance of the composite material.

[0017] The dialdehyde is selected from one or a combination of two or more of glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, terephthalaldehyde and adipaldehyde.

[0018] The microcapsule flame retardant is prepared by a method comprising the following steps:

[0019] The core material and the polymer containing hydroxyl groups in the side chain are added to the organic solvent, ultrasonically dispersed into a suspension, and the dialdehyde solution and the hydrochloric acid aqueous solution are added under stirring conditions. After the addition, the temperature is raised and stirred to react. After the reaction is completed, the microcapsule flame retardant is filtered, washed and dried to obtain the microcapsule flame retardant.

[0020] The concentration of the core material in the suspension is 1.5-2wt%, the concentration of the polymer containing hydroxyl groups on the side chain in the suspension is 2-2.5wt%, the organic solvent is selected from one or a combination of two or more of DMF, tetrahydrofuran, acetone, and chloroform, the concentration of the dialdehyde solution is 2-5wt%, the solvent is selected from one or a combination of two or more of chloroform, benzene, and ether, the concentration of the hydrochloric acid aqueous solution is 25-35wt%, the amount of hydrogen chloride in the hydrochloric acid aqueous solution is 1-3wt% of the sum of the mass of the polymer containing hydroxyl groups on the side chain and the dialdehyde, the dialdehyde solution and the catalyst solution are added dropwise at a dropping speed of 1-3mL / min, the temperature is raised to 50-70°C, and the reaction time is 1-5h.

[0021] The melt index of the polypropylene is 3-12 g / 10 min.

[0022] Furthermore, the raw materials for preparing the aging-resistant flame-retardant polypropylene composite material also include 0-5 parts by mass of auxiliary agents. The auxiliary agents are not particularly limited and can be those commonly used in the art, including but not limited to lubricants, antioxidants, anti-ultraviolet agents, antibacterial agents, and scratch-resistant agents, one or a combination of two or more thereof.

[0023] The lubricant is selected from one or a combination of two or more of n-butyl stearate, zinc stearate, calcium stearate, magnesium stearate, oleamide, and ethylene bisstearamide.

[0024] The present invention also provides a method for preparing the above-mentioned aging-resistant flame-retardant polypropylene composite material, comprising the following steps:

[0025] The polypropylene, microcapsule flame retardant and additive are uniformly mixed, and then melt-extruded and granulated by a twin-screw extruder, and dried to obtain an aging-resistant flame-retardant polypropylene composite material; further, the extrusion temperature is 160-200°C.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The invention provides an aging-resistant flame-retardant polypropylene composite material and a preparation method thereof. A microcapsule flame retardant having good compatibility with polypropylene is prepared by a suspension crosslinking method using flame-retardant particles modified by an aminosilane coupling agent as a core material, a polymer containing a hydroxyl group in a side chain as a wall material, and a dialdehyde as a crosslinking agent. The polypropylene composite material using the flame retardant not only has good flame retardant properties, but can also maintain good flame retardant properties after aging under high temperature and high humidity. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, the "parts" described in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0029] Polypropylene SP179, melt index 8g / 10min, Sinopec Yanshan Petrochemical Company.

[0030] Aluminum hydroxide was purchased from Huber Engineering Materials (Qingdao) Co., Ltd. with the brand name Micral532 and an average particle size of 4.2 μm.

[0031] Silicone resin powder was purchased from Zhejiang Hangyu Technology Co., Ltd., brand HY-7000, with an average particle size of 4.6 μm.

[0032] Magnesium hydroxide was purchased from Qinghai Western Magnesium Industry Co., Ltd. with a brand name of SCH-13 and an average particle size of 5.0 μm.

[0033] Calcium-based montmorillonite was purchased from Guangdong Sihui Feilaifeng Inorganic Mineral Company with an average particle size of 4.5 μm.

[0034] Poly(styrene-co-propylene alcohol) was purchased from Sigma-Aldrich with a weight average molecular weight of 2200 and a hydroxyl value of 255 mg KOH / g.

[0035] core material

[0036] Preparation Example a1

[0037] Use 95g of ethanol and 5g of water to prepare an ethanol-water mixed solution, add 2g of 3-aminopropyltrimethoxysilane to the mixed solution, stir and hydrolyze for 8min, then add 100g of aluminum hydroxide Micral532, stir evenly and react for 5min, filter, wash with ethanol 3 times, and dry at 120℃ for 5min to obtain the core material.

[0038] Preparation Example a2

[0039] The rest is the same as Preparation Example a1, except that an equal mass of silicone resin micropowder HY-7000 is used to replace aluminum hydroxide.

[0040] Preparation Example a3

[0041] The rest is the same as Preparation Example a1, except that an equal mass of magnesium hydroxide SCH-13 is used to replace aluminum hydroxide.

[0042] Preparation Example a4

[0043] The rest is the same as Preparation Example a1, except that an equal mass of calcium-based montmorillonite is used to replace aluminum hydroxide.

[0044] Preparation Example a5

[0045] The rest is the same as Preparation Example a1, except that the amount of 3-aminopropyltrimethoxysilane used is 1 g.

[0046] Comparative Preparation Example a

[0047] The rest is the same as Preparation Example a1, except that 3-aminopropyltrimethoxysilane is replaced by an equal mass of γ-(2,3-epoxypropyloxy)propyltrimethoxysilane.

[0048] Microcapsule flame retardant

[0049] Preparation Example b1

[0050] Add 2.7g of the core material of Preparation Example a1, 0.3g of the core material of Preparation Example a2, and 5g of poly(styrene-co-propylene alcohol) to 192g of DMF, and ultrasonically disperse them into a suspension. While stirring, add 25g of a 2wt% glutaraldehyde solution (the solvent is chloroform) and 0.8g of a 30wt% hydrochloric acid solution (the solvent is water) dropwise at a rate of 3g / min. After the addition, raise the temperature to 60°C and stir to react for 3h. After the reaction is completed, filter, wash alternately with ethanol and water for 3 times, and dry to obtain a microcapsule flame retardant.

[0051] Preparation Example b2

[0052] The rest is the same as Preparation Example b1, except that the core material is made by combining 2.5g of the core material of Preparation Example a1 and 0.5g of the core material of Preparation Example a2.

[0053] Preparation Example b3

[0054] The rest is the same as Preparation Example b1, except that the core material obtained in Preparation Example a1 is replaced by an equal mass of Preparation Example a3.

[0055] Preparation Example b4

[0056] The rest is the same as Preparation Example b1, except that the core material obtained in Preparation Example a1 is replaced by Preparation Example a4 of equal mass.

[0057] Preparation Example b5

[0058] The rest is the same as Preparation Example b1, except that the core material obtained in Preparation Example a1 is replaced by an equal mass of Preparation Example a5.

[0059] Preparation Example b6

[0060] The rest is the same as Preparation Example b1, except that all 3g of core material is the core material of Preparation Example a1.

[0061] Preparation Example b7

[0062] The rest is the same as Preparation Example b1, except that all 3g of core material is the core material of Preparation Example a2.

[0063] Preparation Example b8

[0064] The rest is the same as Preparation Example b1, except that the suspension consists of 3.6 g of the core material of Preparation Example a1, 0.4 g of the core material of Preparation Example a2, 5 g of poly(styrene-co-propylene alcohol), and 191 g of DMF.

[0065] Preparation Example b9

[0066] The rest is the same as Preparation Example b1, except that the suspension consists of 3.33g of the core material of Preparation Example a1, 0.67g of the core material of Preparation Example a2, 4g of poly(styrene-co-propylene alcohol), and 192g of DMF.

[0067] Comparative Preparation Example b

[0068] The rest is the same as Preparation Example b1, except that the core material is prepared according to Comparative Preparation Example a.

[0069] Example 1

[0070] 100 parts of polypropylene SP179, 25 parts of the microcapsule flame retardant of Preparation Example b1, and 2 parts of zinc stearate were mixed evenly, and then melt-extruded and granulated by a twin-screw extruder, and dried to obtain an aging-resistant flame-retardant polypropylene composite material.

[0071] Among them: the length-to-length ratio L:D of the twin-screw extruder is 30:1, the screw speed is 320r / min, and the feeding speed is 15rpm.

[0072] The temperature of each zone of the twin-screw extruder is set as follows: zone 1 170°C, zone 2 180°C, zone 3 190°C, zone 4 190°C, zone 5 190°C, zone 6 200°C, zone 7 200°C, zone 8 190°C, zone 9 190°C, zone 10 190°C.

[0073] Embodiment 2-9

[0074] The rest is the same as Example 1, except that the microcapsule flame retardants are prepared according to Preparation Examples b2-b9 respectively.

[0075] Example 10

[0076] The rest is the same as Example 1, except that the amount of microcapsule flame retardant used in Preparation Example b1 is 20 parts.

[0077] Embodiment 11

[0078] The rest is the same as Example 1, except that the amount of microcapsule flame retardant used in Preparation Example b1 is 10 parts.

[0079] Example 12

[0080] The rest is the same as Example 1, except that the amount of microcapsule flame retardant used in Preparation Example b1 is 40 parts.

[0081] Comparative Example 1

[0082] The rest is the same as Example 1, except that the microcapsule flame retardant is prepared according to Comparative Preparation Example b.

[0083] Comparative Example 2

[0084] The rest is the same as Example 1, except that 25 parts of the microcapsule flame retardant in Preparation Example b1 are replaced by 25 parts of a compound flame retardant composed of aluminum hydroxide and silicone resin micropowder HY-7000 in a weight ratio of 9:1.

[0085] The aging-resistant flame-retardant polypropylene composite materials prepared in the above examples and comparative examples were subjected to the following performance tests:

[0086] Vertical burning test: refer to UL-94 standard, the test specimen thickness is 3.2mm.

[0087] Vertical burning test after aging: The vertical burning test specimens were placed in a constant temperature and humidity chamber at a temperature of 85°C and a humidity of 85 for 30 days, and then the vertical burning test performance was retested.

[0088] Notched impact strength: Refer to standard GB / T 1043-1993, impact energy is 5.5J.

[0089] Tensile strength: tested in accordance with standard GB / T 1040-1992, with a tensile rate of 50 mm / min.

[0090] Table 1

[0091] project UL-94 UL-94 after aging Tensile strength MPa <![CDATA[Impact strength kJ / m 2 > Example 1 V0 V0 50.5 14.9 Example 2 V0 V0 51.4 14.7 Example 3 V1 V2 50.0 14.2 Example 4 V1 / 49.6 14.0 Example 5 V0 V0 50.1 14.8 Example 6 V1 V1 49.9 13.1 Example 7 V1 V1 50.3 13.6 Example 8 V0 V0 50.2 14.5 Example 9 V0 V1 49.7 14.2 Example 10 V0 V0 46.8 13.7 Embodiment 11 V1 V1 44.1 11.4 Example 12 V0 V0 41.9 16.3 Comparative Example 1 V1 / 40.3 12.4 Comparative Example 2 V2 / 37.2 11.8

[0092] “ / ” indicates that the flame retardant level is lower than V2.

[0093] It can be seen from Table 1 that the microcapsule flame retardant prepared in the present invention has good compatibility with polypropylene. The polypropylene composite material using this flame retardant not only has good flame retardant properties, but also can maintain good flame retardant properties after high temperature and high humidity aging.

[0094] From the mechanical properties test in Table 1, it can be seen that the dosage of the microcapsule flame retardant needs to be appropriate. When the dosage of the microcapsule flame retardant is 20-25 parts, the microcapsule flame retardant has the effect of improving the tensile strength and impact strength of the composite material, and the flame retardant performance has reached the V0 level. However, when the dosage of the microcapsule flame retardant exceeds 25 parts, although the impact strength is significantly improved and the flame retardant performance remains at the V0 level, the tensile strength is significantly reduced.

[0095] From the flame retardant performance comparison of Example 1, Example 2 and Examples 3, 4, 6, and 7, it can be seen that when the core material is a compound of aluminum hydroxide modified by an aminosilane coupling agent and silicone resin micropowder modified by an aminosilane coupling agent, the aging resistance and flame retardant performance of the composite material is the best, indicating that the two have a synergistic effect of improving the flame retardant properties of the composite material.

[0096] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. An aging-resistant flame-retardant polypropylene composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of polypropylene, 20-40 parts of microcapsule flame retardant, the core material of the microcapsule flame retardant is flame retardant particles modified by aminosilane coupling agent, the flame retardant particles are selected from one or two of aluminum hydroxide and silicone resin micropowder; the wall material of the microcapsule flame retardant is obtained by cross-linking reaction of a polymer containing hydroxyl groups in the side chain and a dialdehyde; the polymer containing hydroxyl groups in the side chain is poly(styrene-co-propylene alcohol), the weight average molecular weight of the poly(styrene-co-propylene alcohol) is 2000-3000 g / mol, and the hydroxyl value is 210-255 mg KOH / g.

2. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The mass ratio of the core material, the polymer containing hydroxyl groups in the side chain and the dialdehyde is 3-4:4-5:0.5, and the amount of the aminosilane coupling agent is 1-2wt% of the flame retardant particles.

3. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The aminosilane coupling agent is selected from one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

4. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The average particle size of the flame retardant particles is 1-5 μm.

5. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The core material is prepared by a method comprising the following steps: Prepare an ethanol-water mixed solution, add an aminosilane coupling agent to the mixed solution, stir to hydrolyze, then add flame retardant particles, stir evenly to react, filter, wash, and dry to obtain the core material.

6. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The core material is a complex of aluminum hydroxide modified with an aminosilane coupling agent and silicone resin micropowder modified with an aminosilane coupling agent in a weight ratio of 5-9:

1.

7. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The dialdehyde is selected from one or more of glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, terephthalaldehyde and adipaldehyde.

8. The aging-resistant flame-retardant polypropylene composite material according to claim 1, characterized in that: The microcapsule flame retardant is prepared by a method comprising the following steps: The core material and the polymer containing hydroxyl groups in the side chain are added to the organic solvent, ultrasonically dispersed into a suspension, and the dialdehyde solution and the hydrochloric acid aqueous solution are added under stirring conditions. After the addition, the temperature is raised and stirred to react. After the reaction is completed, the microcapsule flame retardant is filtered, washed and dried to obtain the microcapsule flame retardant.

9. The method for preparing the aging-resistant flame-retardant polypropylene composite material according to any one of claims 1 to 8, characterized in that: The steps include: The polypropylene, microcapsule flame retardant and additives are uniformly mixed, and then melt-extruded and granulated by a twin-screw extruder, and then dried to obtain an aging-resistant flame-retardant polypropylene composite material.

10. The preparation method according to claim 9, characterized in that: The melt extrusion temperature is 160-200°C.