Halogen-free flame-retardant high-load polypropylene masterbatch

Abstract

The application discloses a halogen-free flame-retardant high-load polypropylene master batch, raw materials of which include polypropylene, a compatilizer, a flame retardant, an interface modifier and a lubricant, the flame retardant accounts for more than 43% of the total mass of the master batch, and the flame retardant is a first coupling agent modified phosphorus-nitrogen flame retardant; the interface modifier is prepared by the reaction of long-chain segment end amino polydimethylsiloxane and short-chain segment second coupling agent with 1,4-butanediol diglycidyl ether; and the first coupling agent and / or the second coupling agent is one or a combination of a secondary amino coupling agent and a primary amino coupling agent. The first coupling agent is modified by the phosphorus-nitrogen flame retardant, and the interface modifier is prepared by the reaction of end amino polydimethylsiloxane and the second coupling agent with 1,4-butanediol diglycidyl ether, so that the dispersibility of the flame retardant is optimized, the content of the halogen-free flame retardant in the polypropylene master batch is increased, and the flame-retardant effect is improved under the premise of ensuring the mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant masterbatch, and particularly relates to a halogen-free flame-retardant high-load polypropylene masterbatch. BACKGROUND

[0002] Polypropylene is one of the five general-purpose plastics and is widely used in the fields of electronic and electrical appliance shells, automotive interior parts, etc., but its limiting oxygen index is only 17% to 18%, which has a serious fire hazard. Traditional bromine flame retardants are limited due to environmental problems, and inorganic flame retardants need to be added by more than 50% to achieve V-0 level, which seriously damages the mechanical properties of the material.

[0003] In the prior art, phosphorus-nitrogen flame retardants have environmental advantages, but their high polarity characteristics have a serious interface incompatibility problem with the non-polar molecular chain of polypropylene, which causes the flame retardant to easily agglomerate in the base material, forming a stress concentration point, and when the addition amount exceeds 30%, "powdering" occurs, which reduces the melt strength and causes the surface of the product to frost.

[0004] Therefore, it is necessary to solve the problems of interface compatibility and processing rheology caused by high filling of flame retardants in polypropylene masterbatch. SUMMARY

[0005] One of the purposes of the present application is to overcome the defects in the prior art and provide a halogen-free flame-retardant high-load polypropylene masterbatch. The interface modifier prepared by reacting the end-amino polydimethylsiloxane and the second coupling agent with 1,4-butanediol diglycidyl ether is combined with the first coupling agent modified phosphorus-nitrogen flame retardant to optimize the dispersibility of the flame retardant, increase the content of the halogen-free flame retardant in the polypropylene masterbatch under the premise of ensuring the mechanical properties, and improve the flame-retardant effect.

[0006] In order to achieve the above process effects, the technical scheme of the present application is as follows: a halogen-free flame-retardant high-load polypropylene masterbatch, raw materials including polypropylene, a compatibilizer, a flame retardant, an interface modifier, and a lubricant, the flame retardant accounting for more than 43% of the total mass of the masterbatch, the flame retardant being a first coupling agent modified phosphorus-nitrogen flame retardant.

[0007] The interface modifier is prepared by reacting long-chain segment end-amino polydimethylsiloxane and short-chain segment second coupling agent with 1,4-butanediol diglycidyl ether.

[0008] The first coupling agent and / or the second coupling agent is one or a combination of a secondary amino coupling agent and a primary amino coupling agent.

[0009] The preferred technical scheme is that the raw materials of the polypropylene master batch include polypropylene 21.6-43.3%, a compatilizer 3.8-11.2%, a flame retardant 43-67.3%, an interface modifier 2.3-9.0% and a lubricant 0.7-3.5% by mass fraction. Further, the raw materials of the polypropylene master batch include polypropylene 24-40%, a compatilizer 5-10%, a flame retardant 50-65%, an interface modifier 3-8% and a lubricant 1-3%. Still further, the flame retardant accounts for 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 67.3% or any two values as the maximum and minimum values.

[0010] The preferred technical scheme is that the reaction raw materials of the interface modifier include amino-terminated polydimethylsiloxane 50-80 parts, a second coupling agent 4-16 parts and 1,4-butanediol diglycidyl ether 100 parts by mass fraction. Further, the reaction raw materials of the interface modifier include amino-terminated polydimethylsiloxane 55-75 parts, a second coupling agent 5-15 parts and 1,4-butanediol diglycidyl ether 100 parts. Still further, the reaction raw materials of the interface modifier include amino-terminated polydimethylsiloxane 60-70 parts, a second coupling agent 6-12 parts and 1,4-butanediol diglycidyl ether 100 parts.

[0011] The preferred technical scheme is that the phosphorus-nitrogen flame retardant is composed of ammonium polyphosphate and melamine cyanurate, the mass ratio of the ammonium polyphosphate and the melamine cyanurate is (2-3):1, and the first coupling agent in the flame retardant is added in an amount of 3-5% of the phosphorus-nitrogen flame retardant. Further, the mass ratio of the ammonium polyphosphate and the melamine cyanurate can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1 or any two values as the maximum and minimum values.

[0012] The preferred technical scheme is that the compatilizer includes a combination of maleic anhydride grafted polypropylene and maleic anhydride grafted polyolefin elastomer.

[0013] The preferred technical scheme is that the mass ratio of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer is 1: (0.5-1.2). Further, the mass ratio of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer can be selected as 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2 and an interval value of any two ratio values as a maximum value and a minimum value.

[0014] The preferred technical scheme is that the lubricant comprises a combination of vinyl bis-stearamide and oxidized polyethylene wax. Further, the mass ratio of the vinyl bis-stearamide and the oxidized polyethylene wax is 1: (0.8-1.5). Further, the mass ratio of the vinyl bis-stearamide and the oxidized polyethylene wax can be selected as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 and an interval value of any two ratio values as a maximum value and a minimum value.

[0015] The preferred technical scheme is that the polypropylene is a homopolymer polypropylene with a melt index of 15-30 g / 10 min, and the isotacticity of the homopolymer polypropylene is greater than or equal to 96%.

[0016] The preferred technical scheme is that the first coupling agent and the second coupling agent are both gamma-aminopropyl triethoxysilane.

[0017] The preferred technical scheme is that the preparation method of the interface modifier comprises the following steps: under the protection of a nitrogen atmosphere, first mixing amino-terminated polydimethylsiloxane and the second coupling agent uniformly, then increasing the temperature to 60-70 DEG C, and then adding 1, 4-butanediol diglycidyl ether and keeping the temperature for 5-8 h.

[0018] The advantages and beneficial effects of the present application are that:

[0019] The first coupling agent is modified by the phosphorus-nitrogen flame retardant, and the interface modifier prepared by the reaction of the amino-terminated polydimethylsiloxane, the second coupling agent and 1, 4-butanediol diglycidyl ether is combined, so that the dispersibility of the flame retardant is optimized, the content of the halogen-free flame retardant in the polypropylene master batch is increased under the premise of ensuring the mechanical properties, and the flame retardant effect is improved. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application are further described below in combination with examples. The following examples are only used to more clearly illustrate the technical scheme of the present application, and cannot be used to limit the protection scope of the present application.

[0021] Interface modifier

[0022] The raw materials of the interface modifier comprise 50-80 parts of amino-terminated polydimethylsiloxane, 4-16 parts of the second coupling agent and 100 parts of 1, 4-butanediol diglycidyl ether.

[0023] The molecular weight of the end-amino polydimethylsiloxane is 1000-3000.

[0024] The long-chain end-amino polydimethylsiloxane improves the compatibility of the interface between the resin base material polypropylene, and the short-chain second coupling agent improves the action points between the inorganic flame retardant. Therefore, if the content of the long-chain end-amino polydimethylsiloxane is too much, the compatibility of the interface between the interface modifier and the resin base material polypropylene is improved, but the compatibility between the interface modifier and the flame retardant is weakened, and too much long-chain content produces steric hindrance, and the action points with the flame retardant are reduced, resulting in a decrease in the compatibility of the flame retardant in the master batch; if the content of the long-chain end-amino polydimethylsiloxane is too little, the compatibility of the interface between the interface modifier and the resin base material polypropylene is decreased, and the compatibility of the flame retardant in the master batch is also negatively affected. If the content of the 1,4-butanediol diglycidyl ether is too little, it is not conducive to the formation of the molecular chain of the interface modifier, and therefore, the interface modification effect in the master batch is not good.

[0025] The nitrogen atmosphere protection is used to prevent the second coupling agent from self-condensation or polymerization with the end-amino polydimethylsiloxane.

[0026] Reaction principle: The long-chain end-amino polydimethylsiloxane contains amino groups, the short-chain second coupling agent contains amino groups, and the two react with the epoxy groups of the 1,4-butanediol diglycidyl ether. By adjusting the ratio of the end-amino polydimethylsiloxane and the second coupling agent to the 1,4-butanediol diglycidyl ether, the molecular chain of the interface modifier retains the epoxy groups after the reaction, and further cross-linking reaction occurs with the surface active amino groups of the phosphorus-nitrogen flame retardant treated by the first coupling agent. The non-polar long-chain segment has good compatibility with the non-polar resin base material polypropylene, and further improves the compatibility and dispersibility of the flame retardant in the raw material system.

[0027] The long-chain end-amino polydimethylsiloxane is a flexible segment, has a lubricating and toughening effect, and is not easy to separate from the master batch after further forming a longer molecular chain.

[0028] Flame retardant

[0029] The flame retardant is a first coupling agent modified phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is composed of ammonium polyphosphate and melamine cyanurate, and the mass ratio of the ammonium polyphosphate and the melamine cyanurate is (2-3):1. The modification under the action of the first coupling agent with an addition amount of 3%-5% of the phosphorus-nitrogen flame retardant not only improves the dispersibility of the flame retardant in the master batch raw material, but also gives the master batch amino groups, which cross-link with the interface modifier and the compatibilizer.

[0030] Compatibilizer

[0031] The compatibilizer is a combination of maleic anhydride grafted polypropylene and maleic anhydride grafted polyolefin elastomer.

[0032] Further, the mass ratio of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer is 1: (0.5~1.2). Still further, the grafting rate of the maleic anhydride grafted polypropylene and / or the maleic anhydride grafted polyolefin elastomer is between 1%~1.5%.

[0033] The compound of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer as a compatibilizer, on the one hand, the non-polar segment polypropylene and polyolefin elastomer contained in the compatibilizer are similar to the polarity of the polypropylene base material, the compatibility of the maleic anhydride grafted polypropylene and the polypropylene base material is better, but the polypropylene base material itself is brittle and has poor toughness, and the toughness of the base material is improved by the maleic anhydride grafted polyolefin elastomer; on the other hand, the grafted maleic anhydride is a polar group, which is similar to the high polarity of the phosphorus-nitrogen flame retardant, further improving the compatibility between the master batch raw materials.

[0034] Intermolecular synergistic effect principle: during the processing, the anhydride groups of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer esterify with the hydroxyl groups on the surface of the phosphorus-nitrogen flame retardant particles, and the modified amino groups after the first coupling agent react, forming chemical cross-linking between the interfaces. The polyolefin elastomer base of the maleic anhydride grafted polyolefin elastomer is mainly ethylene-octene copolymer, which has better toughening effect compared to other types of base elastomers. The octene long chain of the maleic anhydride grafted polyolefin elastomer is entangled with the polypropylene molecular chain through van der Waals force, forming a rigid-flexible network structure, and thus improving the toughness of the polypropylene base material.

[0035] Flame-retardant synergistic mechanism: the polyphosphoric acid generated by the thermal decomposition of ammonium polyphosphate (APP) esterifies with the molecular chain of the maleic anhydride grafted polypropylene mixed with the polypropylene base material, forming a continuous expanding carbon layer; the olefin radicals generated by the thermal decomposition of the maleic anhydride grafted polyolefin elastomer undergo quenching reaction with the nitrogen-containing radicals released by melamine cyanurate (MCA) upon heating, thus reducing the propagation speed of the flame. First stage: APP decomposes to generate polyphosphoric acid, catalyzing PP to dehydrate and preform carbon; second stage: MCA sublimates and absorbs heat, reducing the temperature of the system, while releasing inert gas to dilute oxygen; third stage: the decomposition product (cyanuric acid) reacts with the decomposition product (polyphosphoric acid) of APP to form a P-N-C cross-linked network, strengthening the carbon layer.

[0036] The preparation method of the halogen-free flame-retardant high-load polypropylene master batch mixes the raw materials of the halogen-free flame-retardant high-load polypropylene master batch as shown in Tables 1~2, and then extrudes and granulates through a double-screw extruder. The length-diameter ratio L / D of the double-screw extruder is 45, the feeding screw rotation speed is 25 r / min, and the main machine screw rotation speed is 200 r / min.

[0037] The examples and comparative examples include the following raw materials:

[0038] The polypropylene adopts homopolymer polypropylene with a melt index of 15-30 g / 10 min, and the isotacticity of the homopolymer polypropylene is greater than or equal to 96%;

[0039] The grafting rate of the maleic anhydride grafted polypropylene is 1%-1.5%;

[0040] The grafting rate of the maleic anhydride grafted polyolefin elastomer is 1%-1.5%;

[0041] The vinyl bis-stearamide is an industrial grade with 99%;

[0042] The oxidized polyethylene wax is an industrial grade with 99%;

[0043] The ammonium polyphosphate is an industrial grade with 99%;

[0044] The melamine cyanurate is an industrial grade with 99%;

[0045] Both the first coupling agent and the second coupling agent are γ-aminopropyl triethoxysilane, an industrial grade with 99%;

[0046] The molecular weight of the amino-terminated polydimethylsiloxane is 1000-3000;

[0047] The 1,4-butanediol diglycidyl ether is an industrial grade with 99%.

[0048] The raw materials of the polypropylene master batch according to mass fraction are as shown in Table 1 below:

[0049] Table 1

[0050]

[0051] The raw materials of the polypropylene master batch according to mass fraction are as shown in Table 2 below:

[0052] Table 2

[0053]

[0054] Explanation:

[0055] APP represents ammonium polyphosphate; MCA represents melamine cyanurate.

[0056] The compatibilizer A1 represents maleic anhydride grafted polypropylene; the compatibilizer A2 represents maleic anhydride grafted polyolefin elastomer.

[0057] The lubricant B1 represents vinyl bis-stearamide; the lubricant B2 represents oxidized polyethylene wax.

[0058] The reaction raw materials of the interfacial modifier (sample 1) include 66 parts of amino-terminated polydimethylsiloxane, 10 parts of the second coupling agent, and 100 parts of 1,4-butanediol diglycidyl ether;

[0059] The reaction raw materials of the interface modifier (sample 2) include 50 parts of amino-terminated polydimethylsiloxane, 16 parts of the second coupling agent, and 100 parts of 1,4-butanediol diglycidyl ether;

[0060] The reaction raw materials of the interface modifier (sample 3) include 80 parts of amino-terminated polydimethylsiloxane, 4 parts of the second coupling agent, and 100 parts of 1,4-butanediol diglycidyl ether.

[0061] The phosphorus-nitrogen flame retardant APP and MCA are mixed, 4% of the total mass of the first coupling agent is added, and the mixture is further mixed to obtain the flame retardant.

[0062] The interface modifier is prepared as follows: under the protection of a nitrogen atmosphere, the amino-terminated polydimethylsiloxane and the second coupling agent are uniformly mixed, heated to 65°C, and then the 1,4-butanediol diglycidyl ether is added, and the reaction is maintained for 6.5 hours.

[0063] Performance tests of the protective film samples prepared in the examples and comparative examples are carried out.

[0064] 1. Tensile strength and elongation at break: determined according to the GB / T 1040.1-2018 standard.

[0065] 2. Melt flow rate (MFR): determined according to the GB / T 3682.1-2018 standard.

[0066] 3. Limiting oxygen index (LOI): determined according to the GB / T 2406.2-2009 standard.

[0067] The performance test results of the examples and comparative examples are shown in Table 3.

[0068] Table 3

[0069]

[0070] In Example 3, compared with Example 1, although the amount of the flame retardant is increased, the mechanical properties of the masterbatch are optimized by increasing the amount of the interface modifier, so that the mechanical properties are not significantly decreased.

[0071] In Example 7, compared with Example 1, the amount of the amino-terminated polydimethylsiloxane in the interface modifier is increased, the steric hindrance is increased, and the amount of the second coupling agent is reduced, which is not conducive to the grafting of the second coupling agent and has a negative effect on the compatibility of the interface modifier with the flame retardant and the polypropylene base material.

[0072] In Examples 8 and 9, compared with Example 1, the content of the maleic anhydride grafted polyolefin elastomer in the compatibilizer is decreased, which has a negative effect on the toughness of the obtained masterbatch; the maleic anhydride grafted polyolefin elastomer has a strong effect on the flame retardant, and the reduction of the amount of the maleic anhydride grafted polyolefin elastomer easily leads to the agglomeration of the flame retardant, affects the dispersibility of the flame retardant, and further leads to a downward trend of the flame retardation performance.

[0073] Compared with Example 1, the content of the maleic anhydride grafted polyolefin elastomer in the compatilizer is too much in Example 10, which has a negative effect on the tensile strength of the obtained masterbatch; the molecular chain entanglement degree of polypropylene is increased, the melt viscosity is increased, the dispersibility of the flame retardant is affected, and the flame retardant performance has a downward trend.

[0074] Compared with Example 1, the compatilizer and the interface modifier are compounded in Comparative Example 1 and Comparative Example 2, which jointly optimize the compatibility of the flame retardant and the polypropylene base material, and the performance can reach the best state.

[0075] Compared with Example 1, the ammonium polyphosphate and melamine cyanurate are compounded to obtain a phosphorus-nitrogen flame retardant in Comparative Example 3 and Comparative Example 4, which jointly act on the polypropylene and the polyolefin elastomer material in the polypropylene masterbatch, so that the flame retardant effect of the polypropylene masterbatch is better.

[0076] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A halogen-free flame-retardant high load polypropylene masterbatch, characterized in that, The raw materials of the polypropylene master batch by mass fraction include polypropylene 21.6%-43.3%, a compatilizer 3.8%-11.2%, a flame retardant 43%-67.3%, an interface modifier 2.3%-9.0% and a lubricant 0.7%-3.5%, wherein the flame retardant is a first coupling agent modified phosphorus-nitrogen flame retardant; The interface modifier is prepared by the reaction of long-chain segment end amino polydimethylsiloxane and short-chain segment second coupling agent with 1,4-butanediol diglycidyl ether; The reaction raw materials of the interface modifier by mass fraction include end amino polydimethylsiloxane 50-80 parts, second coupling agent 4-16 parts and 1,4-butanediol diglycidyl ether 100 parts; The first coupling agent and the second coupling agent are both γ-aminopropyl triethoxysilane.

2. The halogen-free flame retardant high load polypropylene masterbatch as claimed in claim 1, wherein, The phosphorus-nitrogen flame retardant is composed of ammonium polyphosphate and melamine cyanurate, and the mass ratio of the ammonium polyphosphate and the melamine cyanurate is (2-3):1, and the addition amount of the first coupling agent in the flame retardant is 3%-5% of the phosphorus-nitrogen flame retardant.

3. The halogen free flame retardant high load polypropylene masterbatch as claimed in claim 1, wherein, The compatilizer includes a combination of maleic anhydride grafted polypropylene and maleic anhydride grafted polyolefin elastomer.

4. The halogen-free flame retardant high load polypropylene masterbatch as claimed in claim 3, wherein, The mass ratio of the maleic anhydride grafted polypropylene and the maleic anhydride grafted polyolefin elastomer is 1:(0.5-1.2).

5. The halogen-free flame retardant high load polypropylene masterbatch as claimed in claim 1, wherein, The lubricant includes a combination of vinyl bis-stearamide and oxidized polyethylene wax.

6. The halogen free flame retardant high load polypropylene masterbatch as claimed in claim 1, wherein, The polypropylene base material is homopolymer polypropylene with a melting index of 15-30 g / 10 min, and the isotacticity of the homopolymer polypropylene is ≥96%.

7. The halogen free flame retardant high load polypropylene masterbatch as claimed in claim 1, wherein, the halogen free flame retardant high load polypropylene masterbatch is prepared by using a combination of a phosphorous containing flame retardant and a nitrogen containing flame retardant. The preparation method of the interface modifier is as follows: under the protection of nitrogen atmosphere, the end amino polydimethylsiloxane and the second coupling agent are mixed uniformly, then 1,4-butanediol diglycidyl ether is added after the temperature is raised to 60-70℃, and the reaction is preserved for 5-8 h.

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