Composite flame retardant, composite flame-retardant master batch and preparation method thereof

Abstract

The invention relates to the technical field of flame retardants, in particular to a composite flame retardant, a composite flame-retardant master batch and a preparation method of the composite flame retardant and the composite flame-retardant master batch. The composite flame retardant comprises the following components in percentage by weight: 15-65% of antimony salt and 35-85% of phosphate, wherein the phosphate comprises one or more of strontium hydrogen phosphate, strontium phosphate and aluminum hypophosphite. According to the composite flame retardant, the antimony salt with relatively low content is compounded with the specific phosphate, so that the dependence on antimony resources is reduced, and the composite flame retardant has the characteristics of excellent flame retardant effect and relatively low cost, can be directly used in a mixed powder form, can also be prepared into different master batch forms for use according to requirements, and is suitable for industrial production. Therefore, the flame retardant can be well applied to flame-retardant high polymer material products.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and in particular to a composite flame retardant, a composite flame retardant masterbatch and a preparation method thereof. Background Art

[0002] The rapid development of modern information technology has driven the development of polymer materials. Currently, polymer-based materials are widely used in various fields, including automotive interiors and household appliances. However, most polymer materials, such as general-purpose polyvinyl chloride, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, and ABS resin, are flammable or combustible. If these polymer materials are burned, they can easily cause fires, endangering people's lives and property.

[0003] Flame retardants, also known as fireproofing agents or fireproofing agents, are important additives for synthetic polymers. Their function is to make synthetic materials flame-retardant, self-extinguishing, and smoke-suppressing. They mainly include phosphorus-based, nitrogen-based, silicon-based, halogen-based, intumescent, and inorganic filler-based flame retardants. Among them, antimony-containing flame retardants are the most widely used. They can increase the thermal decomposition temperature of materials, making them less flammable at high temperatures. They absorb the heat released during combustion and produce non-combustible gases such as carbon dioxide and water vapor, thereby diluting the combustible gases and slowing the material's combustion rate.

[0004] Antimony-containing flame retardants generally work synergistically with halogen-based flame retardants to produce better results. However, halogen-based flame retardants contain halogen atoms, which release large amounts of smoke and toxic and corrosive gases when burned. Eighty percent of deaths in fires are caused by suffocation from smoke and harmful gases.

[0005] To reduce the production of harmful gases, some companies use flame retardant color cakes with high antimony content (≥80%). However, excessively high antimony content requires better dispersion, resulting in the remaining 20% ​​of the formula being filled with essential processing ingredients such as resins and plasticizers, leaving no room for other flame retardant synergists. This results in the flame retardant effect of these flame retardant color cakes being limited. Furthermore, antimony, a rare metal, has seen its price skyrocket in recent years. Flame retardants with high antimony content can increase the production cost of flame-retardant polymer materials. Summary of the Invention

[0006] In order to solve at least one aspect of the above problems, the present invention provides a composite flame retardant, a composite flame retardant masterbatch and a preparation method thereof. The composite flame retardant is compounded with a relatively low content of antimony salt and a specific phosphate, which reduces the dependence on antimony resources, has excellent flame retardant effect and low cost, and can be well applied to flame-retardant polymer material products.

[0007] In a first aspect, the present invention provides a composite flame retardant comprising the following components in weight percentage: 15-65% antimony salt and 35-85% phosphate, wherein the phosphate comprises one or more of strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite.

[0008] Optionally, the antimony salt includes one or more of antimony trioxide, antimony pentoxide, and sodium antimonate.

[0009] Optionally, the phosphate comprises, by weight percentage, 10-90% strontium hydrogen phosphate, 0-90% strontium phosphate and 0-90% hypophosphorous acid.

[0010] Optionally, the phosphate comprises, by weight percentage, 10-90% strontium hydrogen phosphate, 0-80% strontium phosphate, 0-80% aluminum hypophosphite and 10-90% melamine polyphosphate.

[0011] Optionally, the phosphate comprises, by weight percentage, 10-90% strontium hydrogen phosphate, 0-80% strontium phosphate, 0-80% aluminum hypophosphite and 10-90% ammonium polyphosphate.

[0012] Optionally, the phosphate comprises, by weight percentage, 10-80% strontium hydrogen phosphate, 0-70% strontium phosphate, 0-70% aluminum hypophosphite, 10-80% melamine polyphosphate and 10-80% ammonium polyphosphate.

[0013] For most polymer combustion, there are three main stages: 1. The polymer decomposes to produce combustible gas under the action of heat source; 2. After the combustible gas accumulates to a certain concentration, it mixes with the surrounding air and burns, continuously releasing heat; 3. The released heat returns to the polymer to continue heating, further promoting the decomposition of the polymer, forming a thermal cycle to expand combustion.

[0014] Based on the aforementioned combustion mechanism, the present invention utilizes a low-antimony formulation containing the necessary amount of antimony salt to maintain its vapor-phase flame-retardant mechanism. This mechanism lowers the combustion temperature through an internal endothermic reaction. Furthermore, post-combustion vaporization forms a protective film that isolates the air, diluting the oxygen concentration in the air and creating a "suffocation" effect, thereby achieving flame retardancy. However, even with oxygen-deficient flame retardancy, the material itself still retains a significant amount of combustible material, which can lead to continued burning, afterburning, and smoldering in low-oxygen conditions.

[0015] To this end, the present invention incorporates appropriate amounts of specific phosphates and antimony salts into its formulation. Strontium hydrogen phosphate and strontium phosphate are commonly used as fluorescence analysis reagents, playing a fundamental role in chemical testing. However, during research, the present invention discovered that these two substances, like aluminum hypophosphite, can be used as inorganic flame retardants, and that the antimony salts combined with these phosphates offer significantly better results than those combined with other phosphates.

[0016] This may be because strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite all contain phosphorus (P) and oxygen (O) elements. When heated, they will decompose to produce water vapor, absorb heat and reduce the ambient temperature. After decomposition, they can also form phosphate melts, which cover the surface of combustible materials, isolate oxygen and combustible materials, and thus superimpose the dual flame retardant effects of heat absorption and gas release of antimony salts; at the same time, phosphorus oxides can capture free radicals (such as ), inhibiting the combustion chain reaction. Furthermore, the combustion of combustible materials is itself a carbon oxidation process. It is known that the heat generated by the oxidation of an equal amount of carbon to CO₂ is approximately four times that of the oxidation of carbon to CO. Therefore, promoting the oxidation of carbon to CO and inhibiting the oxidation of carbon to CO₂ reduces heat generation and the thermal cycle of combustion. The phosphoric acid produced by the thermal decomposition of phosphorus in the low-antimony formula promotes the oxidation of carbon to CO (P₂O₅ + 5C → 2P + 5CO), thereby cooling and extinguishing the burning material.

[0017] Furthermore, strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite can be uniformly dispersed in polymer base materials (such as polyvinyl chloride, polyethylene, polypropylene, and epoxy resin) directly through mechanical blending or melt extrusion, with little chance of agglomeration or phase separation. Their impact on the material's mechanical properties (such as tensile strength and impact toughness) is only 5-10% (much lower than the 20-30% impact of other inorganic flame retardants, such as aluminum hydroxide). Furthermore, the decomposition starting temperature of these three phosphates is higher than the processing temperature of most polymers, making them less susceptible to premature decomposition during high-temperature processes like extrusion and injection molding, thus ensuring production process stability and flame retardant properties.

[0018] In the present invention, the flame retardant properties of strontium hydrogen phosphate and strontium phosphate are better than those of aluminum hypophosphite. This is probably because the phosphorus-strontium in the two also produces a synergistic flame retardant effect. That is, when strontium hydrogen phosphate and strontium phosphate are decomposed by heat, they release phosphoric acid, metaphosphoric acid and other phosphorus-containing active substances, forming a sticky molten glassy carbon layer on the surface of the material, isolating oxygen and heat transfer, and inhibiting the escape of combustible gases. At the same time, the strontium ions (Sr² + ) can bind with groups like hydroxyl and carboxyl in the char layer, enhancing its high-temperature resistance and density, preventing cracking or decomposition at high temperatures and thus improving flame retardancy. Compared to single phosphorus-based flame retardants (such as ammonium phosphate), strontium hydrogen phosphate can increase the residual weight of the char layer formed in polymers by 15-20% and improve the limiting oxygen index (LOI) by 5-8 units. Strontium phosphate can also improve the residual weight of the char layer and the LOI to a certain extent, so composite flame retardants containing strontium hydrogen phosphate and / or strontium phosphate are further preferred.

[0019] Based on this, the present invention can reduce the antimony salt content in the composite flame retardant to 65% or less, thereby reducing costs by reducing the amount of antimony resources added. While effectively reducing the antimony salt content, the composite flame retardant of the present invention not only achieves or even exceeds the effect of antimony salts compounded with halogen flame retardants, but also solves the dispersibility problem caused by high antimony content, and exhibits excellent flame retardancy and processing stability.

[0020] One or more of the above-mentioned strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite are further preferably compounded with melamine polyphosphate (hereinafter referred to as MPP) and ammonium polyphosphate (hereinafter referred to as APP). This is because the above-mentioned phosphates will form metaphosphoric acid, polymetaphosphoric acid, and pyrophosphoric acid protective films after thermal decomposition, among which nitrogen will form a nitrogen-phosphorus foam insulation layer with pyrophosphoric acid after heating, blocking oxygen and further enhancing the gas phase covering method of antimony salt; on the other hand, metaphosphoric acid and polymetaphosphoric acid are strong dehydrating agents, which can promote the dehydration of organic matter in the combustion material. The vaporization of water consumes a large amount of heat, and the carbonization reaction accelerates the consumption of combustible materials to form an expanded paste with a non-combustible coked carbon structure, which produces a covering effect and interrupts the chain reaction of combustion. It belongs to the solid phase covering method. The gas phase and solid phase methods form an expanded carbon layer through the synergistic effect of "phosphorus-nitrogen-carbon", which has a more excellent flame retardant effect.

[0021] In a second aspect, the present invention provides a composite flame retardant masterbatch comprising the following components in weight percentage: 20-95% of the composite flame retardant according to any one of claims 1-4, 0-16% of a polymer base material, and 5-64% of a processing aid.

[0022] Optionally, the polymer base material is one or more of olefin polymers, ester polymers, vinyl polymers, styrene polymers, and polyurethane.

[0023] Using the above technical solution, a flame retardant masterbatch is a concentrate prepared by dispersing a flame retardant at a high concentration in a carrier resin through a special process. This concentrate typically takes the form of cakes, granules, or other materials. The polymer base can be adjusted to meet specific needs. For example, for flame-retardant polymer materials for PVC artificial leather, the polymer base of the composite flame retardant masterbatch can be PVC, and an appropriate amount of plasticizer is added to the additives to improve the masterbatch's moldability. Alternatively, the polymer base can be adjusted to materials such as EVA that are highly compatible with PVC. Processing aids primarily include dispersants, stabilizers, and lubricants, which are used to improve the dispersion and processing properties of the flame retardant. Compared to traditional flame retardant addition, preparing a flame retardant masterbatch improves the dispersion of the flame retardant in the resin, reduces the amount of flame retardant added, and reduces processing difficulty and cost. It also minimizes the impact of the flame retardant on the mechanical properties of the resin, reducing undesirable phenomena such as delamination, patterning, and precipitation after addition, improving the working environment, and saving labor, material costs, and time.

[0024] In a third aspect, the present invention provides a method for preparing a composite flame retardant masterbatch, comprising the following steps: weighing each component according to the formula of the above-mentioned composite flame retardant masterbatch and premixing them, putting the harvested premix into an internal mixer and mixing them evenly, and then grinding and dispersing them and pressing them into shape and cutting them to obtain a composite flame retardant masterbatch with a cake-like structure.

[0025] In a fourth aspect, the present invention provides a method for preparing a composite flame retardant masterbatch, comprising the following steps: weighing each component according to the formula of the above-mentioned composite flame retardant masterbatch and premixing them, adding the harvested premix to a screw extruder for extrusion and granulation to obtain a composite flame retardant masterbatch with a granular structure.

[0026] By adopting the above technical solution, the flame retardant of the present invention can not only be directly used in the form of a mixed powder, but can also be made into a corresponding cake structure or granular structure according to different needs. Compared with the mixed powder form, the composite flame retardant masterbatch with cake and granular structures contains other processing aids, which is helpful for the transportation and storage of the composite flame retardant and its subsequent application in flame-retardant polymer material products.

[0027] In summary, the present invention has the following beneficial effects:

[0028] 1. The composite flame retardant of the present invention adopts a low-antimony formula, so that the antimony salt content can be reduced to 65% or less, which not only reduces the dependence on antimony resources, but also leaves space in the formula to facilitate the compounding of other flame retardants such as strontium hydrogen phosphate, strontium phosphate, and one or more aluminum hypophosphite. Through the superposition of multiple flame retardant mechanisms such as gas phase coverage, solid phase coverage, heat absorption and cooling, and free radical capture, it has the characteristics of excellent flame retardant performance, low cost, good processing stability, and easy and uniform dispersion with polymer materials. It can be well applied to flame-retardant polymer material products.

[0029] 2. Among the composite flame retardants of the present invention, phosphates obtained by compounding one or more of strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite with MPP and APP are further preferred. Phosphates also contain nitrogen and phosphorus. After combustion and heating, they will form a nitrogen and phosphorus foam insulation layer for blocking oxygen, while promoting the dehydration and heat absorption of organic matter in the burning materials, and have a more excellent flame retardant effect.

[0030] 3. The composite flame retardant of the present invention can be directly fed into the feedstock, or it can be made into a composite flame retardant masterbatch in a specific form such as cake or granule, so as to facilitate storage and transportation as well as subsequent rapid dispersion in flame retardant polymer materials. The composite flame retardant in the composite flame retardant masterbatch can be evenly dispersed by mechanical blending or melt extrusion, making the preparation of the composite flame retardant masterbatch simpler and having better application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the combustion performance sample of the present invention;

[0032] Figure 2 This is a sample diagram of the sample group ① after combustion corresponding to Example 38 of the present invention;

[0033] Figure 3 This is a sample diagram of the sample group ① after combustion corresponding to Example 42 of the present invention;

[0034] Figure 4 This is a sample diagram of the sample group ① after combustion corresponding to Example 43 of the present invention;

[0035] Figure 5 This is a sample diagram after combustion of group ① of samples corresponding to Example 44 of the present invention.

[0036] In the figure, 1 is the first marking line; 2 is the second marking line. DETAILED DESCRIPTION

[0037] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] The composite flame retardant and composite flame retardant masterbatch provided by the present invention can be applied to many industries such as military, aerospace, transportation, electricity and civilian use, including but not limited to flame retardant modification of materials such as PVC, EVA, PE, ABS resin, PP, and PET.

[0039] The composite flame retardant provided by the present invention comprises the following components in weight percentage: 15-65% antimony salt and 35-85% phosphate. The preparation method of the composite flame retardant comprises the following steps: weighing each component as needed, adding the components into a mixer, and stirring uniformly at a speed of 1000-3000 r / min to obtain the composite flame retardant.

[0040] The antimony salt includes one or more of antimony trioxide, antimony pentoxide, and sodium antimonate. The phosphate includes one or more of strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite.

[0041] The products produced by the above-mentioned phosphates after combustion and decomposition will produce a synergistic effect with antimony salts, realizing the superposition of multiple flame retardant mechanisms such as gas phase coverage, solid phase coverage, heat absorption and cooling, and free radical capture, thereby effectively reducing the antimony salt content while ensuring that the composite flame retardant has high flame retardant properties.

[0042] In some embodiments of the present invention, the phosphate further comprises melamine polyphosphate (MPP). Furthermore, preferably, the weight ratio of strontium hydrogen phosphate, strontium phosphate, aluminum hypophosphite, and melamine polyphosphate is 10-90:0-80:0-80:10-90. MPP is a gas source component in an intumescent flame retardant (IFR) system. When heated, it decomposes to release nitrogen, which helps form an intumescent char layer.

[0043] In other embodiments of the present invention, the phosphate further comprises ammonium polyphosphate (APP). More preferably, the weight ratio of strontium hydrogen phosphate, strontium phosphate, aluminum hypophosphite, and melamine polyphosphate to APP is 10-80:0-70:0-70:10-80:10-80. APP is the acid and gas source in an intumescent flame retardant (IFR) system. When heated, it releases acidic substances such as polymetaphosphoric acid to promote charring, while also releasing gases such as ammonia to slow combustion. The nitrogen and phosphorus it contains further enhance the flame retardant effect.

[0044] Research has found that when strontium hydrogen phosphate is used alone, its flame retardant efficiency is relatively low, but when it is compounded with MPP and APP, it can form an expanded carbon layer through the synergistic effect of "phosphorus-nitrogen-carbon", effectively improving the flame retardant effect. Therefore, the present invention further prefers to use strontium hydrogen phosphate, MPP and APP in compound.

[0045] The composite flame retardant masterbatch provided by the present invention comprises the following components in percentage by weight: 20-95% of the composite flame retardant disclosed above, 0-16% of a polymer base material, and 5-64% of a processing aid.

[0046] The polymer base material used in the composite flame retardant masterbatch needs to have good compatibility with the flame retardant polymer product to be used. The specific polymer base material can be selected according to the characteristics of the flame retardant polymer product. It can preferably be one or more of olefin polymers, ester polymers, ethylene polymers, styrene polymers, and polyurethane (PU).

[0047] In some embodiments of the present invention, olefin polymers can be listed as polyethylene (PE), polypropylene (PP), etc.; ester polymers can be listed as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), etc.; ethylene polymers can be listed as polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), etc.; styrene polymers can be listed as polystyrene (PS), styrene-acrylonitrile resin (SAN), styrene-butadiene-acrylonitrile resin (ABS), etc.

[0048] The additives used in the composite flame retardant masterbatch of the present invention can be increased or decreased according to the characteristics of the polymer base material, and include one or more of a plasticizer, a dispersant, a stabilizer, and a lubricant.

[0049] The plasticizer can be selected from one or more of pyromellitic acid ester plasticizers, trimellitic acid ester plasticizers, phthalic acid ester plasticizers, terephthalic acid ester plasticizers, isophthalic acid ester plasticizers, phosphate plasticizers, and epoxidized vegetable oils, depending on the properties of the polymer base. The dispersant is preferably calcium carbonate; the stabilizer is preferably a calcium zinc stabilizer and an organotin stabilizer; and the lubricant includes one or more of metal soap lubricants, hydrocarbon lubricants, fatty acid lubricants, and fatty acid ester lubricants. In some embodiments of the present invention, the additives also include colorants, antistatic agents, and other substances that can improve or impart specific properties to the polymer.

[0050] The preparation method of the composite flame retardant masterbatch of the present invention can be adjusted according to the needs of downstream companies, and one of the color cake structure and the granular structure is further preferred.

[0051] The first method for preparing a composite flame-retardant masterbatch with a color cake structure comprises the following steps: weighing and premixing the components according to the composite flame-retardant masterbatch formula, placing the resulting premix in an internal mixer for uniform mixing, grinding and dispersing the premix, pressing and forming the premix, and cutting the premix to obtain a composite flame-retardant masterbatch with a cake structure. The processing parameters in the above steps need to be adjusted according to the characteristics of different polymer base materials. For example, using a PVC color cake as an example, the premix obtained by premixing the components is placed in an internal mixer (or kneader). Mechanical shearing and heating are used to melt the PVC resin. Simultaneously, the other components are further dispersed into the molten resin under the action of shear force, achieving uniform bonding between the components and the carrier. The premix is ​​then rolled into a thin sheet on a double-roll sheeter with the roller temperature controlled at 100-140°C (to maintain a certain fluidity but prevent sticking to the rollers). The thickness is controlled by adjusting the roller gap. Finally, the sheet is pressed into a cake of a specific size using a mold.

[0052] The second method for preparing a granular composite flame-retardant masterbatch comprises the following steps: weighing and premixing the components according to the aforementioned composite flame-retardant masterbatch formula, feeding the resulting premix into a screw extruder for extrusion and pelletization, thereby obtaining a granular composite flame-retardant masterbatch. Similarly, the processing parameters in these steps need to be adjusted based on the characteristics of the polymer base material. For example, for EVA pelletization, the processing temperature is between 120°C and 190°C.

[0053] The raw materials involved in the examples and comparative examples of the present invention are all commercially available products.

[0054] (1) Antimony salts:

[0055] Antimony trioxide was purchased from Hefei Wanran New Material Technology Co., Ltd. with CAS number 1309-64-4, molecular formula Sb2O3, and molecular weight 291.518;

[0056] Antimony pentoxide was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd. with CAS number 1314-60-9, molecular formula Sb2O5, and molecular weight 323.517;

[0057] Sodium antimonate was purchased from Suzhou Jingti New Materials Co., Ltd. with a CAS number of 15432-85-6, a molecular formula of NaSbO3, and a molecular weight of 192.73. It should be noted that the names of sodium antimonate on the market are quite confusing. The sodium antimonate used in the present invention is different from sodium antimonate trihydrate (NaSbO3·3H2O, with a molecular weight of 246.8) and sodium pyroantimonate (C5H4Na3O6Sb, with a molecular weight of 350.81).

[0058] (2) Phosphates:

[0059] Strontium hydrogen phosphate was purchased from Wuhan Chengtian Fine Chemical Co., Ltd. with CAS number 13450-99-2, molecular formula SrHPO4, molecular weight 183.599, and purity ≥99%;

[0060] Strontium phosphate was purchased from Hubei Shuaiyan Ligao Biopharmaceutical Co., Ltd. with CAS number 14414-90-5, molecular formula Sr3P2O8, and purity ≥98%;

[0061] Aluminum hypophosphite was purchased from Hefei Wanran New Material Technology Co., Ltd. with CAS number 7784-22-7, molecular formula Al(H2PO2)3, and purity ≥97%;

[0062] Melamine polyphosphate (hereinafter referred to as MPP): purchased from Budenheim, Budit 3141, CAS No. 218768-84-4, molecular formula ;

[0063] Ammonium polyphosphate (hereinafter referred to as APP): purchased from Shandong Taixing New Materials Co., Ltd., HT-208, CAS No. 68333-79-9, molecular formula (NH4) n +2P n O 3n+1 .

[0064] (3) Polymer base material:

[0065] Taking PVC and EVA as examples, PVC was purchased from Tianjin Bohai Chemical Development Co., Ltd., DG-700; EVA was purchased from Ningbo Shijin Plastic Co., Ltd., DuPont 210, USA.

[0066] (4) Processing aids:

[0067] The plasticizer used was dioctyl phthalate (DOP), purchased from Shandong Shengfan Chemical Co., Ltd., with a CAS number of 117-81-7;

[0068] The dispersant used was light nano-calcium carbonate, purchased from Shanghai Liangjiang Titanium Dioxide Chemical Products, LP-800, with an average particle size of 60-100 nm;

[0069] The stabilizer is a mixture of liquid calcium zinc stabilizer and powdered calcium zinc stabilizer in a mass ratio of 3:1; the liquid calcium zinc stabilizer is purchased from Zhejiang Jiaao Environmental Protection Technology Co., Ltd., JCZ-100; the powdered calcium zinc stabilizer is purchased from Zhejiang Jiaao Environmental Protection Technology Co., Ltd., JCZ-6503B;

[0070] The lubricant used was polyethylene wax, purchased from Hebei Tianyu Chemical Co., Ltd., model 110.

[0071] It should be noted that in the actual production application of PVC artificial leather, most of the PVC artificial leather needs to be bonded with polyester base cloth to increase the tensile properties, comfort, etc., that is, the polyester base cloth is an important component of PVC artificial leather, and the polyester base cloth is a flammable material. In order to truly reflect the flame retardancy of the material of the present invention and the flame retardant effectiveness in actual production, in the flame retardant performance tests of the following examples and comparative examples, the samples with antimony-free composite flame retardant added are bonded to the polyester base cloth and then subjected to a combustion test, wherein the polyester base cloth has a thickness of 0.5mm, the PVC sample has a thickness of 0.6mm, and the total thickness is 1.1mm. In addition, the phthalate plasticizers commonly used in PVC artificial leather are also flammable substances. In order to enhance the test effect, 40% DOP is added to the polymer base material (PVC) used in the following examples and comparative examples. The following is combined with the attached Figure 1-5 , Examples and Comparative Examples further illustrate the present invention in detail.

[0072] Example 1

[0073] This embodiment provides a composite flame retardant, comprising the following components in weight percentage: 30% antimony trioxide and 70% strontium hydrogen phosphate.

[0074] The preparation method of the composite flame retardant comprises the following steps: weighing the components of the composite flame retardant according to the above weight percentages, adding the components into a blender, and stirring at a speed of 2000 r / min for 20 minutes until the mixture is uniform. The combustion results of the flame retardant performance test are shown in the figure below. Figure 1 shown.

[0075] Example 2-10

[0076] Examples 2-10 are based on the method of Example 1, with adjustments made to the specific types and weight percentages of antimony salt and phosphate. The specific scheme can be summarized as "antimony salt + inorganic phosphate". The adjustments are shown in Table 1 below.

[0077] Table 1 Components of the composite flame retardant of Examples 1-10 (unit: %)

[0078]

[0079] Examples 11-20

[0080] Examples 11-20 are based on the method of Example 1, with the type and weight percentage of the phosphate adjusted. The specific scheme can be summarized as "antimony salt + inorganic phosphate + MPP". The adjustment details are shown in Table 2 below.

[0081] Table 2 Components of the composite flame retardant of Examples 11-20 (unit: %)

[0082]

[0083] Examples 21-30

[0084] Examples 21-30 are based on the method of Example 1, with the type and weight percentage of the phosphate adjusted. The specific scheme can be summarized as "antimony salt + inorganic phosphate + APP". The adjustment details are shown in Table 3 below.

[0085] Table 3 Components of the composite flame retardant of Examples 21-30 (unit: %)

[0086]

[0087] Examples 31-37

[0088] Examples 31-37 are based on the method of Example 1, with the type and weight percentage of phosphate adjusted. The specific scheme can be summarized as "antimony salt + inorganic phosphate + MPP + APP". The adjustment details are shown in Table 4 below.

[0089] Table 4 Components of the composite flame retardant of Examples 31-37 (unit: %)

[0090]

[0091] Comparative Example 1

[0092] In this comparative example, based on the method of Example 1, all strontium hydrogen phosphate was replaced by MPP.

[0093] Comparative Example 2

[0094] In this comparative example, based on the method of Example 1, all strontium hydrogen phosphate was replaced by APP.

[0095] Comparative Example 3

[0096] In this comparative example, based on the method of Example 1, strontium hydrogen phosphate was replaced with a mixture of 45% MPP and 25% APP.

[0097] Performance testing

[0098] The flame retardants of Examples 1-37 and Comparative Examples 1-3 were subjected to flame retardant performance tests. Taking the application of the present invention in automotive PVC artificial leather interior materials as an example, the following groups ① and ② of samples were set up.

[0099] ① Group 1 samples: 5 g of the flame retardant masterbatch of each embodiment and comparative example and 100 g of polyvinyl chloride masterbatch were calendered on a two-roller machine to obtain samples with a size of 356 mm × 100 mm × 1.1 mm, wherein the polyester base fabric had a thickness of 0.5 mm and the PVC sample had a thickness of 0.6 mm.

[0100] ② Group 2 samples: 3 g of the flame retardant masterbatch of each embodiment and comparative example and 100 g of polyvinyl chloride masterbatch were calendered on a two-roller machine to obtain samples with a size of 356 mm × 100 mm × 1.1 mm, wherein the polyester base fabric had a thickness of 0.5 mm and the PVC sample had a thickness of 0.6 mm.

[0101] The above-mentioned samples were subjected to flame retardancy tests, specifically referring to GB 8410-2006 Combustion Characteristics of Automotive Interior Materials. A U-shaped bracket was used to clamp both sides and one end of the sample. A gas lamp was lit in a combustion box with a flame height of 38 mm. The free end of the sample was exposed to the flame and ignited for 15 seconds, and then the flame was extinguished.

[0102] The flame burns forward from the free end of the specimen, see Figure 1 The first marking line 1 is located at a position 38 mm away from the free end of the sample along the burning direction, and the second marking line 2 is located at a position 254 mm away from the first marking line along the burning direction.

[0103] Start timing the moment the flame's root passes through the first mark (1). Observe the flame's spread on the faster-burning side, and use the faster-burning side as the basis for timing. Stop timing when the flame reaches the second mark (2), or when it extinguishes before reaching it. Use the faster-burning side as the basis for timing.

[0104] If a specimen remains unburned after being exposed to flame for 15 seconds and the fire source is extinguished, or if it burns but extinguishes before reaching the first mark (1), the specimen is considered to have met the burning rate requirement and is given an A rating. If the flame extinguishes itself within 60 seconds from the start of the test, and the burning distance is ≤88 mm (measured from the free end), the specimen is also considered to have met the burning rate requirement and is given a B rating. If the flame extinguishes between the first mark (1) and the second mark (2) from the start of the burning time, the specimen is considered to have self-extinguished, and the burning behavior differs from the second requirement of the result indication, i.e., a burning distance of 88 mm < x ≤ 292 mm (measured from the free end), the rating is C. If the flame reaches the second mark (2) (burning distance > 292 mm (measured from the free end)) from the start of the burning time, or if the specimen burns slowly over a long period of time (the test is terminated at 20 minutes), the rating is D. The burning distance mentioned above refers to the length of the burned portion of the specimen surface or interior.

[0105] The test results are shown in Table 5 below.

[0106] Table 5 Performance test results of Examples 1-37 and Comparative Examples 1-3

[0107]

[0108] Referring to Table 6 above, the phosphates used in Examples 2 and 3 are strontium phosphate and aluminum hypophosphite, and the flame retardant effect of the corresponding composite flame retardant is not as good as that of Example 1 using strontium hydrogen phosphate; the amount of antimony salt used in Example 4 is relatively small, and the amount of antimony salt used in Example 5 is relatively large, and the flame retardant effect of the corresponding composite flame retardant is not as good as that of Example 1, but the flame retardant effects of Examples 1-5 are better than those of Comparative Examples 1-3. It can be seen that the composite effect of "antimony salt + specific phosphate" of the present invention is not only significantly better than the existing "antimony salt + conventional phosphorus-nitrogen flame retardant MPP, APP", but also comparable to the flame retardant effect of traditional pure antimony trioxide, achieving the purpose of low antimony content flame retardant with excellent flame retardant effect, reducing dependence on antimony resources to a certain extent, reducing costs, and being well suitable for the flame retardant polymer material market.

[0109] In addition, the antimony salts used in Examples 6 and 7 are antimony pentoxide and sodium antimonate. These two examples illustrate that the antimony salts of the present application are not limited to antimony trioxide, but are also applicable to antimony pentoxide and sodium antimonate, and the corresponding flame retardant effects are antimony trioxide > sodium antimonate > antimony pentoxide.

[0110] Examples 8-10 adjust the proportions of the various components of the phosphate. Combined with the test results, it can be seen that the flame retardant effect of strontium hydrogen phosphate is better than that of strontium phosphate and aluminum hypophosphite.

[0111] Examples 11-20 are based on the scheme of "antimony salt + inorganic phosphate + MPP", Examples 21-30 are based on the scheme of "antimony salt + inorganic phosphate + APP", and Examples 31-37 are based on the scheme of "antimony salt + inorganic phosphate + MPP + APP". By comparing the test results of Examples 1-10 with those of Examples 11-20, 21-30, and 31-37, it can be obtained that the compounding of inorganic phosphate with MPP and / or APP can effectively improve the flame retardant effect of the composite flame retardant, especially when inorganic phosphate is compounded with both MPP and APP at the same time, the flame retardant effect obtained is significantly better than the flame retardant effect when using inorganic phosphate alone, compounding inorganic phosphate with MPP, and compounding inorganic phosphate with APP.

[0112] Examples 38-44

[0113] The above embodiments are all used to provide a composite flame retardant masterbatch, which includes the following components in weight percentage: 20-95% composite flame retardant, 0-16% polymer base material, and 5-64% processing aid.

[0114] Among them, Examples 38-40 and Examples 42-44 were all prepared in the form of PVC color cake structures. The specific preparation method included the following steps: weighing a set amount of composite flame retardant, PVC and processing aid for premixing, adding the harvested premix to an internal mixer, controlling the temperature of the internal mixer to maintain within the range of 130-150°C for internal mixing for 35 minutes, melting the PVC by mechanical shearing and heating and mixing it with other components, and rolling it into thin sheets using a double-roll sheeter with the roller temperature controlled at 100-140°C (to maintain a certain fluidity but not stick to the rollers), and cutting it with a cutter to obtain a PVC flame retardant color cake.

[0115] Example 41 is prepared in the form of a mixing powder, and the specific preparation method includes the following steps: weighing a set amount of composite flame retardant and processing aid, putting them into a blender and stirring them evenly.

[0116] In addition, the composite flame retardant obtained in Example 1 is used in Examples 38-40, and the amount of each component of the composite flame retardant masterbatch is adjusted. Example 42, Example 43 and Example 44 respectively correspond to the composite flame retardants obtained in Example 11, Example 21 and Example 31. The specific formula table of each component of the above composite flame retardant masterbatch is shown in Table 6 below.

[0117] Table 6 Component composition of the composite flame retardant masterbatch of Examples 38-44 (unit: %)

[0118]

[0119] Example 45

[0120] This embodiment is used to provide a method for preparing a composite flame retardant masterbatch with an EVA masterbatch structure, which is made into a granular structure. The method specifically includes the following steps: weighing 72% of the composite flame retardant obtained in Example 1, 15% of EVA, 11% of light nano-calcium carbonate, and 2% of polyethylene wax, adding them to a twin-screw extruder, and controlling the barrel temperature gradient of the twin-screw extruder: 120-140°C in the feeding section, 140-160°C in the compression section, and 160-180°C in the extrusion section. The extruded material is cooled and then granulated and dried to obtain the EVA flame retardant masterbatch.

[0121] The flame retardant properties of the composite flame-retardant masterbatches of Examples 38-45 were tested. Again, using the flame retardant as an example, the flame retardant was added to 100 grams of the PVC production mix for automotive PVC artificial leather interior materials. Groups ① and ② were set up. Group ① added 6.94 grams of each example (ensuring approximately 5 grams of the composite flame retardant in Examples 38, 42-45), while Group ② added 4.17 grams of each example (ensuring approximately 3 grams of the composite flame retardant in Examples 38, 42-45). The testing method was the same as above. The test results are shown in Table 7 below.

[0122] Table 7 Performance test results of Examples 38-45

[0123]

[0124] Referring to Table 7 above, Examples 38-45 all have excellent flame retardant effects. By comparing the results of Example 38 with Example 1, Example 42 with Example 11, Example 43 with Example 21, and Example 44 with Example 31, it can be seen that the composite flame retardant of the present invention is sufficient to effectively play its role by direct addition, and the flame retardant performance of the composite flame retardant can be effectively exerted in the form of a masterbatch. It can be seen that the composite flame retardant of the present invention can be used directly as needed, and can also be made into a color cake structure or a granular structure for easy storage and transportation.

[0125] In addition, combining the results of Example 38 and Example 45, it can be obtained that the EVA masterbatch has a more excellent flame retardant effect. This may be based on the fact that a certain amount of plasticizer (dioctyl phthalate) needs to be added during the processing of the PVC color cake, and the EVA masterbatch can reduce the addition of plasticizer, thereby moderately reducing the flame retardant effect of the plasticizer on the composite flame retardant.

[0126] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A composite flame retardant, characterized in that: The invention comprises the following components in weight percentage: 15-65% of antimony salt and 35-85% of phosphate, wherein the phosphate comprises one or more of strontium hydrogen phosphate, strontium phosphate and aluminum hypophosphite.

2. The composite flame retardant according to claim 1, characterized in that The antimony salt includes one or more of antimony trioxide, antimony pentoxide, and sodium antimonate.

3. The composite flame retardant according to claim 1, characterized in that The phosphate comprises, by weight percentage, 10-90% of strontium hydrogen phosphate, 0-90% of strontium phosphate and 0-90% of hypophosphorous acid.

4. The composite flame retardant according to claim 3, characterized in that The phosphate comprises, by weight percentage, 10-90% of strontium hydrogen phosphate, 0-80% of strontium phosphate, 0-80% of aluminum hypophosphite and 10-90% of melamine polyphosphate.

5. The composite flame retardant according to claim 3, characterized in that The phosphate comprises, by weight percentage, 10-90% of strontium hydrogen phosphate, 0-80% of strontium phosphate, 0-80% of aluminum hypophosphite and 10-90% of ammonium polyphosphate.

6. The composite flame retardant according to claim 3, characterized in that The phosphate comprises, by weight percentage, 10-80% of strontium hydrogen phosphate, 0-70% of strontium phosphate, 0-70% of aluminum hypophosphite, 10-80% of melamine polyphosphate and 10-80% of ammonium polyphosphate.

7. A composite flame retardant masterbatch, characterized in that: The invention comprises the following components in weight percentage: 20-95% of the composite flame retardant according to any one of claims 1 to 6, 0-16% of a polymer base material, and 5-64% of a processing aid.

8. The composite flame retardant masterbatch according to claim 7, characterized in that: The polymer base material is one or more of olefin polymers, ester polymers, vinyl polymers, styrene polymers, and polyurethane.

9. A method for preparing a composite flame retardant masterbatch, characterized in that: The method comprises the following steps: weighing each component according to the formula of the composite flame retardant masterbatch according to claim 7 and premixing them, putting the harvested premix into an internal mixer and mixing them evenly, and then grinding and dispersing them, pressing them into shape and cutting them to obtain a composite flame retardant masterbatch with a cake-like structure.

10. A method for preparing a composite flame retardant masterbatch, characterized in that: The method comprises the following steps: weighing the components according to the formula of the composite flame retardant masterbatch according to claim 7 and premixing them; adding the harvested premixed material into a screw extruder for extrusion granulation to obtain a composite flame retardant masterbatch with a granular structure.

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