Antimony-free composite flame retardant, antimony-free flame-retardant master batch and preparation method thereof

Abstract

The invention relates to the technical field of flame retardants, in particular to an antimony-free composite flame retardant, an antimony-free flame-retardant master batch and a preparation method of the antimony-free composite flame retardant. The antimony-free composite flame retardant comprises the following components in percentage by weight: 10-90% of melamine polyphosphate and 10-90% of inorganic phosphate, and the inorganic phosphate comprises strontium hydrogen phosphate and / or strontium phosphate. The antimony-free composite flame retardant adopts an antimony-free composite formula of melamine polyphosphate and strontium hydrogen phosphate and / or strontium phosphate, the flame-retardant efficiency of the antimony-free composite flame retardant is superior to that of an antimony salt flame retardant, the flame-retardant problem can be effectively solved under the condition that antimony resources are deficient, antimony-free flame-retardant products are realized, and the flame-retardant performance of the flame-retardant products is improved. Meanwhile, the preparation method has the characteristics of safety, low toxicity, low cost, wide raw material source, good dispersity and compatibility and the like, and has a wider application prospect.

Description

Technical Field

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

[0002] Most organic polymer materials such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), etc. are flammable to varying degrees in air, which limits the application of polymer materials in many industries such as military, aerospace, transportation, electricity and civilian use. Traditional flame retardant methods mainly improve the fire resistance of materials by adding flame retardants.

[0003] Antimony-containing flame retardants are common and highly effective. They lower combustion temperatures through an internal endothermic reaction. They also vaporize after combustion to form a protective film that isolates the air, diluting the oxygen concentration in the air and creating a "suffocating" effect, thereby providing a flame retardant effect. However, in recent years, the depletion rate of antimony ore reserves has far exceeded the growth rate of recoverable reserves, and the current status of antimony ore resources is not optimistic.

[0004] Inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide usually require high filling amounts to achieve ideal flame retardant effects. However, high filling amounts affect the mechanical properties of the material, making them difficult to be widely used.

[0005] Nitrogen-based flame retardants and phosphorus / phosphonate flame retardants meet the current environmentally friendly requirements of material development. These two types of flame retardants, when combined with charring agents, can create intumescent flame-retardant systems for flame-retardant PVC. Compared to antimony-containing and other low-antimony and antimony-free formulations, these formulations do not contain heavy metals or halogens, are safe and effective, and have a wide range of applications. They also offer advantages such as low toxicity, excellent thermal stability, and low smoke generation. However, due to their chemical structure, phosphorus / phosphonate flame retardants are susceptible to moisture absorption in humid environments, making their flame retardant performance less effective.

[0006] Therefore, there is an urgent need to develop an antimony-free composite flame retardant that can meet the flame retardant requirements of a variety of polymer materials and reduce the excessive exploitation of antimony resources, which is of great practical significance. Summary of the Invention

[0007] In order to solve at least one aspect of the above problems, the present invention provides an antimony-free composite flame retardant, an antimony-free flame retardant masterbatch and a preparation method thereof. The antimony-free composite flame retardant can solve the flame retardant problem at the current time when antimony resources are scarce, and realize the antimony-free flame retardant products. It has the advantages of good flame retardant effect, safety and low toxicity, low cost, and a wide range of raw material sources.

[0008] In a first aspect, the present invention provides an antimony-free composite flame retardant, comprising the following components in weight percentage: 10-90% melamine polyphosphate and 10-90% inorganic phosphate, wherein the inorganic phosphate comprises strontium hydrogen phosphate and / or strontium phosphate.

[0009] Optionally, the inorganic phosphate includes strontium hydrogen phosphate and strontium phosphate, and the weight ratio of the strontium hydrogen phosphate to the strontium phosphate is 1:0.25-4.

[0010] Optionally, the inorganic phosphate further includes aluminum hypophosphite, and the added weight of the aluminum hypophosphite is 0.2-1.5 times that of strontium hydrogen phosphate and / or strontium phosphate.

[0011] Optionally, the antimony-free composite flame retardant comprises the following components in weight percentage: 25-75% melamine polyphosphate and 25-75% inorganic phosphate.

[0012] Optionally, the antimony-free composite flame retardant comprises the following components in weight percentage: 10-80% melamine polyphosphate, 10-80% inorganic phosphate and 10-80% ammonium polyphosphate.

[0013] Optionally, the antimony-free composite flame retardant comprises the following components in weight percentage: 25-70% melamine polyphosphate, 20-70% inorganic phosphate and 5-55% ammonium polyphosphate.

[0014] Typically, strontium hydrogen phosphate and strontium phosphate are used as analytical reagents and also show potential in fluorescent materials, bone cement, lasers, and other fields. In the present invention, the inventors discovered that strontium hydrogen phosphate and strontium phosphate can be used as flame retardants, and their flame retardant mechanism is mainly as follows:

[0015] 1. Phosphorus-strontium synergistic flame retardant effect:

[0016] Carbonization and smoke suppression effects of phosphorus: 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, while suppressing the escape of combustible gases;

[0017] Thermal stabilization of strontium: Strontium ions (Sr 2+ ) can combine with hydroxyl, carboxyl and other groups in the carbon layer to enhance the high temperature resistance and density of the carbon layer, prevent the carbon layer from cracking or decomposing at high temperatures, and thus improve the flame retardant durability.

[0018] In addition, research has found that compared with single phosphorus-based flame retardants (such as ammonium phosphate), the residual weight rate of the carbon layer formed by strontium hydrogen phosphate in polymers can be increased by 15-20%, and the limiting oxygen index (LOI) can be increased by 5-8 units;

[0019] 2. Double flame retardancy of heat absorption and gas release

[0020] Strontium hydrogen phosphate begins to decompose at approximately 200°C, gradually releasing water of crystallization and decomposing into Sr3(PO4)2 and P2O5. The entire process absorbs approximately 1200 kJ / kg of heat, effectively reducing the surface temperature of the material. Although strontium phosphate has a relatively high decomposition temperature, the decomposition process also absorbs a significant amount of heat. The phosphoric acid and polymetaphosphoric acid released by the thermal decomposition of these two substances can act as strong dehydrating agents, promoting surface dehydration and carbonization of oxygen-containing polymers (such as epoxy resins and cellulose). The released water vapor and small amounts of non-combustible gases, such as PO3, dilute the oxygen concentration in the air, inhibiting the combustion chain reaction.

[0021] Unlike halogen flame retardants (such as decabromodiphenyl ether), strontium hydrogen phosphate and strontium phosphate do not contain halogen elements such as chlorine and bromine, and no highly toxic substances such as dioxins are released during combustion. They comply with EU RoHS, REACH and other environmental protection standards and are suitable for use in fields with high safety requirements such as electronic appliances and food packaging. Their combustion smoke density (such as tested with an NBS smoke box) is 30-50% lower than that of halogen flame retardants, avoiding the risk of suffocation caused by smoke, and are especially suitable for crowded scenes such as buildings and vehicles. Unlike antimony salt flame retardants (such as antimony trioxide) with contact toxicity, the acute toxicity test of strontium hydrogen phosphate and strontium phosphate shows that their LD 50 (oral in rats)>2000 mg / kg, which is a low-toxic substance and poses little harm to operators and users.

[0022] In addition, strontium hydrogen phosphate and strontium phosphate can be evenly dispersed in polymer matrices (such as polyvinyl chloride, polyethylene, polypropylene, epoxy resin, etc.) through mechanical blending or melt extrusion, and are not prone to agglomeration or phase separation. The impact on the mechanical properties of the material (such as tensile strength and impact toughness) is only 5-10% (much lower than the 20-30% of some inorganic flame retardants such as aluminum hydroxide), and has good dispersibility and compatibility.

[0023] The present invention adopts an antimony-free composite formula of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate". This is based on the fact that when strontium hydrogen phosphate and / or strontium phosphate are used alone, their flame retardant efficiency is lower than that of halogen-containing or nitrogen-containing flame retardants, and the flame retardant effect obtained by compounding the two can be significantly improved. This may be because strontium hydrogen phosphate and / or strontium phosphate will also produce a certain amount of pyrophosphoric acid when thermally decomposed. This pyrophosphoric acid will form a nitrogen-phosphorus foam insulation layer with the nitrogen in the melamine polyphosphate, which will flame retard oxygen and achieve a gas phase covering effect. At the same time, the metaphosphoric acid and polymetaphosphoric acid formed by the thermal decomposition of strontium hydrogen phosphate and / or strontium phosphate promote the dehydration and carbonization of the combustion material. The vaporization of water consumes a large amount of heat, and the carbonization reaction accelerates the consumption of combustible materials, forming an expanded paste with a non-combustible coked carbon structure, achieving a solid phase covering effect. The gas phase and solid phase methods form an expanded carbon layer through the synergistic effect of "phosphorus-nitrogen-carbon", thereby making the antimony-free composite flame retardant of the present invention have an excellent flame retardant effect.

[0024] On this basis, the inorganic phosphate of the present invention further preferably comprises aluminum hypophosphite compounded with strontium hydrogen phosphate and / or strontium phosphate. Aluminum hypophosphite is an inorganic phosphate with the properties of a phosphate, and can synergistically flame-retardantly combine with strontium hydrogen phosphate and strontium phosphate. Furthermore, aluminum hypophosphite also contains aluminum metal, which, through the "phosphorus-aluminum metal" interaction, strengthens the synergistic effect between aluminum hypophosphite and strontium hydrogen phosphate and / or strontium phosphate, further enhancing the flame retardant effect while also improving the mechanical properties of the material.

[0025] After research, it was found that the present invention further prefers the antimony-free composite formula of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate + ammonium polyphosphate". This is based on the fact that ammonium polyphosphate has a high phosphorus content and can cooperate with strontium hydrogen phosphate and / or strontium phosphate to produce more metaphosphoric acid and polymetaphosphoric acid to promote the dehydration and carbonization of the combustion materials to form a carbonized layer. The effect of the combined use of the three is obvious due to the effect of using them separately or in pairs.

[0026] In a second aspect, the present invention provides an antimony-free composite flame retardant masterbatch, comprising the following components in weight percentage: 20-95% of the above-mentioned antimony-free composite flame retardant, 0-16% of a polymer base material, and 5-64% of a processing aid.

[0027] Optionally, the polymer base material is one or more of olefin polymers, ester polymers, vinyl polymers, styrene polymers, and polyurethane.

[0028] Optionally, the polymer base material is one or more of PVC, EVA, PP, PE, ABS, PC, and PET.

[0029] Using the above technical solution, flame retardant masterbatch is an innovative polymer material additive. By uniformly dispersing the flame retardant in a carrier resin at a high concentration, it is made into a concentrate through a special process. The product has various forms, including granules, cakes, etc., which are convenient for transportation and use. The polymer base material can be adjusted according to different needs. Taking the flame retardant polymer material of PVC artificial leather as an example, the polymer base material in the composite flame retardant masterbatch used can be PVC, and an appropriate amount of plasticizer needs to be added to the additive to improve the moldability of the masterbatch. In addition, the polymer base material can also be adjusted to materials such as EVA that have good compatibility with PVC. Processing aids mainly include dispersants, stabilizers, lubricants, etc., which are used to improve the dispersibility and processing performance of flame retardants. Compared with the traditional addition of flame retardants, the preparation of flame retardant masterbatch can improve the dispersion of flame retardants in resin, reduce the amount of flame retardant added, reduce processing difficulty and processing costs, and at the same time reduce the impact of the addition of flame retardants on the mechanical properties of the resin. After addition, it is less likely to cause delamination, patterns, precipitation and other adverse phenomena, improve the working environment, save manpower, material costs and time, etc.

[0030] In a third aspect, the present invention provides a method for preparing an antimony-free composite flame retardant masterbatch, comprising the following steps: weighing each component according to the formula of the above-mentioned antimony-free 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, pressing them into shape and cutting them to obtain a composite flame retardant masterbatch with a cake-like structure.

[0031] In a fourth aspect, the present invention provides a method for preparing an antimony-free composite flame retardant masterbatch, comprising the following steps: weighing each component according to the formula of the above-mentioned antimony-free 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.

[0032] 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 combines other processing aids into one, which is more conducive to the transportation and storage of the composite flame retardant and its subsequent application in flame-retardant polymer material products.

[0033] In summary, the present invention has the following beneficial effects:

[0034] 1. The antimony-free composite flame retardant of the present invention adopts an antimony-free composite formula of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate". Its flame retardant performance is better than that of antimony salt flame retardants. It can effectively solve the flame retardant problem in the current situation of scarce antimony resources and realize the antimony-free flame retardant products. At the same time, it has the characteristics of safety, low toxicity, low cost, wide raw material source, good dispersibility and compatibility, and has a broader application prospect.

[0035] 2. In the antimony-free composite flame retardant of the present invention, the inorganic phosphate is preferably compounded with aluminum hypophosphite and strontium hydrogen phosphate and / or strontium phosphate, which can not only further enhance the flame retardant effect, but also improve the mechanical properties of the material.

[0036] 3. The antimony-free composite flame retardant of the present invention is further preferably an antimony-free composite formula of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate + ammonium polyphosphate". The three can act synergistically to effectively improve the flame retardant effect.

[0037] 4. The antimony-free 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 granular form, 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

[0038] Figure 1It is a schematic diagram of the structure of the combustion performance sample of the present invention;

[0039] Figure 2 1 is a sample diagram of the sample group ① after combustion corresponding to Example 3 and Example 10 of the present invention, wherein the sample of Example 3 is located at the top and the sample of Example 10 is located at the bottom;

[0040] Figure 3 This is a sample diagram of the sample group ① after combustion according to Example 20 of the present invention;

[0041] Figure 4 This is a sample diagram after combustion of group ① of samples corresponding to Example 28 of the present invention.

[0042] In the figure, 1 is the first marking line; 2 is the second marking line. DETAILED DESCRIPTION

[0043] 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.

[0044] The antimony-free composite flame retardant and antimony-free 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.

[0045] The antimony-free composite flame retardant provided by the present invention specifically comprises the following components in weight percentage: 10-90% melamine polyphosphate and 10-90% inorganic phosphate, more preferably 25-75% melamine polyphosphate and 25-75% inorganic phosphate. The inorganic phosphate includes strontium hydrogen phosphate and / or strontium phosphate. The preparation method of the antimony-free composite flame retardant comprises the following steps: weighing the components as needed, adding the components to a blender, and stirring at a speed of 1000-3000 r / min until uniform.

[0046] In some embodiments of the present invention, the inorganic phosphate is preferably a mixture of strontium hydrogen phosphate and strontium phosphate, with the ratio of strontium hydrogen phosphate to strontium phosphate being 1:0.25-4. Because strontium phosphate has a higher decomposition temperature than strontium hydrogen phosphate, adding both strontium hydrogen phosphate and strontium phosphate simultaneously provides a better flame retardant effect in certain high-temperature combustion environments.

[0047] In some embodiments of the present invention, the inorganic phosphate, preferably strontium hydrogen phosphate and / or strontium phosphate, is compounded with aluminum hypophosphite, with the added weight being 0.2-1.5 times that of the strontium hydrogen phosphate and / or strontium phosphate. Aluminum hypophosphite contains aluminum metal, which, through the synergistic effect of "phosphorus-aluminum metal," further enhances the flame retardancy and improves the mechanical properties of the material.

[0048] In some embodiments of the present invention, a compound of melamine polyphosphate, an inorganic phosphate, and ammonium polyphosphate is used. A preferred combination of "10-80% melamine polyphosphate, 10-80% inorganic phosphate, and 10-80% ammonium polyphosphate" exhibits superior flame retardancy. Although ammonium polyphosphate has a high phosphorus content, it is susceptible to moisture absorption and decomposition. Therefore, the amount of ammonium polyphosphate used in the present invention should not be too high. A further preferred combination is "25-70% melamine polyphosphate, 20-70% inorganic phosphate, and 5-55% ammonium polyphosphate."

[0049] In some embodiments of the present invention, during the compounding of melamine polyphosphate, inorganic phosphate, and ammonium polyphosphate, the inorganic phosphate is further limited to a mixture of strontium hydrogen phosphate, strontium phosphate, and aluminum hypophosphite, wherein the aluminum hypophosphite can not only form a synergistic effect of "phosphorus-aluminum metal" with strontium hydrogen phosphate and strontium phosphate, but also effectively capture H· and OH· free radicals in the combustion chain reaction to interrupt the chain reaction, while promoting the ammonium polyphosphate to form a carbon layer faster, and the generated water vapor dilutes the concentration of the combustible gas, thereby forming a dual flame retardant mechanism of the gas phase and the condensed phase.

[0050] The antimony-free composite flame retardant masterbatch provided by the present invention comprises the following components in percentage by weight: 20-95% of the above-disclosed antimony-free composite flame retardant, 0-16% of a polymer base material, and 5-64% of a processing aid.

[0051] The polymer base material used in the antimony-free 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, and can preferably be one or more of olefin polymers, ester polymers, ethylene polymers, styrene polymers, and polyurethane (PU).

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The preparation method of the antimony-free 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.

[0056] 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.

[0057] 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.

[0058] In addition to the color cake structure and granular structure, the antimony-free composite flame retardant masterbatch can also be used in the form of mixed powder by directly mixing the components.

[0059] The raw materials involved in the examples and comparative examples of the present invention are all commercially available products.

[0060] Melamine polyphosphate (hereinafter referred to as MPP): purchased from Budenheim, Budit 3141, CAS No. 218768-84-4, molecular formula .

[0061] Strontium hydrogen phosphate: purchased from Wuhan Chengtian Fine Chemical Co., Ltd., CAS number 13450-99-2, molecular formula SrHPO4, molecular weight 183.599, purity ≥99%.

[0062] Strontium phosphate: purchased from Hubei Shuaiyan Ligao Biopharmaceutical Co., Ltd., CAS number 14414-90-5, molecular formula Sr3P2O8, purity ≥98%.

[0063] Aluminum hypophosphite: purchased from Hefei Wanran New Material Technology Co., Ltd., CAS number 7784-22-7, molecular formula Al(H2PO2)3, purity ≥97%.

[0064] 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 .

[0065] Antimony trioxide: purchased from Hefei Wanran New Material Technology Co., Ltd., CAS number 1309-64-4, molecular formula Sb2O3, molecular weight 291.518.

[0066] Polymer base materials: 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.

[0067] Processing aids: The plasticizer used was dioctyl phthalate (DOP), purchased from Shandong Shengfan Chemical Co., Ltd., CAS number 117-81-7. The dispersant used was lightweight nano-calcium carbonate, purchased from Shanghai Liangjiang Titanium Dioxide Chemical Products, LP-800, with an average particle size of 60-100 nm. The stabilizer used was a mixture of liquid calcium zinc stabilizer and powdered calcium zinc stabilizer in a mass ratio of 3:1. The liquid calcium zinc stabilizer was purchased from Zhejiang Jiaao Environmental Protection Technology Co., Ltd., JCZ-100; the powdered calcium zinc stabilizer was purchased from Zhejiang Jiaao Environmental Protection Technology Co., Ltd., JCZ-6503B. The lubricant used was polyethylene wax, purchased from Hebei Tianyu Chemical Co., Ltd., Model 110.

[0068] 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 1-4 , Examples and Comparative Examples further illustrate the present invention in detail.

[0069] Example 1

[0070] This embodiment provides an antimony-free composite flame retardant. The preparation method thereof comprises the following steps: weighing 90 g of MPP and 10 g of strontium hydrogen phosphate, adding the materials into a blender, and stirring at a speed of 2000 r / min for 20 minutes until the mixture is uniformly mixed.

[0071] Examples 2-6

[0072] Examples 2-6 are based on the method of Example 1, with adjustments made to the amounts of MPP and strontium hydrogen phosphate. Specific adjustments are shown in Table 1 below.

[0073] Examples 7-13

[0074] Examples 7-13 are based on the method of Example 1, except that strontium hydrogen phosphate is replaced with strontium phosphate or a mixture of strontium hydrogen phosphate and strontium phosphate, and the amount of the inorganic phosphate components is adjusted. For specific adjustments, see Table 1 below.

[0075] Table 1 Components of the antimony-free composite flame retardant of Examples 1-13 (unit: g)

[0076]

[0077] Examples 14-20

[0078] Examples 14-20 are based on the method of Example 1, except that the inorganic phosphate further includes aluminum hypophosphite, and the amounts of the components of the inorganic phosphate are adjusted. For specific adjustments, see Table 2 below.

[0079] Table 2 Components of the antimony-free composite flame retardant of Examples 14-20 (unit: g)

[0080]

[0081] Examples 21-28

[0082] Examples 21-28 are based on the method of Example 1, and the antimony-free composite flame retardant further includes ammonium polyphosphate. When ammonium polyphosphate is included, the amount of each component is adjusted. For specific adjustments, see Table 3 below.

[0083] Table 3 Components of the antimony-free composite flame retardant of Examples 21-28 (unit: g)

[0084]

[0085] Comparative Example 1

[0086] The flame retardant provided in this comparative example is a single-component MPP.

[0087] Comparative Example 2

[0088] The flame retardant provided in this comparative example is a single component of strontium hydrogen phosphate.

[0089] Comparative Example 3

[0090] The flame retardant provided in this comparative example is an antimony-free composite flame retardant prepared by mixing 70 g of MPP and 30 g of APP, and its preparation method is the same as that of Example 1.

[0091] Comparative Example 4

[0092] The flame retardant provided in this comparative example is an antimony-free composite flame retardant prepared by mixing 70 g of MPP and 30 g of aluminum hypophosphite. The preparation method thereof is the same as that in Example 1.

[0093] Performance testing

[0094] The flame retardants of Examples 1-28 and Comparative Examples 1-4 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.

[0095] ① Group 1: 5 g of the flame retardant masterbatch of each embodiment and comparative example and 100 g of PVC masterbatch were calendered on a two-roller machine to obtain samples with dimensions 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.

[0096] ② Group 2 samples: 3 g of the flame retardant masterbatch of each embodiment and comparative example and 100 g of PVC masterbatch were calendered on a two-roller machine to obtain samples with dimensions 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.

[0097] The flame retardant performance test of the above-mentioned samples was conducted with specific reference 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 ignited in a combustion box with a flame height of 38mm. The free end of the sample was exposed to the flame and ignited for 15 seconds, and then the flame was extinguished.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] The test results are shown in Table 4 below.

[0102] Table 4 Performance test of Examples 1-28 and Comparative Examples 1-4

[0103]

[0104] Referring to Table 4 above, Examples 2-6 are all compounded with MPP and strontium hydrogen phosphate; Example 7 is based on the component dosage of Example 3, strontium hydrogen phosphate is replaced with strontium phosphate; Examples 8-13 are based on the component dosage of Example 3, strontium hydrogen phosphate is replaced with a mixture of strontium hydrogen phosphate and strontium phosphate. Compared with single-component MPP (Comparative Example 1), single-component strontium hydrogen phosphate (Comparative Example 2), MPP+APP (Comparative Example 3), and MPP+aluminum hypophosphite (Comparative Example 4), the composite flame retardant of "MPP+strontium hydrogen phosphate and / or strontium phosphate" of the present invention can approach the flame retardant effect of traditional antimony trioxide, and is better than the flame retardant effect of other antimony-free flame retardants. It can be seen that the components in the composite flame retardant of the present invention are uniformly dispersed and compatible with PVC, effectively exerting an excellent flame retardant effect, realizing antimony-free flame retardancy, solving the flame retardant problem of the current shortage of antimony resources, and having the characteristics of excellent flame retardant performance, safety and low toxicity. MPP, strontium hydrogen phosphate, and strontium phosphate are widely available on the market and are lower in cost than antimony-containing flame retardants. They are suitable not only for industrial products such as automotive interiors, but also for consumer products such as food and household goods, thus broadening their application range. The flame retardant properties of Examples 2, 3, 4, and 5 are superior to those of Examples 1 and 6. Therefore, the present invention further prefers an antimony-free composite flame retardant comprising 25-75% melamine polyphosphate and 25-75% inorganic phosphate, with a weight ratio of strontium hydrogen phosphate to strontium phosphate of 1:0.25-4.

[0105] In the antimony-free composite flame retardants of Examples 14-20, the inorganic phosphate also includes aluminum hypophosphite. By comparing the test results of Examples 14-20 and Comparative Example 5, it can be seen that the present invention adds a set amount of aluminum hypophosphite on the basis of "MPP+strontium hydrogen phosphate and / or strontium phosphate". Compared with the single-component MPP and "MPP+aluminum hypophosphite", it has better flame retardant properties. The added weight of aluminum hypophosphite is further preferably 0.2-1.5 times that of strontium hydrogen phosphate and / or strontium phosphate.

[0106] A set amount of APP is also added to the antimony-free composite flame retardants of Examples 21-28. By comparing the test results of Examples 14-20 and Comparative Example 4, it can be seen that the flame retardant properties of the antimony-free composite flame retardant of "MPP+strontium hydrogen phosphate and / or strontium phosphate+APP" of the present invention can be effectively improved. On this basis, by adding a set amount of aluminum hypophosphite, the flame retardant properties of the antimony-free composite flame retardant can be further improved, so it is further preferred.

[0107] Examples 29-35

[0108] The above embodiments are all used to provide an antimony-free composite flame retardant masterbatch, which includes the following components in weight percentage: 20-95% antimony-free composite flame retardant, 0-16% polymer base material, and 5-64% processing aid.

[0109] Among them, Examples 29, 30, 31, 33, 34 and 35 were all prepared in the form of a PVC color cake structure. The specific preparation method included the following steps: weighing a set amount of composite flame retardant, PVC and processing aid for premixing, putting the harvested premix into 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 and mixing it with other components through mechanical shear heating, and rolling it into thin sheets through a double-roller sheet press, 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 an antimony-free PVC flame retardant color cake.

[0110] Example 32 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.

[0111] In addition, the antimony-free composite flame retardant obtained in Example 3 is used in Examples 29-32, and the amount of each component of the composite flame retardant masterbatch is adjusted. Examples 33, 34, and 35 correspond to the composite flame retardants obtained in Examples 10, 20, and 28, respectively. The specific formula table of the components of the above-mentioned composite flame retardant masterbatch is shown in Table 5 below.

[0112] Table 5 Component composition of the composite flame retardant masterbatch of Examples 29-35 (unit: %)

[0113]

[0114] Example 36

[0115] 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 antimony-free composite flame retardant obtained in Example 3, 15% of EVA, 11% of light nano-calcium carbonate, and 2% of polyethylene wax, and adding them to a twin-screw extruder. The barrel temperature gradient of the twin-screw extruder is controlled as follows: 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 an antimony-free EVA flame retardant masterbatch.

[0116] The flame retardancy of the antimony-free composite flame retardant masterbatches of Examples 29-36 was tested. Similarly, using the addition of the flame retardant to 100 grams of the PVC production mix for automotive PVC artificial leather interior materials as an example, two groups of samples were set up. Group 1 contained 6.94 grams of each example (ensuring that approximately 5 grams of the antimony-free composite flame retardant was added to Examples 29, 33-35), while Group 2 contained 4.17 grams of each example (ensuring approximately 3 grams of the antimony-free composite flame retardant was added to Examples 29, 33-35). The testing method was the same as above. The test results are shown in Table 6 below.

[0117] Table 6 Performance test results of Examples 29-36

[0118]

[0119] Referring to Table 6 above, Examples 29-36 all have excellent flame retardant effects. By comparing the results of Example 29 with Example 3, Example 33 with Example 10, Example 34 with Example 20, and Example 35 with Example 28, it can be seen that the antimony-free composite flame retardant of the present invention is sufficient to play an effective role in the form of direct addition, and the flame retardant properties of the composite flame retardant can be effectively exerted in the form of a masterbatch, and under the conditions of high plasticizer addition and application of a polyester base cloth, an obvious flame retardant effect is exhibited. 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.

[0120] In addition, combining the results of Example 29 and Example 36, 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.

[0121] 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. An antimony-free composite flame retardant, characterized in that: The invention comprises the following components in weight percentage: 10-90% of melamine polyphosphate and 10-90% of inorganic phosphate, wherein the inorganic phosphate comprises strontium hydrogen phosphate and / or strontium phosphate.

2. The antimony-free composite flame retardant according to claim 1, characterized in that: The inorganic phosphate includes strontium hydrogen phosphate and strontium phosphate, and the weight ratio of the strontium hydrogen phosphate to the strontium phosphate is 1:0.25-4.

3. The antimony-free composite flame retardant according to claim 1, characterized in that: The inorganic phosphate further comprises aluminum hypophosphite, and the added weight of the aluminum hypophosphite is 0.2-1.5 times that of strontium hydrogen phosphate and / or strontium phosphate.

4. The antimony-free composite flame retardant according to claim 1, characterized in that: The invention comprises the following components in weight percentage: 25-75% of melamine polyphosphate and 25-75% of inorganic phosphate.

5. The antimony-free composite flame retardant according to claim 1, characterized in that: The invention comprises the following components in weight percentage: 10-80% of melamine polyphosphate, 10-80% of inorganic phosphate and 10-80% of ammonium polyphosphate.

6. The antimony-free composite flame retardant according to claim 5, characterized in that: The invention comprises the following components in weight percentage: 25-70% of melamine polyphosphate, 20-70% of inorganic phosphate and 5-55% of ammonium polyphosphate.

7. An antimony-free composite flame retardant masterbatch, characterized in that: The invention comprises the following components in weight percentage: 20-95% of the antimony-free 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 antimony-free 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 an antimony-free composite flame retardant masterbatch, characterized in that: The method comprises the following steps: weighing each component according to the formula of the antimony-free composite flame retardant masterbatch according to claim 7 and premixing the premixed material; putting the premixed material into an internal mixer and mixing it evenly; and then grinding and dispersing it, pressing it into shape and cutting it to obtain a composite flame retardant masterbatch with a cake-like structure.

10. A method for preparing an antimony-free composite flame retardant masterbatch, characterized in that: The method comprises the following steps: weighing the components according to the formula of the antimony-free 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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