Antimony-free composite flame retardant, antimony-free flame retardant masterbatch and manufacturing method thereof

Abstract

To provide an antimony-free composite flame retardant, an antimony-free flame retardant masterbatch, and a manufacturing method thereof, which can solve the flame retardancy problem at present when antimony resources are scarce, realize antimony-free flame retardant products, and have advantages such as high flame retardancy, safety, low toxicity, low cost, and a wide range of raw material origins. The antimony-free composite flame retardant of the present invention contains, by weight percentage, 10% to 90% of melamine polyphosphate and 10% to 90% of an inorganic phosphate containing strontium hydrogen phosphate and / or strontium phosphate.

Description

[Technical Field]

[0001] The present invention relates to the technical field of flame retardants, and more particularly to an antimony-free composite flame retardant, an antimony-free flame-retardant masterbatch and a method for preparing the same. [Background technology]

[0002] Many organic polymeric materials, such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA), are flammable to varying degrees in air, which limits their application in many industries, including military, space, transportation, power, and civilian use. Conventional flame retardant methods mainly involve adding flame retardants to improve the fire resistance of materials.

[0003] Antimony-containing flame retardants are a common and relatively efficient flame retardant, lowering the combustion temperature through an internal endothermic reaction and vaporizing after combustion to form a protective film that blocks the air, diluting the oxygen concentration in the air and creating a "suffocation" effect, thereby fulfilling their flame retardant function. However, in recent years, the consumption rate of antimony ore reserves has far exceeded the rate of increase in extractable reserves, which goes against sustainable development strategies, and the current situation of antimony ore resources is not optimistic.

[0004] Inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide usually require a high loading to achieve ideal flame retardancy, but a high loading affects the mechanical properties of the material, making it difficult to widely apply them.

[0005] Nitrogen-based flame retardants and phosphorus / phosphonate-based flame retardants meet the environmentally friendly requirements of current material development, and by combining these two types of flame retardants with carbon-forming agents, an intumescent flame retardant system can be applied to flame-retardant PVC. Compared with antimony-containing compounding ingredients and other low-antimony and antimony-free compounding ingredients, this compounding ingredient does not contain substances such as heavy metals and halogens, and has the advantages of being safe and effective, having a wide range of applications, low toxicity, good thermal stability, and little smoke. However, due to its own chemical structure, phosphorus / phosphonate-based flame retardants are prone to moisture absorption in humid environments, which makes it difficult for them to effectively exert their flame retardant effect.

[0006] Therefore, in order to reduce the excessive mining of antimony resources, it is necessary to develop an antimony-free composite flame retardant that can meet the flame retardancy requirements of various polymer materials, which has very important practical significance. Summary of the Invention

[0007] In order to solve at least one of the above problems, the present invention provides an antimony-free composite flame retardant, an antimony-free flame-retardant masterbatch, and a manufacturing method thereof. The antimony-free composite flame retardant can solve the flame retardancy problem in the current situation where antimony resources are scarce, and can realize antimony-free flame-retardant products. It has advantages such as high flame retardancy, safety, low toxicity, low cost, and a wide range of raw material sources.

[0008] In a first aspect, the antimony-free composite flame retardant according to the present invention comprises, by weight percentage, 10% to 90% of melamine polyphosphate and 10% to 90% of an inorganic phosphate including strontium hydrogen phosphate and / or strontium phosphate.

[0009] Preferably, the inorganic phosphate salt contains 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] Preferably, the inorganic phosphate further contains aluminum hypophosphite in an amount of 0.2 to 1.5 times the weight of strontium hydrogen phosphate and / or strontium phosphate.

[0011] Preferably, the antimony-free composite flame retardant comprises, by weight percentage, 25% to 75% of melamine polyphosphate and 25% to 75% of inorganic phosphate.

[0012] Preferably, the antimony-free composite flame retardant comprises, by weight percentage, 10% to 80% of melamine polyphosphate, 10% to 80% of inorganic phosphate, and 10% to 80% of ammonium polyphosphate.

[0013] Preferably, the antimony-free composite flame retardant comprises, by weight percentage, 25% to 70% of melamine polyphosphate, 20% to 70% of inorganic phosphate, and 5% to 55% of ammonium polyphosphate.

[0014] Generally, strontium hydrogen phosphate and strontium phosphate are applicable as analytical reagents in the fields of fluorescent materials, bone cement, lasers, etc. In the present invention, the inventors have found that strontium hydrogen phosphate and strontium phosphate can be used as flame retardants, and the flame retardant mechanism is mainly as follows:

[0015] 1. Phosphorus-strontium synergistic flame retardant effect Regarding the charcoal formation and smoke suppression effects of phosphorus, when strontium hydrogen phosphate and strontium phosphate are decomposed by heat, they release phosphorus-containing active materials such as phosphoric acid and metaphosphoric acid, forming a viscous molten glass-like carbon layer on the surface of the material, blocking the transfer of oxygen and heat and suppressing the release of flammable gases. Regarding the thermal stabilizing effect of strontium, the strontium ion (Sr 2+ ) bonds with groups such as hydroxyl groups and carboxyl groups in the carbon layer, strengthening the high-temperature resistance and density of the carbon layer and preventing the carbon layer from cracking or decomposing at high temperatures, thereby improving the durability of flame retardancy.

[0016] In addition, research has shown that compared to a single phosphorus-based flame retardant (e.g., ammonium phosphate), strontium hydrogen phosphate can improve the retention rate of the carbon layer formed on the polymer by 15% to 20%, and the limiting oxygen index (LOI) can be improved by 5 to 8 units. 2. Dual flame retardancy with heat absorption and gas release properties. Strontium hydrogen phosphate begins to decompose at approximately 200°C, gradually releasing water of crystallization and breaking down into Sr3(PO4)2 and P2O5. The entire process absorbs approximately 1200kJ / kg of heat, effectively reducing the surface temperature of materials. Although strontium phosphate has a relatively high decomposition temperature, the decomposition process also absorbs a large amount of heat. The phosphoric acid and polymetaphosphoric acid released after the decomposition of these two compounds act as strong dehydrating agents, promoting the dehydration and carbonization of the surfaces of oxygen-containing polymers (e.g., epoxy resins and cellulose). The released water vapor and small amounts of non-flammable gases, such as PO3, dilute the oxygen concentration in the air and inhibit combustion chain reactions.

[0017] Unlike halogen-based flame retardants (e.g., decabromodiphenyl ether), strontium hydrogen phosphate and strontium phosphate do not contain halogen elements such as chlorine or bromine, and do not emit highly toxic substances such as dioxins during combustion. They comply with environmental protection standards such as the European Union's RoHS and REACH, making them suitable for applications with high safety requirements, such as electronic equipment and food packaging. Their combustion smoke density (e.g., NBS cigarette pack test) is 30% to 50% lower than that of halogen-based flame retardants, eliminating the risk of asphyxiation from smoke and making them particularly suitable for crowded locations such as buildings and vehicles. Unlike the contact toxicity of antimony salt flame retardants (e.g., antimony trioxide), strontium hydrogen phosphate and strontium phosphate have been shown in acute toxicity tests to have LD 50 (Rat oral) >2000mg / kg, which indicates that it is a low-toxicity substance and poses little harm to workers and users.

[0018] Furthermore, strontium hydrogen phosphate and strontium phosphate can be uniformly dispersed in polymer matrices (e.g., polyvinyl chloride, polyethylene, polypropylene, epoxy resin, etc.) by mechanical mixing or melt extrusion, and are unlikely to aggregate or undergo phase separation. They have good dispersibility and compatibility, with only a 5-10% effect on the mechanical properties of the material (e.g., tensile strength, impact toughness) (much lower than the 20-30% effect of some inorganic flame retardants, e.g., aluminum hydroxide).

[0019] The present invention uses an antimony-free composite compounding component of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate," 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- or nitrogen-containing flame retardants, but the flame retardant effect obtained by combining the two is significantly improved. This is thought to be because strontium hydrogen phosphate and / or strontium phosphate are decomposed by heat to produce a certain amount of pyrophosphate, which, together with the nitrogen in the melamine polyphosphate, forms a nitrogen-phosphorus foam insulation layer, inhibiting oxygen and achieving a gas-phase coating 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, thereby consuming a large amount of heat through the vaporization of water and accelerating the consumption of the combustible material through the carbonization reaction, forming a foamed paste with a coked carbon structure that is difficult to burn, thereby realizing a solid-phase coating effect. In both the gas-phase and solid-phase methods, a foamed carbon layer is formed through the synergistic action of "phosphorus-nitrogen-carbon", so that the antimony-free composite flame retardant of the present invention has excellent flame retardant effect.

[0020] Based on this, the inorganic phosphate of the present invention is more preferably a technical means of combining aluminum hypophosphite, which belongs to inorganic phosphates and has the properties of a phosphate and can synergistically impart flame retardancy by combining strontium hydrogen phosphate and strontium phosphate, with strontium hydrogen phosphate and / or strontium phosphate. Furthermore, the aluminum hypophosphite further contains aluminum metal element, which strengthens the synergistic effect of aluminum hypophosphite and strontium hydrogen phosphate and / or strontium phosphate through "phosphorus-aluminum metal," further enhancing the flame retardant effect and improving the mechanical properties of the material.

[0021] As can be seen from research, the present invention further prefers an antimony-free composite compound 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 when combined with strontium hydrogen phosphate and / or strontium phosphate, it produces more metaphosphoric acid and polymetaphosphoric acid, which can promote the dehydration and carbonization of the combustion material and form a carbonized layer, and the effect of the combined use of these three is significantly superior to the effect of using them alone or in combination.

[0022] In a second embodiment, the antimony-free composite flame-retardant masterbatch according to the present invention comprises, by weight percentage, 20% to 95% of the antimony-free composite flame retardant, 0% to 16% of a polymer base material, and 5% to 64% of a processing aid.

[0023] Preferably, the polymer substrate is one or more of an olefin-based polymer, an ester-based polymer, an ethylene-based polymer, a styrene-based polymer, and a polyurethane.

[0024] Preferably, the polymer substrate is one or more of PVC, EVA, PP, PE, ABS, PC, PET.

[0025] According to the above technical means, flame-retardant masterbatches are a novel polymeric material additive. A concentrate is produced by uniformly dispersing a high concentration of flame retardant into a carrier resin through a special process. The product forms vary, including granules and cakes, making them convenient for transportation and use. The polymer substrate can be tailored to meet different needs. Taking the flame-retardant polymer material used in PVC artificial leather as an example, the polymer substrate in the composite flame-retardant masterbatch can be PVC. An appropriate amount of plasticizer needs to be added to the additive to improve the masterbatch's moldability. Alternatively, the polymer substrate can be tailored to materials such as EVA, which are highly compatible with PVC. Processing aids, primarily including dispersants, stabilizers, and lubricants, are used to improve the dispersion and processing performance of the flame retardant. Compared with adding conventional flame retardants, preparing a flame retardant masterbatch improves the dispersibility of the flame retardant in the resin, reduces the amount of flame retardant added, reduces the difficulty and cost of processing, and reduces the impact of adding the flame retardant on the mechanical properties of the resin. After adding, defects such as layer splitting, patterns, and precipitation are less likely to occur, improving the working environment and saving manpower, material costs, time, etc.

[0026] In a third aspect, the method for producing the antimony-free composite flame-retardant masterbatch according to the present invention includes the steps of weighing and premixing each component according to the formulation of the antimony-free composite flame-retardant masterbatch, introducing the obtained premix into an internal mixer and mixing uniformly, grinding and dispersing the mixture, and then press-molding and cutting the mixture to obtain a cake-like structure of the composite flame-retardant masterbatch.

[0027] In a fourth aspect, the method for producing the antimony-free composite flame-retardant masterbatch according to the present invention includes the steps of weighing and premixing each component according to the formulation of the antimony-free composite flame-retardant masterbatch, and feeding the obtained premix into a screw extruder for extrusion granulation to obtain a composite flame-retardant masterbatch with a granular structure.

[0028] According to the above technical means, the flame retardant of the present invention can not only be directly applied in the form of mixed powder, but also be prepared in a cake-like structure or granular structure according to different needs. Compared to the mixed powder form, the composite flame retardant masterbatch of cake-like structure and granular structure can be blended with other processing aids, which is more convenient for the transportation and storage of the composite flame retardant and for subsequent application in flame-retardant polymer material products.

[0029] From the above, the present invention has the following beneficial effects.

[0030] 1. The antimony-free composite flame retardant of the present invention uses an antimony-free composite component of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate", and its flame retardant efficacy is superior to that of antimony salt flame retardants. It effectively solves the flame retardant problem at present when antimony resources are scarce and realizes antimony-free flame retardant products. It also has the characteristics of safety, low toxicity, low cost, wide range of raw material sources, good dispersibility and compatibility, etc., and has wider application prospects.

[0031] 2. In the antimony-free composite flame retardant of the present invention, the inorganic phosphate is preferably a combination of aluminum hypophosphite and strontium hydrogen phosphate and / or strontium phosphate, which not only further improves the flame retardant effect but also improves the mechanical properties of the material.

[0032] 3. The antimony-free composite flame retardant of the present invention is preferably an antimony-free composite compound of "melamine polyphosphate + strontium hydrogen phosphate and / or strontium phosphate + ammonium polyphosphate", as the three components act synergistically to effectively improve the flame retardant effect.

[0033] 4. The antimony-free composite flame retardant of the present invention can be directly added or prepared into a composite flame retardant masterbatch in a specific form such as cake or granules, so as to facilitate storage, transportation, and rapid dispersion in subsequent flame retardant polymer materials. The composite flame retardant in the composite flame retardant masterbatch can be uniformly dispersed by mechanical mixing or melt extrusion, which makes the preparation of the composite flame retardant masterbatch easier and has better application prospects. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic diagram of a combustion performance sample of the present invention. [Figure 2] 1 is a sample diagram of the (1) group of samples corresponding to Examples 3 and 10 of the present invention after combustion, with the Example 3 sample positioned at the top and the Example 10 sample positioned at the bottom. [Figure 3] FIG. 10 is a sample diagram of the (1) group of samples corresponding to Example 20 of the present invention after combustion. [Figure 4] FIG. 10 is a sample diagram of the (1) group of samples corresponding to Example 28 of the present invention after combustion. DETAILED DESCRIPTION OF THE INVENTION

[0035] In order to make the above-mentioned objects, features, and advantages of the present invention more clear, specific embodiments of the present invention will be described in detail below. In order to fully understand the present invention, many specific details will be described in the following description. However, the present invention can be implemented in many ways other than those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention, so the present invention is not limited to the specific examples disclosed below.

[0036] The antimony-free composite flame retardant and antimony-free composite flame retardant masterbatch of the present invention can be applied to many industries such as military, space, transportation, power and civilian, including but not limited to flame retardant modification of materials such as PVC, EVA, PE, ABS resin, PP, PET, etc.

[0037] The antimony-free composite flame retardant according to the present invention specifically contains, by weight percentage, 10% to 90% melamine polyphosphate and 10% to 90% inorganic phosphate, more preferably 25% to 75% melamine polyphosphate and 25% to 75% inorganic phosphate. The inorganic phosphate includes strontium hydrogen phosphate and / or strontium phosphate. A method for producing the antimony-free composite flame retardant includes the steps of weighing each component as needed, adding the components to a mixer, and stirring the mixture uniformly at a rotation speed of 1000 r / min to 3000 r / min.

[0038] In some embodiments of the present invention, the inorganic phosphate is preferably a mixture of strontium hydrogen phosphate and strontium phosphate, and the ratio of strontium hydrogen phosphate to strontium phosphate is 1:0.25 to 4. Since the decomposition temperature of strontium phosphate is higher than that of strontium hydrogen phosphate, in a certain high-temperature combustion environment, adding strontium hydrogen phosphate and strontium phosphate simultaneously has a higher flame retardant effect.

[0039] In some embodiments of the present invention, the inorganic phosphate is preferably obtained by blending strontium hydrogen phosphate and / or strontium phosphate with aluminum hypophosphite, and the added weight is 0.2 to 1.5 times that of the strontium hydrogen phosphate and / or strontium phosphate. The aluminum hypophosphite contains aluminum metal, which can further enhance the flame retardant effect and improve the mechanical properties of the material due to the synergistic effect of "phosphorus-aluminum metal."

[0040] In some embodiments of the present invention, a technical means of blending melamine polyphosphate, inorganic phosphate, and ammonium polyphosphate in a ratio of 10% to 80% melamine polyphosphate, 10% to 80% inorganic phosphate, and 10% to 80% ammonium polyphosphate is preferred, as it has a superior flame retardant effect. Ammonium polyphosphate has a high phosphorus content but is prone to moisture absorption and decomposition, so the amount of ammonium polyphosphate used in the present invention should not be too high, and a more preferred ratio is "25% to 70% melamine polyphosphate, 20% to 70% inorganic phosphate, and 5% to 55% ammonium polyphosphate."

[0041] In some embodiments of the present invention, in the compounding process of melamine polyphosphate, inorganic phosphate, and ammonium polyphosphate, the inorganic phosphate is further limited to a mixture of strontium hydrogen phosphate and strontium phosphate with aluminum hypophosphite. The aluminum hypophosphite, together with the strontium hydrogen phosphate and strontium phosphate, not only forms a "phosphorus-aluminum metal" synergistic effect, but also effectively captures H and OH free radicals in the combustion chain reaction to interrupt the chain reaction, and promotes the rapid formation of a carbon layer by ammonium polyphosphate. The generated water vapor dilutes the concentration of combustible gases, thereby forming a dual flame retardant mechanism of gas phase and condensed phase.

[0042] The antimony-free composite flame-retardant masterbatch of the present invention comprises, by weight percentage, 20% to 95% of the antimony-free composite flame retardant disclosed above, 0% to 16% of a polymer base material, and 5% to 64% of a processing aid.

[0043] The polymer substrate used in the antimony-free composite flame-retardant masterbatch must have good compatibility with the flame-retardant polymer material product to which it is applied. Specifically, the polymer substrate can be selected according to the properties of the flame-retardant polymer material product, and preferably may be one or more of olefin-based polymers, ester-based polymers, ethylene-based polymers, styrene-based polymers, and polyurethane (PU).

[0044] In some embodiments of the present invention, olefin-based polymers include polyethylene (PE), polypropylene (PP), etc.; ester-based polymers include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), etc.; ethylene-based polymers include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), etc.; and styrene-based polymers include polystyrene (PS), styrene-acrylonitrile resin (SAN), styrene-butadiene-acrylonitrile resin (ABS), etc.

[0045] The auxiliary agents used in the composite flame-retardant masterbatch of the present invention can be increased or decreased depending on the properties of the polymer substrate, and include one or more of plasticizers, dispersants, stabilizers, and lubricants.

[0046] Depending on the properties of the polymer substrate, the plasticizer may be one or more selected from pyromellitic ester-based plasticizers, trimellitic ester-based plasticizers, phthalic ester-based plasticizers, terephthalic ester-based plasticizers, isophthalic ester-based plasticizers, phosphate ester-based plasticizers, and epoxidized vegetable oils. 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-based lubricants, hydrocarbon-based lubricants, fatty acid-based lubricants, and fatty acid ester-based lubricants. In some embodiments of the present invention, the auxiliary further includes a series of substances that can improve or impart specific performance to the polymer, such as colorants and antistatic agents.

[0047] The antimony-free composite flame-retardant masterbatch of the present invention can be manufactured in a manner that meets the needs of downstream companies, and preferably has one of a color cake structure and a granular structure.

[0048] The first method for preparing a flame-retardant masterbatch with a color cake structure involves weighing and premixing the components according to the composition of the composite flame-retardant masterbatch, then introducing the resulting premix into an internal mixer, mixing uniformly, grinding, dispersing, and then pressing and cutting to obtain a cake-shaped composite flame-retardant masterbatch. The processing parameters for these steps need to be adjusted according to the characteristics of different polymer substrates. For example, in the case of PVC color cake, the premix is ​​introduced into an internal mixer (or kneader) to melt the PVC resin through mechanical shear heating, while the other components are further dispersed in the molten resin under shear force to achieve uniform bonding between the components and the carrier. The premix is ​​then rolled into a sheet using a double-roll press, the roll temperature is controlled between 100°C and 140°C (to maintain a certain fluidity but not adhere to the rolls), and the roll distance is adjusted to control the thickness. Finally, the sheet is pressed into a cake of a specific size using a mold.

[0049] The second method for preparing a flame-retardant masterbatch includes weighing and premixing the components of the flame-retardant masterbatch, and then extruding and granulating the resulting premix in a screw extruder to obtain a flame-retardant masterbatch. Similarly, the processing parameters in the above steps need to be adjusted according to the characteristics of different polymer substrates. For example, the processing temperature for EVA granulation is 120°C to 190°C.

[0050] 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 a mixed powder by directly mixing the components together.

[0051] The raw materials used in the examples and comparative examples of the present invention are all commercially available products.

[0052] Melamine polyphosphate (hereinafter abbreviated as MPP) was purchased from Budenheim, with the model number Budit 3141, CAS number 218768-84-4, and molecular formula C3H6N6·(H3PO4) nis.

[0053] Strontium hydrogen phosphate was purchased from Wuhan Chengtian Fine Chemical Co., Ltd., with a CAS number of 13450-99-2, molecular formula of SrHPO4, molecular weight of 183.599, and purity of ≥99%.

[0054] Strontium phosphate was purchased from Hubei Shuaiyan Ligao Biomedicine Co., Ltd., with a CAS number of 14414-90-5, molecular formula of Sr3P2O8, and purity of ≥98%.

[0055] Aluminum hypophosphite was purchased from Hefei Wanran New Materials Technology Co., Ltd., with a CAS number of 7784-22-7, a molecular formula of Al(H2PO2)3, and a purity of ≥97%.

[0056] Ammonium polyphosphate (hereinafter referred to as APP) was purchased from Shandong Taixing New Materials Co., Ltd., with model number HT-208, CAS number 68333-79-9, and molecular formula (NH4) n +2P n O 3n+1 is.

[0057] Antimony trioxide was purchased from Hefei Wanran New Materials Technology Co., Ltd., with a CAS number of 1309-64-4, a molecular formula of Sb2O3, and a molecular weight of 291.518.

[0058] For the polymer substrate, PVC and EVA are taken as examples. PVC is purchased from Tianjin Bohua Chemical Development Co., Ltd. with model number DG-700, and EVA is purchased from Ningbo Shijin Plastics Co., Ltd. with model number US DuPont 210.

[0059] For processing aids, dioctyl phthalate (DOP) was selected as the plasticizer, purchased from Shandong Shengfan Chemical Co., Ltd., with a CAS number of 117-81-7. For dispersants, light nano-calcium carbonate was selected, purchased from Shanghai Liangjiang Titanium White Chemical Products Co., Ltd., with a model number of LP-800 and an average particle size of 60-100 nm. For stabilizers, a mixture of liquid calcium zinc stabilizer and powder calcium zinc stabilizer in a mass ratio of 3:1 was selected. The liquid calcium zinc stabilizer was purchased from Zhejiang Jiao Environmental Protection Technology Co., Ltd., with a model number of JCZ-100, and the powder calcium zinc stabilizer was purchased from Zhejiang Jiao Environmental Protection Technology Co., Ltd., with a model number of JCZ-6503B. For lubricants, polyethylene wax was selected, purchased from Hebei Tianyu Chemical Co., Ltd., with a model number of 110.

[0060] In practical manufacturing applications, many PVC artificial leathers require the lamination of a polyester-based backing fabric to improve tensile strength and comfort. While polyester backing fabric is an important component of PVC artificial leather, it is a highly flammable material. To demonstrate the flame retardancy of the material of the present invention and its effectiveness in actual manufacturing, the flame retardancy performance tests in the following examples and comparative examples were conducted by laminating samples containing an antimony-free composite flame retardant to a polyester backing fabric and then conducting a flame test. The polyester backing fabric was 0.5 mm thick, the PVC sample was 0.6 mm thick, and the total thickness was 1.1 mm. Furthermore, phthalate ester plasticizers, which are commonly used in PVC artificial leather, are also highly flammable. To enhance the test results, 40% DOP was added to the polymer substrate (PVC) used in the following examples and comparative examples. The present invention will now be described in more detail with reference to Figures 1-4 and the examples and comparative examples.

[0061] Example 1 This example provides an antimony-free composite flame retardant, calculated as 100g, and its preparation method includes the steps of weighing 90g of MPP and 10g of strontium hydrogen phosphate, putting them into a mixer, and stirring at a rotation speed of 2000 r / min for 20 minutes until they are uniformly mixed.

[0062] Examples 2 to 6 In Examples 2 to 6, the amounts of MPP and strontium hydrogen phosphate used were adjusted based on the method of Example 1, and the specific adjustment conditions are shown in Table 1 below.

[0063] (Examples 7 to 13) In Examples 7 to 13, based on the method of Example 1, strontium hydrogen phosphate was replaced with strontium phosphate or a mixture of strontium hydrogen phosphate and strontium phosphate, and the amount of the inorganic phosphate component used was adjusted. The specific adjustment conditions are shown in Table 1 below.

[0064] Table 1: Composition of antimony-free composite flame retardants of Examples 1 to 13 (unit: g) [Table 1]

[0065] (Examples 14 to 20) In Examples 14 to 20, the inorganic phosphate further contains aluminum hypophosphite according to the method of Example 1, and the amount of the inorganic phosphate component used is adjusted. The specific adjustment conditions are shown in Table 2 below.

[0066] Table 2: Composition of antimony-free composite flame retardants of Examples 14 to 20 (unit: g) [Table 2]

[0067] (Examples 21 to 28) In Examples 21 to 28, based on the method of Example 1, the antimony-free composite flame retardant further contains ammonium polyphosphate. When ammonium polyphosphate is contained, the amount of each component used is adjusted. The specific adjustment conditions are shown in Table 3 below.

[0068] Table 3: Ingredient composition of antimony-free composite flame retardants of Examples 21 to 28 (unit: g) [Table 3]

[0069] (Comparative Example 1) The flame retardant according to this comparative example is a single-component MPP.

[0070] (Comparative Example 2) The flame retardant according to this comparative example is a single component strontium hydrogen phosphate.

[0071] (Comparative Example 3) The flame retardant according to this comparative example is an antimony-free composite flame retardant formed by mixing 70 g of MPP and 30 g of APP, and its manufacturing method is the same as that of Example 1.

[0072] Comparative Example 4 The flame retardant according to this comparative example is an antimony-free composite flame retardant formed by mixing 70 g of MPP and 30 g of aluminum hypophosphite, and its manufacturing method is the same as that of Example 1.

[0073] Performance Detection Test Flame retardant performance tests were carried out on the flame retardants of Examples 1 to 28 and Comparative Examples 1 to 4. The present invention is exemplified by application to PVC artificial leather interior materials for automobiles, and the following samples of Group (1) and Group (2) were set.

[0074] For the samples in group (1), 5 g of the flame-retardant masterbatch of each example and comparative example and 100 g of the PVC masterbatch were rolled and molded using two rolls to obtain samples with dimensions of 356 mm × 100 mm × 1.1 mm, with the polyester base fabric having a thickness of 0.5 mm and the PVC sample having a thickness of 0.6 mm.

[0075] For the samples in group (2), 3 g of the flame-retardant masterbatch of each example and comparative example and 100 g of the PVC masterbatch were rolled and molded using two rolls to obtain samples with dimensions of 356 mm × 100 mm × 1.1 mm, with the polyester base fabric having a thickness of 0.5 mm and the PVC sample having a thickness of 0.6 mm.

[0076] The above samples were subjected to a flame retardancy test, specifically, with reference to GB8410-2006, Combustion Characteristics of Automotive Interior Materials. The samples were clamped at both sides and one end with a U-shaped bracket, and a gas lamp was lit in a combustion chamber with a flame height of 38 mm. The free end of the sample was placed in the flame and ignited for 15 seconds, after which the flame was extinguished.

[0077] The flame burns forward from the free end of the sample, and as shown in Figure 1, the first marked line 1 is located 38 mm in the linear direction from the free end of the sample along the burning direction, and the second marked line 2 is located 254 mm in the linear direction from the first marked line of the sample along the burning direction.

[0078] Start timing from the moment the base of the propagating flame passes the first marked line 1, and pay attention to observing the flame propagation on the side with the fastest burning speed, and use the side with the fastest flame propagation as the reference point for timing. When the flame reaches the second marked line 2 or is extinguished before it reaches the second marked line 2, stop timing at that time, and use the side with the fastest flame propagation as the reference point for timing.

[0079] If the sample is exposed to the flame for 15 seconds and the ignition source sample has not yet burned, or if the sample can burn but extinguishes before the flame reaches the first reference line 1, it is considered to meet the combustion rate requirement. Mark both combustion levels as A. Starting from the test timing, if the flame self-extinguishes within 60 seconds and the combustion distance ≤ 88 mm (calculated from the free end), it is also considered to meet the combustion rate requirement. Mark the combustion level as B. Starting from the combustion time timing, if the flame extinguishes between the first reference line 1 and the second reference line 2, it is a self-extinguishing sample, and the combustion situation is different from the result showing the requirement of item 2. That is, the combustion distance is 88 mm < x ≤ 292 mm (calculated from the free end). Mark the combustion level as C. Starting from the combustion time timing, if the flame reaches the second reference line 2 (combustion distance > 292 mm (calculated from the free end)), or if the sample burns slowly for a long time (the test ends when timing up to 20 minutes), mark the combustion level as D. The above combustion distance refers to the length of the part where the surface or interior of the sample is burned out.

[0080] The detection results are shown in Table 4 below.

[0081] Table 4 Performance Detection of Examples 1 - 28 and Comparative Examples 1 - 4

Table 4

[0082] As shown in Table 4 above, Examples 2 to 6 all contain a blend of MPP and strontium hydrogen phosphate, Example 7 is based on the component amounts used in Example 3, but strontium hydrogen phosphate is replaced with strontium phosphate, and Examples 8 to 13 are based on the component amounts used in Example 3, but strontium hydrogen phosphate is replaced with a mixture of strontium hydrogen phosphate and strontium phosphate, and the following are the blends: single-component MPP (Comparative Example 1), single-component strontium hydrogen phosphate (Comparative Example 2), MPP + APP (Comparative Example 3), MPP + Compared with aluminum hypophosphite (Comparative Example 4), the composite flame retardant of "MPP + strontium hydrogen phosphate and / or strontium phosphate" of the present invention has a flame retardant effect similar to that of conventional antimony trioxide and superior to that of other antimony-free flame retardants. This indicates that the components of the composite flame retardant of the present invention are uniformly dispersed and compatible with PVC, effectively exerting excellent flame retardancy. This enables the flame retardant to be antimony-free, solving the current flame retardancy problem of scarce antimony resources, and offering excellent flame retardancy, safety, and low toxicity. MPP, strontium hydrogen phosphate, and strontium phosphate are widely available on the market and are less expensive than antimony-containing flame retardants. Their specific application range is broader, ranging from industrial applications such as automotive interiors to household products such as food. Since the flame retardant performance of Examples 2, 3, 4, and 5 is superior to that of Examples 1 and 6, the present invention further preferably provides an antimony-free composite flame retardant that contains 25% to 75% of melamine polyphosphate and 25% to 75% of inorganic phosphate, with a weight ratio of strontium hydrogen phosphate to strontium phosphate of 1:0.25 to 4.

[0083] In the antimony-free composite flame retardants of Examples 14 to 20, the inorganic phosphate further contains aluminum hypophosphite. Comparing the detection results of Examples 14 to 20 and Comparative Example 5, it is found that the present invention further adds a set amount of aluminum hypophosphite based on "MPP + strontium hydrogen phosphate and / or strontium phosphate", and has better flame retardant performance than single-component MPP and "MPP + aluminum hypophosphite". The added weight of aluminum hypophosphite is more preferably 0.2 to 1.5 times that of strontium hydrogen phosphate and / or strontium phosphate.

[0084] In the antimony-free composite flame retardants of Examples 21 to 28, a set amount of APP was further added. Comparing the detection results of Examples 14 to 20 and Comparative Example 4, it was found that the flame retardant performance of the antimony-free composite flame retardant of the present invention, "MPP + strontium hydrogen phosphate and / or strontium phosphate + APP", can be effectively improved. On this basis, adding a set amount of aluminum hypophosphite can further improve the flame retardant performance of the antimony-free composite flame retardant, making this solution more preferable.

[0085] (Examples 29 to 35) The above examples are all intended to provide an antimony-free composite flame-retardant masterbatch, which contains, by weight percentage, 20% to 95% of an antimony-free composite flame retardant, 0% to 16% of a polymer base material, and 5% to 64% of a processing aid.

[0086] In Examples 29, 30, 31, 33, 34 and 35, all of them are prepared in the form of PVC color cake structure. The specific preparation method includes the steps of weighing and premixing a set amount of composite flame retardant, PVC and processing aid, putting the obtained premix into an internal mixer, controlling the temperature of the internal mixer to maintain it within the range of 130-150°C for 35 minutes, melting the PVC by mechanical shear heating and mixing it uniformly with other components, rolling it into a sheet using a double roll press, controlling the roll temperature to 100-140°C (maintaining a certain fluidity but not sticking to the roll), and cutting it with a cutter to obtain an antimony-free PVC flame-retardant color cake.

[0087] In Example 32, it is prepared in the form of mixed powder, and the specific preparation method includes the steps of weighing a set amount of composite flame retardant and processing aid, putting them into a mixer, and stirring them uniformly to obtain the mixture.

[0088] In addition, in Examples 29 to 32, the antimony-free composite flame retardant obtained in Example 3 was used, and the amount of each component used in the composite flame-retardant masterbatch was adjusted. In Examples 33, 34, and 35, the composite flame retardants obtained in Examples 10, 20, and 28 were used, respectively. For the composition of each component of the composite flame-retardant masterbatch, see Table 5 below.

[0089] Table 5: Composition of composite flame-retardant masterbatches of Examples 29 to 35 (units: %) [Table 5]

[0090] Example 36 This example provides a method for producing a composite flame-retardant masterbatch with an EVA masterbatch structure, which is produced in the form of a granular structure. The method specifically includes the steps of weighing 72% of the antimony-free composite flame retardant obtained in Example 3, 15% EVA, 11% light nano-calcium carbonate, and 2% polyethylene wax, adding them to a twin-screw extruder, controlling the cylinder temperature gradient of the twin-screw extruder so that the feed section is 120°C to 140°C, the compression section is 140°C to 160°C, and the extrusion section is 160°C to 180°C, and cooling the extruded material, followed by granulation and drying to obtain an antimony-free EVA flame-retardant masterbatch.

[0091] Flame retardant performance tests were conducted on the antimony-free composite flame retardant masterbatches of Examples 29 to 36. Similarly, using the application of flame retardant to 100 grams of PVC manufacturing mixture for PVC artificial leather interior materials for automobiles as an example, samples of Groups (1) and (2) were set up. 6.94 g of flame retardant was added to the sample of Group (1) (ensuring that approximately 5 g of antimony-free composite flame retardant was added in Examples 29, 33 to 35), and 4.17 g of flame retardant was added to the sample of Group (2) (ensuring that approximately 3 g of antimony-free composite flame retardant was added in Examples 29, 33 to 35). The test method was the same as above, and the test results are shown in Table 6 below.

[0092] Table 6 Performance detection results for Examples 29 to 36 [Table 6]

[0093] As shown in Table 6 above, Examples 29 to 36 all had excellent flame retardant effects. Comparing the results of Examples 29 and 3, Examples 33 and 10, Examples 34 and 20, and Examples 35 and 28, it can be seen that the antimony-free composite flame retardant of the present invention can fully and effectively exert its effect when added directly, and can effectively exert the flame retardant performance of the composite in the form of a masterbatch. Furthermore, under the application conditions of a high amount of plasticizer added and being attached to a polyester base fabric, all of them showed significant flame retardant effects. This shows that the composite flame retardant of the present invention can be used directly or, as needed, can be prepared in a color cake structure or granular structure for easy storage and transportation.

[0094] In addition, referring to the results of Examples 29 and 36, it can be seen that a better flame retardant effect can be achieved in the form of EVA masterbatch, based on the need to add a certain amount of plasticizer (dioctyl phthalate) during the processing of PVC color cake. EVA masterbatch can moderately reduce the flame retardant effect of the plasticizer on the composite flame retardant by reducing the addition of plasticizer.

[0095] The specific examples are merely illustrative of the present invention and do not limit the present invention. After reading this specification, a person skilled in the art may make modifications to the examples as necessary without making any creative contribution, but the modifications will be protected by patent law as long as they are within the scope of the claims of the present invention. [Explanation of symbols]

[0096] 1 1st marked line 2 Second marked line

Claims

1. The composition comprises, by weight percentage, 10% to 90% of melamine polyphosphate and 10% to 90% of an inorganic phosphate containing strontium hydrogen phosphate and / or strontium phosphate. An antimony-free composite flame retardant characterized by:

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

3. The inorganic phosphate further contains aluminum hypophosphite in an amount of 0.2 to 1.5 times the amount of strontium hydrogen phosphate and / or strontium phosphate by weight. The antimony-free composite flame retardant according to claim 1.

4. The composition comprises, by weight percentage, 25% to 75% of melamine polyphosphate and 25% to 75% of inorganic phosphate; The antimony-free composite flame retardant according to claim 1.

5. The composition comprises, by weight percentage, 10% to 80% of melamine polyphosphate, 10% to 80% of inorganic phosphate, and 10% to 80% of ammonium polyphosphate; The antimony-free composite flame retardant according to claim 1.

6. The composition comprises, by weight percentage, 25% to 70% of melamine polyphosphate, 20% to 70% of inorganic phosphate, and 5% to 55% of ammonium polyphosphate. The antimony-free composite flame retardant according to claim 5.

7. In weight percentage, the composition comprises 20% to 95% of the antimony-free composite flame retardant according to any one of claims 1 to 6, more than 0% and not more than 16% of a polymer base material, and 5% to 64% of a processing aid; An antimony-free composite flame-retardant masterbatch characterized by:

8. The polymer substrate is one or more of an olefin-based polymer, an ester-based polymer, an ethylene-based polymer, a styrene-based polymer, and a polyurethane. The antimony-free composite flame-retardant masterbatch according to claim 7.

9. The method includes the steps of weighing and premixing each component according to the compounding components of the antimony-free composite flame-retardant masterbatch of claim 7, introducing the resulting premix into an internal mixer, uniformly mixing, grinding and dispersing, and then press-molding and cutting to obtain a cake-like structure composite flame-retardant masterbatch. A method for producing an antimony-free composite flame-retardant masterbatch.

10. The method includes the steps of weighing and premixing each component according to the compounding components of the antimony-free composite flame-retardant masterbatch of claim 7, and then feeding the resulting premix into a screw extruder to extrusion granulate the composite flame-retardant masterbatch with a granular structure. A method for producing an antimony-free composite flame-retardant masterbatch.

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