Antimony-free flame retardant synergist, preparation method thereof, and polyester material

Abstract

The present invention belongs to the technical field of flame retardant materials and discloses an antimony-free flame retardant synergist, a preparation method thereof, and a polyester material. The antimony-free flame retardant synergist of the present invention comprises zinc borate-coated hydrotalcite and pentaerythritol phosphate, wherein the pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent. The raw materials for preparing the zinc borate-coated hydrotalcite include hydrotalcite, a boron source, a zinc source, and a solvent. The antimony-free flame retardant synergist of the present invention can replace traditional antimony-containing compounds and be compounded with a brominated flame retardant to work together. The antimony-free flame retardant synergist is primarily condensed-phase flame retardant (charring), while the brominated flame retardant is gas-phase flame retardant (radical capture). The two can form a gas-condensed phase synergistic effect. When added to a polyester material, the polyester material achieves a high glow-wire temperature (GWIT) greater than 850°C while meeting the UL94 V-0 flame retardancy (1.6 mm) and exhibiting good mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardant materials, and in particular relates to an antimony-free flame retardant synergist, a preparation method thereof, and a polyester material. Background Art

[0002] Polyesters (such as PBT and PET) have excellent mechanical properties, electrical insulation, and a low price, making them widely used in fibers, packaging materials, films, and engineering plastics. However, polyester and its fibers are flammable. Currently, flame-retardant polyesters are primarily prepared by adding flame retardants to the polyester system. Patent publication number CN119570214A discloses a new, environmentally friendly, flame-retardant, reinforced, high-glow-wire PBT material. The material comprises the following components: PBT resin, PET resin, a toughening agent, a brominated flame retardant, a synergistic flame retardant, melamine cyanurate, a phosphorus-based environmentally friendly flame retardant, a glow-wire synergist, an antioxidant, a lubricant, and glass fiber. The synergistic flame retardant is one or more of sodium antimonate, antimony trioxide, and antimony pentoxide. Antimony compounds are not only costly but also toxic, posing potential health and environmental risks during use.

[0003] Therefore, how to avoid the use of antimony-containing compounds while improving the flame retardant properties of polyester is an urgent problem to be solved in this field. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention provides an antimony-free flame retardant synergist, a preparation method thereof, and a polyester material. This antimony-free flame retardant synergist can replace traditional antimony-containing compounds and, when combined with a brominated flame retardant, enhances the flame retardancy and glow-wire temperature of polyester while substantially not affecting the mechanical properties of the polyester material.

[0005] In a first aspect, the present invention provides an antimony-free flame retardant synergist, comprising zinc borate-coated hydrotalcite and pentaerythritol phosphate, wherein the pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent, and the raw materials for preparing the zinc borate-coated hydrotalcite include hydrotalcite, a boron source, a zinc source, and a solvent.

[0006] In some embodiments of the present invention, the mass ratio of the hydrotalcite, boron source, and zinc source is 20:(1-2.5):(1-2.5). By controlling the mass ratio of the raw hydrotalcite, boron source, and zinc source, the present invention can achieve partial or complete coating of the hydrotalcite surface with zinc borate generated from the boron source and zinc source.

[0007] In some embodiments of the present invention, the silane coupling agent includes at least one of KH550, KH560 and KH570.

[0008] In some embodiments of the present invention, the mass ratio of the zinc borate-coated hydrotalcite, the silane coupling agent, and the pentaerythritol phosphate is 15:(0.2-0.8):(0.2-1).

[0009] In some embodiments of the present invention, the boron source includes at least one of boric acid, borax and potassium borate.

[0010] In some embodiments of the present invention, the zinc source includes at least one of zinc nitrate, zinc chloride, and zinc sulfate.

[0011] In some embodiments of the present invention, the solvent comprises water and / or ethanol.

[0012] The second aspect of the present invention provides a method for preparing the antimony-free flame retardant synergist according to the first aspect of the present invention, comprising the following steps:

[0013] S1. Mixing hydrotalcite, a boron source, a zinc source, and a solvent, adjusting the pH to alkaline, heating and preserving the mixture, filtering, and drying to obtain zinc borate-coated hydrotalcite;

[0014] S2. Mixing the zinc borate-coated hydrotalcite, a solvent, a silane coupling agent, and pentaerythritol phosphate, heating and stirring, filtering, and drying to obtain the antimony-free flame retardant synergist.

[0015] In some embodiments of the present invention, the pH is adjusted to 8-10.

[0016] In some embodiments of the present invention, in step S1, the heating and insulation temperature is 100-140° C.; and / or the heating and insulation time is 6-8 hours.

[0017] In some embodiments of the present invention, in step S2, the temperature of the heating and stirring is 60-80° C.; and / or the time of the heating and stirring is 6-8 h.

[0018] A third aspect of the present invention provides a polyester material, wherein the raw materials for preparing the polyester material include PBT resin and / or PET resin, glass fiber, an additive, a brominated flame retardant, and the antimony-free flame retardant synergist described in the first aspect of the present invention. The raw materials for preparing the polyester material of the present invention do not contain antimony-containing compounds.

[0019] In some embodiments of the present invention, the intrinsic viscosity of the PET resin is 0.5-1.0 dL / g at 25°C.

[0020] In some embodiments of the present invention, the intrinsic viscosity of the PBT resin is 0.8-1.0 dL / g at 25°C.

[0021] Specifically, the intrinsic viscosity of the PET and PBT resins is tested with reference to GB / T14190-2017.

[0022] In some embodiments of the present invention, the glass fiber is an alkali-free chopped glass fiber with a single filament diameter of 3-9 μm and an aspect ratio of (30-60):1.

[0023] In some embodiments of the present invention, the auxiliary agent includes at least one of a toughening agent, a lubricant, an antioxidant, and a plasticizer.

[0024] In some embodiments of the present invention, the toughening agent includes at least one of ethylene-acrylates-glycidyl methacrylate copolymer, ethylene-acrylate copolymer, and methacrylate-styrene-butadiene copolymer.

[0025] In some embodiments of the present invention, the lubricant includes at least one of silicone powder, ethylene bisstearamide, and pentaerythritol stearate.

[0026] In some embodiments of the present invention, the antioxidant includes at least one of antioxidant 168 , antioxidant 1010 , and antioxidant 1076 .

[0027] In some embodiments of the present invention, the plasticizer includes at least one of trinonyl trimellitate, dioctyl adipate, dioctyl sebacate, and dioctyl terephthalate.

[0028] In some embodiments of the present invention, the brominated flame retardant includes at least one of brominated epoxy resin, brominated polystyrene, brominated polycarbonate and decabromodiphenylethane.

[0029] In some embodiments of the present invention, the mass percentage of the antimony-free flame retardant synergist in the polyester material is 2%-8%.

[0030] In some embodiments of the present invention, the raw materials for preparing the polyester material include, by weight percentage, 40%-60% of PBT resin and / or PET resin, 20%-40% of glass fiber, 0.1%-2% of additives, 10%-15% of brominated flame retardant, and 2%-8% of the antimony-free flame retardant synergist.

[0031] In some embodiments of the present invention, the method for preparing the polyester material comprises the following steps:

[0032] The prepared raw materials are mixed, melt-extruded through a twin-screw extruder, cooled, and granulated to obtain the polyester material.

[0033] In some embodiments of the present invention, the temperature of the melt extrusion is 200-240° C., and the screw speed is 250-400 rpm.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Both zinc borate and hydrotalcite in the antimony-free flame retardant synergist of the present invention have good flame retardant properties, such as glassy carbonization and gas-phase free radical capture of zinc borate; endothermic decomposition, release of flame-retardant gas and catalytic carbonization of hydrotalcite; by coating hydrotalcite with zinc borate, the interaction between the two can more effectively exert flame retardant properties, specifically, hydrotalcite endothermic decomposition, releases a large amount of water vapor and carbon dioxide (dilutes oxygen and other combustible gases), and generates metal oxides (mainly MgO and / or Al2O3) at the same time. The thermal decomposition products of zinc borate (such as B2O3) will immediately come into contact with the metal oxides generated by the decomposition of the coated hydrotalcite, reacting to form a more stable, denser and better-covering glassy borate ceramic layer (such as magnesium borate and aluminum borate), which is more effective in isolating heat. The present invention also couples pentaerythritol phosphate to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent. The phosphate group of pentaerythritol phosphate is similar in structure to the ester group of polyester, thereby enhancing interfacial bonding strength, facilitating dispersion, and preventing agglomeration of the zinc borate-coated hydrotalcite. Pentaerythritol phosphate serves as a carbon source, undergoes dehydration through an esterification reaction to form carbon, and decomposition products of the hydrotalcite can also catalyze the cross-linking of pentaerythritol phosphate, thereby enhancing the strength of the carbon layer.

[0036] (2) The antimony-free flame retardant synergist of the present invention can replace the traditional antimony-containing compounds and be compounded with brominated flame retardants to work together. The antimony-free flame retardant synergist is mainly a condensed phase flame retardant (carbon formation), while the brominated flame retardant is a gas phase flame retardant (free radical capture). The two can form a gas-condensed phase synergistic effect. When they are added to polyester materials, the polyester materials can achieve a high glow wire temperature GWIT>850℃ while meeting the flame retardancy UL94 V-0 level (1.6mm) and have good mechanical properties. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below by way of specific examples. Unless otherwise specified, the raw materials, reagents, or devices used in the examples can be obtained from conventional commercial sources or by existing methods. Unless otherwise specified, the experiments or testing methods are conventional methods in the art.

[0038] Example 1

[0039] An antimony-free flame retardant synergist comprises zinc borate-coated hydrotalcite and pentaerythritol phosphate, wherein the pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent.

[0040] The preparation method of the zinc borate-coated hydrotalcite comprises the following steps:

[0041] Hydrotalcite, boric acid, zinc sulfate and water were mixed, and 0.5 mol / L sodium hydroxide solution was added to adjust the pH to 8. The mixture was then kept at 120°C for 6 hours, filtered, and the solid was collected. The solid was washed with water three times and then dried in a 60°C oven to obtain zinc borate-coated hydrotalcite. The mass ratio of hydrotalcite, boric acid and zinc sulfate was 20:2:1.5.

[0042] The method for preparing the antimony-free flame retardant synergist comprises the following steps:

[0043] Zinc borate-coated hydrotalcite was added to an ethanol aqueous solution, and a silane coupling agent KH-550 was added. The mixture was stirred at 350 rpm at 60°C for 30 minutes, and then pentaerythritol phosphate was added. The mixture was further stirred at 350 rpm for 6 hours. The solid was collected by filtration and then dried in an oven at 60°C to obtain an antimony-free flame retardant synergist. The mass ratio of the zinc borate-coated hydrotalcite, the silane coupling agent KH-550, and the pentaerythritol phosphate was 15:0.5:0.7.

[0044] Example 2

[0045] An antimony-free flame retardant synergist comprises zinc borate-coated hydrotalcite and pentaerythritol phosphate, wherein the pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent.

[0046] The preparation method of the zinc borate-coated hydrotalcite comprises the following steps:

[0047] Hydrotalcite, boric acid, zinc sulfate and water were mixed, and 0.5 mol / L sodium hydroxide solution was added to adjust the pH to 8. The mixture was then kept at 120°C for 6 hours, filtered, and the solid was collected. The solid was washed with water three times and then dried in a 60°C oven to obtain zinc borate-coated hydrotalcite. The mass ratio of hydrotalcite, boric acid and zinc sulfate was 20:1:2.5.

[0048] The method for preparing the antimony-free flame retardant synergist comprises the following steps:

[0049] Zinc borate-coated hydrotalcite was added to an ethanol aqueous solution, and a silane coupling agent KH-550 was added. The mixture was stirred at 350 rpm at 60°C for 30 minutes, and then pentaerythritol phosphate was added. The mixture was further stirred at 350 rpm for 6 hours. The solid was collected by filtration and then dried in an oven at 60°C to obtain an antimony-free flame retardant synergist. The mass ratio of the zinc borate-coated hydrotalcite, the silane coupling agent KH-550, and the pentaerythritol phosphate was 15:0.2:1.

[0050] Example 3

[0051] An antimony-free flame retardant synergist comprises zinc borate-coated hydrotalcite and pentaerythritol phosphate, wherein the pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite via a silane coupling agent.

[0052] The preparation method of the zinc borate-coated hydrotalcite comprises the following steps:

[0053] Hydrotalcite, boric acid, zinc sulfate and water were mixed, and 0.5 mol / L sodium hydroxide solution was added to adjust the pH to 8. The mixture was then kept at 120°C for 6 hours, filtered, and the solid was collected. The solid was washed three times with water and then dried in a 60°C oven to obtain zinc borate-coated hydrotalcite. The mass ratio of hydrotalcite, boric acid and zinc sulfate was 20:2.5:1.

[0054] The method for preparing the antimony-free flame retardant synergist comprises the following steps:

[0055] Zinc borate-coated hydrotalcite was added to an ethanol aqueous solution, and a silane coupling agent KH-550 was added. The mixture was stirred at 350 rpm at 60°C for 30 minutes, and then pentaerythritol phosphate was added. The mixture was further stirred at 350 rpm for 6 hours. The solid was collected by filtration and then dried in an oven at 60°C to obtain an antimony-free flame retardant synergist. The mass ratio of the zinc borate-coated hydrotalcite, the silane coupling agent KH-550, and the pentaerythritol phosphate was 15:0.8:0.2.

[0056] Comparative Example 1

[0057] The difference from Example 1 is that no coating and coupling were performed, that is, a physical mixture of equal amounts of zinc borate, hydrotalcite and pentaerythritol phosphate was used as the non-antimony flame retardant synergist in Comparative Example 1.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that no coupling is performed, that is, Comparative Example 2 uses a physical mixture of equal amounts of zinc borate-coated hydrotalcite and pentaerythritol phosphate as the non-antimony flame retardant synergist.

[0060] Comparative Example 3

[0061] The difference from Example 1 is that pentaerythritol phosphate is absent, that is, Comparative Example 3 uses an equal amount of zinc borate-coated hydrotalcite as the non-antimony flame retardant synergist.

[0062] Comparative Example 4

[0063] The difference from Example 1 is that zinc borate is absent, that is, Comparative Example 4 uses pentaerythritol phosphate coupled to at least a portion of the surface of the hydrotalcite via a silane coupling agent as an antimony-free flame retardant synergist.

[0064] Comparative Example 5

[0065] Comparative Example 5 uses traditional antimony trioxide as a flame retardant synergist.

[0066] Application Example 1

[0067] A polyester material, prepared from raw materials comprising, by weight percentage, 50% PBT resin, 30% glass fiber, 0.3% methacrylate-styrene-butadiene copolymer, 0.7% ethylene bisstearamide, 0.5% antioxidant (1010), 0.5% trinonyl trimellitate, 12% brominated epoxy resin, and 6% antimony-free flame retardant synergist provided in Example 1; wherein the PBT resin has an intrinsic viscosity of 1.0 dL / g at 25°C, the glass fiber is alkali-free chopped glass fiber, has a single filament diameter of 5 μm, and an aspect ratio of 40:1.

[0068] The preparation method of the above polyester material comprises the following steps:

[0069] The prepared raw materials are mixed, melt-extruded through a twin-screw extruder, cooled, and granulated to obtain a polyester material; wherein the temperature of each section of the extruder is 220-240° C., and the screw speed is 250-400 rpm.

[0070] Application Example 2-3

[0071] The difference from Application Example 1 is that in Application Examples 2-3, the antimony-free flame retardant synergist provided in Example 1 is replaced by the antimony-free flame retardant synergist provided in Examples 2-3 respectively.

[0072] Comparative Application Examples 1-5

[0073] The difference from Application Example 1 is that in Application Comparative Examples 1-5, the antimony-free flame retardant synergist provided in Example 1 is replaced by the flame retardant synergists provided in Comparative Examples 1-5 respectively.

[0074] Polyester material performance test

[0075] Related performance test methods:

[0076] (1) Flame retardant performance test: The flame retardant performance test was performed on a sample with a thickness of 1.6 mm according to the UL-94 standard.

[0077] (2) Glow-wire (GWIT) test: Glow-wire test is performed on a sample with a thickness of 1.0 mm according to IEC60695-2-13 standard.

[0078] (3) Tensile strength test: The tensile strength test was performed on a sample with a thickness of 4.0 mm according to ISO527-2 standard.

[0079] (4) Izod notched impact strength test: Tested in accordance with ISO180 standard.

[0080] The performance test results of polyester materials are shown in Table 1.

[0081] Table 1

[0082]

[0083] As can be seen from Table 1, the polyester materials of Application Examples 1-3 employ the antimony-free flame retardant synergist of the present invention, and their flame retardancy can reach the same level of flame retardancy (V-0) as that of conventional antimony trioxide. Furthermore, the polyester materials of Application Examples 1-3 also have high glow-wire ignition temperatures and high mechanical properties, and their performance is even better than that of conventional antimony trioxide.

[0084] Compared with Application Example 1, the flame retardant synergist in Comparative Example 1 was used by simply physically mixing zinc borate, hydrotalcite, and pentaerythritol phosphate. The flame retardant synergist in Comparative Example 2 was used by simply physically mixing zinc borate-coated hydrotalcite and pentaerythritol phosphate. Due to uneven dispersion and poor compatibility, their flame retardancy and GWIT were significantly worse than those in Application Example 1, and their mechanical properties were also significantly affected.

[0085] Compared with Application Example 1, Application Comparative Example 3 lacks pentaerythritol phosphate, resulting in its flame retardancy, GWIT and mechanical properties being significantly worse than those of Application Example 1; Application Comparative Example 4 lacks zinc borate, resulting in its flame retardancy and GWIT being significantly worse than those of Application Example 1.

[0086] The above specifically describes the preferred embodiments of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An antimony-free flame retardant synergist, characterized in that: The antimony-free flame retardant synergist includes zinc borate-coated hydrotalcite and pentaerythritol phosphate. The pentaerythritol phosphate is coupled to at least a portion of the surface of the zinc borate-coated hydrotalcite through a silane coupling agent. The raw materials for preparing the zinc borate-coated hydrotalcite include hydrotalcite, a boron source, a zinc source and a solvent.

2. The antimony-free flame retardant synergist according to claim 1, characterized in that: The mass ratio of the hydrotalcite, the boron source and the zinc source is 20:(1-2.5):(1-2.5).

3. The antimony-free flame retardant synergist according to claim 1, characterized in that: The mass ratio of the zinc borate-coated hydrotalcite, the silane coupling agent and the pentaerythritol phosphate is 15:(0.2-0.8):(0.2-1).

4. The antimony-free flame retardant synergist according to claim 1, characterized in that: The solvent includes water and / or ethanol.

5. The method for preparing the antimony-free flame retardant synergist according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Mixing hydrotalcite, a boron source, a zinc source, and a solvent, adjusting the pH to alkaline, heating and preserving the mixture, filtering, and drying to obtain zinc borate-coated hydrotalcite; S2. Mixing the zinc borate-coated hydrotalcite, a solvent, a silane coupling agent, and pentaerythritol phosphate, heating and stirring, filtering, and drying to obtain the antimony-free flame retardant synergist.

6. The method for preparing the antimony-free flame retardant synergist according to claim 5, characterized in that: In step S1, the heating and heat preservation temperature is 100-140° C.; and / or the heating and heat preservation time is 6-8 hours.

7. The method for preparing the antimony-free flame retardant synergist according to claim 5, characterized in that: In step S2, the temperature of the heating and stirring is 60-80°C; and / or the time of the heating and stirring is 6-8h.

8. A polyester material, characterized in that: The raw materials for preparing the polyester material include PBT resin and / or PET resin, glass fiber, additives, brominated flame retardant and the antimony-free flame retardant synergist according to any one of claims 1 to 4.

9. The polyester material according to claim 8, characterized in that The auxiliary agent includes at least one of a toughening agent, a lubricant, an antioxidant and a plasticizer.

10. The polyester material according to claim 8, characterized in that The mass percentage of the antimony-free flame retardant synergist in the polyester material is 2%-8%.

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