Flame-retardant reinforced PBT (polybutylene terephthalate) micro-foaming material as well as preparation method and application thereof

Abstract

The invention discloses a flame-retardant reinforced PBT (polybutylene terephthalate) micro-foaming material as well as a preparation method and application thereof. The PBT micro-foaming material comprises polybutylene terephthalate, a brominated flame retardant, a synergistic flame retardant, a flexibilizer, a micro-crosslinking agent and a foaming agent, the intrinsic viscosity of the polybutylene terephthalate is 0.9 to 1.2 dL / g; the micro-crosslinking agent comprises epoxy resin and / or polyhydric alcohol, the epoxy equivalent of the epoxy resin is 400-4000 g / eq, and the hydroxyl functionality of the polyhydric alcohol is 3-7. According to the PBT micro-foaming material disclosed by the invention, the PBT resin is taken as a matrix, the introduced micro-crosslinking agent can react with a terminal hydroxyl group or a terminal carboxyl group of the PBT resin, and meanwhile, the functionality of the micro-crosslinking agent is controlled, so that the micro-foaming material generates a micro-crosslinking structure, and therefore, the overall melt strength of the material is improved, and the foaming efficiency of the material is greatly improved; meanwhile, a specific amount of the flexibilizer, the brominated flame retardant and the synergistic flame retardant are added, so that the PBT micro-foaming material has relatively good mechanical properties and flame retardance.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-foam materials, and more specifically, to a flame retardant reinforced PBT micro-foam material and a preparation method and application thereof. Background Art

[0002] PBT is a widely used crystalline polyester engineering plastic with relatively excellent mechanical properties, heat resistance, electrical properties, solvent resistance, fatigue resistance and creep resistance, etc. In addition, PBT materials have the characteristics of fast crystallization speed, excellent dimensional stability, short molding cycle and low water absorption, making it widely used in the fields of electronics, electrical engineering, home appliances, automobiles, etc.

[0003] With the lightweight development trend of new energy vehicles, product foaming has become an important way to lightweight. Flame-retardant reinforced PBT is widely used in new energy vehicles due to its excellent mechanical properties, solvent resistance and stable electrical properties. At present, a large amount of PBT materials are used in parts such as high-voltage distribution boxes and micromotors of new energy batteries. Micro-foamed PBT material is a semi-crystalline polymer / gas composite engineering plastic with excellent performance. It has the advantages of good heat resistance, chemical resistance, electrical properties, etc. At the same time, its low density characteristics can greatly reduce the weight of the same parts, and become a new engineering material with high application value and market potential in the new energy vehicle market; however, due to the poor toughness and low melt strength of PBT resin, conventional foamed PBT is prone to defects such as uneven cells, cell rupture and poor mechanical properties.

[0004] For example, patent CN117700953A proposes a high flame retardant and low smoke density PBT composite material, including PBT, glass fiber, inorganic particles, flame retardant, smoke suppressant and nitrogen-containing foaming agent. By rationally selecting the types of raw materials and rationally controlling the amount and particle size of the raw materials, the obtained PBT composite material has high nitrogen, carbon and phosphorus content, good synergistic flame retardant effect and mechanical properties. However, it fails to improve the foaming effect of the PBT composite material. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and shortcomings of existing PBT micro-foam materials and provide a PBT micro-foam material with a high foaming rate and good mechanical properties and flame retardancy.

[0006] Another object of the present invention is to provide a PBT micro-foam material.

[0007] Another object of the present invention is to provide a method for preparing a PBT micro-foam material.

[0008] Another object of the present invention is to provide an application of a PBT micro-foam material in the preparation of new energy vehicle accessories.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention protects a PBT micro-foam material, comprising the following components in parts by weight:

[0011]

[0012] The intrinsic viscosity of the polybutylene terephthalate is 0.9-1.2 dL / g; the intrinsic viscosity is tested according to the ISO1628 standard method;

[0013] The micro-crosslinking agent comprises epoxy resin and / or polyol, the epoxy equivalent of the epoxy resin is 400-4000 g / eq, and the hydroxyl functionality of the polyol is 3-7.

[0014] The PBT micro-foam material of the present invention takes PBT resin as a matrix, introduces a micro-crosslinking agent that can react with the terminal hydroxyl group or the terminal carboxyl group of the PBT resin, and controls the functionality of the micro-crosslinking agent so that the micro-foam material produces a micro-crosslinking structure, thereby improving the overall melt strength of the material, greatly improving the foaming efficiency of the material, and improving the density and uniformity of the foaming. At the same time, a specific amount of a toughening agent, a bromine-based flame retardant and a synergistic flame retardant are added, so that the PBT micro-foam material has good mechanical properties and flame retardant properties, and maintains good foaming properties.

[0015] In some of these embodiments, the polyol has a hydroxyl functionality of 3, 4, 5, 6, or 7.

[0016] Optionally, the polyol is selected from C3-C14 fatty alcohols, or fatty alcohol derivatives in which one or more secondary carbons are substituted by O atoms. Preferably, the polyol is a primary alcohol.

[0017] Optionally, the polyol is any one or more of dipentaerythritol, glycerol, pentaerythritol or sorbitol; preferably, the polyol is dipentaerythritol. In some embodiments, the content of polybutylene terephthalate (PBT) that can achieve the purpose of the present invention can be 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts.

[0018] In some embodiments, the content of the micro-crosslinking agent that can achieve the purpose of the present invention can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part.

[0019] In some embodiments, the intrinsic viscosity of the polybutylene terephthalate is 0.95-1.1 dL / g; preferably, the intrinsic viscosity is 0.98-1.05 dL / g; the intrinsic viscosity of the present invention is tested according to the ISO1628 standard method.

[0020] The inventors found that the viscosity of low-viscosity PBT resin (such as intrinsic viscosity ≤ 0.85dL / g) is relatively low, and the melt strength of the PBT micro-foamed material prepared therefrom is relatively weak, and the foaming efficiency is low; when the viscosity of the PBT resin increases, the overall fluidity decreases, so the excessively high viscosity of the PBT resin reduces the molding processing performance and affects the foaming efficiency; the present invention further optimizes the intrinsic viscosity of the PBT resin so that the micro-foamed material has good foaming rate and mechanical properties.

[0021] In some embodiments, the brominated flame retardant is any one or two or more of brominated epoxy resin, brominated polystyrene, brominated imine or polypentabromobenzyl acrylate.

[0022] In some embodiments, the synergistic flame retardant is antimony trioxide and / or sodium antimonate.

[0023] In some embodiments, the toughening agent is ethylene acrylate and / or ethylene acrylate-glycidyl ester.

[0024] Preferably, the ethylene-acrylate is selected from ethylene-methyl acrylate or ethylene-butyl acrylate.

[0025] Preferably, the ethylene-acrylate-glycidyl ester is selected from ethylene-methyl acrylate-glycidyl methacrylate.

[0026] In some embodiments, the PBT micro-foam material further includes: 20-30 parts of glass fiber.

[0027] Preferably, the glass fiber is chopped E glass fiber (alkali-free glass fiber) with a fiber diameter of 7 to 15 μm and a length of 3 to 5 mm.

[0028] The PBT micro-foam material of the present invention may also be added with conventional additives in the field of PBT processing, including but not limited to lubricants and antioxidants.

[0029] Preferably, the lubricant is selected from at least one of an ester lubricant, an amide lubricant, a polyethylene lubricant or a stearic acid lubricant. More preferably, the lubricant is an ester lubricant. Specifically, the ester lubricant is any one of a lower alcohol ester, a higher alcohol ester, a polyol ester or a polyethylene glycol ester of a fatty acid.

[0030] Preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant; specifically, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076 or antioxidant 168.

[0031] In some embodiments, the foaming agent includes a chemical foaming agent and / or a physical foaming agent, and the chemical foaming agent is an azo compound, a sulfonylhydrazine compound, a nitroso compound, or a triazole compound; specifically, the sulfonylhydrazine compound includes but is not limited to 4,4'-oxybisbenzenesulfonylhydrazine. Exemplarily, it includes but is not limited to CELLCOM-OBSH and Guangdong Duba New Material Technology Co., Ltd.

[0032] Optionally, the physical foaming agent is sodium bicarbonate. Exemplarily, it includes but is not limited to the foaming agent masterbatch EE25C and foaming agent masterbatch F-70 of Japan Yonghe Company.

[0033] The present invention provides a method for preparing a PBT micro-foam material, comprising the following steps:

[0034] (1) uniformly mixing the raw materials except the foaming agent, and melt-blending and extruding to obtain the PBT composition;

[0035] (2) The PBT composition and the foaming agent are uniformly mixed, and injection molding is performed for foaming to obtain the PBT micro-foam material.

[0036] In some embodiments, the method for preparing the PBT micro-foam material comprises the following steps:

[0037] (1) mixing a brominated flame retardant and a synergistic flame retardant uniformly to obtain a flame retardant mixture;

[0038] After PBT, toughening agent, micro-crosslinking agent, glass fiber and additives are uniformly mixed, a flame retardant mixture is added, and melt blending and extrusion are performed to obtain a pre-foamed PBT composition;

[0039] (2) The pre-foamed PBT composition is uniformly mixed with a foaming agent, and injection-molded and foamed at 250-260° C. to obtain the PBT micro-foamed material.

[0040] In some embodiments, in step (1), the melt blending adopts a twin-screw extruder, and the temperature of zone 1 from the feed port to the die head of the twin-screw extruder is 200-230°C, the temperature of zone 2 is 240-260°C, the temperature of zone 3 is 235-255°C, the temperature of zone 4 is 235-255°C, the temperature of zone 5 is 235-255°C, the temperature of zone 6 is 240-260°C, the temperature of zone 7 is 240-260°C, the temperature of zone 8 is 220-240°C, the temperature of zone 9 is 220-240°C, the temperature of zone 10 is 240-260°C, and the screw speed of the twin-screw extruder is 200-450 rpm.

[0041] In some embodiments, in step (2), the temperature of the injection molding and foaming is 250-260° C. Specifically, the injection molding and foaming is processed by an injection molding machine.

[0042] The present invention protects the use of a PBT micro-foam material in preparing a high-voltage distribution box and a micro-motor which are new energy vehicle accessories of new energy vehicles.

[0043] Optionally, the new energy vehicle accessories include but are not limited to high-voltage distribution boxes and micromotors.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The invention provides a PBT micro-foam material, which takes PBT resin as a matrix, introduces a micro-crosslinking agent that can react with a terminal hydroxyl group or a terminal carboxyl group of the PBT resin, and controls the functionality of the micro-crosslinking agent so that the micro-foam material produces a micro-crosslinking structure, thereby improving the overall melt strength of the material and greatly improving the foaming efficiency of the material. At the same time, a specific amount of a toughening agent, a bromine-based flame retardant and a synergistic flame retardant are added so that the PBT micro-foam material has good mechanical properties and flame retardant properties. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0047] The raw materials used in the following examples and comparative examples are as follows:

[0048] Polybutylene terephthalate (PBT):

[0049] PBT 1#: PBT GX122J, Yizheng Chemical Fiber Company, intrinsic viscosity 1.05dL / g;

[0050] PBT 2#: PBT GX121, Jiangsu Yizheng Chemical Fiber Company, intrinsic viscosity is 0.98dL / g;

[0051] PBT 3#: PBT GX111, Jiangsu Yizheng Chemical Fiber Company, intrinsic viscosity 0.73dL / g;

[0052] PBT 4#: 1100-211X, Changchun Chemical (Jiangsu) Co., Ltd.; intrinsic viscosity 1.3 dL / g.

[0053] Brominated flame retardant: F-2100, manufacturer ICL-IP.

[0054] Synergistic flame retardant: antimony white, S-05N, purchased from Foshan Chenti Economic and Trade Co., Ltd.

[0055] Glass fiber: HMG436S-10-4.0, Taishan Glass Fiber Co., Ltd.; diameter 10 μm, length 10 mm.

[0056] Toughening agent 1#: EMA-GMA ternary block copolymer, DuPont PTW.

[0057] Toughening agent 2#: ethylene-acrylate copolymer (EMA), DuPont Elvaloy AC resin 1125.

[0058] Micro-crosslinking agent:

[0059] Micro-crosslinking agent 1#: epoxy resin, YD-019, Guodu Chemical (Kunshan) Co., Ltd., epoxy equivalent is 2500-3100 g / eq.

[0060] Micro-crosslinking agent 2#: epoxy resin, CYD-011, Yueyang Baling Huaxing Petrochemical Co., Ltd., epoxy equivalent is 450-500g / eq.

[0061] Micro-crosslinking agent 3#: epoxy resin, YD-020, Guodu Chemical (Kunshan) Co., Ltd., epoxy equivalent is 4000-6000g / eq.

[0062] Micro cross-linking agent 4#: dipentaerythritol, CHARMOR DP40, Perstorp.

[0063] Micro-crosslinking agent 5#: propylene glycol, Shanghai Aladdin Company.

[0064] Micro-crosslinking agent 6#: Tripentaerythritol, Tianjin Xiensi Biochemical Technology Co., Ltd.

[0065] Micro-crosslinking agent 7#, ethylene glycol, commercially available.

[0066] Micro cross-linking agent 8#, carbodiimide, commercially available.

[0067] Lubricant: Grease lubricant, PETS, Italy Faji Private S.A.

[0068] Antioxidant: Antioxidant 1076, RIANOX 1076, Tianjin Li'anlong New Materials Co., Ltd.

[0069] Foaming agent: EE25C, purchased from Eiwa Co., Ltd., Japan.

[0070] The preparation method of the PBT micro-foam material in the following examples and comparative examples comprises the following steps:

[0071] (1) placing a brominated flame retardant and a synergistic flame retardant in a high-speed mixer and dry mixing them for 3 minutes at a speed of 800 rpm to obtain a flame retardant mixture;

[0072] (2) PBT, toughening agent, micro-crosslinking agent, glass fiber and additives (lubricant, antioxidant) were placed in a high-speed mixer and dry-mixed for 3 minutes at a speed of 800 rpm. The flame retardant mixture and glass fiber were then added, melt-blended, extruded and granulated to obtain a pre-foamed PBT composition.

[0073] Wherein, the melt blending adopts a twin-screw extruder, the temperature of zone 1 from the feeding port to the die head of the twin-screw extruder is 200-230°C, the temperature of zone 2 is 240-260°C, the temperature of zone 3 is 235-255°C, the temperature of zone 4 is 235-255°C, the temperature of zone 5 is 235-255°C, the temperature of zone 6 is 240-260°C, the temperature of zone 7 is 240-260°C, the temperature of zone 8 is 220-240°C, the temperature of zone 9 is 220-240°C, the temperature of zone 10 is 240-260°C, and the screw speed of the twin-screw extruder is 200-450 rpm.

[0074] (3) The pre-foamed PBT composition is mixed evenly with a foaming agent, and added into an injection molding machine for injection molding and foaming at 250-260° C. to obtain the PBT micro-foamed material.

[0075] Examples 1 to 14

[0076] This embodiment provides a series of PBT micro-foam materials, and the raw material components thereof are shown in Table 1.

[0077] Table 1 Raw material components of Examples 1 to 14 (parts by mass)

[0078]

[0079]

[0080] Comparative Examples 1 to 8

[0081] This embodiment provides a series of PBT micro-foam materials, and the raw material components thereof are shown in Table 3.

[0082] Table 3 Raw material components of comparative examples 1 to 8 (parts by mass)

[0083]

[0084] Performance Testing

[0085] The PBT micro-foam materials of various embodiments and comparative examples were subjected to the following tests. The results are shown in Table 4.

[0086] 1. Tensile strength: Tested according to standard ISO 527.

[0087] 2. Izod notched impact strength: tested according to standard ISO 180.

[0088] 3. Density: Tested according to standard ISO 1183.

[0089] 4. Foaming rate: The calculation formula is: Foaming rate = (density before foaming - density after foaming) / density before foaming.

[0090] 5. Flame retardancy: standard UL 94.

[0091] Table 4

[0092]

[0093]

[0094] The PBT micro-foam material of the present invention has a tensile strength of more than 115 MPa and a notched impact strength of 8.0 kJ / m 2 Above, the foaming rate is above 6.6%.

[0095] Compared with Example 1, the PBT with too low intrinsic viscosity used in Comparative Example 1 has insufficient melt strength and significantly reduced overall foaming rate. The PBT with too high intrinsic viscosity used in Comparative Example 2 has reduced processing fluidity and reduced overall foaming rate.

[0096] In the PBT micro-foamed material of Comparative Example 3, no micro-crosslinking agent is added, and its tensile strength and impact strength are reduced, and the foaming rate is greatly reduced.

[0097] Comparative Examples 4-5 use different types of micro-crosslinking agents, which fail to effectively improve the melt strength of the material and have a low foaming rate.

[0098] In Comparative Example 6, the micro-crosslinking agent is excessive. Although the mechanical properties of the material are improved, the foaming effect is low.

[0099] The epoxy equivalent of the epoxy resin or the hydroxyl functionality of the polyol in the micro-foamed materials of Comparative Examples 7-8 leads to a decrease in the foaming rate of the material.

[0100] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A PBT micro-foam material, characterized in that: The composition includes the following components in parts by weight: The intrinsic viscosity of the polybutylene terephthalate is 0.9-1.2 dL / g; The micro-crosslinking agent comprises epoxy resin and / or polyol, the epoxy equivalent of the epoxy resin is 400-4000 g / eq, and the hydroxyl functionality of the polyol is 3-7.

2. The PBT micro-foam material according to claim 1, characterized in that: The polyol is selected from C3-C14 fatty alcohols, or fatty alcohol derivatives in which one or more secondary carbons are replaced by O atoms.

3. The PBT micro-foam material according to claim 1 or 2, characterized in that: The polyol is any one or more of dipentaerythritol, glycerol, pentaerythritol or sorbitol.

4. The PBT micro-foam material according to claim 1, characterized in that: The intrinsic viscosity of the polybutylene terephthalate is 0.95-1.1 dL / g.

5. The PBT micro-foam material according to claim 1, characterized in that: The brominated flame retardant is any one or more of brominated epoxy resin, brominated polystyrene, brominated imine or polypentabromobenzyl acrylate.

6. The PBT micro-foam material according to claim 1, characterized in that: The synergistic flame retardant is antimony trioxide and / or sodium antimonate.

7. The PBT micro-foam material according to claim 1, characterized in that: The toughening agent is ethylene-acrylate and / or ethylene-acrylate-glycidyl ester.

8. The PBT micro-foam material according to claim 1, characterized in that: Also includes: 20-30 parts of glass fiber.

9. A method for preparing the PBT micro-foam material according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) uniformly mixing the raw materials except the foaming agent, and melt-blending and extruding to obtain a pre-foamed PBT composition; (2) The pre-foamed PBT composition is uniformly mixed with a foaming agent, and injection-molded and foamed to obtain the PBT micro-foamed material.

10. Use of the PBT micro-foam material according to any one of claims 1 to 8 in preparing new energy vehicle accessories.

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