Nylon composition as well as preparation method and application thereof

Abstract

The invention discloses a nylon composition as well as a preparation method and application thereof, and belongs to the technical field of engineering plastics. Specifically, the nylon composition provided by the invention comprises the following components in parts by weight: 24-82.5 parts of PA resin; 10 to 50 parts of glass fiber; 0.5 to 2 parts of sodium lignin sulfonate; and 7-23 parts of a halogen-free flame retardant. The invention can be used for preparing electrical management parts or electric tools. The nylon composition provided by the invention has the effects of low mold scale, damp-heat aging resistance and ultraviolet resistance, and by-product lignin in the papermaking industry is used, so that the material cost is reduced, and waste is turned into wealth.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering plastics, and in particular relates to a nylon composition and a preparation method and application thereof. Background Art

[0002] Halogen-free flame-retardant glass fiber reinforced polyamide (PA) refers to a polyamide material that does not contain halogen elements (such as chlorine, bromine, etc.) and has flame retardant properties. Halogen-free flame retardant polyamide usually achieves flame retardant effect by adding flame retardants containing elements such as phosphorus and nitrogen. These flame retardants can release flame retardant gases or form a protective film during combustion, thereby reducing the combustion performance of the material. At the same time, this type of material does not produce toxic halogen compounds during combustion, so it has good environmental protection and safety. Halogen-free flame retardant glass fiber reinforced polyamide combines the excellent performance of polyamide, the reinforcement effect of glass fiber and the safety of halogen-free flame retardants. With its green and environmentally friendly flame retardant properties, excellent mechanical properties and good heat resistance, it is widely used in fields such as electronics and electrical, automobiles, aerospace, rail transportation, and construction.

[0003] Although polyamide has many advantages and application scenarios, for products used outdoors, the material is usually required to have good UV resistance and resistance to wet and hot aging. PA itself has poor UV resistance, and the addition of halogen-free flame retardants will accelerate the aging of PA in a wet and hot environment, causing the color of polyamide products to change greatly and the mechanical properties to decline, affecting the appearance and use.

[0004] Lignin sulfonate, also known as sulfonated lignin, is a multi-component high molecular polymer anionic surfactant extracted from wood. It is mainly produced through the by-product of sulfite process papermaking pulp. Summary of the invention

[0005] The object of the present invention is to overcome the above-mentioned technical problems and provide a nylon composition, which overcomes the defects that halogen-free flame retardants cause the polyamide system to accelerate aging in a hot and humid environment, the color of the polyamide system changes greatly, and the mechanical properties decrease. The nylon composition provided by the present invention has the characteristics of low mold deposit, resistance to hot and humid aging, and resistance to ultraviolet rays.

[0006] Another object of the present invention is to provide a method for preparing the above nylon composition.

[0007] Another object of the present invention is to provide applications of the nylon composition.

[0008] The present invention is achieved through the following technical solutions: A nylon composition comprises the following components in parts by weight: PA resin 24-82.5 parts; Glass fiber 10-50 parts; Sodium lignin sulfonate 0.5-2 parts; 7-23 parts of halogen-free flame retardant; The sulfonation degree of sodium lignin sulfonate is 1.0-1.2 mmol / g, and the weight average molecular weight is 10000-14000 Da.

[0009] Preferably, the amount of sodium lignin sulfonate added is 1-2 parts by weight.

[0010] After testing, sodium lignin sulfonate has good anti-ultraviolet properties, and can neutralize the acidity of halogen-free flame retardants, improve the anti-ultraviolet aging properties and moisture-heat aging properties of halogen-free flame retardant glass fiber reinforced polyamide, and can also effectively reduce the weight of mold deposits.

[0011] When the degree of sulfonation is too low, the hydrophilicity of sodium lignin sulfonate decreases, and it is difficult to migrate to the surface during the UV resistance process, affecting the UV resistance effect. When the degree of sulfonation is too high, the hydrophilicity of sodium lignin sulfonate increases, and it is easy to precipitate to the surface during the wet heat aging process, and it cannot neutralize with the flame retardant; when the molecular weight is too low, sodium lignin sulfonate is easy to precipitate to the surface, and it cannot neutralize with the flame retardant during the wet heat aging process; when the molecular weight is too high, sodium lignin sulfonate is not easy to disperse, and it is difficult to migrate to the surface, affecting the UV resistance effect.

[0012] Preferably, the PA resin is selected from any one or more of nylon 6, nylon 66, or a copolymer of nylon 6 and nylon 66.

[0013] Preferably, the mass percentage of the PA resin in the nylon composition is not less than 20%.

[0014] Preferably, the glass fiber is selected from chopped fibers treated with a silane coupling agent containing an amino functional group or an epoxy functional group.

[0015] Preferably, the halogen-free flame retardant is selected from phosphorus-nitrogen halogen-free flame retardants.

[0016] Specifically, the phosphorus-nitrogen halogen-free flame retardant is selected from any one or more of red phosphorus, diethyl aluminum hypophosphite, melamine polyphosphate or melamine cyanurate.

[0017] Those skilled in the art can add 0.01-2 parts by weight of a processing aid according to actual needs, wherein the aid is selected from any one or more of an antioxidant or a lubricant.

[0018] Preferably, the antioxidant is selected from any one or more of hindered phenols, phosphites or thiophosphates; the lubricant is selected from any one or more of oxidized polyethylene wax, ethylene bis fatty acid amide or pentaerythritol stearate.

[0019] The present invention also provides a method for preparing the above nylon composition, characterized in that it comprises the following steps: M1: Dry the PA resin, mix the dried PA resin and other components except glass fiber evenly according to the proportion, and put the mixture into the main feeding hopper of the twin-screw extruder; M2: feeding glass fiber into the side feed hopper of the twin-screw extruder; M3: Set the temperature of each zone of the twin-screw extruder to 230-280°C, the feed rate to 300-500kg / h, and the main engine speed to 300-400rpm; M4: The melt is extruded through an extruder, cooled, and air-dried to obtain a nylon composition.

[0020] The present invention also provides an application of the nylon composition, characterized in that it is used to prepare electrical management components or electric tools.

[0021] The present invention has the following beneficial effects: Compared with the prior art, the nylon composition prepared by the present invention can simultaneously meet the following requirements: the injection mold deposit is less than 0.025 g; after a moisture and heat aging resistance test, the tensile strength retention rate is more than 50%; after a UV aging resistance test, the color difference before and after UV aging is less than 5.

[0022] The test shows that sodium lignin sulfonate has good anti-ultraviolet performance, and can neutralize the acidity of halogen-free flame retardant, improve the anti-ultraviolet aging performance and wet heat aging resistance of halogen-free flame retardant glass fiber reinforced polyamide, and at the same time, the weight of mold scale can be effectively reduced by adding sodium lignin sulfonate. The present invention uses lignin, a by-product of the papermaking industry, reduces the cost of materials, and realizes the transformation of waste into treasure. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0024] The raw materials used in the present invention come from: PA resin 1: Nylon 6, brand PA6 BE3270, Jiangsu Hongsheng.

[0025] PA resin 2: Nylon 66, brand PA66 EPR24, Chongqing Huafeng.

[0026] PA resin 3: nylon 66 / 6 copolymer, brand M093G02, Xinhui Meida.

[0027] Fiberglass 1: ECS10-3.0-568H, Jushi, China.

[0028] Glass fiber 2: HM435TM-10-3.0, Taishan Fiberglass.

[0029] Sodium lignin sulfonate was obtained by self-production. The self-production method is as follows: alkaline lignin and different amounts of sodium sulfite react under alkaline conditions, and sulfonic acid groups are connected to obtain lignin with different sulfonation degrees. The S content of alkaline lignin and sulfomethylated alkaline lignin is determined by elemental analysis and the sulfonation degree is calculated; further, lignin with different molecular weights is prepared by alkyl bridging.

[0030] The alkali lignin for preparing sodium lignin sulfonate was purchased from Xiangjiang, Hunan. After preparing sodium lignin sulfonate by sulfite method, it was washed, dialyzed, rotary evaporated and freeze-dried to obtain the following sodium lignin sulfonate raw materials.

[0031] Sodium lignin sulfonate 1: Sulfonation degree 1.06 mmol / g, weight average molecular weight 10473 Da.

[0032] Sodium lignin sulfonate 2: sulfonation degree 1.11 mmol / g, weight average molecular weight 12654 Da.

[0033] Sodium lignin sulfonate 3: sulfonation degree 1.15 mmol / g, weight average molecular weight 11891 Da.

[0034] Sodium lignin sulfonate 4: sulfonation degree 1.10 mmol / g, weight average molecular weight 13562 Da.

[0035] Sodium lignin sulfonate 5: Sulfonation degree 1.42 mmol / g, weight average molecular weight 12477 Da.

[0036] Sodium lignin sulfonate 6: sulfonation degree 0.76 mmol / g, weight average molecular weight 12612 Da.

[0037] Sodium lignin sulfonate 7: sulfonation degree 1.08 mmol / g, weight average molecular weight 16378 Da.

[0038] Sodium lignin sulfonate 8: sulfonation degree 1.14 mmol / g, weight average molecular weight 8270 Da.

[0039] Calcium lignin sulfonate: Sulfonation degree is about 1.13 mmol / g, and weight average molecular weight is about 12732 Da.

[0040] Magnesium lignin sulfonate: Sulfonation degree is about 1.15 mmol / g, and weight average molecular weight is about 12213 Da.

[0041] Halogen-free flame retardant 1: diethyl aluminum hypophosphite, brand OP1230, Clariant.

[0042] Halogen-free flame retardant 2: melamine polyphosphate, brand BUDIT 342, Budenheim.

[0043] Halogen-free flame retardant 3: red phosphorus, brand FR9950T, red phosphorus masterbatch, red phosphorus content 50%, same process.

[0044] Halogen-free flame retardant 4: melamine cyanurate, brand MCA-01, Sichuan Fine Chemicals.

[0045] Antioxidant 1: RIANOX 1010.

[0046] Antioxidant 2: RIANOX 168, RIANOX.

[0047] Lubricant: LOXIOL® P 861 / 3.5, Emery Oleochemicals GmbH.

[0048] Various test methods: The nylon composition prepared by the present invention is placed in a dehumidification drying oven at 120° C. and dried for 4 hours.

[0049] (1) Mold scale test: Use patented CN216544417U equipment to measure the mold scale weight of the material. The temperature of the injection molding machine is 290℃. After continuous injection of 200 molds, the weight difference △M of the scale before and after injection is measured, in g.

[0050] (2) Moisture and heat aging test: Injection molded tensile specimens were prepared according to ISO 527-2 standard. The specimens were placed in an aging box at 85°C and 85% RH for 1000 h. The tensile strength retention rate (TR) before and after aging was tested (in %).

[0051] (3) UV aging test: Aging was carried out according to the cycle one condition of method A in ISO4892-3. The color plate was placed in a UV aging box for 168 hours and the color difference △E before and after aging was tested.

[0052] Table 1 Weight parts of each component of nylon composition and test results of Examples 1-10:

[0053] It can be seen from Examples 1-13 that the nylon composition prepared by the present invention can simultaneously achieve the characteristics of low mold deposit, resistance to moisture and heat aging, and resistance to ultraviolet rays. Example 10 uses melamine cyanurate as a halogen-free flame retardant, which is easier to decompose than other halogen-free flame retardants and will cause a slight increase in the quality of mold deposit.

[0054] Table 2 Comparative Examples 1-7 Parts by weight of each component of the nylon composition and test results:

[0055] It can be seen from Comparative Examples 1-4 that when sodium lignin sulfonate does not simultaneously meet the range of sulfonation degree of 1.0-1.2 mmol / g and weight average molecular weight of 10000-14000 Da, experimental results show that the prepared nylon composition cannot simultaneously meet the requirements of low mold deposit, resistance to moisture and heat aging, and resistance to ultraviolet rays.

[0056] From Comparative Examples 5-6, it can be seen that when calcium lignin sulfonate and magnesium lignin sulfonate are used instead of sodium lignin sulfonate, the moisture and heat resistance and UV resistance of the prepared nylon composition are greatly reduced. It is speculated that the reason may be that calcium lignin sulfonate and magnesium lignin sulfonate are acidic and cannot neutralize the acidity of the halogen-free flame retardant.

[0057] Comparative Example 7 is a blank control without adding sodium lignin sulfonate.

Claims

1. A nylon composition, characterized in that: According to weight parts, it contains the following components: PA resin 24-82.5 parts; Glass fiber 10-50 parts; Sodium lignin sulfonate 0.5-2 parts; 7-23 parts of halogen-free flame retardant; The sulfonation degree of sodium lignin sulfonate is 1.0-1.2 mmol / g, and the weight average molecular weight is 10000-14000 Da.

2. A nylon composition according to claim 1, characterized in that: The PA resin is selected from any one or more of nylon 6, nylon 66, or a copolymer of nylon 6 and nylon 66.

3. A nylon composition according to claim 1, characterized in that: The glass fiber is selected from short-cut fibers treated with a silane coupling agent containing an amino functional group or an epoxy functional group.

4. A nylon composition according to claim 1, characterized in that: The halogen-free flame retardant is selected from phosphorus-nitrogen halogen-free flame retardants.

5. A nylon composition according to claim 4, characterized in that: The phosphorus-nitrogen halogen-free flame retardant is selected from any one or more of red phosphorus, diethyl aluminum hypophosphite, melamine polyphosphate or melamine cyanurate.

6. A nylon composition according to claim 1, characterized in that: According to the weight percentage, 0.01-2 parts of processing aids are also included, and the aids are selected from any one or more of antioxidants or lubricants.

7. A nylon composition according to claim 6, characterized in that: The antioxidant is selected from any one or more of hindered phenols, phosphites or thiophosphates; the lubricant is selected from any one or more of oxidized polyethylene wax, ethylene bis fatty acid amide or pentaerythritol stearate.

8. The method for preparing the nylon composition according to any one of claims 1 to 7, characterized in that: The following steps are involved: M1: Dry the PA resin, mix the dried PA resin and other components except glass fiber evenly according to the proportion, and put the mixture into the main feeding hopper of the twin-screw extruder; M2: feeding glass fiber into the side feed hopper of the twin-screw extruder; M3: Set the temperature of each zone of the twin-screw extruder to 230-280°C, the feed rate to 300-500kg / h, and the main engine speed to 300-400rpm; M4: The melt is extruded through an extruder, cooled, and air-dried to obtain a nylon composition.

9. The use of the nylon composition according to any one of claims 1 to 7, characterized in that: For use in the preparation of electrical management components or power tools.

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