Polyamide composition as well as preparation method and application thereof

Abstract

The invention discloses a polyamide composition which comprises the following components in parts by weight: 50-80 parts of polyamide resin; 0.2 to 10 parts of zinc sulfide coated with silicon dioxide; 0.1 to 2 parts of an antioxidant; wherein less than 50 mmol of HCl can be consumed per 1 kg of the polyamide composition. The silicon dioxide coated zinc sulfide is added into the polyamide composition, and the content of alkaline groups / alkaline substances in the polyamide composition is controlled to be within a specific range, so that the advantage of excellent yellowing resistance can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a polyamide composition and a preparation method and application thereof. Background Art

[0002] Modified polyamides, due to their excellent comprehensive properties, including good mechanical properties, chemical resistance, and heat resistance, are widely used in internal load-bearing parts or housing components in industries such as rail transit, consumer electronics, power tools, and shared bicycles. Currently, reinforced polyamide materials are increasingly used in products such as kitchen appliances, hairdressing equipment, and power tools. These products often face high temperature environments and have relatively strict requirements on product appearance. Since the polyamide matrix is ​​prone to yellowing when used at temperatures exceeding 80°C for a long time, and the whitening zinc sulfide in the polyamide composition will also yellow, it will significantly affect the user experience. Therefore, the industry has put forward increasingly stringent requirements for the high-temperature color stability and anti-yellowing performance of such materials, as well as the molded appearance.

[0003] Currently, literature and patents have reported some polyamide anti-yellowing technologies, and some solutions to improve high-temperature yellowing have been proposed, but there are few efficient high-temperature anti-yellowing solutions for white or light-colored polyamide / polyester alloy systems. Summary of the Invention

[0004] The object of the present invention is to provide a polyamide composition with good yellowing resistance.

[0005] The present invention is achieved through the following technical solutions: A polyamide composition comprising the following components in parts by weight: 50-80 parts of polyamide resin; 0.2-10 parts of silicon dioxide-coated zinc sulfide; 0.1-2 parts of antioxidant; Wherein, less than 50 mmol of HCl can be consumed per 1 kg of the polyamide composition.

[0006] In the polyamide composition of the present invention, the polyamide resin accounts for no less than 50 wt % of the total weight.

[0007] The substances or groups that can consume HCl in the polyamide molding composition are mainly basic groups and basic substances, the sources of which are mainly the terminal amino groups of the polyamide resin, as well as other organic basic substances or inorganic basic substances, organic basic substances such as basic antioxidants (such as aromatic amine antioxidants, hydroxylamine antioxidants), weathering agents (such as histamine-sensitive light stabilizers), inorganic basic substances such as alkaline earth metal oxides, inorganic hydroxides, etc.

[0008] The test method for the amount of HCl that a polyamide molding composition can consume is as follows: refer to standard HG / T 4182-2012 and titrate with a fully automatic potentiometric titrator; take 0.6500±0.0500g of the polyamide molding composition, place it in a 100mL flask with a condenser, add 40-50mL of 88% trifluoroethanol reagent, heat and stir to dissolve for 30-60 minutes, place the conical flask in a beaker filled with water and cool to room temperature, transfer the entire solution to a titration cup, start the automatic potentiometric titrator, and titrate with 0.02mol / L HCl standard solution while stirring. Stop the titration when the potential reaches pH 7.0.

[0009] The coating amount of silicon dioxide in the silicon dioxide-coated zinc sulfide accounts for 0.1-5.5% of the total weight.

[0010] Preferably, the silica coating amount in the silica-coated zinc sulfide accounts for 0.3-5% of the total weight.

[0011] More preferably, the silica coating content of the silica-coated zinc sulfide is 1.5-3.3% of the total weight. The silica coating content of the silica-coated zinc sulfide can be tested by the following method: reacting zinc sulfide with dilute sulfuric acid, filtering, drying, and weighing the silica that does not participate in the reaction.

[0012] Silica-coated zinc sulfide can be prepared according to the following method: zinc sulfide is dispersed in 10-30 times the weight of ethanol, dispersed by ultrasonic vibration, heated to 50-70°C, and 0.1-0.5 times the weight (based on zinc sulfide) of deionized water is added while stirring; then, the pH is controlled between 9 and 11 with ammonia water, and an orthosilicate compound (which can be methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, etc.) is added. After the addition of the orthosilicate compound, continuous mechanical stirring is carried out at a speed of 200-300 rpm for 10-14 hours. The orthosilicate compound reacts to generate silica, which is coated on the surface of the zinc sulfide; after the stirring is completed, an appropriate amount of anhydrous alcohol solvent is added for washing 2-4 times, and the powder is placed in a vacuum drying oven and vacuum dried. After drying, it is filtered through a mesh to remove agglomerated powder to obtain silica-coated zinc sulfide. The coating weight percentage of silicon dioxide can be adjusted by changing the addition ratio of zinc sulfide and orthosilicate compound.

[0013] The polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin and polylactam resin.

[0014] The aliphatic polyamide resin is selected from PA66, PA46, PA610, PA612, PA56, PA510, PA512, PA910, PA912, PA913, PA914, PA915, PA616, PA936, PA1010, PA1012, PA1013, PA1014, PA1210, PA1212, PA1213, PA1214, PA614, PA613, PA615, PA616, PAPACM12, etc.

[0015] The semi-aromatic polyamide is selected from PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, PA9T and the like.

[0016] The polylactam is selected from PA5, PA6, PA11, PA12 and the like.

[0017] The raw material polyamide resin of the present invention can be a commercially available product or can be obtained in-house. The preparation method comprises the following steps: adding a diamine and a diacid in a 1:1 molar ratio to an autoclave; then adding a capping agent (benzoic acid), a catalyst (sodium hypophosphite), and deionized water; evacuating the autoclave and introducing high-purity nitrogen as a protective gas; raising the temperature to 210-230°C over 1-3 hours while stirring; stirring the reaction mixture for 0.5-1.5 hours; and then raising the temperature to 230-250°C while stirring; continuing the reaction at a constant temperature and pressure for 1-3 hours, maintaining the pressure constant by removing the formed water; and discharging the prepolymer after completion of the reaction. The prepolymer is vacuum-dried at 75-85°C to obtain a prepolymerized product, and the prepolymerized product is solid-phase thickened at 240-260°C and 40-60 Pa under vacuum conditions for 8-12 hours to obtain the polyamide resin. The end amino group content can be adjusted by adjusting the amount of the capping agent.

[0018] The terminal amino group content of polyamide resin is also tested by acid-base titration.

[0019] The antioxidant is selected from at least one of hindered phenol antioxidants and phosphite antioxidants.

[0020] Specifically, the hindered phenol antioxidant is selected from: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (CAS: 23128-74-7), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS: 6683-19-8), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS: 2082-79-3), 2,4-bis(n-octylthiomethylene)-6-methylphenol (CAS: 110553-27-0), etc. The phosphite antioxidant is selected from: tris(2,4-di-tert-butylphenyl)phosphite (CAS: 31570-04-4); bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (CAS: 26741-53-7); bis(2,4-dicumylphenyl)diphosphite (CAS: 154862-43-8); bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate (CAS: 80693-00-1), etc.

[0021] Whether to add 0-30 parts by weight of glass fiber can be selected according to actual needs.

[0022] The polyamide composition further comprises 0-3 parts by weight of one or more organic alkaline substances and inorganic alkaline substances, so as to consume less than 50 mmol of HCl per kg of the polyamide composition.

[0023] The preparation method of the polyamide molding composition of the present invention comprises the following steps: uniformly mixing the components according to the proportion, and extruding and granulating the components through a twin-screw extruder at a temperature range of 180-320° C. and a rotation speed range of 200-700 rpm to obtain the polyamide molding composition.

[0024] The polyamide molding composition of the present invention is used for preparing electrical appliance housings.

[0025] The present invention has the following beneficial effects: 1. The present invention can significantly improve the yellowing resistance of zinc sulfide by coating zinc sulfide with silicon dioxide.

[0026] 2. The present invention has found that when the polyamide molding composition contains basic groups or basic substances that can consume a specific amount of HCl, the yellowing resistance effect will be significantly affected. By controlling the content of the basic substance in the composition within a specific range, the advantage of excellent yellowing resistance can be obtained. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to 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 skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0028] The raw materials used in the present invention come from the following sources: The following polyamide resins were prepared according to the method described in the Summary of the Invention. The terminal amino group content was controlled by controlling the amount of end-capping agent added. The molecular weights of the following polyamide resins are similar: PA66-A: amino terminal content is 20 mmol / kg; PA66-B: terminal amino content is 33 mmol / kg; PA66-C: terminal amino content is 43 mmol / kg; PA66-D: terminal amino content is 54 mmol / kg; PA66-E: The terminal amino group content is 72 mmol / kg.

[0029] PA6: terminal amino content is 51mmol / kg; PA10T: terminal amino group content is 29 mmol / kg; Hydroxylamine antioxidant: REVONOX 420, CAS No. 143925-92-2, Taiwan Qitai; Histamine-sensitive light stabilizer: IRESORB-944, CAS No. 70624-18-9, Suqian Liansheng; Hindered phenol antioxidant: IRGANOX 1098, CAS No. 23128-74-7; Alkaline earth metal oxides: magnesium oxide, Aladdin reagent; Phosphite antioxidant: IRGAFOS 168, BASF, Germany; The following zinc sulfide was purchased from Sachliben, Germany, brand HD-S; The following silica-coated zinc sulfide was prepared in-house according to the method described in the Summary of the Invention. The silica coating weight percentage can be adjusted by controlling the ratio of zinc sulfide and orthosilicate compound. The zinc sulfide raw material is HD-S, from Sachsenhalben, Germany: Silica-coated zinc sulfide A: The silica coating content accounts for 0.3% of the total weight; Silica-coated zinc sulfide B: The silica coating content accounts for 1.5% of the total weight; Silica-coated zinc sulfide C: The silica coating accounts for 3.3% of the total weight; Silica-coated zinc sulfide D: The silica coating accounts for 4.8% of the total weight; Silica-coated zinc sulfide E: The silica coating content accounts for 0.1% of the total weight; Silica-coated zinc sulfide F: The silica coating accounts for 5.5% of the total weight; Ordinary zinc sulfide: zinc sulfide HD-S, from Germany; Glass fiber: Glass fiber ECS301CL-3-H, CPIC Chongqing International; Preparation method of the polyamide composition of the embodiment and comparative example: According to the ratio, the components are mixed uniformly, and granulated by extrusion through a twin-screw extruder at a temperature range of 180-320°C (when the embodiment of the present invention and the comparative example are the same polyamide type) and a rotation speed range of 360 rpm to obtain a polyamide composition.

[0030] Various test methods: (1) The test method for the amount of HCl that a polyamide composition can consume is as follows: titrate the alkaline substance content of the sample using a fully automatic potentiometric titrator; take 0.6500±0.0500g of the polyamide molding composition, put it into a 100mL flask with a condenser, add 40-50mL of 88% trifluoroethanol reagent, heat and stir to dissolve for 30-60min, put the conical flask into a beaker filled with water and cool to room temperature, transfer the entire solution to the titration cup, turn on the automatic potentiometric titrator, and titrate with 0.02mol / L HCl standard solution while stirring, and stop titrating when the potential reaches pH 7.0.

[0031] (2) Color stability: Evaluate the color stability after high-temperature baking. The color plate is baked at 140°C for 24 hours, and the color change △E is tested according to the color difference test standard GB / T 3979:2008 to evaluate the material's baking yellowing resistance.

[0032] Table 1: Content of each component (parts by weight) and test results of polyamide compositions of Examples 1-6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PA66-A 50 65 80 PA66-B 65 PA66-C 65 PA66-D 65 Silica coated zinc sulfide A 0.2 5 10 5 5 5 Hindered phenol antioxidants 0.05 0.2 1 0.2 0.2 0.2 Phosphite antioxidant 0.05 0.2 1 0.2 0.2 0.2 Amount of HCl consumed mmol / kg 21 19 18 31 40 49 Color stability △E 8.7 7.8 7.1 9.0 9.8 10.5 It can be seen from Examples 1-6 that the amount of HCl consumed by the polyamide composition and the antioxidant content both significantly affect the color stability.

[0033] Table 2: Content of each component (parts by weight) and test results of the polyamide molding compositions of Examples 7-11 Example 7 Example 8 Example 9 Example 10 Example 11 PA66-A 65 65 65 65 65 Silica coated zinc sulfide A Silica coated zinc sulfide B 5 Silica coated zinc sulfide C 5 Silica coated zinc sulfide D 5 Silica coated zinc sulfide E 5 Silica coated zinc sulfide F 5 Hindered phenol antioxidants 0.2 0.2 0.2 0.2 0.2 Phosphite antioxidant 0.2 0.2 0.2 0.2 0.2 Amount of HCl consumed mmol / kg 18 19 18 18 18 Color stability △E 7.4 7.6 8.0 8.2 8.4 It can be seen from Examples 2 / 7-11 that the color stability is higher when the silica coating content in the silica-coated zinc sulfide is preferably higher.

[0034] Table 3: Content of each component (parts by weight) and test results of the polyamide molding compositions of Examples 12-16 Example 12 Example 13 Example 14 Example 15 Example 16 PA66-A 65 65 65 PA6 65 PA10T 65 Silica coated zinc sulfide A 5 5 5 5 5 Hindered phenol antioxidants 0.2 0.2 0.2 Phosphite antioxidant 0.2 0.2 0.2 Hydroxylamine antioxidants 0.4 Histamine-sensitive light stabilizers 0.4 Alkaline earth metal oxides 0.08 fiberglass 20 Amount of HCl consumed mmol / kg 26 25 46 47 26 Color stability △E 9.6 10.6 10.4 10.8 8.7 It can be seen from Examples 12-13 that the hindered phenol antioxidants and phosphite antioxidants in the technical solution of the present invention have better antioxidant properties.

[0035] It can be seen from the above examples that the more HCl the polyamide molding composition consumes, the lower the color stability.

[0036] Table 4: Content of each component (parts by weight) and test results of the comparative polyamide molding composition Comparative Example 1 Comparative Example 2 Comparative Example 3 PA66-D 65 PA66-E 65 PA66-A 65 Silica coated zinc sulfide A 5 5 Ordinary zinc sulfide 5 Hindered phenol antioxidants 0.2 0.2 0.2 Phosphite antioxidant 0.2 0.2 0.2 Alkaline earth metal oxides 0.3 fiberglass 10 Amount of HCl consumed mmol / kg 48 71 64 Color stability △E 12.6 13.3 11.9 It can be seen from Comparative Example 1 and Example 2 that ordinary zinc sulfide has poor yellowing resistance.

[0037] It can be seen from Comparative Example 3 that if other alkaline substances are added to make the amount of HCl consumed greater than 50 mmol / kg, the yellowing resistance will be significantly reduced.

Claims

1. A polyamide composition, characterized in that Calculated by weight, it includes the following components: 50-80 parts of polyamide resin; 0.2-10 parts of silicon dioxide-coated zinc sulfide; 0.1-2 parts of antioxidant; Wherein, less than 50 mmol of HCl can be consumed per 1 kg of the polyamide composition.

2. The polyamide composition according to claim 1, characterized in that The test method for the amount of HCl that can be consumed per 1 kg of the polyamide composition is to titrate with a fully automatic potentiometric titrator: take 0.6500±0.0500g of the polyamide composition, put it into a 100mL flask with a condenser, add 40-50mL of 88% trifluoroethanol reagent, heat and stir to dissolve for 30-60 minutes, put the conical flask into a beaker filled with water and cool to room temperature, transfer the entire solution to the titration cup, start the automatic potentiometric titrator, and titrate with 0.02mol / L HCl standard solution under stirring. Stop the titration when the potential reaches pH 7.

0.

3. The polyamide composition according to claim 1, characterized in that The amount of silica coated in the silica coated zinc sulfide accounts for 0.1-5.5% of the total weight. Preferably, the amount of silica coated in the silica coated zinc sulfide accounts for 0.3-5% of the total weight.

4. The polyamide composition according to claim 3, characterized in that The coating amount of silicon dioxide in the silicon dioxide-coated zinc sulfide accounts for 1.5-3.3% of the total weight.

5. The polyamide composition according to claim 1, characterized in that The antioxidant is selected from at least one of hindered phenol antioxidants and phosphite antioxidants.

6. The polyamide composition according to claim 1, characterized in that The polyamide resin is selected from at least one of semi-aromatic polyamide resin, aliphatic polyamide resin and polylactam resin.

7. The polyamide composition according to claim 1, characterized in that By weight, 0-30 parts of glass fiber are also included.

8. The polyamide composition according to claim 1, characterized in that Calculated by weight, it also includes 0-3 parts of one or more organic alkaline substances and inorganic alkaline substances.

9. The method for preparing the polyamide composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: uniformly mixing the components according to the proportion, extruding and granulating the components through a twin-screw extruder at a temperature of 180-320° C. and a rotation speed of 200-700 rpm to obtain a polyamide composition.

10. Use of the polyamide composition according to any one of claims 1 to 7, characterized in that: Used for preparing electrical appliance casings.