Polyamide composite material, method for producing same, and use thereof

Abstract

The application discloses a kind of polyamide composite materials, by weight parts, including the following components: polyamide 75-95 parts;Melamine cyanurate 5-20 parts;Organic amine acid-base regulator 0.3-1.4 parts;The free cyanuric acid content in the melamine cyanurate is 2-6wt%;The pH value of polyamide composite material is 5.0-6.0.The application can effectively inhibit the precipitation of melamine cyanurate in the processing process by controlling the free cyanuric acid content in melamine cyanurate, and adjusting the pH value of the composite material by organic amine acid-base regulator, thereby significantly reducing mold scale.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polyamide composite material, its preparation method, and its application. Background Technology

[0002] Polyamide, commonly known as nylon, is an important thermoplastic engineering plastic. Due to its many excellent properties such as high strength, good self-lubrication, wear resistance, oil resistance, and ease of molding and processing, it is widely used in automobiles, mechanical parts, electronics, home appliances, and new energy fields. Nitrogen-based flame-retardant nylon refers to modified polyamide using melamine cyanurate (MCA) as a flame retardant. It features high mechanical properties, good flame retardancy, low smoke density, and a relatively high tracking index, and is widely used in connectors, low-voltage electrical appliances, and other industries. However, because MCA easily releases melamine during processing, mold fouling is prone to occur during injection molding. Mold fouling buildup can clog venting pipes, leading to appearance problems in the product. Therefore, mold fouling needs to be cleaned periodically, increasing production costs and hindering continuous production.

[0003] In existing technologies, the free cyanuric acid content in melamine cyanurate is generally less than 1 wt%. The main methods for modifying melamine cyanurate precipitation are: 1. Using other halogen-free flame retardants to replace or reduce the amount of MCA added; 2. Performing surface modification treatment on the material to inhibit MCA precipitation. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical defects and provide a polyamide composite material that is resistant to precipitation and has low mold fouling.

[0005] This invention is achieved through the following technical solution:

[0006] A polyamide composite material, by weight, comprises the following components:

[0007] 75-95 parts of polyamide;

[0008] 5-20 parts of melamine cyanurate;

[0009] Organic amine acid-base regulator: 0.3-1.4 parts;

[0010] The free cyanuric acid content in the melamine cyanurate is 2-6 wt%.

[0011] The pH value of the polyamide composite material is 5.0-6.0.

[0012] The pH test method for polyamide composite materials is as follows: Take 8g of polyamide composite material particles (particle diameter range is 1.5-4mm, length is 3-5mm) and place them in a glass bottle, add 20g of deionized water, seal, and then place in an oven at 80℃ for 24h. After taking it out and cooling it to room temperature, use a pH meter to test the pH value of the upper solution.

[0013] Preferably, the pH value of the polyamide composite material is 5.3-5.7.

[0014] Preferably, the free cyanuric acid content in the melamine cyanurate is 3-4 wt%.

[0015] Melamine cyanurate with a specific cyanuric acid content can be a commercially available product or can be obtained in-house. The preparation process is as follows: Melamine cyanurate and cyanuric acid are ground separately to 300-1500 mesh, then thoroughly and uniformly mixed in a specific ratio, placed in a high-temperature reactor at 310-330℃, and purged with nitrogen gas. The reaction is carried out for 0.5-2 hours to obtain the target melamine cyanurate.

[0016] Test method for free cyanuric acid content: Weigh 2g of melamine cyanurate using a balance, add it to a certain amount of dimethylformamide solution to fully dissolve the free cyanuric acid in the sample, then filter it, place the filter cake in a vacuum oven at 120℃ to dry, weigh the obtained filter cake, and the free cyanuric acid content is calculated as follows: Free cyanuric acid content = (initial weight of sample - remaining weight) / initial weight of sample × 100%.

[0017] The organic amine acid-base regulator is selected from at least one of 4,4'-di(phenylisopropyl)diphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-di(α,α-dimethylbenzyl)diphenylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-phenyl-N'-cyclohexyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-(1-methylisopentyl)-N'-phenyl-p-phenylenediamine, N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, 4,4'-diisooctyldiphenylamine, and N,N'-di(2-naphthyl)-p-phenylenediamine.

[0018] The polyamide is selected from aliphatic polyamide resins, and the aliphatic polyamide resin is selected from at least one of PA6, PA11, PA12, PA66, PA610, PA612, PA1010, PA1012, and PA1212.

[0019] The relative viscosity of the polyamide is 2-3.4. The test conditions are 0.01 g / mL concentrated sulfuric acid solution at 25°C. The method for detecting the relative viscosity is as follows: Weigh 0.5 g of polyamide resin, transfer it to a 50 ml volumetric flask, add about 40 ml of 96% (w / v) concentrated sulfuric acid, and sonicate until the polyamide resin is completely dissolved. Cool the solution to 25°C, dilute it to the mark with concentrated sulfuric acid, and mix well. Measure the flow time of the 0.01 g / mL polyamide resin solution at 25°C through an Ubbelohde viscometer, and record it as t1. Measure the flow time of the concentrated sulfuric acid solvent using the same viscometer, and record it as t2. t1 / t2 is the relative viscosity.

[0020] Depending on actual needs, 0-2 parts of an additive may be added. The additive is selected from at least one of antioxidants and lubricants. Antioxidants may be hindered phenolic antioxidants, phosphite antioxidants, cuprous halide complex antioxidants, or antioxidants containing benzophenone functional groups, etc. Lubricants may be hydrocarbons, esters, alcohols, stearates, fatty acids, fatty acid amides, etc.

[0021] You can choose whether to add 0-10 parts toughening agent depending on the actual needs.

[0022] The preparation method of the polyamide composite material of the present invention includes the following steps: according to the formula, the components are mixed evenly, and granulated by extrusion through a twin-screw extruder. The barrel temperature range is 160-250℃, the die head temperature is 230-260℃, and the rotation speed is 250-500rpm to obtain the polyamide composite material.

[0023] The polyamide composite material of this invention is used to manufacture connectors, industrial plugs, miniature circuit breaker housings, molded case circuit breaker housings, etc.

[0024] The present invention has the following beneficial effects:

[0025] This invention effectively inhibits the precipitation of melamine cyanurate during processing by controlling the content of free cyanuric acid in melamine cyanurate and adjusting the pH value of the composite material with an organic amine acid-base regulator, thereby reducing mold fouling. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0027] PA66: PA66 EPR24, relative viscosity 2.4, Shenma Group;

[0028] PA6: PA6 HY2800A, relative viscosity 2.8, Jiangsu Haiyang Chemical Fiber Co., Ltd.;

[0029] PA610: PA610 F120, relative viscosity 2.2, Shandong Guangyin New Materials Co., Ltd.;

[0030] Cyanuric acid: Aladdin;

[0031] Melamine cyanurate B~G were prepared by the following method: Melamine cyanurate A and cyanuric acid were ground to a particle size of less than 300 mesh, then thoroughly mixed in proportion, placed in a high-temperature reactor at 320°C, and charged with nitrogen gas. The reaction was carried out for 1 hour to obtain melamine cyanurate B, melamine cyanurate C, melamine cyanurate D, melamine cyanurate E, melamine cyanurate F, and melamine cyanurate G, respectively. Finally, the free cyanuric acid content was determined.

[0032] Free cyanuric acid content / % source Melamine cyanurate A 0.09 Shouguang Weidong Chemical Co., Ltd. Melamine cyanurate B 0.67 self made Melamine cyanurate C 2.12 self made Melamine cyanurate D 3.12 self made Melamine cyanurate E 4.00 self made Melamine cyanurate F 5.95 self made Melamine cyanurate G 8.44 self made

[0033] Acid-base regulator A: 4,4'-Di(phenylisopropyl)diphenylamine: NAUGARD 445, manufactured by Saint-Gobain;

[0034] Acid-base regulator B: 4,4'-dioctyldiphenylamine, manufactured by Maclean's Reagents;

[0035] Acid-base regulator C: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, manufactured by Anaiji Chemical;

[0036] Acid-base regulator D: N-isopropyl-N'-phenyl-p-phenylenediamine, manufactured by Anaiji Chemical;

[0037] Acid-base regulator E: calcium hydroxide, manufactured by Aladdin;

[0038] Antioxidant: IRGANOX 1098, a hindered phenolic antioxidant, manufactured by BASF;

[0039] Lubricant: BS-3818, calcium stearate, manufactured by Bailihe Chemical (Zhongshan) Co., Ltd.

[0040] Preparation method of polyamide composite material in the examples and comparative examples: According to the formula, the components are mixed evenly and extruded and granulated by twin-screw extruder. The barrel temperature range is 160-250℃, the die head temperature is 230-260℃, and the speed is 250-500rpm to obtain polyamide composite material.

[0041] Test methods:

[0042] (1) Flame retardancy: The flame retardancy performance of the injection-molded 125*13*0.8mm burning sample strip was tested according to UL 94 standard.

[0043] (2) pH value of polyamide composite material: Take 8g of plastic particles and place them in a glass bottle, add 20g of deionized water, seal, and then place in an oven at 80℃ for 24h. After taking it out and cooling it to room temperature, use a pH meter to test the pH value of the upper layer solution.

[0044] (3) Mold fouling weight: A groove is designed at the venting end of the mold, and a metal sheet is placed inside to collect mold fouling (both the moving mold and the fixed mold have metal sheets for collecting mold fouling). The injection temperature is set to 290℃, the injection cycle is 20s, and 150 molds are continuously injected. The weight of mold fouling is calculated by the following formula: Mold fouling weight = weight of metal sheet after injection - weight of metal sheet before injection.

[0045] Table 1: Component content and test results of polyamide composites in Examples 1-6

[0046] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PA610 75 PA66 85 85 85 85 PA6 95 Melamine cyanurate grade E E E C D F Melamine cyanurate content 20 10 5 10 10 10 Acid-base regulator label A A A A A A Acid-base regulator content 1.4 0.9 0.3 0.9 0.9 0.9 antioxidants 0.2 0.2 0.2 0.2 0.2 lubricant 0.5 0.5 0.5 0.5 0.5 pH value 5.06 5.36 5.45 5.64 5.55 5.11 Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 Scale weight, mg 1.0 0.5 0.5 0.9 0.6 1.0

[0047] As can be seen from Examples 2 / 4 / 5 / 6, when the free cyanuric acid content of melamine cyanurate is preferred, there is less mold buildup.

[0048] Table 2: Component content and test results of polyamide composites in Examples 7-12

[0049] Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 PA66 85 85 85 85 85 85 Melamine cyanurate E 10 10 10 10 10 10 Acid-base regulator label B C D A A A Acid-base regulator content 0.9 0.9 0.9 0.3 1.2 1.4 antioxidants 0.2 0.2 0.2 0.2 0.2 0.2 lubricant 0.5 0.5 0.2 0.2 0.2 0.2 pH value 5.58 5.86 5.52 5.02 5.67 5.81 Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 Scale weight, mg 0.7 0.9 0.6 0.9 0.6 1.0

[0050] As can be seen from Examples 2 / 7-12, the scale content is better when the pH is within the preferred range.

[0051] Table 3: Component content and test results of comparative polyamide composite materials

[0052] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 PA66 85 85 85 85 Melamine cyanurate grade A B G G Melamine cyanurate content 10 10 10 10 Acid-base regulator label A A A A Acid-base regulator content 1.2 0.9 1.4 1.5 antioxidants 0.2 0.2 0.2 0.2 lubricant 0.5 0.5 0.5 0.5 pH value 5.92 5.81 4.88 5.03 Flame retardancy V-0 V-0 V-0 V-0 Scale weight, mg 3.2 2.5 3.7 3.4

[0053] As can be seen from Comparative Example 1 / 2, when the free cyanuric acid content in melamine cyanurate is too low, even if the pH is within the range of the present invention, there is still too much fouling.

[0054] As can be seen from Comparative Example 3 / 4, if the free cyanuric acid content in melamine cyanurate is too high, even if the pH is brought within the range of the present invention by adding acid-base regulators, there will still be too much fouling.

[0055] Continued from Table 3:

[0056] Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 PA66 85 85 85 85 Melamine cyanurate grade E E E E Melamine cyanurate content 10 10 10 10 Acid-base regulator label A A E E Acid-base regulator content 0 2 0.9 0.3 antioxidants 0.2 0.2 0.2 0.2 lubricant 0.5 0.5 0.5 0.5 pH value 4.55 6.36 6.74 5.91 Flame retardancy V-0 V-2 V-2 V-2 Scale weight, mg 1.8 2.8 4.2 3.3

[0057] As can be seen from Comparative Example 5, Examples 10 / 2 / 11 / 12, and Comparative Example 6, when the pH is outside the range of the present invention, the scale content is too high. Moreover, when the pH value of Comparative Example 6 is too high, it also affects the flame retardancy.

[0058] As can be seen from Comparative Example 7, calcium hydroxide, due to its granular state in the screw barrel and small specific surface area, is insufficient for consuming free cyanuric acid. At the same time, its strong alkalinity may corrode the resin matrix, resulting in a decrease in flame retardancy and an increase in mold fouling.

[0059] As can be seen from Comparative Example 8, even if the pH value of the present invention is obtained by adjusting the calcium hydroxide content, its strong alkalinity damages the resin matrix, resulting in poor flame retardancy and excessive mold fouling.

Claims

1. A polyamide composite material, characterized in that, By weight, it includes the following components: 75-95 parts of polyamide; 5-20 parts of melamine cyanurate; Organic amine acid-base regulator: 0.3-1.4 parts; The free cyanuric acid content in the melamine cyanurate is 2-6 wt%. The pH value of the polyamide composite material is 5.0-6.0; The pH test method for polyamide composite materials is as follows: Take 8g of plastic particles and place them in a glass bottle, add 20g of deionized water, seal the bottle, and then place it in an oven at 80℃ for 24h. After taking it out and cooling it to room temperature, use a pH meter to test the pH value of the upper solution. The organic amine acid-base regulator is selected from at least one of 4,4'-di(phenylisopropyl)diphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-di(α,α-dimethylbenzyl)diphenylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-phenyl-N'-cyclohexyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-(1-methylisopentyl)-N'-phenyl-p-phenylenediamine, N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, 4,4'-diisooctyldiphenylamine, and N,N'-di(2-naphthyl)-p-phenylenediamine.

2. The polyamide composite material according to claim 1, characterized in that, The pH value of the polyamide composite material is 5.3-5.

7.

3. The polyamide composite material according to claim 1, characterized in that, The free cyanuric acid content in the melamine cyanurate is 3-4 wt%.

4. The polyamide composite material according to claim 1, characterized in that, The polyamide is selected from aliphatic polyamide resins, and the aliphatic polyamide resin is selected from at least one of PA6, PA11, PA12, PA66, PA610, PA612, PA1010, PA1012, and PA1212.

5. The polyamide composite material according to claim 1, characterized in that, The relative viscosity of the polyamide is 2-3.

4. The detection method is as follows: Weigh 0.5g of polyamide resin, transfer it to a 50ml volumetric flask, add 40ml of 96% concentrated sulfuric acid, and sonicate until the polyamide resin is completely dissolved. Cool the solution to 25℃, dilute it to the mark with concentrated sulfuric acid, and mix it evenly. Measure the flow time of the 0.01g / mL polyamide resin solution at 25℃ through the Ubbelohde viscometer and record it as t1. Measure the flow time of the concentrated sulfuric acid solvent using the same viscometer and record it as t2. t1 / t2 is the relative viscosity.

6. The polyamide composite material according to claim 1, characterized in that, The product also includes 0-2 parts by weight of additives, the amount of which is not 0, wherein the additives are selected from at least one of antioxidants and lubricants.

7. The polyamide composite material according to claim 1, characterized in that, It also includes 0-10 parts toughening agent by weight, with the amount not being 0.

8. A method for preparing the polyamide composite material according to any one of claims 1-7, characterized in that, The process includes the following steps: mixing the components evenly according to the formula, granulating the mixture by extrusion through a twin-screw extruder, with the barrel temperature range being 160-250℃, the die head temperature being 230-260℃, and the rotation speed being 250-500rpm, to obtain a polyamide composite material.

9. The application of the polyamide composite material according to any one of claims 1-7, characterized in that, Used in the manufacture of connectors and miniature circuit breaker housings.

10. The application of the polyamide composite material according to any one of claims 1-7, characterized in that, Used in the manufacture of industrial plugs and molded case circuit breaker housings.