A polyamide composite material and its preparation method and application

Abstract

A polyamide composite material comprises the following components, by weight: 40-60 parts polyamide resin (PA6 or PA66); 4-15 parts polybutylene terephthalate (PBT) resin; and 0.5-3 parts compatibilizer. The polyamide resin has a terminal amino group content of 0.05-0.15 mg / L; and the compatibilizer is selected from at least one of ethylene-butyl acrylate copolymer and ethylene-methyl acrylate copolymer. By selecting a specific polyamide resin with a specific terminal amino group content and a PBT resin with a specific terminal carboxyl group content to achieve a specific terminal group ratio, and also selecting a specific compatibilizer, the present invention significantly reduces cracking in finished parts caused by excessive internal stress due to the addition of semi-crystalline PBT resin, and improves notched impact strength, making it suitable for the production of thick-walled parts.

Description

Technical Field

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

[0002] Nylon has good strength and toughness and is widely used in the electrical and electronic fields. As the scope of application expands, some products with thicker walls are also applied to polyamide.

[0003] However, polyamide is a crystalline material that crystallizes during cooling as the temperature changes. Crystalline materials shrink more than amorphous materials, which in turn creates more stress in the product. Excessive stress in a product can significantly impact its subsequent use, causing cracking or even collapse under minimal force.

[0004] Currently, the primary method for addressing product stress in industry is through annealing. However, annealing increases equipment investment, complicates the process, and significantly prolongs the manufacturing process, leading to low efficiency and increased costs, which has been a persistent problem for industrial manufacturing. Optimizing structural design, on the other hand, has limited potential to reduce product stress.

[0005] In this field, amorphous materials are often added to nylon materials to reduce the shrinkage of the later products and reduce the internal stress of the parts. However, amorphous materials will affect the notched impact strength of nylon itself. Summary of the Invention

[0006] The object of the present invention is to solve the above technical defects and provide a polyamide composite material with low internal stress.

[0007] The present invention is achieved through the following technical solutions:

[0008] A polyamide composite material, comprising the following components in parts by weight:

[0009] 40-60 parts of polyamide resin;

[0010] 4-15 parts of PBT resin;

[0011] Compatibilizer 0.5-3 parts;

[0012] The polyamide resin has an amino group content of 0.05-0.15 mg / L, and the PBT resin has a carboxyl group content of 0.015-0.03 mg / L.

[0013] The compatibilizer is selected from at least one of ethylene-butyl acrylate copolymer and ethylene-methyl acrylate copolymer;

[0014] The polyamide resin is selected from at least one of PA6 and PA66.

[0015] The preferred PBT resin content is 8-10 parts.

[0016] The test method for the terminal carboxyl content of PBT resin is as follows: titrate the terminal carboxyl content of the sample using a fully automatic potentiometric titrator; weigh 2g of the sample, add 50mL of a phenol / chloroform mixed solvent (phenol:chloroform mixed in a volume ratio of 2:3), heat until the sample is dissolved, cool to room temperature, and titrate with a calibrated potassium hydroxide-ethanol standard solution to obtain the terminal carboxyl content of the PBT resin.

[0017] The test method for the amino group content of polyamide resin is as follows: titrate the amino group content of the sample using a fully automatic potentiometric titrator; take 0.5g of polymer, add 45mL of phenol and 3mL of anhydrous methanol, heat to reflux, observe that the sample is completely dissolved, cool to room temperature, and titrate the amino group content with a calibrated hydrochloric acid standard solution.

[0018] Preferably, the polyamide resin has a terminal amino group content of 0.08-0.12 mg / L.

[0019] The viscosity of the polyamide resin of the present application (according to ISO 307 test standard) can be 2.5-3.0.

[0020] In the compatibilizer, the weight content of ethylene units is 63-83 wt%, preferably 72-77 wt%.

[0021] Preferably, the compatibilizer is selected from ethylene-butyl acrylate copolymer.

[0022] Preferably, the content of the compatibilizer is in the range of 1.2-2 parts.

[0023] Preferably, the polyamide resin is selected from PA6.

[0024] The addition of 0-30 parts of fillers or other additives may be selected based on actual needs. Fillers may include glass fiber, talc, etc. Other additives may include antioxidants, lubricants, weathering agents, etc. The weight content of the polyamide resin in the polyamide composite material of the present invention is not less than 60 wt%.

[0025] The preparation method of the polyamide composite material 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 with a screw temperature range of 220-270°C and a screw speed of 200-450 rpm.

[0026] The polyamide composite material of the present invention is used to prepare parts with a wall thickness greater than 10 mm, such as railway-related parts, automobile tire pads, and rear walls that replace steel with plastic.

[0027] The present invention has the following beneficial effects:

[0028] The present invention selects a polyamide resin of a specific type and a specific terminal amino group content and a PBT resin with a specific terminal carboxyl group content to form a specific terminal group ratio, so that the polyamide resin / PBT resin undergoes a certain degree of reaction, thereby reducing the crystallization performance of nylon. At the same time, a specific compatibilizer is selected to significantly improve the defect of cracking of the product caused by excessive internal stress of the polyamide composite material, and to improve the notched impact strength, making it suitable for preparing thick-walled products. DETAILED DESCRIPTION

[0029] 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.

[0030] The raw materials used in the present invention come from the following sources:

[0031] The following end group contents of PBT resin and polyamide resin are actual measured contents.

[0032] PBT-A: terminal carboxyl content is 0.03 mg / L, PBT 1100-211M, Changchun Chemical Industry, Taiwan, China;

[0033] PBT-B: terminal carboxyl content is 0.015 mg / L, PBT GX111, Yizheng Chemical;

[0034] PBT-C: terminal carboxyl content is 0.012 mg / L, GL236, Yizheng Chemical;

[0035] PA66-A: PA66 EPR32, Shenma, terminal amino content is 0.05 mg / L.

[0036] PA66-B: PA66 EP26CL, Zhejiang Huafeng, terminal amino content is 0.08 mg / L.

[0037] PA66-C: PA66 27AE1K, Rhodia, amino group content 0.12 mg / L.

[0038] PA66-D: PA66 21ZLV, ASCEND, amino group content of 0.15 mg / L.

[0039] PA66-F: PA66 EP158NH, Zhejiang Huafeng, terminal amino content is 0.19 mg / L.

[0040] PA6: PA6 HY2800A, Haiyang Chemical Fiber, terminal amino content is 0.12mg / L.

[0041] PA10T: Vicnyl 6100, Zhuhai Wantong Special Engineering Plastics Co., Ltd., terminal amino content is 0.11 mg / L.

[0042] PA56: Ecopent-1273, Caesar Biotechnology, terminal amino content is 0.13 mg / L.

[0043] Ethylene-butyl acrylate copolymer-A: the weight content of ethylene units is 65 wt%, 35BA40, Arkema, France.

[0044] Ethylene-butyl acrylate copolymer-B: the weight content of ethylene units is 72 wt%, 28BA175, Arkema, France.

[0045] Ethylene-butyl acrylate copolymer-C: the weight content of ethylene units is 83 wt%, 17BA04, Arkema, France.

[0046] Ethylene-methyl acrylate copolymer: the weight content of ethylene units is 75 wt%, Elvaloy® AC resin 1125, purchased from DuPont Company, USA.

[0047] Glass fiber: Glass fiber ECS301CL-3, Chongqing International Composite Materials Co., Ltd.

[0048] Preparation method of polyamide composite material of embodiment and comparative example: according to the ratio, each component is mixed uniformly, and granulated by extrusion through a twin-screw extruder, with the screw temperature set at 220-270° C. and the speed at 200-450 rpm.

[0049] Various test methods:

[0050] (1) Internal stress test: Injection molded products (circular structure, outer diameter 200mm, inner diameter 150mm, 4 gates evenly distributed along the inner diameter, product thickness 20mm) were observed for cracking during natural placement. Slight cracking refers to small cracks near the gate of the part with a depth of less than 1mm. Obvious cracking refers to small cracks near the gate of the part with a depth of 1~3mm. Severe cracking refers to large cracks near the gate of the part with a depth of more than 5mm.

[0051] (2) Izod notched impact strength: Injection molding ISO 180 standard specimens to test the Izod notched impact strength.

[0052] Table 1: Polyamide composite materials of Examples 1-7 (parts by weight) and test results

[0053] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 PBT-A 10 10 10 10 10 15 4 PA66-A 50 40 60 PA66-B 50 PA66-C 50 PA66-D 50 PA6 50 Ethylene-butyl acrylate copolymer-A 1.7 1.7 1.7 1.7 1.7 0.5 3 fiberglass 15 15 15 15 15 0 20 Internal stress cracking slight none none slight none none slight <![CDATA[Izod impact strength, kJ / m 2 > 8.1 8.4 8.6 8.5 8.9 6.0 9.1

[0054] It can be seen from Examples 1-4 that within the preferred range of the end amino group content of PA66, not only is there no internal stress cracking, but also the notched impact strength is higher.

[0055] It can be seen from Examples 3 / 5 that PA6 is preferred for better mechanical properties.

[0056] Table 2: Polyamide composite materials of Examples 8-14 (parts by weight) and test results

[0057] Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 PBT-A 10 10 10 4 8 15 PBT-B 10 PA66-A 50 50 50 50 PA66-B 50 50 50 Ethylene-butyl acrylate copolymer-A 1.7 1.7 1.7 1.7 Ethylene-butyl acrylate copolymer-B 1.7 Ethylene-butyl acrylate copolymer-C 1.7 Ethylene-methyl acrylate copolymer 1.7 fiberglass 15 15 15 15 15 15 15 Internal stress cracking none slight none slight slight none none <![CDATA[Izod impact strength, kJ / m 2 > 8.2 7.8 7.5 8.3 8.8 8.5 8.0

[0058] It can be seen from Examples 1 / 8-10 that the preferred weight content of the ethylene unit of the compatibilizer is 72-77 wt %. At the same time, ethylene-butyl acrylate copolymer is preferred because of its better mechanical properties.

[0059] It can be seen from Examples 2 / 12-14 that the preferred PBT content has a good effect in overcoming internal stress cracking, better mechanical properties, and better comprehensive application value.

[0060] Table 3: Comparative Example Polyamide Composite Materials (Parts by Weight) and Test Results

[0061] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 PBT-A 10 2 20 10 10 10 10 PBT-C 10 PA66-A 50 50 50 50 50 PA66-F 50 PA10T 50 PA56 50 Ethylene-butyl acrylate copolymer-A 1.7 1.7 1.7 0 5 1.7 1.7 1.7 fiberglass 15 15 15 15 15 15 15 15 Internal stress cracking serious serious slight serious obvious serious serious obvious <![CDATA[Izod impact strength, kJ / m 2 > 8.5 7.1 5.3 5.6 9.1 6.7 6.9 7.5

[0062] It can be seen from Examples 1-4 and Comparative Example 1 that when the terminal amino group content of PA66 is too high, internal stress cracking is severe.

[0063] It can be seen from Comparative Examples 2-3 that if the content of the PBT resin is not within the range of the present invention, not only will the internal stress cracking be severe, but the notched impact strength will also be low.

[0064] It can be seen from Comparative Examples 4 / 5 that the internal stress cracking is serious when no compatibilizer is added. If the compatibilizer content is too high, the internal stress cracking will also be aggravated.

[0065] It can be seen from Comparative Examples 6 / 7 that the composition of the present invention is difficult to be applied to polyamide resins other than PA66 and PA6.

[0066] It can be seen from Comparative Example 8 that if the terminal carboxyl content of PBT is too low, the internal stress cracking defect is serious.

[0067] It can be seen from the above examples that the notched impact strength of the polyamide composite material of the present application is ≥6 kJ / m 2 .

Claims

1. A polyamide composite material, characterized in that: Calculated by weight, it includes the following components: 40-60 parts of polyamide resin; 4-15 parts of PBT resin; Compatibilizer 0.5-3 parts; The polyamide resin has an amino group content of 0.05-0.15 mg / L, and the PBT resin has a carboxyl group content of 0.015-0.03 mg / L. The compatibilizer is selected from at least one of ethylene-butyl acrylate copolymer and ethylene-methyl acrylate copolymer, wherein the weight content of the ethylene unit is 63-83wt%; The polyamide resin is selected from at least one of PA6 and PA66; The test method for the terminal carboxyl content of PBT resin is as follows: the terminal carboxyl content of the sample is titrated using a fully automatic potentiometric titrator; 2g of sample is weighed, 50mL of a phenol / chloroform mixed solvent is added, and the mixture is mixed in a volume ratio of phenol to chloroform of 2:

3. The mixture is heated until the sample is dissolved, cooled to room temperature, and titrated with a calibrated potassium hydroxide-ethanol standard solution to obtain the terminal carboxyl content of the PBT resin; The test method for the amino group content of polyamide resin is as follows: titrate the amino group content of the sample using a fully automatic potentiometric titrator; take 0.5g of polymer, add 45mL of phenol and 3mL of anhydrous methanol, heat to reflux, observe that the sample is completely dissolved, cool to room temperature, and titrate the amino group content with a calibrated hydrochloric acid standard solution.

2. The polyamide composite material according to claim 1, characterized in that The content of PBT resin is 8-10 parts.

3. The polyamide composite material according to claim 1, characterized in that The terminal amino group content of the polyamide resin is 0.08-0.12 mg / L.

4. The polyamide composite material according to claim 1, characterized in that In the compatibilizer, the weight content of ethylene units is 72-77wt%.

5. The polyamide composite material according to claim 4, characterized in that The content of the compatibilizer ranges from 1.2 to 2 parts.

6. The polyamide composite material according to claim 1, characterized in that The compatibilizer is selected from ethylene-butyl acrylate copolymer.

7. The polyamide composite material according to claim 1, characterized in that The polyamide resin is selected from PA6.

8. The polyamide composite material according to claim 1, characterized in that By weight, the invention further comprises 0-30 parts of fillers or other additives, wherein the fillers are selected from at least one of glass fiber and talcum powder, and the other additives are selected from at least one of antioxidants, lubricants and weathering agents.

9. The method for preparing the polyamide composite material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing the components according to a proportion, and extruding and granulating the components through a twin-screw extruder, wherein the screw temperature range is 220-270° C. and the rotation speed is 200-450 rpm.

10. Use of the polyamide composite material according to any one of claims 1 to 8, characterized in that: Used to prepare parts with thick walls >10mm.