CN117820854A - A polyamide composite material and its preparation method and application - Google Patents

Abstract

The polyamide composite material comprises the following components in parts by weight: 40-60 parts of polyamide resin (PA 6 or PA 66); 4-15 parts of PBT resin; 0.5-3 parts of compatilizer; wherein the amino end content of the polyamide resin is 0.05-0.15mg/L; the compatilizer is at least one selected from ethylene-butyl acrylate copolymer and ethylene-methyl acrylate copolymer. According to the invention, the specific end group ratio of the polyamide resin with specific types and specific end amino content and the PBT resin with specific end carboxyl content is formed, and the specific compatilizer is selected, so that the cracking of the workpiece caused by overlarge internal stress due to the addition of the semi-crystalline PBT resin can be remarkably improved, the notch impact strength can be improved, and the method is suitable for preparing thick-wall workpieces.

Description

A polyamide composite material and its preparation method and application

Technical Field

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

Background technique

Nylon materials have good strength and toughness and are widely used in the field of electronics and electrical engineering. As the scope of application expands, some products with thicker walls are also applied to polyamide.

However, polyamide is a crystalline material. During the cooling process, it will crystallize as the temperature changes. Crystalline materials will shrink more than amorphous materials, thus generating more stress in the product. When the stress in the product is large, it will have a great impact on the later use of the product, such as cracking, or collapse when subjected to a small force.

At present, the main method to solve product stress in industry is through annealing, but annealing will increase equipment investment, make the process complicated, and significantly prolong the time, resulting in low efficiency and increased costs, which has always been a problem for industrial manufacturing. The optimization of structural design can only reduce product stress to a limited extent.

In the art, 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

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

The present invention is achieved through the following technical solutions:

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

Polyamide resin 40-60 parts;

PBT resin 4-15 parts;

Compatibilizer 0.5-3 parts;

Wherein, the terminal amino content of the polyamide resin is 0.05-0.15 mg/L, and the terminal carboxyl content of the PBT resin is in the range 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;

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

The preferred PBT resin content is 8-10 parts.

The test method for the terminal carboxyl content of PBT resin is as follows: titrate the terminal carboxyl content of the sample with 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.

The test method for the terminal amino group content of polyamide resin is as follows: use a fully automatic potentiometric titrator to titrate the terminal amino group content of the sample; 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 terminal amino group content with a calibrated hydrochloric acid standard solution.

Preferably, the terminal amino group content of the polyamide resin is 0.08-0.12 mg/L.

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

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

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

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

Preferably, the polyamide resin is selected from PA6.

It is possible to choose whether to add 0-30 parts of fillers or other additives according to actual needs. The fillers may be glass fiber, talcum powder, etc. Other additives may be 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 60wt%.

The preparation method of the polyamide composite material of the present invention comprises the following steps: mixing the components uniformly according to the proportion, extruding and granulating through a twin-screw extruder, wherein the screw temperature ranges from 220 to 270° C. and the rotation speed is from 200 to 450 rpm.

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.

The present invention has the following beneficial effects:

The present invention selects a polyamide resin of a specific type and a specific terminal amino group content and a PBT resin of a specific terminal carboxyl group content to form a specific terminal group ratio, so that the polyamide resin/PBT resin reacts to a certain extent, 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, so that the present invention is suitable for preparing thick-walled products.

Implementation

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 can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The sources of raw materials used in the present invention are as follows:

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

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

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

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

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

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

PA66-C: PA66 27AE1K, Rhodia, terminal amino content is 0.12 mg/L.

PA66-D: PA66 21ZLV, ASCEND, terminal amino content is 0.15mg/L.

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

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

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

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

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

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

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

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

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

Embodiment and comparative example Preparation method of polyamide composite material: according to the ratio, each component is mixed evenly, and extruded into granules by a twin-screw extruder, and the screw temperature is set at 220-270° C. and the rotation speed is 200-450 rpm.

Various test methods:

(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 product with a depth of less than 1mm. Obvious cracking refers to small cracks near the gate of the product with a depth of 1-3mm. Severe cracking refers to large cracks near the gate of the product with a depth of more than 5mm.

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

Table 1: Examples 1-7 polyamide composite materials (parts by weight) and test results

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 glass fiber 15 15 15 15 15 0 20 Internal stress cracking slight none none slight none none slight Notched impact strength, kJ/m ² 8.1 8.4 8.6 8.5 8.9 6.0 9.1

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

It can be seen from Examples 3/5 that the mechanical properties are better when PA6 is preferred.

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

Example 8 Example 9 Example 10 Embodiment 11 Example 12 Example 13 Embodiment 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 glass fiber 15 15 15 15 15 15 15 Internal stress cracking none slight none slight slight none none Notched impact strength, kJ/m ² 8.2 7.8 7.5 8.3 8.8 8.5 8.0

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, the preferred ethylene-butyl acrylate copolymer has better mechanical properties.

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.

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

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 glass fiber 15 15 15 15 15 15 15 15 Internal stress cracking serious serious slight serious obvious serious serious obvious Notched impact strength, kJ/m ² 8.5 7.1 5.3 5.6 9.1 6.7 6.9 7.5

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.

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

It can be seen from comparative examples 4/5 that the internal stress cracking is serious when no compatibilizer is added. If the content of the compatibilizer is too high, the internal stress cracking will also be aggravated.

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.

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.

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 (10)

1. A polyamide composite material, characterized in that it comprises the following components in parts by weight: Polyamide resin 40-60 parts; PBT resin 4-15 parts; Compatibilizer 0.5-3 parts; Wherein, the terminal amino content of the polyamide resin is 0.05-0.15 mg/L, and the terminal carboxyl content of the PBT resin is in the range 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; The polyamide resin is selected from at least one of PA6 and PA66. 2. The polyamide composite material according to claim 1, characterized in that the content of the 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 the weight content of the ethylene unit in the compatibilizer is 63-83wt%, preferably the weight content of the ethylene unit is 72-77wt%. 5. The polyamide composite material according to claim 4, characterized in that the content of the compatibilizer is in the range of 1.2-2 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 it further comprises 0-30 parts of filler by weight. 9. The method for preparing the polyamide composite material according to any one of claims 1 to 8, characterized in that it comprises the following steps: mixing the components uniformly according to the proportion, and extruding and granulating them through a twin-screw extruder, wherein the screw temperature ranges from 220 to 270°C and the rotation speed is from 200 to 450 rpm. 10. Use of the polyamide composite material according to any one of claims 1 to 8, characterized in that it is used to prepare a product with a wall thickness greater than 10 mm.