Polyamide molding composition as well as preparation method and application thereof

Abstract

The invention discloses a polyamide molding composition which comprises the following components in parts by weight: 80-90 parts of polyamide resin, 0-120 parts of filler and a hole improving agent which is 0.003-0.04 time of the weight of the polyamide resin. By selecting the hole improving agent with a specific structure and a specific content, the defect that tiny holes are easy to appear when the polyamide molding composition is used for injection molding of a workpiece with the thickness of greater than 2mm can be effectively improved.

Description

Technical Field

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

[0002] Due to the characteristics of strength and rigidity, impact resistance, chemical corrosion resistance, high temperature resistance, dimensional stability, electrical insulation and processability, polyamide molding compositions have been used in many fields to replace metal materials for parts such as defense, aviation, subway, shipbuilding, automobiles, construction, machinery, and home appliances. When used in these industries, the thickest size of the parts is greater than 2mm, which is usually called medium and large parts.

[0003] Because the thermal conductivity of polyamide molding compositions is poor, when the thickness of the part is greater than 2mm, the surface layer will first cool and solidify, and then the "core" layer will cool and shrink, resulting in obvious holes inside; or because of the large size and thickness, the plastic material is easy to entrap gas when it flows, resulting in holes in the part. This is more likely to occur in parts with a thickness greater than 2mm. When holes appear in medium and large parts, the mechanical properties and service life of the parts will be significantly reduced.

[0004] At present, most of the methods used in the industry to eliminate holes in large parts are to reduce holes through injection molding process or mold design or to transfer holes to non-critical parts, but neither can fundamentally eliminate holes in parts. Summary of the invention

[0005] The object of the present invention is to provide a polyamide molding composition which does not produce voids when injection molding is used to produce articles having a thickness of more than 2 mm.

[0006] The present invention is achieved through the following technical solutions: A polyamide molding composition, comprising, by weight, 80-90 parts of a polyamide resin, 0-120 parts of a filler, and 0.003-0.04 times the amount of a pore improver of the polyamide resin; The hole improving agent is selected from at least one of hole improving agent A and hole improving agent B; The molecular formula of hole improver A is: , wherein R1, R2, and R3 are independently at least one of hydrogen, ammonium ion, alkyl with 1 to 6 carbon atoms, aryl, and derivatives thereof, and the molecular weight of the pore improving agent A is in the range of 100-400 g / mol; The molecular formula of hole improver B is: , wherein L1 and L2 are independently at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an aryl group and its derivatives, silane and its derivatives, an alkali metal ion, aminopyrimidine and its derivatives, and the molecular weight range of the pore improving agent A is 100-400 g / mol; And, the melting point range of polyamide resin is 155-265°C.

[0007] Preferably, the weight of the pore improver is 0.005-0.015 times that of the polyamide resin. If the content of the pore improver is too high, agglomeration is likely to occur, which in turn reduces the performance.

[0008] Preferably, the pore improving agent is selected from pore improving agent B.

[0009] The hole improving agent A is selected from at least one of tricresyl phosphate, ditolyl phosphate, triphenyl phosphate, diphenyl phosphate, tributyl phosphate, triethyl phosphate, trimethyl phosphate, di-tert-butyl phosphate, triammonium phosphate, and diammonium phosphate.

[0010] The hole improving agent B is selected from at least one of diphenyl sulfate, dimethyl sulfate, dibutyl sulfate, 4-acetaminophen-d3 potassium sulfate, bis(trimethylsilyl) sulfate, and 6-hydroxy-2,4,5-triaminopyrimidine sulfate.

[0011] The polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin and polylactamide resin, and the melting point of the polyamide resin is in the range of 155-265° C. If the melting point of the polyamide resin is too high, the pore improving agent will be degraded, reducing the effect of pore improvement; and if the melting point of the polyamide resin is too low, the pore improving agent cannot be depolymerized and has no effect.

[0012] The aliphatic polyamide resin is selected from at least one of 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, and PA616; the semi-aromatic polyamide is selected from at least one of PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, and PA9T; and the polylactam is selected from at least one of PA5, PA6, PA11, and PA12.

[0013] The relative viscosity range of polyamide resin is 1.6-2.8. The test method of relative viscosity is: refer to GB12006.1-89, polyamide viscosity number determination method; the specific test method is: measure the relative viscosity ηr of polyamide with a concentration of 10 mg / ml in 98% concentrated sulfuric acid at 25℃±0.01℃.

[0014] In the polyamide molding composition of the present invention, the polyamide resin accounts for no less than 35wt% of the total weight.

[0015] The filler is selected from at least one of fibrous reinforcing fillers and non-fibrous reinforcing fillers; the fibrous reinforcing filler is selected from at least one of glass fiber, potassium titanate fiber, metal-clad glass fiber, ceramic fiber, wollastonite fiber, metal carbide fiber, metal-cured fiber, asbestos fiber, aluminum oxide fiber, silicon carbide fiber, gypsum fiber or boron fiber, aromatic polyamide fiber and / or carbon fiber, potassium titanate whisker, zinc oxide whisker, and aluminum borate whisker; the non-fibrous reinforcing filler is selected from one or more of wollastonite, zeolite, kaolin, mica, talc, clay, pyrophyllite, bentonite, montmorillonite, hectorite, asbestos, aluminosilicate, aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, iron oxide, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, silicon carbide or silicon dioxide.

[0016] It is possible to choose whether to add 0-2 parts of an auxiliary agent according to actual needs, wherein the auxiliary agent is selected from at least one of an antioxidant and a lubricant.

[0017] The preparation method of the polyamide molding composition of the present invention comprises the following steps: mixing the components uniformly according to the proportion, extruding and granulating through a twin-screw extruder to obtain the polyamide molding composition.

[0018] The polyamide molding composition of the present invention is used for injection molding to prepare products with a thickness exceeding 2 mm, especially products with a thickness of ≥10 mm.

[0019] The hole improving agent of the present invention is used for improving the hole defects that occur when the polyamide molding composition is injection molded into a product with a thickness greater than 2 mm.

[0020] The present invention has the following beneficial effects: The present invention selects a hole improving agent containing lone pair electrons and containing sulfur and phosphorus in a specific content, which is evenly dispersed in the resin matrix and forms a complex with the polyamide resin to stabilize the melt viscosity. The complex can also reduce crystallization, so that small hole defects will not occur when thick parts are injection molded.

[0021] If the polyamide resin absorbs water, the polyamide molding composition will continue to absorb water during storage, so that the pore improver will self-depolymerize in the composition under the action of water molecules to form stable sulfur- or phosphorus-containing alkyl carboxyl, phenolic hydroxyl, alkyl hydroxyl and other groups. These highly stable groups can also form complexes with the polyamide resin during the injection molding process of the composition, which plays a role in stabilizing the melt viscosity, and the complex can reduce crystallization. The defect of small holes caused by the change in the melt viscosity of the polyamide molding composition after water absorption is improved when injecting thick parts. DETAILED DESCRIPTION

[0022] 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.

[0023] The sources of raw materials used in the examples and comparative examples of the present invention are as follows: PA6: PA6-HY2800, Haiyang Technology Co., Ltd., melting point 220°C; PA66: PA66 EPR27, Pingdingshan Shenma Engineering Plastics, melting point 260℃; PA6I / PA66: Vicnyl 2500 NC003, Zhuhai Wantong Special Engineering Plastics Co., Ltd., melting point 257°C; PA1012: PA1012-H, Wuxi Yinda Nylon Co., Ltd., melting point 190°C; PA10T / 66: Vicnyl 2100 NC003, Zhuhai Wantong Special Engineering Plastics Co., Ltd., melting point 290°C; PA6T / 66: Vicnyl 400 NC003, Zhuhai Wantong Special Engineering Plastics Co., Ltd., melting point 305°C; Tricresyl phosphate: aladdin, molecular weight 368.36; Ditoluene phosphate: aladdin, molecular weight 278.24; Trimethyl phosphate: aladdin, molecular weight 140.07; Dimethyl sulfate: aladdin, molecular weight 126.13; Diammonium phosphate: aladdin, molecular weight 115; 4-acetaminophen-d3 potassium sulfate: aladdin, molecular weight 272.33; Bis(trimethylsilyl)sulfate: aladdin, molecular weight 242.44; 6-Hydroxy-2,4,5-triaminopyrimidine sulfate: aladdin, molecular weight 239.21; Glass fiber: E7CS10-03-568H, China Jushi Co., Ltd.; Wollastonite: GY-1250, Jiangxi Guangyuan Chemical Co., Ltd.; Talc: HTPULTRA5, IMIFABI; Embodiment and comparative example Preparation method of polyamide molding composition: according to the ratio, each component is mixed evenly, and extruded and granulated by a twin-screw extruder to obtain a polyamide molding composition, wherein the maximum temperature of the barrel is the melting point of polyamide + 25°C, and the rotation speed range is 400-600 r / min.

[0024] Various test methods: (1) Part hole test: The polyamide molding composition is injection molded into a 10 mm thick square plate, and the part is scanned using an industrial CT device to observe whether there are any holes and the number of holes. Specifically, the diameter of the hole is defined as greater than 0.02 mm, and the number of holes within the selected range of 200 mm*150 mm, the number of holes with a diameter of 0.05-0.1 mm, and the number of holes with a diameter greater than 0.2 mm are observed. When the hole is greater than 0.2 mm, the performance of the part will be significantly affected.

[0025] Table 1: Weight parts of each component of polyamide molding composition of Examples 1-6 and test results Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PA6 80 30 80 80 PA66 45 PA6I / PA66 40 60 PA1012 90 Tricresyl phosphate 0.8 0.85 0.9 0.9 0.24 0.4 Fiberglass 10 Wollastonite 50 talcum powder 120 Total number of holes 4 5 7 9 5 4 Hole diameter 0.05-0.1mm quantity 1 0 1 2 1 0 Number of holes larger than 0.2 mm 0 0 0 0 0 0 Table 2: Weight parts of each component of polyamide molding composition of Examples 7-12 and test results Example 7 Example 8 Example 9 Example 10 Embodiment 11 Example 12 PA6 80 80 80 80 80 80 Tricresyl phosphate 1.2 3.2 Ditolyl phosphate 0.8 Trimethyl phosphate 0.8 Dimethyl sulfate 0.8 Ammonium dihydrogen phosphate 0.8 Total number of holes 3 10 4 1 2 3 Hole diameter 0.05-0.1mm quantity 0 3 0 1 0 1 Number of holes larger than 0.2 mm 0 0 0 0 0 0 It can be seen from Examples 1 / 5-9 that the optimal content of the pore improving agent results in the least pores.

[0026] Table 3: Weight parts of each component of polyamide molding composition of Examples 13-15 and test results Example 13 Embodiment 14 Embodiment 15 PA6 80 80 80 4-Acetaminophen-d3 Potassium Sulfate 0.8 Bis(trimethylsilyl) sulfate 0.8 6-Hydroxy-2,4,5-triaminopyrimidine sulfate 0.8 Total number of holes 1 0 1 Hole diameter 0.05-0.1mm quantity 0 0 0 Number of holes larger than 0.2 mm 0 0 0 It can be seen from Examples 1 / 9-15 that pore improver B is preferred.

[0027] Table 4: Weight parts of each component of the comparative polyamide molding composition and test results Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PA6 80 80 80 PA10T / 66 80 PA6T / 66 80 Tricresyl phosphate 0 0.08 4 0.8 0.8 Total number of holes 48 26 15 56 62 Hole diameter 0.05-0.1mm quantity 17 9 5 21 27 Number of holes larger than 0.2 mm 5 3 2 7 9 It can be seen from Comparative Example 1 that when no pore improving agent is contained, the number of pores is large, and a large number of pores with diameters greater than 0.2 mm are contained.

[0028] It can be seen from Comparative Example 2 that when the content of the hole improving agent is too low, the improvement of the hole defects is also limited.

[0029] It can be seen from Comparative Example 3 that if the content of the pore improving agent is too high, the pore improving effect will also be reduced.

[0030] It can be seen from the above examples and comparative examples that the polyamide molding composition of the present invention can effectively inhibit the formation of holes when injection molding thick parts, especially no holes with a diameter greater than 0.2 mm will be generated.

Claims

1. A polyamide molding composition, characterized in that By weight, it includes 80-90 parts of polyamide resin, 0-120 parts of filler, and 0.003-0.04 times the weight of the polyamide resin as a hole improving agent; The hole improving agent is selected from at least one of hole improving agent A and hole improving agent B; The molecular formula of hole improver A is: , wherein R1, R2, and R3 are independently at least one of hydrogen, ammonium ion, alkyl with 1 to 6 carbon atoms, aryl, and derivatives thereof, and the molecular weight of the pore improving agent A is in the range of 100-400 g / mol; The molecular formula of hole improver B is: , wherein L1 and L2 are independently at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an aryl group and its derivatives, silane and its derivatives, an alkali metal ion, aminopyrimidine and its derivatives, and the molecular weight range of the pore improving agent A is 100-400 g / mol; And, the melting point range of polyamide resin is 155-265°C.

2. The polyamide molding composition according to claim 1, characterized in that The weight portion of the hole improving agent is 0.005-0.015 times that of the polyamide resin.

3. The polyamide molding composition according to claim 1, characterized in that The pore improving agent is selected from pore improving agent B.

4. The polyamide molding composition according to claim 1, characterized in that The hole improver A is selected from at least one of tricresyl phosphate, ditolyl phosphate, triphenyl phosphate, diphenyl phosphate, tributyl phosphate, triethyl phosphate, trimethyl phosphate, di-tert-butyl phosphate, triammonium phosphate, and diammonium phosphate; the hole improver B is selected from at least one of diphenyl sulfate, dimethyl sulfate, dibutyl sulfate, 4-acetaminophen-d3 potassium sulfate, bis(trimethylsilyl) sulfate, and 6-hydroxy-2,4,5-triaminopyrimidine sulfate.

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

6. The polyamide molding composition according to claim 1, characterized in that The filler is selected from at least one of fibrous reinforcing fillers and non-fibrous reinforcing fillers; the fibrous reinforcing filler is selected from at least one of glass fiber, potassium titanate fiber, metal-clad glass fiber, ceramic fiber, wollastonite fiber, metal carbide fiber, metal-cured fiber, asbestos fiber, aluminum oxide fiber, silicon carbide fiber, gypsum fiber or boron fiber, aromatic polyamide fiber and / or carbon fiber, potassium titanate whisker, zinc oxide whisker, and aluminum borate whisker; the non-fibrous reinforcing filler is selected from one or more of wollastonite, zeolite, kaolin, mica, talc, clay, pyrophyllite, bentonite, montmorillonite, hectorite, asbestos, aluminosilicate, aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, iron oxide, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, silicon carbide or silicon dioxide.

7. The polyamide molding composition according to claim 1, characterized in that The invention also comprises 0-2 parts of auxiliary agents by weight, wherein the auxiliary agents are selected from at least one of antioxidants and lubricants.

8. A method for preparing a polyamide molding composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components uniformly according to the proportion, extruding and granulating through a twin-screw extruder to obtain a polyamide molding composition.

9. Use of the polyamide molding composition according to any one of claims 1 to 7, characterized in that Used for injection molding of parts with a thickness exceeding 2mm.

10. An injection molded part having a thickness greater than 2 mm obtained by injection molding the polyamide molding composition according to any one of claims 1 to 7.

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