Polyamide resin composition and preparation method thereof

Abstract

The invention provides a polyamide resin composition and a preparation method thereof. The polyamide resin composition comprises long-carbon-chain polyamide resin, a long-carbon-chain polyamide thermoplastic elastomer, maleic anhydride grafted polytetrafluoroethylene subjected to plasma surface treatment and an antioxidant. According to the preparation method, polytetrafluoroethylene is treated and then mixed with the long carbon chain polyamide resin and the long carbon chain polyamide thermoplastic elastomer, and through twin-screw extrusion granulation, the ultra-thin-wall product with good self-lubricating performance and demolding performance is obtained, the excellent toughness and tear resistance of the ultra-thin-wall product are reserved, and the ultra-thin-wall product is suitable for preparing plastic badminton ball groups and other ultra-thin-wall products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polyamide resin, and particularly relates to a polyamide resin composition and a preparation method thereof. BACKGROUND

[0002] In the face of the price surge of natural feather shuttlecock, plastic shuttlecock is applied more and more, and compared with natural feather shuttlecock, plastic shuttlecock has great cost advantage, and has super durability, mainly because the mechanical properties of the ball group prepared by high polymer material are far superior to natural feather shuttlecock, although the hand feeling when hitting has certain gap with natural feather shuttlecock, but it is widely welcomed in outdoor and amateur players. In order to simulate the effect of natural feather, the plastic shuttlecock skirt needs to be designed to have a thickness of less than 1mm. At present, the plastic shuttlecock skirt on the market is all polyamide resin, but due to the polarity problem of polyamide resin, the sticking phenomenon is easy to occur in the forming process, the continuity of forming is not good, which seriously affects the production efficiency.

[0003] Based on the above, it is necessary to develop a polyamide material with toughness and impact resistance, and self-lubricity and easy demolding. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a polyamide resin composition, which can prepare a polyamide resin composition with self-lubricity and easy demolding.

[0005] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0006] In the first aspect, the present application provides a polyamide resin composition, and the raw materials thereof include, by mass fraction:

[0007] 65-80 parts of long carbon chain polyamide resin,

[0008] 10-30 parts of long carbon chain polyamide thermoplastic elastomer,

[0009] 5-10 parts of maleic anhydride grafted polytetrafluoroethylene treated by plasma surface treatment,

[0010] 0.1-3 parts of antioxidant.

[0011] The long carbon chain polyamide resin has an average number of carbon atoms Nc of 6-18 per nitrogen atom; preferably, the long carbon chain polyamide resin includes any one or a combination of at least two of PA612, PA614, PA1012, PA11, PA12, PA1212, PA616 or PA618, preferably a combination of PA12 and PA11;

[0012] Preferably, the molar ratio of terminal carboxyl groups to terminal amino groups in the long-chain polyamide resin is 1-20, more preferably 1-10.

[0013] In this invention, the hard segment of the long-chain polyamide thermoplastic elastomer is an aliphatic long-chain polyamide, preferably one or more of PA12, PA11, PA1212, PA1010, PA610, and PA612. The soft segment of the long-chain polyamide thermoplastic elastomer is one or more of hydroxyl-terminated polytetrahydrofuran ether, polyethylene glycol, polypropylene glycol, copolyether diol, polyether diamine, polyester, polycarbonate, polyolefin, and polysiloxane. More preferably, the molar ratio of hard segment to soft segment is 1:0.9-1.5.

[0014] Preferably, the Shore hardness of the long-chain polyamide thermoplastic elastomer is 35-70D.

[0015] The preparation process of maleic anhydride-grafted polytetrafluoroethylene (PTFE) with plasma surface treatment described in this invention includes two steps: preparing maleic anhydride-grafted PTFE and plasma surface treatment of maleic anhydride-grafted PTFE. Specifically, it includes the following steps:

[0016] (1) Surface-activated polytetrafluoroethylene, and the activated polytetrafluoroethylene is grafted with maleic anhydride to obtain maleic anhydride-grafted polytetrafluoroethylene.

[0017] (2) Maleic anhydride-grafted polytetrafluoroethylene is subjected to plasma treatment.

[0018] Specifically, step (1) of surface activation treatment of polytetrafluoroethylene involves surface activation using a sodium naphthalene treatment solution. Specifically, this includes:

[0019] S1. Prepare a sodium naphthalene treatment solution using anhydrous tetrahydrofuran as a solvent for later use;

[0020] S2. Mix polytetrafluoroethylene (PTFE) with sodium naphthalene treatment solution to obtain activated polytetrafluoroethylene.

[0021] In step S1 of this invention, the preparation of the sodium-naphthalene treatment solution can refer to existing technology. Specifically, pre-dried tetrahydrofuran and naphthalene are stirred and mixed in a water bath at 15-40°C, sodium is added in batches, stirring is continued while nitrogen is purged, and the sodium-naphthalene treatment solution is obtained after 2-3 hours. Preferably, the concentration of the sodium-naphthalene treatment solution is 0.2 mol / L-1.0 mol / L, more preferably 0.4 mol / L-0.8 mol / L; wherein, naphthalene and sodium are preferably in equimolar amounts.

[0022] In step S2 of this invention, polytetrafluoroethylene (PTFE) is added to a sodium naphthalene treatment solution. Preferably, the PTFE is pre-dried (e.g., dried in an oven at 80-100°C for 20-50 minutes). It is then uniformly dispersed under stirring or ultrasonication for 5-10 minutes at room temperature (e.g., 15°C-30°C). After removing the powder, it is preferably rinsed with water and hot water to obtain surface-activated PTFE.

[0023] The polytetrafluoroethylene of the present invention is preferably in powder form, with a weight-average molecular weight of 500,000 to 5,000,000, more preferably 2,000,000 to 4,000,000, and an average particle size of 1 to 15 μm, more preferably 3 to 8 μm.

[0024] The grafting reaction of activated polytetrafluoroethylene and maleic anhydride described in this invention can refer to the maleic anhydride grafting reaction method in the prior art; preferably, the maleic anhydride grafting rate in maleic anhydride-grafted polytetrafluoroethylene is 2wt%-12wt%.

[0025] Specifically, maleic anhydride-grafted polytetrafluoroethylene can be prepared by the following reaction: activated polytetrafluoroethylene is mixed with maleic anhydride, acrylate, initiator, and solvent, and the reaction is carried out to obtain grafted polytetrafluoroethylene.

[0026] Specifically, the amount of maleic anhydride used is 0.1wt%-3wt% of the weight of activated polytetrafluoroethylene; the amount of acrylate used is 1wt%-30wt% of the weight of activated polytetrafluoroethylene.

[0027] Specifically, the solvent includes any one of tetrahydrofuran, xylene, toluene, cyclohexanone, ethyl acetate, and butyl acetate.

[0028] Specifically, the acrylate includes at least one of methyl acrylate, ethyl acrylate, butyl acrylate, etc.

[0029] Specifically, the initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile, tert-butyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide, and the amount of initiator used is 0.5wt%-3.0wt% of the weight of the activated polytetrafluoroethylene.

[0030] Specifically, the grafting reaction temperature is 60-80℃, and the reaction time is 4-8 hours.

[0031] Step (2) of the present invention involves plasma treatment of maleic anhydride-grafted polytetrafluoroethylene. Specifically, the treatment is carried out in an argon atmosphere using low-pressure plasma with a gas pressure of 50-70 Pa, a glow discharge power of 30-40 W, and a treatment time of 2-3 min.

[0032] In the polyamide resin composition of the present invention, the antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants, wherein the hindered phenolic antioxidant is selected from at least one of antioxidants 1098, 1010, and 1076, and the phosphite antioxidant is selected from at least one of antioxidants 168, 626, and 619.

[0033] In a second aspect, the present invention provides a method for preparing the above-mentioned polyamide resin composition, comprising the following steps: mixing long-chain polyamide resin, long-chain polyamide thermoplastic elastomer, plasma-treated maleic anhydride-grafted polytetrafluoroethylene, and antioxidant in proportion, and obtaining the polyamide resin composition by melt extrusion, granulation, and drying.

[0034] Specifically, the temperature of the melting section during the extrusion process is 250-275℃, and the temperature of the mixing section is 265-295℃.

[0035] The polyamide composition of the present invention has good self-lubricating and demolding properties, and retains its excellent toughness and tear resistance, making it suitable for preparing ultra-thin wall parts such as plastic badminton shuttlecocks.

[0036] Compared with existing technologies, this invention has several advantages:

[0037] This invention significantly improves the fluidity and self-lubricating properties of the composition by adding polytetrafluoroethylene (PTFE) powder, thus providing processability and release properties for injection molding. The innovative activation, maleic anhydride grafting, and plasma treatment of PTFE powder solve the compatibility problem between PTFE powder and the polyamide matrix. By combining the rigidity of long-chain polyamide resin with the toughness of long-chain polyamide thermoplastic elastomer, the composition exhibits good processability and release properties while possessing a balance of rigidity and toughness and excellent tear resistance. Detailed Implementation

[0038] To facilitate researchers in the field to better understand the polyamide resin composition, preparation method, and properties prepared by the present invention, the present invention will be further described below with specific examples. However, this is only for further detailed description and is not intended to limit the scope of the present invention.

[0039] The sources of raw materials are shown in Table 1.

[0040] Table 1 Source of Raw Materials

[0041]

[0042] Test methods and standards:

[0043] (1) Tensile strength and elongation at break: ISO 527-2 / 5A, tensile speed 50 mm / min.

[0044] (2) Tear strength: ISO 34-1, Method B, right-angled specimen.

[0045] (3) Demolding force test method:

[0046] Using a 120-ton Haitian injection molding machine, a national standard stretching template mold, a template wall thickness of 4mm, a cavity demolding angle of 0.5°, and a runner demolding angle of 30°, the following molding process was used during testing: injection temperature 250℃, mold temperature 40℃, injection and holding pressure 60MPa, injection speed 60mm / s, holding time 25s. The ejection pressure was continuously adjusted to find the minimum force required for complete demolding, which was recorded as the ejection force.

[0047] (4) Liquidity testing methods:

[0048] A 120-ton Haitian injection molding machine and a national standard stretching template mold for spiral lines were used. The spiral mold size was 5mm*2.5mm, and the demolding angle was 15°. The following molding process was used during the test: injection temperature 250℃, mold temperature 40℃, injection and holding pressure 150MPa, and holding time 5s. The flowability was characterized by calculating the length of the spiral line after molding.

[0049] Preparation Example 1 (Preparation of plasma-surface-treated maleic anhydride-grafted polytetrafluoroethylene)

[0050] (1) Tetrahydrofuran was refluxed for 3 hours to remove moisture, yielding dry tetrahydrofuran (THF). The tetrahydrofuran was kept in a 30°C water bath, and naphthalene was added and stirred until completely dissolved to obtain a naphthalene-tetrahydrofuran solution. Sodium, in equimolar amounts to naphthalene, was added to the naphthalene-tetrahydrofuran solution in batches, with continuous stirring and the introduction of dry nitrogen gas. After 2 hours, a sodium-naphthalene treatment solution was obtained. Polytetrafluoroethylene (PTFE) powder was pre-dried in an oven at 100°C for 30 minutes. The dried PTFE powder was added to the sodium-naphthalene treatment solution, with a concentration of 0.6 mol / L. The powder was uniformly dispersed under magnetic stirring for 5 minutes, while maintaining the temperature at 20°C. The powder was removed and quickly rinsed three times with room temperature deionized water, followed by one rinse with 90°C hot water to obtain activated polytetrafluoroethylene powder.

[0051] (2) The activated polytetrafluoroethylene powder was mixed with maleic anhydride, butyl acrylate, benzoyl peroxide initiator and tetrahydrofuran solvent, wherein the mass ratio of polytetrafluoroethylene, butyl acrylate, maleic anhydride and initiator was 100:20:2:0.5. The mixture was reacted at 70°C for 6 h to obtain grafted polytetrafluoroethylene with a grafting rate of 5.5 wt%.

[0052] (3) The grafted polytetrafluoroethylene powder was treated by low-pressure plasma treatment under an argon atmosphere. The low-pressure plasma treatment gas ionization pressure was 50 Pa, the glow discharge power was 40 W, and the treatment time was 3 min, to obtain plasma-treated maleic anhydride grafted polytetrafluoroethylene 1.

[0053] Preparation Example 2

[0054] Referring to Preparation Example 1, the difference is that the impregnation time in step (1) is 8 minutes, and in step (2), the amount of maleic anhydride is changed to obtain grafted polytetrafluoroethylene with a grafting rate of 3wt%; in step (3), the low-pressure plasma treatment gas plasma pressure is 60 Pa, the glow discharge power is 30 W, and the treatment time is 2 min, to obtain plasma-treated maleic anhydride grafted polytetrafluoroethylene 2.

[0055] Preparation Example 3

[0056] Referring to Preparation Example 1, the difference is that the impregnation time in step (1) is 10 minutes, and in step (2), the amount of maleic anhydride is changed to obtain grafted polytetrafluoroethylene with a grafting rate of 12 wt%; in step (3), the low-pressure plasma treatment gas plasma pressure is 68 Pa, the glow discharge power is 35 W, and the treatment time is 2 min, to obtain plasma-treated maleic anhydride grafted polytetrafluoroethylene 3.

[0057] Preparation Example 4

[0058] Referring to Preparation Example 1, the difference is that in step (3), the pressure of the low-pressure plasma treatment gas ionizer is 80 Pa, and plasma-treated maleic anhydride-grafted polytetrafluoroethylene 4 is obtained.

[0059] Preparation Example 5

[0060] Referring to Preparation Example 1, the difference is that plasma treatment was not performed, i.e. step (3) was missing, and maleic anhydride-grafted polytetrafluoroethylene 5 was obtained.

[0061] Preparation Example 6

[0062] Referring to Preparation Example 1, the difference is that maleic anhydride grafting was not performed, i.e. step (2) was missing, and plasma-treated polytetrafluoroethylene 6 was obtained.

[0063] Preparation Example 7

[0064] Referring to Preparation Example 1, the difference is that no activation treatment was performed, i.e. step (1) was missing, and maleic anhydride-grafted polytetrafluoroethylene 7 with plasma surface treatment was obtained.

[0065] Examples and Comparative Examples (Preparation of Polyamide Resin Compositions)

[0066] Weigh the raw materials according to the mass proportions in Tables 3 and 4. Dry the long-chain polyamide resin in a vacuum oven at 100℃ for 4 hours, and then dry it again in a vacuum oven at 70℃ for 4 hours until the water content drops to ≤0.01wt%. Add the long-chain polyamide resin, long-chain polyamide thermoplastic elastomer, plasma-treated maleic anhydride-grafted polytetrafluoroethylene, and antioxidant to a mixer and mix for 5 minutes at a speed of 80 rpm to obtain a mixed raw material. Then, add the mixture to the main feed hopper and melt-extrude it using a twin-screw extruder. During extrusion, the temperature of the extruder's melt section is 265℃, the temperature of the mixing section is 280℃, and the screw speed is 260 rpm.

[0067] The properties of the materials were tested, and the results are shown in Tables 3 and 4.

[0068] Table 3. Examples and their performance tests

[0069]

[0070] Table 4 Comparative examples and their performance tests

[0071]

[0072]

[0073] The polyamide composition provided by this invention has excellent rigidity, as well as excellent demolding performance and good flowability, and has a wide range of applications in thin-walled injection molded parts such as badminton shuttlecock skirts.

Claims

1. A polyamide resin composition, characterized in that, By mass, its raw materials include: 65-80 parts of long-chain polyamide resin, 10-30 parts of long-chain polyamide thermoplastic elastomer, 5-10 parts of plasma-treated maleic anhydride-grafted polytetrafluoroethylene. Antioxidant 0.1-3 parts.

2. The polyamide resin composition according to claim 1, characterized in that, The long-chain polyamide resin includes any one or a combination of at least two of PA612, PA614, PA1012, PA11, PA12, PA1212, PA616, or PA618; preferably, the average number of carbon atoms Nc per nitrogen atom in the long-chain polyamide resin is 6-18; preferably, the molar concentration ratio of terminal carboxyl groups to terminal amino groups in the long-chain polyamide resin is 1-20, more preferably 1-10.

3. The polyamide resin composition according to claim 1, characterized in that, The hard segment of the long-chain polyamide thermoplastic elastomer is an aliphatic long-chain polyamide, preferably one or more of PA12, PA11, PA1212, PA1010, PA610, and PA612; the soft segment of the long-chain polyamide thermoplastic elastomer is one or more of hydroxyl-terminated polytetrahydrofuran ether, polyethylene glycol, polypropylene glycol, copolyether glycol, polyether diamine, polyester, polycarbonate, polyolefin, and polysiloxane; preferably, the molar ratio of hard segment to soft segment in the long-chain polyamide thermoplastic elastomer is 1:0.9-1.

5.

4. The polyamide resin composition according to claim 1, characterized in that, The preparation method of maleic anhydride-grafted polytetrafluoroethylene (PTFE) with plasma surface treatment includes the preparation of maleic anhydride-grafted PTFE and plasma surface treatment of maleic anhydride-grafted PTFE.

5. The polyamide resin composition according to claim 4, characterized in that, The maleic anhydride grafting rate in maleic anhydride-grafted polytetrafluoroethylene is 2wt% to 12wt%. And / or, the plasma surface treatment is a low-pressure plasma treatment performed under an argon atmosphere; preferably, the low-pressure plasma treatment gas pressure is 50-70 Pa, the glow discharge power is 30-40 W, and the treatment time is 2-3 min.

6. The polyamide resin composition according to claim 5, characterized in that, Before preparing maleic anhydride-grafted polytetrafluoroethylene, the polytetrafluoroethylene is activated, preferably by using a sodium naphthalene treatment solution for surface activation.

7. The polyamide resin composition according to claim 6, characterized in that, The concentration of the sodium naphthalene treatment solution is 0.2 mol / L-1.0 mol / L, preferably 0.4 mol / L-0.8 mol / L; and / or, the activation treatment time is 5-10 min.

8. The polyamide resin composition according to any one of claims 4-7, characterized in that, The polytetrafluoroethylene powder has a weight-average molecular weight of 500,000 to 5,000,000, preferably 2,000,000 to 4,000,000; and / or the polytetrafluoroethylene particle size is 1 to 15 micrometers, preferably 3 to 8 micrometers.

9. The polyamide resin composition according to claim 1, characterized in that, The antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants, wherein the hindered phenolic antioxidant is selected from at least one of antioxidant 1098, antioxidant 1010, and antioxidant 1076, and the phosphite antioxidant is selected from at least one of antioxidant 168, antioxidant 626, and antioxidant 619.

10. A method for preparing the polyamide resin composition according to any one of claims 1-9, characterized in that, The process includes the following steps: mixing long-chain polyamide resin, long-chain polyamide thermoplastic elastomer, plasma-treated maleic anhydride-grafted polytetrafluoroethylene, and antioxidant, followed by melt extrusion, granulation, and drying to obtain the polyamide resin composition. Preferably, the temperature of the melting section during the extrusion process is 250-275℃, and the temperature of the mixing section is 265-295℃.

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