Highly crystalline bio-based semi-aromatic polyamide material and preparation method thereof

Abstract

The present invention discloses a highly crystalline bio-based semi-aromatic polyamide material and a preparation method thereof. The highly crystalline bio-based semi-aromatic polyamide material is composed of the following materials: bio-based semi-aromatic polyamide, glass fiber, brominated polystyrene, a boric acid compound, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate, and an auxiliary agent. The highly crystalline bio-based semi-aromatic polyamide material is prepared by a twin-screw extruder. The present invention utilizes 1,1-bis(diphenylphosphino)ferrocene palladium dibromide and dibenzyl sebacate to form a composite, thereby achieving excellent mechanical properties, flame retardant properties, and processability of the bio-based semi-aromatic polyamide material obtained by the present invention. The material also has the advantages of excellent crystallization performance, short molding cycle, and good high-temperature creep performance.

Description

Technical Field

[0001] The present invention relates to a polyamide material, in particular to a bio-based semi-aromatic polyamide material with excellent crystallization performance and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] Semi-aromatic polyamides, common high-temperature nylons, combine the excellent properties of aromatic nylons with the processing characteristics of aliphatic nylons. They are a class of materials with exceptional performance and are widely used in electronics, LED lighting, the automotive industry, and other fields. However, with the continuous development of society, the requirements for semi-aromatic polyamides are gradually increasing, especially for flame retardancy. Numerous fires caused by the poor flame retardancy of polyamides have caused significant losses. Therefore, the flame retardant modification of polyamides has become a topic of joint concern and research in academia and industry.

[0003] Currently, one of the flame-retardant modification approaches for semi-aromatic polyamides is the use of boric acid compounds. Boric acid compounds are environmentally friendly, non-halogen flame retardants characterized by non-toxicity, low water solubility, high thermal stability, and a low particle size and specific gravity. National Invention Patent CN1 14292517A combines borates, hypophosphites, and melamine polyphosphates as a highly effective flame retardant to produce a composite material with a V0 rating. National Invention Patent CN1 12029280A utilizes a combination of borate, hypophosphites, melamine derivatives, and flame retardant synergists to produce a polyamide composite with a superior flame retardancy rating, without negatively impacting electrical properties. National Invention Patent CN 111073307A utilizes a flame-retardant masterbatch prepared from borates, polyphosphamide, and phosphate esters, which is then applied to polyamide resin to produce a composite material with a limiting oxygen index ≥30. However, it is worth noting that although the use of borates as flame retardants can effectively improve the flame retardant properties of polyamide composites, it has a negative effect on the crystallization properties of the composites, further affecting the mechanical properties and processing properties of the polyamide composites.

[0004] To improve the crystallization properties of polyamide materials, adding inorganic and organic nucleating agents to polyamide resins to promote crystallization is a common method and approach. However, nucleating agents alone have limited effectiveness in improving polyamide crystallization properties, and their dispersion during use requires a high degree of nucleating agent dispersion. Therefore, there is an urgent need to develop polyamide composite materials with both high flame retardancy and high crystallization properties to meet market demand. Summary of the Invention

[0005] The main purpose of the present invention is to solve the defects of the above-mentioned technology and provide a bio-based semi-aromatic polyamide material with excellent crystallization performance and a preparation method thereof. The material not only has excellent crystallization performance, but also has excellent mechanical properties, flame retardant properties and processability.

[0006] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0007] An embodiment of the present invention provides a highly crystalline bio-based semi-aromatic polyamide material, which is composed of the following materials: bio-based semi-aromatic polyamide, glass fiber, brominated polystyrene, a boric acid compound, 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide, dibenzyl sebacate, and an additive.

[0008] In some embodiments, the highly crystalline bio-based semi-aromatic polyamide material is composed of the following materials calculated in parts by weight: 32.0 to 52.0 parts of bio-based semi-aromatic polyamide, 15.0 to 45.0 parts of glass fiber, 15.0 to 25.0 parts of brominated polystyrene, 1.0 to 3.0 parts of a boric acid compound, 1.0 to 6.0 parts of 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide, 0.5 to 3.0 parts of dibenzyl sebacate, and 0.5 to 1.5 parts of an additive.

[0009] An embodiment of the present invention also provides a method for preparing a highly crystalline bio-based semi-aromatic polyamide material, which comprises: fully melting and plasticizing a mixture of bio-based semi-aromatic polyamide, brominated polystyrene, a boric acid compound, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate, an additive and glass fiber, and then drawing, cooling and pelletizing the mixture to obtain a highly crystalline bio-based semi-aromatic polyamide material.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] The present invention uses 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide as a flame retardant and crystallization nucleating agent, and a compound dibenzyl sebacate accelerator, so that the bio-based semi-aromatic polyamide material of the present invention has excellent mechanical properties, flame retardant properties and processability. The material also has the advantages of excellent crystallization performance, short molding cycle, good high-temperature creep performance, and the like. DETAILED DESCRIPTION

[0012] To overcome the deficiencies of the aforementioned prior art, the inventors of this case, after extensive research and extensive practice, have come up with the technical solution of the present invention. The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0013] One aspect of an embodiment of the present invention provides a highly crystalline bio-based semi-aromatic polyamide material composed of the following materials calculated in parts by weight: 32.0 to 52.0 parts of bio-based semi-aromatic polyamide, 15.0 to 45.0 parts of glass fiber, 15.0 to 25.0 parts of brominated polystyrene, 1.0 to 3.0 parts of a boric acid compound, 1.0 to 6.0 parts of 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide, 0.5 to 3.0 parts of dibenzyl sebacate, and 0.5 to 1.5 parts of an additive.

[0014] In some embodiments, the bio-based semi-aromatic polyamide is a PA5T-56 multipolymer having a melting point of 305° C. to 320° C. and a relative viscosity of 2.0 to 2.5.

[0015] In some embodiments, the glass fiber is a chopped glass fiber with a diameter of 9 to 12 μm and a length of 3 to 4.5 mm.

[0016] In some embodiments, the mass ratio of the 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide to dibenzyl sebacate is 3:1 to 1:1.

[0017] Furthermore, the boric acid compound includes any one or a mixture of two of anhydrous zinc borate, borax and boric acid, but is not limited thereto.

[0018] The heat resistance of semi-aromatic polyamides is closely related to the crystallization of the material, and the crystallization performance of the material is closely related to the resin structure and the type of added components. The inventors of this case discovered that in flame-retardant reinforced semi-aromatic polyamide materials, the flame retardant anhydrous borate (such as zinc borate) can inhibit the crystallization of the material. This is mainly because the anhydrous borate, as an inorganic filler, has an inhibitory effect on the polyamide chain segments, thereby reducing the crystallization performance. In the present invention, in order to achieve good flame retardancy of polyamide, the organic flame retardant synergist 1,1-bis(diphenylphosphino)ferrocene palladium dibromide is used in combination with a boric acid compound. While maintaining excellent flame retardancy, the amount of borate flame retardant is significantly reduced. In addition, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide is in a molten state during processing and can be effectively dispersed in the resin matrix. During the cooling process, it preferentially forms crystal nuclei to promote the occurrence of heterogeneous crystallization of the polyamide resin. Furthermore, dibenzyl sebacate, introduced into the material as a crystallization accelerator, has a long, flexible carbon chain structure and a benzene ring structure, ensuring its compatibility within the polyamide matrix. Furthermore, the long carbon chain structure activates the polyamide segments, promoting their mobility and effectively improving the material's crystallization properties. Furthermore, brominated polystyrene also exhibits flame retardancy, acting synergistically with boric acid compounds.

[0019] Furthermore, the auxiliary agent includes a combination of an antioxidant and a lubricant.

[0020] The weight portion of the antioxidant in the highly crystalline bio-based semi-aromatic polyamide material is 0.1 to 0.5 parts, and the weight portion of the lubricant in the highly crystalline bio-based semi-aromatic polyamide material is 0.2 to 1.0 parts.

[0021] Furthermore, the auxiliary agent includes an antioxidant and a lubricant. The antioxidant may include antioxidant 1098, and the lubricant may include lubricant PTEs, but is not limited thereto.

[0022] Another aspect of an embodiment of the present invention provides a method for preparing a highly crystalline bio-based semi-aromatic polyamide material, comprising: fully melting and plasticizing a mixture of a base material of bio-based semi-aromatic polyamide, brominated polystyrene, a boric acid compound, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate, an additive, and glass fiber, followed by drawing into strips, cooling, and pelletizing to obtain a highly crystalline bio-based semi-aromatic polyamide material.

[0023] The types of bio-based semi-aromatic polyamide, boric acid compound and additives used in the preparation process of the present invention are as described above and will not be repeated here.

[0024] In some more specific embodiments, the highly crystalline bio-based semi-aromatic polyamide material is prepared by a twin-screw extruder, and the preparation method may specifically include:

[0025] Bio-based semi-aromatic polyamide (high-temperature nylon base material), brominated polystyrene, anhydrous zinc borate, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate and additives are fed into the main feed port of a twin-screw extruder, and glass fiber is added through a side feed. After twin-screw conveying and shearing, the mixture is fully melted and plasticized, and then drawn into strips, cooled, and pelletized to obtain a bio-based semi-aromatic polyamide material with excellent crystallization properties.

[0026] The temperature of melt plasticization in the twin-screw extruder is 320° C. to 335° C., and the number of screw revolutions is 400 rpm to 600 rpm.

[0027] Another aspect of the embodiments of the present invention further provides a bio-based semi-aromatic polyamide material with excellent crystallization properties prepared by any of the aforementioned preparation methods.

[0028] In summary, the present invention uses 1,1-bis(diphenylphosphino)ferrocene palladium dibromide as a flame retardant and crystallization nucleating agent, and a compound dibenzyl sebacate accelerator, so that the obtained bio-based semi-aromatic polyamide material has excellent mechanical properties, flame retardant properties and processability. In addition, the material has excellent crystallization properties, a short molding cycle, and good high-temperature creep properties.

[0029] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on it. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention. The experimental methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or under the conditions recommended by the manufacturer. The raw materials used in the following examples are:

[0030] Bio-based high-temperature nylon PA5T-56 (Zhejiang Xinli, SH1270), brominated polystyrene (Shandong Brother, 7010), chopped glass fiber (Jushi, alkali-free chopped glass fiber, diameter 9-12 μm, length 3-4.5 mm), lubricant PETs (commercially available), antioxidant 1098 (BASF), 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide (Aladin reagent), dibenzyl sebacate (commercially available).

[0031] Examples 1 to 5 and Comparative Examples 1 to 6

[0032] High-temperature nylon base material PA5T-56, brominated polystyrene, anhydrous zinc borate, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate and additives are fed into the main feed port of a twin-screw extruder, and glass fiber is added through the side feed. After being fully melted and plasticized under the action of twin-screw conveying and shearing, the material is drawn into strips, cooled and pelletized to obtain a bio-based semi-aromatic polyamide material with excellent crystallization properties.

[0033] The temperature of the melt plasticization in the twin-screw extruder is 320° C. to 335° C., and the screw speed is 400 rpm to 600 rpm. In addition, the anhydrous zinc borate can also be replaced by boric acid or borax.

[0034] The specific ratios of the raw materials in Examples 1-5 and Comparative Examples 1-6 are shown in Table 1.

[0035] Table 1 Ratios of raw materials in Examples 1-5 and Comparative Examples 1-6

[0036]

[0037]

[0038] The obtained pellets were injection molded into corresponding specimens according to ISO test standards, and then placed in an environment of 23±2°C and 50±5% relative humidity for 24 hours before testing; the tensile strength was measured according to ISO527 standard; the flexural strength was measured according to ISO178 standard; and the Charpy (Charpy impact test) unnotched impact strength was measured according to ISO179 standard.

[0039] Crystallization performance evaluation: DSC test was performed in a nitrogen atmosphere. The temperature was increased from 30°C to 350°C at a rate of 10°C / min. After keeping at 350°C for 5 minutes, the temperature was cooled to 30°C at a rate of 20°C / min. The crystallization temperature Tc was recorded.

[0040] Processing performance evaluation: Continuous injection molding of a miniature circuit breaker shaft (1 die, 32 cavities) was performed at a temperature of 300°C to 325°C and a mold temperature of 100°C. The injection cycle time for normal demolding was recorded in seconds.

[0041] High-temperature creep testing: Using a static thermomechanical analyzer (TMA), the sample is heated from a starting temperature of 25°C to 180°C at a rate of 10°C / min. A 2N force is then applied perpendicular to the center of the sample for 4 hours. The creep value is calculated as the dimensional change. Creep value = displacement difference between the starting and ending points / specimen thickness × 100%.

[0042] The test results are shown in Table 2.

[0043] Table 2 Test results of Examples 1-5 and Comparative Examples 1-6

[0044]

[0045]

[0046] Examples 1-5 of the present invention are modified by using 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide and dibenzyl sebacate in a specific ratio, meeting the flame retardant V0 grade while reducing the amount of borate and obtaining a higher crystallization temperature and excellent high-temperature creep performance.

[0047] It can be seen from the above that the bio-based semi-aromatic polyamide materials obtained in Examples 1-5 have excellent mechanical properties, flame retardant properties and processability, and the materials have the advantages of excellent crystallization properties, short molding cycle, good high-temperature creep performance, etc.

[0048] Comparative Examples 1-6 differ from Examples 1-5 in that, while conventional zinc borate was used as a flame retardant in Comparative Example 1, the addition of either 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide (Comparative Example 2) or dibenzyl sebacate (Comparative Example 3) alone did not significantly improve the crystallization properties of the polyamide composite. Furthermore, in Comparative Examples 4 and 5, the 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide and dibenzyl sebacate were not modified in a specific ratio, resulting in no improvement in the material's crystallization properties. Comparative Example 6, which lacked zinc borate, failed to form a dense carbon layer during combustion, resulting in a vertical combustion rating of only V1.

[0049] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0050] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A highly crystalline bio-based semi-aromatic polyamide material, characterized in that: The highly crystalline bio-based semi-aromatic polyamide material is composed of the following materials calculated in parts by weight: 32.0 to 52.0 parts of bio-based semi-aromatic polyamide, 15.0 to 45.0 parts of glass fiber, 15.0 to 25.0 parts of brominated polystyrene, 1.0 to 3.0 parts of a boric acid compound, 1.0 to 6.0 parts of 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide, 0.5 to 3.0 parts of dibenzyl sebacate, and 0.5 to 1.5 parts of an auxiliary agent, and the mass ratio of the 1,1-bis(diphenylphosphino)ferrocenepalladium dibromide to the dibenzyl sebacate is 3:1 to 1:

1.

2. The highly crystalline bio-based semi-aromatic polyamide material according to claim 1, characterized in that: The bio-based semi-aromatic polyamide is a PA5T-56 multipolymer with a melting point of 305° C. to 320° C. and a relative viscosity of 2.0 to 2.

5.

3. The highly crystalline bio-based semi-aromatic polyamide material according to claim 1, characterized in that: The glass fibers are chopped glass fibers with a diameter of 9 to 12 μm and a length of 3 to 4.5 mm.

4. The highly crystalline bio-based semi-aromatic polyamide material according to claim 1, characterized in that: The boric acid compound includes any one of anhydrous zinc borate, borax and boric acid, or a mixture of two or more thereof.

5. The highly crystalline bio-based semi-aromatic polyamide material according to claim 1, characterized in that: The auxiliary agent includes a combination of an antioxidant and a lubricant.

6. The highly crystalline bio-based semi-aromatic polyamide material according to claim 5, characterized in that: The weight portion of the antioxidant in the highly crystalline bio-based semi-aromatic polyamide material is 0.1 to 0.5 parts, and the weight portion of the lubricant in the highly crystalline bio-based semi-aromatic polyamide material is 0.2 to 1.0 parts.

7. The highly crystalline bio-based semi-aromatic polyamide material according to claim 5, characterized in that: The antioxidant includes antioxidant 1098, and the lubricant includes lubricant PTEs.

8. The method for preparing a highly crystalline bio-based semi-aromatic polyamide material according to any one of claims 1 to 7, wherein: include: A mixture of bio-based semi-aromatic polyamide, brominated polystyrene, boric acid compound, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate, additives and glass fiber is fully melted and plasticized, and then drawn into strips, cooled and pelletized to obtain a highly crystalline bio-based semi-aromatic polyamide material.

9. The preparation method according to claim 8, characterized in that Specifically include: Bio-based semi-aromatic polyamide, brominated polystyrene, boric acid compound, 1,1-bis(diphenylphosphino)ferrocene palladium dibromide, dibenzyl sebacate and additives are fed into the main feed port of a twin-screw extruder, and glass fiber is added through the side feed. The mixture is fully melted and plasticized under the action of twin-screw conveying and shearing, and then drawn into strips, cooled and pelletized to obtain a highly crystalline bio-based semi-aromatic polyamide material.

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