Yellowing-resistant nylon material

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a yellowing-resistant nylon material which comprises the following raw materials in parts by weight: 30-60 parts of nylon, 20-40 parts of glass fibers, 0.5-1 part of a composite antioxidant, 1-2 parts of a coupling agent and 0.1-3 parts of an auxiliary agent, and the composite antioxidant is a composition of a hindered phenol antioxidant, a phosphite ester antioxidant and carnosic acid. According to the invention, the hindered phenol antioxidant, the phosphite antioxidant and the carnosic acid are compounded to obtain the composite antioxidant, and the three antioxidants can synergistically play a role, so that the nylon can be prevented from being oxidized, and the problem that the existing antioxidant is easy to cause yellowing in the nylon is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a yellowing-resistant nylon material. Background Art

[0002] Nylon (PA) is the most widely used and most diverse engineering plastic. This material has good mechanical properties, heat resistance, wear resistance, chemical solvent resistance, self-lubrication and certain flame retardancy. It is widely used in automobiles, electronic appliances, machinery, rail transit, sports equipment and other fields.

[0003] However, nylon is prone to yellowing during processing and use, which affects product quality. This is because nitrogen oxides in the air cause oxidation of amino groups in nylon to generate yellow substances. Generally, this yellowing phenomenon can be improved by adding antioxidants to nylon. Commonly used antioxidants are a combination of phenolic antioxidants and phosphite antioxidants, such as antioxidants 1010 and 168. However, the presence of phenolic antioxidants can easily form nitro compounds inside the nylon, which can also easily cause yellowing. In addition, phenolic antioxidants form quinone substances after oxidation, which can also easily cause yellowing of nylon materials. Generally speaking, acidic formulas can overcome the yellowing defects of phenolic antioxidants, but nylon materials are unstable under acidic conditions.

[0004] Therefore, how to effectively solve the yellowing problem of nylon materials remains a challenge. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a yellowing-resistant nylon material, which comprises the following raw materials in parts by weight: 30-60 parts of nylon, 20-40 parts of glass fiber, 0.5-1 parts of composite antioxidant, 1-2 parts of coupling agent and 0.1-3 parts of auxiliary agent.

[0006] Furthermore, the nylon includes PA6 or PA66.

[0007] Furthermore, the glass fiber is any one of continuous glass fiber, chopped glass fiber, milled glass fiber, alkali-free glass fiber, medium-alkali glass fiber, and high-alkali glass fiber, or a mixture of several of them.

[0008] Furthermore, the composite antioxidant is a combination of a hindered phenol antioxidant, a phosphite antioxidant and carnosic acid.

[0009] Furthermore, the mass ratio of the hindered phenol antioxidant, the phosphite antioxidant and carnosic acid in the composite antioxidant is 1:1:1-3.

[0010] Furthermore, the composite antioxidant is prepared as follows: a hindered phenol antioxidant and a phosphite antioxidant are dissolved in a benzene solvent, carnosic acid is added, stirred at 0-4° C. for 1-2 hours, and freeze-dried to obtain the composite antioxidant.

[0011] Furthermore, the benzene solvent is selected from at least one of benzene, toluene or xylene.

[0012] Furthermore, the hindered phenol antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076), and N,N-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (antioxidant 1098).

[0013] Furthermore, the phosphite antioxidant is selected from at least one of tris(2,4-tert-butylphenyl) phosphite (antioxidant 168) and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (antioxidant 626).

[0014] Furthermore, the coupling agent is selected from at least one of γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560).

[0015] Furthermore, the coupling agent is a 1:1 mixture of γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560).

[0016] Furthermore, the auxiliary agent is at least one of a glass fiber leakage prevention agent, a lubricant and a light stabilizer.

[0017] Furthermore, examples of the glass fiber leakage prevention agent may include ethylene bis stearamide grafted compound (TAF).

[0018] Further, examples of the lubricant may include at least one of calcium stearate, stearic acid, ethylene bis stearamide, pentaerythritol stearate, silicone powder, and polyethylene wax.

[0019] Furthermore, examples of the light stabilizer may include hindered amine light stabilizers, such as light stabilizer 622, chemical name: polymer of succinic acid and (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol; light stabilizer 770, chemical name: bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0020] The present invention also provides a method for preparing the yellowing-resistant nylon material as described herein, comprising the following steps:

[0021] Nylon, composite antioxidant, coupling agent and auxiliary agent are mixed and added to the main feeding system of the extruder, and glass fiber is added to the side feeding system of the extruder. After melt mixing and extrusion granulation, the yellowing-resistant nylon material is obtained.

[0022] Beneficial effects of the present invention

[0023] Carnosic acid is a natural antioxidant with strong performance, which is often used in food, but its application in the field of engineering plastics is extremely rare. Since carnosic acid has excellent thermal stability compared with other natural antioxidants, it has the potential for application in the field of engineering plastics. The present invention compounds hindered phenolic antioxidants, phosphite antioxidants and carnosic acid to obtain a composite antioxidant, and it is found that these three antioxidants can work synergistically, not only to prevent nylon oxidation, but also to overcome the problem that existing antioxidants are easy to cause yellowing in nylon. Not bound by theory, it is believed that the present invention uses carnosic acid to add to the traditional hindered phenolic antioxidant and phosphite antioxidant compounding system, which can be combined with the hindered phenolic antioxidant through the interaction of hydrogen bonds, so that the composite antioxidant is acidic as a whole, thereby avoiding the generation of yellow products after the hindered phenolic antioxidant is oxidized. In order to avoid the adverse effects of the composite antioxidant used in the present invention on the nylon material, the present invention also adds a coupling agent in the formula, utilizes the cross-linking effect of the coupling agent, improves the acid and alkali resistance of the nylon material, and avoids the damage of the acidic composite antioxidant to the nylon material. DETAILED DESCRIPTION

[0024] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0025] The PA6 used in the following examples is the Dutch DSM 1010C2 brand. The glass fiber is a chopped glass fiber with a diameter of about 13 microns. The coupling agent is a combination of silane coupling agents KH550 and KH560 in a mass ratio of 1:1. The composite antioxidant is prepared as follows: Antioxidant 1010 and antioxidant 168 are dissolved in benzene, then carnosic acid is added, stirred at 0°C for 2 hours, and freeze-dried in a freeze dryer to obtain the composite antioxidant, wherein the mass ratio of KH550, KH560 and carnosic acid is 1:1:2.

[0026] Example 1

[0027] A yellowing-resistant nylon material is prepared as follows:

[0028] 40 parts by weight of PA6, 0.5 parts by weight of composite antioxidant, 1 part by weight of coupling agent, 1.0 parts by weight of glass fiber leakage prevention agent TAF, 0.5 parts by weight of lubricant polyethylene wax and 0.2 parts by weight of light stabilizer 622 are added to a high-speed mixer and mixed at a high speed for 5 minutes. Then, the mixture is added to the main feeding system of a twin-screw extruder, and 20 parts by weight of glass fiber is added to the side feeding system of the extruder. After melt mixing and extrusion granulation, a yellowing-resistant nylon material is obtained.

[0029] Example 2

[0030] A yellowing-resistant nylon material is prepared as follows:

[0031] 55 parts by weight of PA6, 1 part by weight of composite antioxidant, 2 parts by weight of coupling agent, 1.0 part by weight of glass fiber leakage prevention agent TAF, 0.5 part by weight of lubricant polyethylene wax and 0.2 part by weight of light stabilizer 622 were added to a high-speed mixer and mixed at a high speed for 5 minutes. Then, the mixture was added to the main feeding system of a twin-screw extruder, and 30 parts by weight of glass fiber was added to the side feeding system of the extruder. After melt mixing and extrusion granulation, a yellowing-resistant nylon material was obtained.

[0032] Comparative Example 1

[0033] A nylon material is prepared in the same manner as in Example 1, except that the composite antioxidant used is composed of only antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0034] Comparative Example 2

[0035] A nylon material is prepared in the same manner as in Example 1, except that no coupling agent is used.

[0036] Comparative Example 3

[0037] A nylon material is prepared in the same manner as in Example 1, except that the composite antioxidant used is composed of only antioxidant 1010, antioxidant 168 and carnosine in a mass ratio of 1:1:2.

[0038] Comparative Example 4

[0039] A nylon material is prepared in the same manner as in Example 1, except that the composite antioxidant used is composed of only antioxidant 1010, antioxidant 168 and levorotatory pimaric acid (a hydroxyl-free diterpene carboxylic acid) in a mass ratio of 1:1:2.

[0040] Comparative Example 5

[0041] A nylon material is prepared in the same manner as in Example 1, except that the composite antioxidant used is prepared by directly mixing antioxidant 1010, antioxidant 168 and carnosic acid in powder form.

[0042] The nylon materials of Examples 1-2 and Comparative Examples 1-5 were subjected to performance tests. The tensile strength was tested according to the method specified in ASTM D638, the notched impact strength was tested according to the method specified in ASTM D256, the yellowness index (YI) was determined according to ASTM D1925-70, and the tensile strength was tested after the nylon material was immersed in water for 7 days, and the tensile strength loss rate was calculated. The test results are shown in Table 1.

[0043] Table 1

[0044]

[0045] From the results in Table 1, it can be seen that the nylon materials prepared in Examples 1 and 2 of the present invention do not turn yellow after being treated at 120° C. for 48 hours, and the loss of mechanical properties is small after being immersed in water for 7 days. When carnosic acid is not used in the composite antioxidant (Comparative Example 1), it can be seen that the initial YI of the nylon material increases, and yellowing is significant under high temperature treatment, indicating that the addition of carnosic acid is essential for improving yellowing; when the coupling agent is not used (Comparative Example 2), it can be seen that the mechanical property loss of the nylon material increases significantly after being immersed in water for 7 days. This is because the addition of carnosic acid makes the nylon material acidic, thereby reducing its stability, and the coupling agent used in the present invention can overcome this problem; when carnosic acid is replaced by carnosin without carboxyl or levorotatory pimaric acid without hydroxyl (Comparative Examples 3-4), the yellowing resistance of the nylon material is weakened, further illustrating the irreplaceability of carnosic acid; when the composite antioxidant is a powder in which the components are evenly mixed (Comparative Example 5), due to the lack of advance compounding through hydrogen bond interaction in a solution state, the overall antioxidant performance and yellowing resistance of the composite antioxidant are weakened, thereby affecting the yellowing resistance of nylon.

[0046] It should be noted that the preferred embodiments of the present invention are given in the specification of the present invention, but the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the present invention specification; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the protection scope of the claims attached to the present invention.

Claims

1. A yellowing-resistant nylon material, characterized in that: The raw materials include the following parts by weight: 30-60 parts of nylon, 20-40 parts of glass fiber, 0.5-1 parts of composite antioxidant, 1-2 parts of coupling agent and 0.1-3 parts of auxiliary agent. The composite antioxidant is a composition of a hindered phenol antioxidant, a phosphite antioxidant and carnosic acid.

2. The nylon material according to claim 1, characterized in that: The nylon includes PA6 or PA66.

3. The nylon material according to claim 1, characterized in that: The glass fiber is any one of continuous glass fiber, chopped glass fiber, milled glass fiber, alkali-free glass fiber, medium-alkali glass fiber, and high-alkali glass fiber, or a mixture of several of them.

4. The nylon material according to claim 1, characterized in that: The mass ratio of the hindered phenol antioxidant, the phosphite antioxidant and carnosic acid in the composite antioxidant is 1:1:1-3.

5. The nylon material according to claim 1, characterized in that: The composite antioxidant is prepared as follows: a hindered phenol antioxidant and a phosphite antioxidant are dissolved in a benzene solvent, carnosic acid is added, the mixture is stirred at 0-4° C. for 1-2 hours, and freeze-dried to obtain the composite antioxidant.

6. The nylon material according to claim 1, characterized in that: The hindered phenol antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and N,N-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide).

7. The nylon material according to claim 1, characterized in that: The phosphite antioxidant is selected from at least one of tris(2,4-tert-butylphenyl)phosphite and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

8. The nylon material according to claim 1, characterized in that: The coupling agent is selected from at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

9. The nylon material according to claim 8, characterized in that: The coupling agent is a 1:1 mixture of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

10. The nylon material according to claim 1, characterized in that: The auxiliary agent is at least one of a glass fiber leakage prevention agent, a lubricant and a light stabilizer.

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