Polyamide fiber

Abstract

The invention discloses a polyamide fiber. The polyamide fiber contains polyamide, a component a of a phosphate antioxidant and a component b of a hindered amine antioxidant, after the polyamide fiber is subjected to dry heat treatment at the temperature of 200 DEG C for 1 min, the yellowness change value YI is 7.0 or below, the strength maintenance rate is 70% or above, the polyamide fiber has good heat yellowing resistance, strength maintenance property and durability, and the possibility of application expansion of the polyamide fiber in the field of clothing is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of polyamide fibers, specifically, it relates to a kind of polyamide fiber with good yellowing resistance and strength retention characteristics after high temperature heat treatment, good durability. BACKGROUND

[0002] Polyamide fiber has good elasticity, light weight, high moisture absorption rate, good wear resistance, and the resilience rate can be comparable to wool, it is one of the highest strength synthetic fibers, and can be widely used in industrial products and clothing. However, as a fiber for clothing, the polyamide fiber has insufficient crispness, poor light resistance, and is prone to yellowing and strength reduction after long-term exposure to sunlight or heat treatment.

[0003] Although the crispness of polyamide fiber can be improved by copolymerization or blending spinning, making profiled cross-section yarn, blending or interweaving with other varieties of fibers, etc., the yellowing problem has not been effectively solved, especially the yellowing problem of polyamide 66, polyamide 56 and polyamide 510 is particularly prominent, which limits the application range of polyamide fiber.

[0004] In the past patents, the research on the yellowing resistance of such fibers is also involved. For example, Chinese patent CN106906533A discloses a kind of polyamide 5X fiber and its manufacturing method, which uses polyamide 5X resin as raw material, and the polyamide 5X resin includes: polyamide polymerized by 1,5-pentanediamine and dibasic acid, and the water content of the polyamide 5X resin is 50-1300 ppm. By controlling the water content of the polyamide 5X resin to be 50-1300 ppm, the polyamide 5X fiber produced has greatly reduced yellowing degree while ensuring the viscosity of oil-free yarn and various mechanical strengths. However, this method of controlling the water content of the resin can only ensure the initial yellowness value of the fiber, and cannot protect the fiber from various heat treatments in the garment process.

[0005] Adding antioxidants is one of the effective means to improve the heat yellowing resistance of polyamide. Chinese patent CN113564745A discloses a kind of polyamide fiber, which is mainly made of polyamide copolymer and antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate by melt spinning. The antioxidant reduces the oxidation and yellowing of the polyamide copolymer during the melt spinning process. However, this patent only adds one kind of hindered phenol antioxidant, and the antioxidant effect is not outstanding, and the yellowing phenomenon cannot be effectively prevented during the melt spinning process. Therefore, it is necessary to improve the existing antioxidant formula or the ratio of compounded antioxidants to improve the heat yellowing resistance while maintaining the original mechanical properties of the product. SUMMARY

[0006] The present application aims to provide a polyamide fiber which is not prone to yellowing after high-temperature heat treatment, and has good strength retention characteristics and excellent durability.

[0007] The technical solution of the present application is:

[0008] The polyamide fiber contains polyamide, a component of phosphate ester antioxidant, and b component of hindered amine antioxidant; the yellowness change value △YI of the polyamide fiber after dry heat treatment at 200℃×1min is less than 7.0, and the strength retention rate is more than 70%.

[0009] The content A of the a component and the content B of the b component preferably satisfy the relationship B / A≥2.0, and A is preferably 0.01-0.30wt%.

[0010] The polyamide fiber also preferably contains c component of hindered phenolic antioxidant, and the content C of the c component and A, B preferably satisfy the relationship A+B+C≤2.00wt%; A, B, C also preferably satisfy the relationship (A+C) / B≤4.0.

[0011] The relationship between A, B, C and the polyamide fiber monofilament fineness T is preferably A+B+C=-0.15×T+D; wherein D is the antioxidant additive amount correction value, and the value is preferably 0.65-2.20.

[0012] The molecular weight of the a component, b component, and c component is preferably 400-2500g / mol, respectively.

[0013] The yellowness change value △YI is preferably less than 5.0; and the strength retention rate is preferably more than 90%.

[0014] The polyamide fiber is preferably polyamide 5X fiber or polyamide 6X fiber.

[0015] The present application adds multiple high-molecular-weight antioxidants in a compounded manner, which on one hand endows the polyamide fiber with good heat yellowing resistance and strength retention characteristics, and on the other hand solves the problem of poor washing resistance and durability of the small-molecular-weight antioxidant in traditional polyamide fiber, thereby increasing the possibility of expanding the application of polyamide fiber in the clothing field. DETAILED DESCRIPTION

[0016] In the process of producing polyamide fiber, amide groups are decomposed to generate free radicals, which are heated to generate colored peroxide, thus causing the yellowing of polyamide fiber, and the free radicals also promote the decomposition of amide groups. In the prior art, only a single antioxidant or antioxidant with small molecular weight is added, which cannot effectively capture all types of free radicals decomposed from amide groups and further generated peroxide, and has poor durability. Therefore, it is necessary to improve the selection of existing antioxidants and apply them to polyamide fiber to improve the heat yellowing resistance of polyamide fiber while having good strength retention and durability.

[0017] The polyamide fiber of the present application adds two antioxidants, a component phosphate antioxidant and b component hindered amine antioxidant. The a component functions to reduce the colored peroxide generated by heat; the b component is a light stabilizer, which functions to inhibit the decomposition of amide groups, thereby reducing the generation of free radicals. Through the use of the above two antioxidants, the yellowness change value ΔYI of the polyamide fiber after dry heat treatment at 200°C for 1 min is less than 7.0, and the strength retention rate is more than 70%.

[0018] The content of the a component phosphate antioxidant (hereinafter referred to as letter A) and the content of the b component hindered amine antioxidant (hereinafter referred to as letter B) in the polyamide fiber of the present application can not be particularly limited, as long as they are within the content range of conventional antioxidants in general fibers.

[0019] In addition to the above functions, the a component can also inhibit the oxidation of the b component in air, thereby improving the anti-yellowing efficiency of the b component, effectively inhibiting the yellowing of polyamide fiber and its products, and improving the strength retention rate of polyamide fiber. In order to achieve the above effects, the content A of the a component and the content B of the b component preferably satisfy the relationship B / A≥2.0. If B / A is too small, after the tasks of reducing the colored peroxide and inhibiting the oxidation of the b component are completed, part of the a component will still remain, which not only increases the preparation cost of polyamide fiber, but also makes the strength of polyamide fiber lower, the processing difficulty greater, and the durability worse.

[0020] Meanwhile, the present application also preferably has A being 0.01-0.30wt%, when A is too small, the antioxidant effect of polyamide fiber tends to be poor, and the oxidation of the b component in air cannot be inhibited, the yellowing of polyamide fiber and the strength retention rate tend to be poor; when A is too large, the a component will promote the tackiness of polyamide in the form of a catalyst in melt spinning, which tends to increase the pressure of the spinning assembly and the spinning performance.

[0021] The present application is not particularly limited to the specific compounds of the a component and the b component, and the effects of heat resistance yellowing and high strength maintenance can be achieved as long as the compounds used belong to the aforementioned antioxidant classification. From the aspects of cost, compatibility of the antioxidant with the polymer matrix, and the like, the following antioxidants are listed in the present application, which have better effects.

[0022] The a component can be one or more of poly(dipropylene glycol) phenyl phosphite (antioxidant PDP), bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythrityl diphosphite (antioxidant PEP-36), tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), bis(2,4,6-tri-tert-butylphenyl) pentaerythrityl diphosphite (antioxidant RC633), tetrakis(2,4-di-tert-butylphenyl)-4,4'-diphenyldiphosphite (antioxidant P-EPQ), 3,9-bis-octadecyloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (antioxidant 618), bis(2,4-dicumylphenyl) pentaerythrityl diphosphite (antioxidant 9228).

[0023] The b component can be one or more of poly{[6-[(1,1,3,3-tetramethylbutyl) amino]]-1,3,5-triazine-2,4-[(2,2,6,6-tetramethyl-4-piperidyl) imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl) imino]} (HS944), poly(butane-1,4-dioic acid-4-hydroxyethyl-2,2,6,6-tetramethyl-1-piperidinylethyl ester) (UV622), carbonic acid-2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinyl ester (LA-81), 1,3,5-triazine-2,4,6-triamine-N-N”’-[1,2-ethanediylbis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidyl) amino]-1,3,5-triazin-2-yl] imino] 3,1-propanediyl]]-bis[N’-N”-dibutyl-N’,N”-bis(1,2,2,6,6-pentamethyl-4-piperidyl)] (HALS119), N,N’-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,3-benzenedicarboxamide (UV660), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (TINUVIN770).

[0024] The polyamide fiber according to the present application preferably further contains a component c of a hindered phenol antioxidant. The component c functions to prevent further decomposition of the amide group by reacting with the free radicals generated by the decomposition of the amide group, and also to some extent suppresses the generation of colored peroxides. The component c of the hindered phenol antioxidant is not particularly limited, and can be one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (antioxidant 330), 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (antioxidant TH-1790), N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (antioxidant 1024), 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (AO80), 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (antioxidant 2246), 2,6-di-tert-butyl-4-methylphenol (antioxidant BHT), and N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (antioxidant 1098), from the viewpoint of cost, compatibility of the antioxidant with the polymer matrix, and the like.

[0025] The content of the component c of the hindered phenol antioxidant (hereinafter referred to as "C") in the polyamide fiber according to the present application is not particularly limited, and can be within the range of the content of conventional antioxidants in general fibers.

[0026] The components a, b, and c are added components that are not compatible with the polyamide. If the total of A, B, and C (i.e., A+B+C) is too large, there is a problem in that the fiber manufacturing process is prone to cause floating and breaking of the fiber, and the spinning property is poor. Therefore, A, B, and C preferably satisfy the relationship: A+B+C≤2.00 wt%.

[0027] Since the phenol structure in the component c is apt to react with nitrogen and oxygen in the air to cause yellowing, the component c is apt to cause the polyamide fiber to yellow when the content of the component c is large, and the effect of capturing free radicals is poor when the content of the component c is small, and the heat yellowing resistance and the strength retention characteristics of the polyamide fiber cannot be effectively improved. Therefore, the component c can only be used as an auxiliary antioxidant of the components a and b. Meanwhile, the antioxidant effects of the component a, the component b and the component c all have their own limits, i.e. when the content of any one of the antioxidants exceeds a certain value (hereinafter referred to as the saturated content of the antioxidant), the antioxidant exceeding the saturated content cannot improve the antioxidant properties of the polyamide fiber, thereby causing waste. In view of the respective effects of the components a, b and c and the relationship between the saturated contents of the components a, b and c, the application optimizes the ratio of A, B and C so that the components a, b and c can exert their effects to the maximum extent without causing waste. In the case where the total amount of A and C is constant, as B decreases, i.e. the amount of the component b mainly acting to prevent the decomposition of the amide group to generate free radicals decreases, the amount of generated free radicals increases. When B decreases to a certain amount, the amount of free radicals decomposed from the amide group and the amount of peroxides converted from the free radicals increase, and the components a and c are insufficient to completely reduce the peroxides and capture the free radicals, thereby weakening the heat yellowing resistance and the strength retention characteristics of the polyamide fiber.

[0028] Therefore, in view of the action mechanism, the saturated content, the components and the heat yellowing resistance and the strength retention characteristics of the polyamide fiber, when the polyamide fiber contains the component c, the A, B and C preferably satisfy the relationship: (A+C) / B≤4.0. By making the contents of the antioxidant components satisfy the above relationship, the antioxidant components will not be wasted, and the polyamide fiber with excellent heat yellowing resistance can be obtained.

[0029] The oxidation yellowing of the polyamide fiber mainly occurs on the outer surface of the fiber in contact with oxygen, so the surface area of the single fiber of different fineness is not the same, the contact area with oxygen is not the same, and the oxidation degree in the same environment is also not the same. The present application finds that the smaller the single filament fineness, the more the single filaments, the larger the total surface area, and the easier to be oxidized, and vice versa, by studying the relationship between the single filament fineness and the antioxidant content. The dependent relationship between them can be represented by the formula A+B+C=-0.15T+D, wherein T is the single filament fineness, unit: dtex, and D is the antioxidant additive amount correction value. In the case of constant T, the smaller the D value, the smaller the total content of the antioxidant; the larger the D value, the larger the total content of the antioxidant. In order to make all the antioxidant components play an antioxidant effect and not be wasted, while achieving the expected heat yellowing resistance and strength retention effect, the value of D is preferably 0.65-2.20.

[0030] In addition, the molecular weight of the a component, the b component and the c component has an influence on the durability of the polyamide fiber. When the molecular weight of the antioxidant is too small, the antioxidant is easy to precipitate from the inside of the fiber when heated, such as when clothes are made into fabric, and further falls off after washing, which has a tendency to deteriorate the durability; when the molecular weight of the antioxidant is too large, the compatibility of the antioxidant with the polyamide is poor, and there is a tendency for frequent filament breakage during the production of the polyamide fiber. Therefore, considering the actual production and durability of the polyamide fiber, the molecular weight of the a component, the b component and the c component is preferably 400-1500 g / mol, respectively.

[0031] Through the above preferred technical solutions, the yellowness change value △YI of the polyamide fiber after dry heat treatment at 200℃×1min is further preferably below 5.0, and the strength retention rate is also further preferably above 90%.

[0032] The present application does not make special limitation to the composition of the polyamide, which can be a polyamide or a polyamide copolymer containing an amide group structure. The heat yellowing resistance of the antioxidant used in the present application is excellent, and when it is used in the polyamide 5X fiber or the polyamide 6X fiber which is most prone to heat yellowing, the effect is more prominent. The polyamide 5X fiber refers to a long-chain polyamide containing a pentanediamine structural unit, such as polyamide 54, polyamide 56, polyamide 510, polyamide 512, etc. The polyamide 6X fiber refers to a long-chain polyamide containing a hexanediamine structure, such as polyamide 66, polyamide 610, polyamide 612, etc.

[0033] The polyamide fiber can be a single fiber formed by a single polymer, a composite fiber formed by multiple polymers, a composite fiber made of polyamide and polyamide, or a composite fiber composed of polyamide and other polymers; or can be a core-sheath composite fiber, a side-by-side composite fiber, an eccentric core-sheath composite fiber, etc.

[0034] The preparation method of the polyamide fiber is not particularly limited in the present application, and one of the common melt spinning preparation methods is listed below, but is not limited to this method.

[0035] The polyamide chips and antioxidant master batches are mixed and fed into the feeding port, melted by the melt spinning machine, and then extruded into filaments through the spinneret. After the cooling and oiling steps, the polyamide fiber is obtained by using the one-step spinning and drawing process.

[0036] The spinning and drawing method preferably adopts the one-step spinning and drawing process, the spinning speed is 1000-4000 m / min, preferably 3000-4000 m / min; the extension temperature is 20-90℃, preferably 20-50℃; the extension ratio is 1.0-3.0; and the setting temperature is 140-180℃, preferably 150-170℃.

[0037] The present application uses a combination of a component phosphate ester antioxidant and a component hindered amine antioxidant to make the polyamide fiber have good yellowing resistance, strength retention and durability after high temperature heat treatment. In the preferred technical solution, by accurately compounding two or three antioxidants, the use amount of antioxidants is reduced as much as possible to reduce the cost and improve the durability while obtaining excellent yellowing resistance and strength retention.

[0038] The evaluation methods of the physical properties mentioned in the present application are as follows.

[0039] 1. Yellowing change value ΔYI

[0040] ① The polyamide fiber is fed into a circular knitting machine according to the 36G weft plain weave structure double yarn, and knitted into a circular knitted fabric with a density of 52 / 68 (warp / weft);

[0041] ② The circular knitted fabric is immersed in 90℃ water (bath ratio 1:50), 2g / L refining agent (YK66) is added, and then treated for 20min, taken out, dried in a 40℃ oven for 2 hours, and cut into a size of 20cm x 20cm (length x width) to obtain sample 1;

[0042] ③ The Datacolor 650 spectrophotometer is used to fold sample 1 four times, and test it with a 30mm hole to obtain the yellowing value YI1 of sample 1;

[0043] YI2is obtained by testing according to step ③;

[0044] YI2is obtained by testing according to step ③;

[0045] YI2is obtained by testing according to step ③;

[0046] 2. Yellowing change rate (durability)

[0047] ① The same as step ① and ② of test method 1, take 20 cm x 20 cm (length x width) size of sample 2, and treat it in a constant temperature and humidity environment at 70°C and 90% RH for 164 hours, then wash it 50 times according to JIS L 1930C4M standard and dry it;

[0048] ② Use Datacolor 650 spectrophotometer to fold sample 2 four times, and test it with a 30 mm hole to obtain the yellowing value YI3 of sample 2;

[0049] ③ Heat set sample 2 at 200°C for 1 minute, and test it according to step ② to obtain YI4;

[0050] YI2is obtained by testing according to step ③;

[0051]

[0052] When the yellowing change rate is < 15%, it indicates good durability; when the yellowing change rate is 15% ~ 30%, it indicates good durability; and when the yellowing change rate is > 30%, it indicates poor durability.

[0053] 3. Strength maintenance rate

[0054] ① Take 10 meters of polyamide fiber and test it by RTC-1225A type strength tester, with a test speed of 200 mm / min and a distance between two clamps of 200 mm, to obtain strength 1;

[0055] ② Take 10 meters of polyamide fiber from the same fiber roll, and put it into an oven for dry heat treatment at 200°C for 1 minute to obtain heat-treated polyamide fiber;

[0056] ③ Test the heat-treated polyamide fiber of step ② according to step ① to obtain strength 2;

[0057] YI2is obtained by testing according to step ③;

[0058] Strength maintenance rate = (strength 2 / strength 1) x 100%.

[0059] 4. Filament fineness

[0060] The fiber's single filament fineness (dtex) was obtained according to standard GB / T4743-2009.

[0061] 5. Antioxidant content and molecular weight

[0062] 0.5 g of polyamide fiber was dissolved in 20 ml of 1,1,3,3,3-hexafluoroisopropanol-D2 to prepare a solution, and then analyzed by 1H-NMR using a Bruker nuclear magnetic resonance spectrometer. The content and molecular weight of each antioxidant were calculated based on the peak area values.

[0063] 6. Evaluation of silk-making properties

[0064] During spinning, observe the frequency of filament drift. A frequency of 0 to 1 cycle / 24h is defined as excellent, 2 to 4 cycles / 24h as good, and more than 5 cycles / 24h as poor.

[0065] 7. Evaluation of component pressure rise

[0066] The spinning temperature was 280℃, and the polymer throughput through the filter screen was 34.2 g / min / cm. 2 Under the specified conditions, the component pressure change during spinning is judged as follows: when the component pressure rises by less than 0.5 MPa / 24h, it is judged as excellent; when the component pressure rises by 0.5 to 2.0 MPa / 24h, it is judged as good; and when the component pressure rises by more than 2.0 MPa / 24h, it is judged as poor.

[0067] The antioxidants involved in the embodiments of this invention are abbreviated as follows.

[0068] a ingredient:

[0069] (1) Tris(2,4-di-tert-butylphenyl) phosphite (abbreviation: IR168);

[0070] (2) Bis(2,4-dicumylphenyl)pentaerythritol diphosphite (abbreviation: Antioxidant 9228);

[0071] Component b:

[0072] (1) 1,3,5-triazine-2,4,6-triamine-NN”'-[1,2-ethanediylbis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]3,1-propanediyl]]-bis[N'-N”-dibutyl-N',N”-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)](HALS119);

[0073] (2) Poly(4-hydroxyethyl-2,2,6,6-tetramethyl-1-piperidineethanol) ester (UV622);

[0074] (3) N, N'-bis(2, 2, 6, 6-tetramethyl-4-piperidinyl)-1, 3-benzene dicarboxamide (abbreviation: UV660).

[0075] c component:

[0076] (1) Tetra[β-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester (abbreviation: IR1010);

[0077] (2) 3, 9-bis[1, 1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl]-2, 4, 8, 10-tetraoxaspiro[5.5]undecane (abbreviation: AO80);

[0078] (3) N, N'-(hexane-1, 6-diyl) bis[3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionamide] (abbreviation: antioxidant 1098).

[0079] (4) β-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid isooctanol ester (abbreviation: IR1135).

[0080] The present application will be described in detail below with reference to specific examples.

[0081] Example 1

[0082] The polyamide 56 chip and the antioxidant master batch (containing a component (antioxidant 9228) 2.0 wt%, b component (UV660) 15.0 wt%) were mixed in a ratio of 9:1 and fed into the inlet, and after melting by the melt spinning machine, the yarn was discharged through the spinneret. After the cooling and oiling steps, the yarn was obtained by the one-step process of spinning and drawing at a spinning speed of 3000 m / min, an extension temperature of 25°C, an extension ratio of 1.5, and a setting temperature of 160°C. The polyamide fiber having a specification of 44T-34F (single yarn fineness 1.3T) was obtained. The yellowing change value ΔYI of the obtained polyamide fiber was 4.6, the strength maintenance rate was 85%, and the spinning property, module pressure rise, and durability evaluation were all excellent. The specific formulation and physical properties are shown in Table 1.

[0083] Examples 2 to 22

[0084] The preparation method was the same as in Example 1, and the type and content of each antioxidant, the type of polyamide, and the molecular weight were changed. The specific formulation and physical properties are shown in Tables 1 to 3.

[0085] Comparative Example 1

[0086] The preparation method was the same as in Example 1, and no antioxidant master batch was added to prepare the polyamide fiber. The specific formulation and physical properties are shown in Table 3.

[0087] The polyamide fiber obtained has a large change in yellowness, poor heat resistance, poor anti-yellowing property and poor strength maintenance rate because no antioxidant is added.

[0088] Comparative Example 2

[0089] The polyamide fiber is prepared by the same method as in Example 1, and the antioxidant master batch contains only component c. The specific formulation and physical properties are shown in Table 3.

[0090] The strength maintenance rate of the obtained fiber is low because only component c is added, and the effect of a single component antioxidant is limited and cannot further improve the overall antioxidant effect of the polyamide fiber after reaching the saturated content.

[0091] Comparative Example 3

[0092] The polyamide fiber is prepared by the same method as in Example 1, and the antioxidant master batch contains only component a. The specific formulation and physical properties are shown in Table 3.

[0093] The strength maintenance rate of the obtained fiber is low because only component a is added, and the effect of a single component antioxidant is limited and cannot further improve the overall antioxidant effect of the polyamide fiber after reaching the saturated content.

[0094] Comparative Example 4

[0095] The polyamide fiber is prepared by the same method as in Example 1, and the antioxidant master batch contains only component b. The specific formulation and physical properties are shown in Table 3.

[0096] The strength maintenance rate of the obtained fiber is low because only component b is added, and the effect of a single component antioxidant is limited and cannot further improve the overall antioxidant effect of the polyamide fiber after reaching the saturated content.

[0097] Comparative Example 5

[0098] The polyamide fiber is prepared by the same method as in Example 1, and the antioxidant master batch contains components a and c. The specific formulation and physical properties are shown in Table 3.

[0099] The strength maintenance rate of the obtained fiber is low because only components a and c are added, and the effect of the antioxidant is limited due to the lack of component b.

[0100]

[0101]

[0102]

Claims

1. Polyamide fiber, characterized in that: The polyamide fiber contains polyamide, a component phosphoric acid ester antioxidant, and b component hindered amine antioxidant; the yellowness change value △YI of the polyamide fiber after dry heat treatment at 200℃×1min is below 7.0, and the strength retention rate is above 70%.

2. The polyamide fiber according to claim 1, characterized in that: The content A of the a component and the content B of the b component satisfy the relationship: B / A≥2.0, and A is 0.01-0.30wt%.

3. The polyamide fiber according to claim 2, characterized in that: The polyamide fiber further contains c component hindered phenol antioxidant, and the content C of the c component and A, B satisfy the relationship: A+B+C≤2.00wt%.

4. The polyamide fiber according to claim 3, characterized in that: The A, B, C satisfy the relationship: (A+C) / B≤4.

0.

5. The polyamide fiber according to claim 3 or 4, characterized in that: The relationship of A, B, C and the polyamide fiber monofilament fineness T is A+B+C = -0.15×T+D; wherein D is the antioxidant additive amount correction value, and the value is 0.65-2.

20.

6. The polyamide fiber according to claim 3 or 4, characterized in that: The molecular weight of the a component, b component, and c component is respectively 400-2500g / mol.

7. The polyamide fiber according to any one of claims 1 to 4, characterized in that: The yellowness change value △YI is below 5.

0.

8. The polyamide fiber according to any one of claims 1 to 4, characterized in that: The strength retention rate is above 90%.

9. The polyamide fiber according to any one of claims 1 to 4, characterized in that: The polyamide fiber is polyamide 5X fiber or polyamide 6X fiber.

Images