Yellowing-resistant bra cotton foam material and production process thereof

Abstract

The present invention relates to the technical field of underwear materials, and discloses a yellowing-resistant bra cotton foaming material and a production process thereof. The bra cotton foaming material in the present invention comprises the following raw materials in parts by weight: 60-80 parts of polyethylene glycol, 45-55 parts of hexamethylene diisocyanate, 15-25 parts of isophorone diisocyanate, 7-10 parts of modified chain extender, 5-8 parts of ethylenediamine, 3-5 parts of reinforcing fiber, 2-4 parts of foaming agent, and 0.5-1 parts of dibutyltin dilaurate; the bra cotton foaming material reduces the presence of double bonds and multiple bonds in the polyurethane molecular chain by selecting raw materials, improves the stability of the foaming material by changing the polyurethane molecular structure, and then improves the anti-yellowing performance; the introduced reinforcing fiber can provide a supporting effect in the foaming material, while improving the antibacterial performance and yellowing resistance of the foaming material; the introduction of the modified chain extender and ethylenediamine further improves the anti-yellowing performance.

Description

Technical Field

[0001] The invention relates to the technical field of underwear materials, and in particular to a yellowing-resistant bra cotton foam material and a production process thereof. Background Art

[0002] Bras are essential daily necessities for women, and bras are usually made of foam and textiles. The commonly used material for foam is polyurethane foam. Bras made of this material have the advantages of good air permeability, wear resistance, light weight, softness, easy cleaning, good elasticity, etc. However, polyurethane foam is often exposed to ultraviolet rays in sunlight for a long time during use, and it is easy to turn yellow and has no antibacterial properties. Polyurethane foam will turn yellow under the action of ultraviolet rays. This is because certain chemical groups in polyurethane foam, such as benzene rings directly connected to isocyanate groups, will cause the decomposition of urethane bonds under the action of light, heat, and oxygen, especially ultraviolet rays, to generate aromatic amines. After oxidative rearrangement, the benzene nucleus on the aromatic amine generates quinone-type structure and other chromophores, which makes polyurethane foam products easy to turn yellow, and at the same time causes the mechanical properties of the material to decline, ultimately affecting the service life.

[0003] At present, the methods for improving the yellowing of polyurethane materials mainly include the following: 1) replacing aromatic isocyanates with aliphatic isocyanates to improve the yellowing effect caused by the aromatic ring structure absorbing ultraviolet rays and easily generating quinone structures; 2) by mixing additives such as antioxidants, light stabilizers and ultraviolet absorbers with polyurethane to prepare anti-yellowing polyurethane materials. Therefore, the above methods can be used to develop a bra cotton foam material with excellent yellowing resistance and high efficiency antibacterial properties to meet actual needs. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a yellowing-resistant bra cotton foam material and a production process thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A yellowing-resistant bra cotton foam material comprises the following raw materials in parts by weight: 60-80 parts of polyethylene glycol, 45-55 parts of hexamethylene diisocyanate, 15-25 parts of isophorone diisocyanate, 7-10 parts of a modified chain extender, 5-8 parts of ethylenediamine, 3-5 parts of reinforcing fibers, 2-4 parts of a foaming agent, and 0.5-1 part of dibutyltin dilaurate;

[0007] The reinforcing fiber is prepared by the following steps:

[0008] Step A1: Add benzotriazole into a reactor containing methanol, stir and mix evenly under nitrogen, then drop allylamine while stirring, raise the temperature to 35°C after the dropwise addition is completed, react for 4-5 hours, and rotary evaporate to obtain a benzotriazole derivative;

[0009] Step A2: adding the seaweed fiber to a 2-3wt% glutaraldehyde solution and stirring to mix evenly, heating to 40-50°C and stirring for 30-60min, centrifuging and washing, then adding a benzotriazole derivative aqueous solution and reacting at 40-50°C for 2h, then adding a tris(hydroxymethyl)aminomethane aqueous solution and continuing to react for 2-3h, centrifuging, washing and drying to obtain the reinforced fiber;

[0010] Further, in step A1, the usage ratio of benzotriazole, allylamine and methanol is 0.1 mol: 0.13-0.23 mol: 100 mL;

[0011] Furthermore, in step A2, the amount ratio of the seaweed fiber, the glutaraldehyde solution, the benzotriazole derivative aqueous solution and the tris(hydroxymethyl)aminomethane aqueous solution is 1 g: 30-40 mL: 10 mL: 10 mL;

[0012] Furthermore, in step A2, the benzotriazole derivative aqueous solution is prepared by mixing the benzotriazole derivative and deionized water in a dosage ratio of 0.01-0.02 mol:10 mL, and the tris(hydroxymethyl)aminomethane aqueous solution is prepared by mixing tris(hydroxymethyl)aminomethane and deionized water in a dosage ratio of 0.015-0.025 mol:10 mL;

[0013] The modified chain extender is prepared by the following steps:

[0014] Step B1: Add 4,4'-dihydroxybenzophenone, methyl acrylate, dibutyltin dilaurate and p-hydroxyanisole into a reactor, slowly heat to 120°C under stirring conditions, maintain the top temperature of the fractionation column at 55-65°C, keep the reaction for 2-5 hours, and distill under reduced pressure to obtain intermediate product 1;

[0015] Step B2: 1H-benzimidazole-4-ol was added to a reactor containing methanol, and mixed and stirred evenly under nitrogen, and then the intermediate product 1 was slowly added while stirring, and the system temperature was raised to 35-45° C., and the reaction was carried out for 4-5 hours, and the intermediate product 2 was obtained by rotary evaporation;

[0016] Step B3: adding the intermediate product methyl 2,4-aminobenzoate, dibutyltin dilaurate and p-hydroxyanisole into a reactor, slowly heating to 100-120° C. under stirring conditions, maintaining the top temperature of the fractionation column at 50-60° C., maintaining the reaction for 4-6 hours, and distilling under reduced pressure to obtain a modified chain extender;

[0017] Further, in step B1, the usage ratio of 4,4'-dihydroxybenzophenone, methyl acrylate, dibutyltin dilaurate and p-hydroxyanisole is 0.01-0.02 mol: 0.25-0.5 mol: 0.8-1.6 g: 0.02 g;

[0018] Further, in step B2, the usage ratio of 1H-benzimidazol-4-ol, methanol and intermediate 1 is 0.023-0.043 mol:100 mL:0.01-0.02 mol;

[0019] Furthermore, in step B3, the usage ratio of the intermediate product methyl 2,4-aminobenzoate, dibutyltin dilaurate and p-hydroxyanisole is 0.01 mol: 0.02-0.03 mol: 0.6-1 g: 0.015 g.

[0020] A production process of a yellowing-resistant bra cotton foam material comprises the following steps:

[0021] Weigh the raw materials by weight, add polyethylene glycol, hexamethylene diisocyanate and isophorone diisocyanate into a stirrer, stir at 30°C for 40-60min, then add modified chain extender, ethylenediamine, reinforcing fiber, foaming agent and dibutyltin dilaurate, mix and stir evenly, and then perform foaming and aging treatment to obtain a yellowing-resistant bra cotton foam material.

[0022] Beneficial effects of the present invention:

[0023] The bra cotton foam material of the present invention selects raw materials, reduces the presence of double bonds and multiple bonds in the polyurethane molecular chain, improves the stability of the foam material by changing the polyurethane molecular structure, and further improves the yellowing resistance; the introduced reinforcing fiber can provide a supporting effect in the foam material, and at the same time improves the antibacterial property and yellowing resistance of the foam material; the introduction of the modified chain extender and ethylenediamine further improves the yellowing resistance.

[0024] In the reinforcing fiber, the secondary amine in benzotriazole and the carbon-carbon double bond in allylamine are firstly reacted to synthesize a benzotriazole derivative containing an amino terminal structure; then glutaraldehyde is used as a cross-linking agent to modify the benzotriazole derivative and trishydroxymethylaminomethane on the surface of the seaweed fiber to obtain the reinforcing fiber. The introduction of reinforcing fibers can provide support in the foaming material and improve the antibacterial and yellowing resistance of the foaming material; among them, seaweed fibers, as the base of reinforcing fibers, can play a supporting role in the foaming material and have a certain fixing effect on the shape of the foaming material after molding, making it not easy to deform. At the same time, seaweed fibers also give the foaming material certain antibacterial properties. This is because the polysaccharides, alginate compounds and special structures contained in seaweed fibers can inhibit the growth and reproduction of bacteria, fungi and other microorganisms, thereby achieving biological antibacterial and deodorizing effects; the introduction of benzotriazole derivatives improves the yellowing resistance of the foaming material. This is because it has a good ultraviolet absorption effect, can convert ultraviolet rays into heat energy, effectively reduce the direct damage of ultraviolet rays to the foaming material, thereby slowing down the yellowing caused by ultraviolet radiation. In addition, the hydroxyl group in the reinforcing fiber can also react with the isocyanate group in the polyurethane molecular chain, and the reinforcing fiber is fixed in the matrix by chemical bonding, avoiding the migration phenomenon caused by the poor compatibility of traditional reinforcing materials.

[0025] In the modified chain extender, an ester exchange reaction between a hydroxyl group in 4,4'-dihydroxybenzophenone and an ester group in methyl acrylate is used to synthesize an intermediate product 1 containing a terminal double bond structure; the terminal double bond in the intermediate product 1 is then reacted with a secondary amine in 1H-benzimidazole-4-ol to generate an intermediate product 2; and the hydroxyl group in the intermediate product 2 is then reacted with an ester group in methyl 4-aminobenzoate to generate a modified chain extender containing a terminal amino group structure. The introduction of modified chain extenders improves the UV resistance and yellowing resistance of foaming materials. This is because the terminal amino group in the modified chain extender reacts with the isocyanate group in the polyurethane molecular chain to form a urea bond. The increase in urea bonds reduces the percentage of carbamate groups in the polyurethane molecular chain, thereby reducing the generation of colored groups caused by the breaking of carbamate groups under light and heat conditions, thereby improving the yellowing resistance of the matrix; among them, the benzophenone group has excellent ultraviolet absorption ability. Its introduction can effectively reduce the yellowing of foaming materials caused by ultraviolet rays, and at the same time avoids the migration and incompatibility of traditional ultraviolet absorbers; the introduction of benzimidazole structure and benzene ring increases the stability of the polyurethane molecular chain, thereby reducing the yellowing phenomenon caused by environmental factors. In addition, the benzimidazole structure also has certain antibacterial properties, which can work together with the reinforcing fiber to improve the antibacterial properties of the foaming material. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1:

[0027] The reinforcing fibers are prepared by the following steps:

[0028] Step A1: Add 0.1 mol of benzotriazole into a reactor containing 100 mL of methanol, stir and mix evenly under nitrogen, then dropwise add 0.13 mol of allylamine while stirring, raise the temperature to 35°C after the dropwise addition is completed, react for 4 hours, and rotary evaporate to obtain a benzotriazole derivative;

[0029] Step A2: Add 1 g of seaweed fiber to 30 mL of 2 wt% glutaraldehyde solution and stir to mix evenly, heat to 40 ° C and stir for 30 minutes, centrifuge and wash, then add 10 mL of benzotriazole derivative aqueous solution, react at 40 ° C for 2 hours, then add 10 mL of tris(hydroxymethyl)aminomethane aqueous solution and continue to react for 2 hours, centrifuge, wash and dry to obtain reinforced fiber. In step A2, the benzotriazole derivative aqueous solution is prepared by mixing a benzotriazole derivative and deionized water in a dosage ratio of 0.01 mol: 10 mL, and the tris(hydroxymethyl)aminomethane aqueous solution is prepared by mixing tris(hydroxymethyl)aminomethane and deionized water in a dosage ratio of 0.015 mol: 10 mL.

[0030] The modified chain extender is prepared by the following steps:

[0031] Step B1: 0.01 mol of 4,4'-dihydroxybenzophenone, 0.25 mol of methyl acrylate, 0.8 g of dibutyltin dilaurate and 0.02 g of p-hydroxyanisole were added to a reactor, slowly heated to 120°C under stirring conditions, and the top temperature of the distillation column was maintained at 55°C. The reaction was maintained for 2 hours, and the intermediate product 1 was obtained by distillation under reduced pressure;

[0032] Step B2: 0.023 mol of 1H-benzimidazole-4-ol was added to a reactor containing 100 mL of methanol, and mixed and stirred evenly under nitrogen, and then 0.01 mol of intermediate 1 was slowly added while stirring, and the system temperature was raised to 35° C., reacted for 4 hours, and rotary evaporated to obtain intermediate 2;

[0033] Step B3: Add 0.01 mol of intermediate product 2, 0.02 mol of methyl 4-aminobenzoate, 0.6 g of dibutyltin dilaurate and 0.015 g of p-hydroxyanisole into a reactor, slowly heat to 100°C under stirring conditions, and maintain the top temperature of the distillation column at 50°C. Keep the reaction for 4 hours, and distill under reduced pressure to obtain a modified chain extender. Embodiment 2:

[0034] The reinforcing fibers are prepared by the following steps:

[0035] Step A1: Add 0.1 mol of benzotriazole into a reactor containing 100 mL of methanol, stir and mix evenly under nitrogen, then dropwise add 0.18 mol of allylamine while stirring, raise the temperature to 35°C after the dropwise addition is completed, react for 4.5 hours, and rotary evaporate to obtain a benzotriazole derivative;

[0036] Step A2: Add 1 g of seaweed fiber to 35 mL of 2.5 wt% glutaraldehyde solution and stir to mix evenly, heat to 45 ° C and stir for 45 minutes, centrifuge and wash, then add 10 mL of benzotriazole derivative aqueous solution, react at 45 ° C for 2 hours, then add 10 mL of tris(hydroxymethyl)aminomethane aqueous solution and continue to react for 2.5 hours, centrifuge, wash and dry to obtain reinforced fiber. In step A2, the benzotriazole derivative aqueous solution is prepared by mixing a benzotriazole derivative and deionized water in a dosage ratio of 0.015 mol: 10 mL, and the tris(hydroxymethyl)aminomethane aqueous solution is prepared by mixing tris(hydroxymethyl)aminomethane and deionized water in a dosage ratio of 0.02 mol: 10 mL.

[0037] The modified chain extender is prepared by the following steps:

[0038] Step B1: 0.015 mol of 4,4'-dihydroxybenzophenone, 0.35 mol of methyl acrylate, 1.2 g of dibutyltin dilaurate and 0.02 g of p-hydroxyanisole were added into a reactor, slowly heated to 120°C under stirring conditions, and the top temperature of the fractionation column was maintained at 60°C. The reaction was maintained for 3.5 hours, and the mixture was distilled under reduced pressure to obtain an intermediate product 1;

[0039] Step B2: 0.033 mol of 1H-benzimidazole-4-ol was added to a reactor containing 100 mL of methanol, and mixed and stirred evenly under nitrogen, and then 0.015 mol of intermediate 1 was slowly added while stirring, and the system temperature was raised to 40° C., and the reaction was carried out for 4.5 hours, and the intermediate 2 was obtained by rotary evaporation;

[0040] Step B3: Add 0.01 mol of intermediate product 2, 0.025 mol of methyl 4-aminobenzoate, 0.8 g of dibutyltin dilaurate and 0.015 g of p-hydroxyanisole into a reactor, slowly heat to 110°C under stirring conditions, and maintain the top temperature of the distillation column at 55°C. Keep the reaction for 5 hours, and distill under reduced pressure to obtain a modified chain extender. Embodiment 3:

[0041] The reinforcing fibers are prepared by the following steps:

[0042] Step A1: add 0.1 mol of benzotriazole into a reactor containing 100 mL of methanol, stir and mix evenly under nitrogen, then dropwise add 0.23 mol of allylamine while stirring, raise the temperature to 35°C after the dropwise addition is completed, react for 5 hours, and rotary evaporate to obtain a benzotriazole derivative;

[0043] Step A2: Add 1 g of seaweed fiber to 40 mL of 3 wt% glutaraldehyde solution and stir to mix evenly, heat to 50 ° C and stir for 60 min, centrifuge and wash, then add 10 mL of benzotriazole derivative aqueous solution, react at 50 ° C for 2 h, then add 10 mL of tris(hydroxymethyl)aminomethane aqueous solution and continue to react for 3 h, centrifuge, wash and dry to obtain reinforced fiber. In step A2, the benzotriazole derivative aqueous solution is prepared by mixing a benzotriazole derivative and deionized water in a dosage ratio of 0.02 mol: 10 mL, and the tris(hydroxymethyl)aminomethane aqueous solution is prepared by mixing tris(hydroxymethyl)aminomethane and deionized water in a dosage ratio of 0.025 mol: 10 mL.

[0044] The modified chain extender is prepared by the following steps:

[0045] Step B1: 0.02 mol of 4,4'-dihydroxybenzophenone, 0.5 mol of methyl acrylate, 1.6 g of dibutyltin dilaurate and 0.02 g of p-hydroxyanisole were added to a reactor, slowly heated to 120°C under stirring conditions, and the top temperature of the fractionation column was maintained at 65°C. The reaction was maintained for 5 hours, and the mixture was distilled under reduced pressure to obtain an intermediate product 1;

[0046] Step B2: 0.043 mol of 1H-benzimidazole-4-ol was added to a reactor containing 100 mL of methanol, and mixed and stirred evenly under nitrogen, and then 0.02 mol of intermediate 1 was slowly added while stirring, and the system temperature was raised to 45° C., reacted for 5 h, and rotary evaporated to obtain intermediate 2;

[0047] Step B3: Add 0.01 mol of intermediate product 2, 0.03 mol of methyl 4-aminobenzoate, 1 g of dibutyltin dilaurate and 0.015 g of p-hydroxyanisole into a reactor, slowly heat to 120°C under stirring conditions, and maintain the top temperature of the distillation column at 60°C. Keep the reaction for 6 hours and distill under reduced pressure to obtain a modified chain extender. Embodiment 4:

[0048] A production process of a yellowing-resistant bra cotton foam material comprises the following steps:

[0049] Polyethylene glycol ( Mn =3000) 60 parts, hexamethylene diisocyanate 45 parts, isophorone diisocyanate 15 parts, modified chain extender prepared in Example 1 7 parts, ethylenediamine 5 parts, reinforcing fiber prepared in Example 1 3 parts, deionized water 2 parts, dibutyltin dilaurate 0.5 parts;

[0050] The raw materials were weighed by weight, polyethylene glycol, hexamethylene diisocyanate and isophorone diisocyanate were added into a stirrer, stirred at 30° C. for 40 min, and then the modified chain extender prepared in Example 1, ethylenediamine, the reinforcing fiber prepared in Example 1, deionized water and dibutyltin dilaurate were added and mixed and stirred evenly, and then foamed and aged to obtain a yellowing-resistant bra cotton foam material. Embodiment 5:

[0051] A production process of a yellowing-resistant bra cotton foam material comprises the following steps:

[0052] Polyethylene glycol ( Mn =3000) 70 parts, hexamethylene diisocyanate 50 parts, isophorone diisocyanate 20 parts, modified chain extender prepared in Example 2 8 parts, ethylenediamine 7 parts, reinforcing fiber prepared in Example 2 4 parts, deionized water 3 parts, dibutyltin dilaurate 0.7 parts;

[0053] The raw materials were weighed by weight, polyethylene glycol, hexamethylene diisocyanate and isophorone diisocyanate were added into a stirrer, stirred at 30°C for 50 min, and then the modified chain extender prepared in Example 2, ethylenediamine, the reinforcing fiber prepared in Example 2, deionized water and dibutyltin dilaurate were added and mixed and stirred evenly, and then foamed and aged to obtain a yellowing-resistant bra cotton foam material. Embodiment 6:

[0054] A production process of a yellowing-resistant bra cotton foam material comprises the following steps:

[0055] Polyethylene glycol ( Mn=3000) 80 parts, hexamethylene diisocyanate 55 parts, isophorone diisocyanate 25 parts, modified chain extender prepared in Example 3 10 parts, ethylenediamine 8 parts, reinforcing fiber prepared in Example 3 5 parts, deionized water 4 parts, dibutyltin dilaurate 1 part;

[0056] The raw materials were weighed by weight, polyethylene glycol, hexamethylene diisocyanate and isophorone diisocyanate were added into a stirrer, stirred at 30°C for 60 min, and then the modified chain extender prepared in Example 3, ethylenediamine, the reinforcing fiber prepared in Example 3, deionized water and dibutyltin dilaurate were added, mixed and stirred evenly, and then foamed and aged to obtain a yellowing-resistant bra cotton foam material.

[0057] Comparative Example 1

[0058] This comparative example is a foaming material, which differs from Example 6 in that an equal amount of 1,4-butanediamine is used to replace the modified chain extender prepared in Example 3, and the rest are the same.

[0059] Comparative Example 2

[0060] This comparative example is a foaming material, which differs from Example 6 in that an equal amount of seaweed fibers is used to replace the reinforcing fibers prepared in Example 3, and the rest are the same.

[0061] The foaming materials prepared in Examples 4-6 and Comparative Examples 1-2 were subjected to performance tests:

[0062] Yellowing resistance test: The obtained foaming material is tested for yellowing resistance under ultraviolet light of 290-400nm;

[0063] Antibacterial performance test: Tested in accordance with GB15979-2002 standard;

[0064] The test results are shown in the following table:

[0065]

[0066] It can be seen from the above table that the foaming material prepared by the present invention has a yellowing resistance time of 102-111 hours after ultraviolet light irradiation, indicating that it has excellent yellowing resistance; after the antibacterial performance test, the antibacterial rates of Escherichia coli and Staphylococcus aureus are both 99.9%, indicating that the foaming material has an excellent antibacterial rate.

[0067] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A yellowing-resistant bra cotton foam material, characterized in that: The invention comprises the following raw materials in parts by weight: 60-80 parts of polyethylene glycol, 45-55 parts of hexamethylene diisocyanate, 15-25 parts of isophorone diisocyanate, 7-10 parts of modified chain extender, 5-8 parts of ethylenediamine, 3-5 parts of reinforcing fiber, 2-4 parts of foaming agent and 0.5-1 part of dibutyltin dilaurate; The reinforcing fiber is prepared by the following steps: Step A1: Add benzotriazole into a reactor containing methanol, stir and mix evenly under nitrogen, then drop allylamine while stirring, raise the temperature to 35°C after the dropwise addition is completed, react for 4-5 hours, and rotary evaporate to obtain a benzotriazole derivative; Step A2: adding the seaweed fiber to a 2-3wt% glutaraldehyde solution and stirring to mix evenly, heating to 40-50°C and stirring for 30-60min, centrifuging and washing, then adding a benzotriazole derivative aqueous solution and reacting at 40-50°C for 2h, then adding a tris(hydroxymethyl)aminomethane aqueous solution and continuing to react for 2-3h, centrifuging, washing and drying to obtain the reinforced fiber; The modified chain extender is prepared by the following steps: Step B1: Add 4,4'-dihydroxybenzophenone, methyl acrylate, dibutyltin dilaurate and p-hydroxyanisole into a reactor, slowly heat to 120°C under stirring conditions, maintain the top temperature of the fractionation column at 55-65°C, keep the reaction for 2-5 hours, and distill under reduced pressure to obtain intermediate product 1; Step B2: 1H-benzimidazole-4-ol was added to a reactor containing methanol, and mixed and stirred evenly under nitrogen, and then the intermediate product 1 was slowly added while stirring, and the system temperature was raised to 35-45° C., and the reaction was carried out for 4-5 hours, and the intermediate product 2 was obtained by rotary evaporation; Step B3: Add the intermediate product methyl 2,4-aminobenzoate, dibutyltin dilaurate and p-hydroxyanisole into the reactor, slowly heat to 100-120°C under stirring conditions, and maintain the top temperature of the distillation column at 50-60°C, keep the reaction for 4-6 hours, and distill under reduced pressure to obtain the modified chain extender.

2. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step A1, the usage ratio of benzotriazole, allylamine and methanol is 0.1 mol: 0.13-0.23 mol: 100 mL.

3. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step A2, the usage ratio of the seaweed fiber, the glutaraldehyde solution, the benzotriazole derivative aqueous solution and the tris(hydroxymethyl)aminomethane aqueous solution is 1 g:30-40 mL:10 mL:10 mL.

4. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step A2, the benzotriazole derivative aqueous solution is prepared by mixing the benzotriazole derivative and deionized water in a dosage ratio of 0.01-0.02 mol:10 mL, and the tris(hydroxymethyl)aminomethane aqueous solution is prepared by mixing tris(hydroxymethyl)aminomethane and deionized water in a dosage ratio of 0.015-0.025 mol:10 mL.

5. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step B1, the usage ratio of 4,4'-dihydroxybenzophenone, methyl acrylate, dibutyltin dilaurate and p-hydroxyanisole is 0.01-0.02 mol: 0.25-0.5 mol: 0.8-1.6 g: 0.02 g.

6. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step B2, the usage ratio of 1H-benzimidazole-4-ol, methanol and intermediate 1 is 0.023-0.043 mol:100 mL:0.01-0.02 mol.

7. The yellowing-resistant bra cotton foam material according to claim 1, characterized in that: In step B3, the usage ratio of the intermediate product 2,4-aminobenzoic acid methyl ester, dibutyltin dilaurate and p-hydroxyanisole is 0.01 mol: 0.02-0.03 mol: 0.6-1 g: 0.015 g.

8. The production process of the yellowing-resistant bra cotton foam material according to claim 1, characterized in that: The following steps are involved: Weigh the raw materials by weight, add polyethylene glycol, hexamethylene diisocyanate and isophorone diisocyanate into a stirrer, stir at 30°C for 40-60 minutes, then add a modified chain extender, ethylenediamine, reinforcing fiber, a foaming agent and dibutyltin dilaurate, mix and stir evenly, and then perform foaming and aging treatment to obtain a yellowing-resistant bra cotton foam material.

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