CN116120181A - Liquid hindered phenol antioxidant and preparation method and application thereof - Google Patents

Abstract

，所述R₁、R₂为C₁～C₈的烷基，R₃为C₁～C₅的烷撑基，所述R₄基为脂肪醇酯化或酯交换反应之后保留在酯结构中的有机基团；本发明所制备的液态受阻酚类抗氧剂不仅能够有效抑制聚醚在储存过程中醛的产生，还具备一定的耐热抗氧化性能和热稳定性，并且与聚氨酯泡沫具有极佳的相容性，特别适用于聚氨酯软泡沫胶板。The invention discloses a liquid hindered phenolic antioxidant and its preparation method and application. The liquid hindered phenolic antioxidant has a molecular structure of:

, the R ₁ and R ₂ are C ₁ to C ₈ alkyl groups, R ₃ is a C ₁ to C ₅ alkylene group, and the R ₄ group is retained in the ester structure after fatty alcohol esterification or transesterification organic groups in the organic group; the liquid hindered phenolic antioxidant prepared by the present invention can not only effectively inhibit the production of aldehydes in the storage process of polyether, but also has certain heat resistance and oxidation resistance and thermal stability, and is compatible with polyurethane foam It has excellent compatibility, especially suitable for polyurethane soft foam rubber sheet.

Description

A kind of liquid hindered phenolic antioxidant and its preparation method and application

technical field

The invention belongs to antioxidants for polymer materials, and the classification number is C07C67/03. Specifically, it relates to a liquid hindered phenolic antioxidant and its preparation method and application.

Background technique

Polyurethane material has excellent performance, wide adjustable range, and strong adaptability. It is widely used in many fields of the national economy, especially in the field of polyurethane foam for vehicles. Due to the improvement of people's living standards, cars have become a part of people's homes and workplaces. However, because polyurethane foam is inevitably subjected to heat, light, air, oxygen and water during use, its aging will be reduced, its performance will also be attenuated, and it will eventually lose its use value. Therefore, people generally add antioxidants to prevent the aging and decomposition of polyurethane foam.

The current antioxidants mainly include hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants. Among them, hindered phenolic antioxidants are one of the most widely used and effective antioxidants, but the current hindered phenolic antioxidants such as antioxidant 1076 can prevent the aging and decomposition of polyurethane foam to a certain extent, but Because it is a solid, it cannot be well compatible with polyurethane foam during use, which will greatly reduce its antioxidant performance. Therefore, the current demand for hindered phenolic antioxidants in the market is greatly increased.

However, there are certain difficulties in developing liquid hindered phenolic antioxidants for polyurethane foams. First, polyurethane foams need to have certain compatibility with antioxidants. Secondly, even if the compatibility between antioxidants and polyurethane foams is satisfied, due to Various factors such as molecular weight, volatility and dispersibility may also affect its antioxidant effect. Therefore, on the basis of the above, it is necessary to overcome the defects of existing liquid hindered phenolic antioxidants and improve heat resistance stability. The problem to be solved by the present invention.

The patent application number CN1247737C has developed a liquid antioxidant and its preparation method. The main advantages of the liquid antioxidant are high carbon number, low volatility, and low freezing point. Although it shows that it can be compatible with materials, But did not specify the specific composition of the material.

The patent application number is CN113264869B has developed a hindered phenolic antioxidant and its preparation method, which solves the problem that phenolic antioxidants are easily volatilized and lost when heated during processing and use, and are compatible with non-polar polymers It also has good compatibility, but the hindered phenolic antioxidant is mainly used in natural rubber, which is significantly different from the present application.

Contents of the invention

In order to solve the above problems, the first aspect of the present invention provides a liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C ₁ to C ₈ alkyl groups, R ₃ is a C ₁ to C ₅ alkylene group, and the R ₄ group is retained in the ester structure after esterification or transesterification of fatty alcohols of organic groups.

Further preferably, the R ₁ and R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, and the R ₄ group remains in the ester _structure after transesterification of isomeric 18 alcohols organic groups in .

Preferably, the relative molecular mass of the liquid hindered phenolic antioxidant is 400-800.

Further preferably, the relative molecular mass of the liquid hindered phenolic antioxidant is 400-600.

Further preferably, the relative molecular mass of the liquid hindered phenolic antioxidant is 530.

Preferably, the raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 100-200 parts of branched chain fatty alcohol, 1-4 parts of catalyst, and 90-150 parts of organic antioxidant.

Further preferably, the raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 100-150 parts of branched chain fatty alcohol, 1-3 parts of catalyst, and 90-100 parts of organic antioxidant.

Further preferably, the raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight: 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

Preferably, the branched chain fatty alcohol is a C ₁₆ -C ₂₅ branched chain fatty alcohol.

Further preferably, the branched chain fatty alcohol is a C ₁₈ -C ₂₄ branched chain fatty alcohol.

Further preferably, the branched chain fatty alcohol is a C ₁₈ -C ₂₀ branched chain fatty alcohol.

Further preferably, the branched chain fatty alcohol is _C18 branched chain fatty alcohol.

Further preferably, the _C18 branched chain fatty alcohol is isomerized 18 alcohol.

Preferably, the catalyst includes at least one of aluminum alkoxides, alkali metal compounds, aluminum phenoxides, organotin compounds and organozinc salts.

Further preferably, the catalyst is an organotin compound.

Further preferably, the catalyst is monobutyltin oxide.

Preferably, the organic antioxidant is 3,5 methyl ester.

Preferably, the molar ratio between the organic antioxidant and the branched fatty alcohol is (1-1.5):1.

Further preferably, the molar ratio between the organic antioxidant and the branched fatty alcohol is (1-1.2):1.

Further preferably, the molar ratio between the organic antioxidant and the branched fatty alcohol is 1.1:1.

The second aspect of the present invention provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add organic antioxidant, catalyst and branched chain fatty alcohol into the reaction device in parts by weight, gradually increase the temperature and increase the pressure to 0.08～-0.1MPa, after a period of reaction, distill off excess methanol, cool down to 25-35°C, Filter out the catalyst to obtain the product.

Preferably, the reaction temperature after the heating is 150-180°C, and the reaction time is 5-9h.

Further preferably, the reaction temperature after the heating is 160-170° C., and the reaction time is 6-8 hours.

Further preferably, the reaction temperature after the heating is 165° C., and the reaction time is 7 hours.

The third aspect of the present invention provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

The present invention also provides a preparation method of an organic antioxidant, the steps are as follows: add 2776kg of 2,6-di-tert-butylphenol into a 100°C oven for dehydration for 1.5h, perform nitrogen replacement three times, and raise the temperature to 125°C, then add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, then add 20kg of formic acid to neutralize the alkali catalyst, filter, then add methanol After crystallization, it can be obtained by washing and filtering.

The applicant found that the liquid hindered phenolic antioxidant prepared in the present invention is an asymmetric phenolic antioxidant, wherein the ortho-substituents are all tert-butyl, and the para-substituents are C _{18 -C 24} The heterogeneous branched chain, because its carbon chain is a long-chain alkane, it can not only be better compatible with polyurethane, but also unexpectedly found that it can also improve its thermal stability and heat resistance to a certain extent. Oxidation performance, it is speculated that the heterogeneous branch of C _18- C ₂₄ is an electron-donating group, which can accelerate the separation of hydrogen atoms on the phenolic hydroxyl group, so that the antioxidant activity is improved, and the tert-butyl groups on both sides make the benzene ring and The phenolic hydroxyl groups are not on the same plane, which makes it difficult for the electrons on the P orbital of the oxygen atom to conjugate with the electrons on the benzene ring, which further improves its heat resistance and oxidation resistance. Although the larger steric hindrance of the ortho-tert-butyl group can It has a certain protective effect on phenolic oxygen radicals, and its thermal stability has been improved to a certain extent, but the steric hindrance effect of the heterogeneous branched chain with C _18- C ₂₄ substituents in the ortho-tert-butyl group and the para-position is too high, It may reduce its heat resistance and oxidation resistance. Therefore, the relative molecular mass of the antioxidant is limited to only 400-600. While ensuring the steric hindrance effect of the adjacent substituents, it also avoids the The resistance effect is too strong and its thermal oxidation resistance is reduced.

Beneficial effect:

(1) The liquid hindered phenolic antioxidant prepared by the present invention can effectively inhibit the production of aldehydes in the storage process of polyether, and has excellent compatibility with polyurethane foam, and can provide polyurethane foam with excellent anti-burning core and Anti-ultraviolet performance, as well as certain heat and oxidation resistance and thermal stability, especially suitable for polyurethane soft foam rubber sheet.

(2) The liquid hindered phenolic antioxidant prepared by the present invention has low volatility, prevents it from fogging on the surface of polyurethane products used in automobiles, and can also avoid the coloring problem of textiles.

(3) The liquid hindered phenolic antioxidant prepared by the present invention is in a liquid state, which is convenient for transportation and use, and can be dissolved, dispersed or kept in a pure liquid state during processing, which greatly improves its practicability.

Example

Example 1

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, and the R ₄ group is an organic _group remaining in the ester structure after transesterification of isomeric 18 alcohols group.

The molecular weight of the liquid hindered phenolic antioxidant is 530.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

Described branched chain fatty alcohol is isomerism 18 alcohol, is purchased from Germany Sasol company, and model is ISOFOL 18T.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3,5 methyl ester.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

Example 2

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, _and the R ₄ group is an organic group remaining in the ester structure after transesterification of isomeric 20 alcohols group.

The molecular weight of the liquid hindered phenolic antioxidant is 558.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

Described branched chain fatty alcohol is isomerism 20 alcohol, is purchased from German Sasol company, and model is ISOFOL 20.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3,5 methyl ester.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

Example 3

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, _and the R ₄ group is an organic group remaining in the ester structure after transesterification of isomeric 24 alcohols group.

The molecular weight of the liquid hindered phenolic antioxidant is 614.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

The branched fatty alcohol is isomerism 24 alcohol, purchased from Germany Sasol Company, model is ISOFOL 24.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3,5 methyl ester.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

Comparative example 1

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, _and the R ₄ group is an organic group remaining in the ester structure after transesterification of isomeric 12 alcohols group.

The molecular weight of the liquid hindered phenolic antioxidant is 446.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

Described branched chain fatty alcohol is isomerism 12 alcohol, is purchased from Germany Sasol company, and model is ISOFOL 12.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3,5 methyl ester.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

Comparative example 2

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R _{1 and} R ₂ are C tert-butyl groups, the R ₃ is a C ₂ alkylene group, and the R ₄ group is the organic compound remaining in the ester structure after the transesterification of n-eicosanol. group.

The molecular weight of the liquid hindered phenolic antioxidant is 558.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

The branched fatty alcohol is n-eicosanol.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3,5 methyl ester.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

Comparative example 3

A liquid hindered phenolic antioxidant, the molecular structure of the liquid hindered phenolic antioxidant is:

The R ₁ is a C tert-butyl group, the R ₂ is a C ₁ methyl group, the _{R 3} is a C ₂ alkylene group, and the R ₄ group is after transesterification of isomeric 18 alcohols Organic groups remaining in the ester structure.

The molecular weight of the liquid hindered phenolic antioxidant is 488.

The raw materials for the preparation of the liquid hindered phenolic antioxidant include, in parts by weight, 110 parts of branched chain fatty alcohol, 2 parts of catalyst, and 95 parts of organic antioxidant.

Described branched chain fatty alcohol is isomerism 18 alcohol, is purchased from Germany Sasol company, and model is ISOFOL 18T.

The catalyst is monobutyl tin oxide.

The organic antioxidant is 3-(3-tert-butyl-4-hydroxy-5-methylphenyl) methyl propionate, purchased from Jinjinle (Hunan) Chemical Co., Ltd.

The molar ratio between the organic antioxidant and the branched chain fatty alcohol is 1.1:1.

The second aspect of this embodiment provides a method for preparing a liquid hindered phenolic antioxidant, the steps are as follows:

Add the organic antioxidant, catalyst and branched fatty alcohol into the reaction device in parts by weight, gradually raise the temperature to 165°C, increase the pressure to 0.09MPa, react for 7 hours, distill off excess methanol, cool down to 30°C, and filter out the catalyst Butyl tin oxide, that is the product.

The third aspect of this embodiment provides the application of a liquid hindered phenolic antioxidant in polyurethane foam for vehicles.

This example also provides a preparation method of an organic antioxidant, the steps are as follows: Add 2776 kg of 2,6-di-tert-butylphenol into a 100° C. To 125°C, add 40kg of catalyst sodium methoxide, react for 1.5h, add 1110kg of methyl acrylate, react for 2.5h, then keep warm at 125°C for 5.5h, then add 20kg of formic acid to neutralize the alkali catalyst, filter, then add After crystallization of methanol, it can be obtained by washing and filtering.

performance evaluation

1. Oxidation induction period test and anti-burning test:

a Oxidation induction period test: After stirring polyether and 4000ppm liquid hindered phenolic antioxidant (ST-1912) at 25°C for 10 minutes, it was measured by Shanghai Hesheng HS-DSC-101 oxidation induction period tester. First, set the temperature at 50°C in a pure nitrogen environment, keep it for 1min, then start to raise the temperature, control the heating rate at 40°C/min, rise to 170°C after 3min, keep it for 3 minutes, and then switch to a pure oxygen environment, oxygen The purity is more than 99.99%. When the heat is released, the curve rises obviously, and the test is stopped.

b Foam core test: Cut the polyurethane foam prepared below into a size of 100*50*10mm, place it in an electric heating constant temperature blower box at a temperature of 165°C, take it out after 5 hours, and use a PRECISION COLORIMETER NR10QC instrument to read the ΔB value.

Table 1

The hindered phenolic antioxidant (ST-1912) in embodiment 1 is carried out the initial oxidation temperature test: a initial oxidation temperature test: polyether and 4000ppm liquid hindered phenolic antioxidant (ST-1912) at 25 ℃ After stirring for 10 minutes, it was measured by a Netzsch DSC204HP differential scanning calorimeter. The heating rate was set at 10°C/min, and the oxygen purity was above 99.99%. The test results are shown in Table 2.

Table 2

The antioxidants 1076 and 1135 described in the present invention are commercially available.

2. Foaming test:

Table 2 polyurethane foam formula

polyether 100 antioxidant 0.4 silicone oil 1 A1 0.06 33LV 0.1 water 4 T9 0.21 TDI 52.1

The preparation method of polyurethane: put 100g polyether into a plastic cup, add 0.4g antioxidant ST-1912 (prepared in Example 1), 1g silicone oil, 0.16gA1/33LV, 4g water, turn on the mixer, set the speed at 1500-2000rpm /min, stir for 1min, then add T90.21g, continue stirring for 15s, add weighed TDI 52.1g, stir for 8s, pour into foaming box, aging time is 24h, temperature is 35-40℃.

The polyether was purchased from Xindian Chemical Materials Co., Ltd., the hydroxyl value was 56 mgKOH/g, the T9 was T9 polyurethane foam, purchased from Daohang Supply Chain Management Co., Ltd., and the 33LV was a polyurethane amine foaming catalyst, purchased from From Evonik, the model is Dabco 33LV, the A1 is A1 type polyurethane foam, purchased from Langfang Kunchuang Energy Saving Technology Co., Ltd.

aUV test: Cut the prepared polyurethane foam into a size of 100*30*10mm, and then place it in a UV oven at a temperature of 50°C. After standing for 12 hours, use a PRECISION COLORIMETER NR10QC instrument to test its ΔB value.

b Phenol yellow test: Cut the polyurethane foam prepared above into a size of 100*30*10mm, then wrap the polyurethane foam with phenol yellow test paper, separate layers, and then separate them with thin glass sheets, and then Wrap it with plastic paper, seal it with transparent tape, put it into a phenol yellow test box, keep it at a constant temperature of 50°C for 16 hours, take it out, and read the ΔB value with a PRECISION COLORIMETER NR10QC instrument.

c Foam placement test: Cut the polyurethane foam prepared above into a size of 300*150*10mm, place it on a mesh stainless steel frame for 48 hours, and use a PRECISION COLORIMETER NR10QC instrument to read the ΔB value.

dHot pressing test: cut the polyurethane foam prepared above into a size of 300*200*10mm, set the temperature of the hot press at 205°C, and the temperature of the lower mold at 215°C, take out the polyurethane foam after 300s, and read it with a PRECISION COLORIMETERNR10QC instrument ΔB value. (antioxidant 1135 and 1076 are commercially available in table 3)

table 3

3. Prepolymer test: Take 100g of polyether with a hydroxyl value of 56mgKOH/g, put it into a 250mL three-necked flask, add 0.15g of antioxidant ST-1912 (prepared in Example 1), stir for 10min, and heat to 80°C. Then add 17.2g of TDI dropwise, keep the temperature at 80°C, stabilize for 30 minutes, and turn into a colorless and transparent prepolymer, then put it into the oven, bake it continuously for 24 hours at a temperature of 80°C, and observe whether the liquid turns yellow , it is unqualified if it turns yellow, otherwise it is qualified.

name Exterior 1135 qualified 1076 unqualified ST-1912 qualified

Claims (10)

1. a liquid hindered phenolic antioxidant, is characterized in that, the molecular structure of described liquid hindered phenolic antioxidant is:

The R ₁ and R ₂ are C ₁ to C ₈ alkyl groups, R ₃ is a C ₁ to C ₅ alkylene group, and the R ₄ group is retained in the ester structure after esterification or transesterification of fatty alcohols of organic groups. 2. A liquid hindered phenolic antioxidant according to claim 1, characterized in that the relative molecular mass of the liquid hindered phenolic antioxidant is 400-800. 3. A kind of liquid hindered phenolic antioxidant according to claim 1, is characterized in that, the preparation raw material of described liquid hindered phenolic antioxidant, by weight, its raw material comprises: branched chain fatty alcohol 100 -200 parts, 1-4 parts of catalyst, 90-150 parts of organic antioxidant. 4 . A liquid hindered phenolic antioxidant according to claim 3 , wherein the branched fatty alcohol is a C ₁₆ -C ₂₅ branched fatty alcohol. 5. A kind of liquid hindered phenolic antioxidant according to claim 3, is characterized in that, described catalyst comprises alkoxy aluminum, alkali metal compound, phenoxy aluminum, organotin compound and organozinc salt at least one of the classes. 6. A liquid hindered phenolic antioxidant according to claim 3, characterized in that the organic antioxidant is 3,5 methyl ester. 7. A liquid hindered phenolic antioxidant according to claim 3, characterized in that the molar ratio between the organic antioxidant and the branched fatty alcohol is (1-1.5):1. 8. A preparation method of liquid hindered phenolic antioxidant according to claim 3, characterized in that, the steps are as follows: The organic antioxidant, catalyst and branched fatty alcohol are mixed and stirred, and at the same time, the temperature is gradually raised, after a period of reaction, evaporated, the temperature is lowered, and the catalyst is filtered out. 9 . The preparation method of a liquid hindered phenolic antioxidant according to claim 8 , wherein the reaction temperature after the heating is 150-180° C., and the reaction time is 5-9 hours. 10. An application of the liquid hindered phenolic antioxidant according to any one of claims 1-9 on polyurethane foam for vehicles.