阅读说明：本技术 采用溶剂法制备受阻胺类光稳定剂的方法 (Method for preparing hindered amine light stabilizer by adopting solvent method ) 是由 代广星 王慧君 王晓东 陈志强 孙春光 李海平 于 2020-12-22 设计创作，主要内容包括：本发明提供了一种采用溶剂法制备受阻胺类光稳定剂的方法。采用溶剂法制备受阻胺类光稳定剂的方法包括：在催化剂的作用下,在有机溶剂中,使2,2,6,6-四甲基哌啶基母体和癸二酸二甲酯进行酯交换反应,得到酯交换产物；将酯交换产物依次进行水洗、过滤和脱溶剂处理,得到受阻胺类光稳定剂和废水。采用上述制备方法制备受阻胺类光稳定剂不仅有利于降低工艺成本,还有利于提高受阻胺类光稳定剂的纯度和回收率及透光率。(The invention provides a method for preparing a hindered amine light stabilizer by a solvent method. The method for preparing the hindered amine light stabilizer by adopting a solvent method comprises the following steps: under the action of a catalyst, carrying out ester exchange reaction on a 2,2,6, 6-tetramethyl piperidyl parent body and dimethyl sebacate in an organic solvent to obtain an ester exchange product; and (3) sequentially washing, filtering and desolventizing the ester exchange product to obtain the hindered amine light stabilizer and the wastewater. The hindered amine light stabilizer prepared by the preparation method is not only beneficial to reducing the process cost, but also beneficial to improving the purity, the recovery rate and the light transmittance of the hindered amine light stabilizer.)

1. A method for preparing a hindered amine light stabilizer by a solvent method is characterized by comprising the following steps:

under the action of a catalyst, carrying out ester exchange reaction on a 2,2,6, 6-tetramethyl piperidyl parent body and dimethyl sebacate in an organic solvent to obtain an ester exchange product;

and (2) sequentially carrying out water washing, filtering and solvent removal treatment on the ester exchange product to obtain the hindered amine light stabilizer and wastewater, wherein the 2,2,6, 6-tetramethyl piperidyl matrix has the following structure:

r is H, methyl, ethyl, isopropyl, n-propyl, n-butyl or C₁-C₁₀Alkoxy, A is H or hydroxy;

the organic solvent is selected from solvent oil, petroleum ether and C₅～C₁₂At least one of an alkane or a cycloalkane.

2. The method for preparing a hindered amine light stabilizer by a solvent process according to claim 1, wherein the method for preparing a hindered amine light stabilizer by a solvent process further comprises:

prior to the water washing step, acid washing the transesterified product; and/or the presence of a gas in the gas,

adding liquid alkali and solvent into the wastewater for extraction to recover the unreacted 2,2,6, 6-tetramethyl piperidyl parent.

3. The method for preparing hindered amine light stabilizer by solvent method according to claim 1, wherein C is₅～C₁₂The alkane or cycloalkane is selected from heptane, n-hexane, cyclohexane, n-octaneOne or more of an alkane and a nonane; the solvent oil is at least one selected from solvent oil D30 and solvent oil D20.

4. A method for preparing hindered amine light stabilizer by solvent method as claimed in any of claims 1 to 3, wherein said 2,2,6, 6-tetramethylpiperidyl precursor, when A is hydroxy, R is H, methyl, ethyl, isopropyl, n-propyl, n-butyl.

5. The method for preparing a hindered amine light stabilizer by a solvent method according to any one of claims 1 to 3, wherein the weight ratio of the 2,2,6, 6-tetramethylpiperidyl precursor to the organic solvent is 1 (1.2-1.8).

6. The method for preparing hindered amine light stabilizer by solvent method according to any of claims 1 to 5, wherein the weight ratio of the 2,2,6, 6-tetramethylpiperidyl precursor, the dimethyl sebacate and the catalyst is 1 (0.4-0.9) to (0.004-0.02).

7. The method for preparing a hindered amine light stabilizer by a solvent method according to claim 6, wherein the catalyst is one or more selected from the group consisting of n-butyl titanate, tetraisopropyl titanate, sodium methoxide, aluminum isopropoxide, lithium amide and dibutyltin oxide.

8. The method for preparing the hindered amine light stabilizer by the solvent method according to claim 6, wherein the temperature of the ester exchange reaction is 110-160 ℃ and the reaction time is 4-24 h.

9. The method for preparing a hindered amine light stabilizer by a solvent method according to any one of claims 2 to 8, wherein the acid washing step uses one or more acids selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid and p-toluenesulfonic acid, and the acid is added in an amount of 1 to 20 wt% of the 2,2,6, 6-tetramethylpiperidyl precursor.

10. The method for preparing the hindered amine light stabilizer by the solvent method according to any one of claims 2 to 9, wherein when the method for preparing the hindered amine light stabilizer by the solvent method comprises the acid washing step and the extraction step, the molar ratio of the addition amount of the liquid alkali to the addition amount of the acid in the acid washing step is 1-2: 1; preferably, the extraction solvent is selected from the group consisting of mineral spirits, petroleum ether and C₅～C₁₂At least one of an alkane or a cycloalkane.

Technical Field

The invention relates to the field of synthesis of hindered amine light stabilizers, and particularly relates to a method for preparing a hindered amine light stabilizer by a solvent method.

Background

Hindered Amine Light Stabilizer (HALS for short) is an efficient assistant for inhibiting the photooxidative degradation of high polymer materials, and the stabilizing effect of the Hindered Amine Light Stabilizer is 2-4 times that of the traditional absorption Light Stabilizer. The light stabilizer not only has good synergistic effect with an ultraviolet absorber and an antioxidant, but also has good compatibility with various high polymer materials.

Bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, UV-770, has long been commercialized and is a representative species of low molecular weight HALS. To complete the performance of hindered amine light stabilizers, many companies developed novel hindered amine light stabilizers, such as UV-292, a mixture of bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate and mono (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate, which have a better ability to absorb ultraviolet rays. At present, the research of non-polymeric low molecular HALS in China has been developed rapidly.

The prior art for the preparation of non-polymeric low molecular HALS has employed transesterification. For example, patent application CN200910036230.2 provides a light stabilizer bis (2,2,6, 6-tetramethylpiperidyl) sebacate and a production method thereof, which synthesizes bis (2,2,6, 6-tetramethylpiperidyl) sebacate by using dimethyl sebacate, 2,6, 6-tetramethylpiperidine and xylene as raw materials and dibutyltin oxide as a catalyst. The xylene used in the above synthesis process has pungent odor and low toxicity, and is carcinogenic.

And the existing process has the problems of low esterification rate, poor product light transmittance, unstable quality and the like. In view of the above problems, it is desirable to develop a novel method for preparing a non-polymeric light stabilizer with energy saving, high production yield and stable product performance.

Disclosure of Invention

The invention mainly aims to provide a method for preparing a hindered amine light stabilizer by a solvent method, and aims to solve the problems of low production efficiency, high energy consumption, high cost and poor light transmittance of products in the conventional preparation method of the hindered amine light stabilizer.

In order to achieve the above object, the present invention provides a method for preparing a hindered amine light stabilizer by a solvent method, the method for preparing a hindered amine light stabilizer by a solvent method comprising: under the action of a catalyst, carrying out ester exchange reaction on a 2,2,6, 6-tetramethyl piperidyl parent body and dimethyl sebacate in an organic solvent to obtain an ester exchange product; and (3) sequentially washing, filtering and desolventizing the ester exchange product to obtain the hindered amine light stabilizer and wastewater, wherein the 2,2,6, 6-tetramethyl piperidyl matrix has the following structure:

r is H, methyl, ethyl, isopropyl, n-propyl, n-butyl or C₁-C₁₀Alkoxy, A is H or hydroxy; the organic solvent is selected from mineral spirit, petroleum ether and C₅～C₁₂At least one of an alkane or a cycloalkane.

Further, the method for preparing the hindered amine light stabilizer by using the solvent method further comprises the following steps: before the water washing step, acid washing is carried out on the ester exchange product; and/or, adding liquid alkali and solvent into the waste water for extraction to recover unreacted 2,2,6, 6-tetramethyl piperidyl parent body.

Further, C₅～C₁₂The alkane or cycloalkane is selected from one or more of heptane, n-hexane, cyclohexane, n-octane and nonane; the solvent oil is at least one selected from solvent oil D30 and solvent oil D20.

Further, when A is hydroxy, R is H, methyl, ethyl, isopropyl, n-propyl or n-butyl, a 2,2,6, 6-tetramethylpiperidinyl parent.

Furthermore, the weight ratio of the 2,2,6, 6-tetramethyl piperidyl parent body to the organic solvent is 1 (1.2-1.8).

Furthermore, the weight ratio of the 2,2,6, 6-tetramethyl piperidyl parent body to the dimethyl sebacate to the catalyst is 1 (0.4-0.9) to (0.004-0.02).

Further, the catalyst is selected from one or more of the group consisting of n-butyl titanate, tetraisopropyl titanate, sodium methoxide, aluminum isopropoxide, lithium amide and dibutyltin oxide.

Further, the temperature of the ester exchange reaction is 110-160 ℃, and the reaction time is 4-24 h.

Further, the acid adopted in the acid washing step is one or more selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid and p-toluenesulfonic acid, and the addition amount of the acid is 1-20 wt% of the 2,2,6, 6-tetramethyl piperidyl parent.

Further, when the method for preparing the hindered amine light stabilizer by adopting the solvent method simultaneously comprises an acid washing step and an extraction step, the molar ratio of the addition amount of the liquid alkali to the addition amount of the acid in the acid washing step is 1-2: 1; preferably, the extraction solvent is selected from the group consisting of mineral spirits, petroleum ether and C₅～C₁₂At least one of an alkane or a cycloalkane.

By applying the technical scheme of the invention, when the hindered amine light stabilizer is synthesized in the presence of a solvent, the product quality is easy to control, the process is simple, the large-scale production is facilitated, and the improvement of the light transmittance of the product is facilitated.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background art, the existing preparation method of the hindered amine light stabilizer has the problems of low production efficiency, high energy consumption, high cost and poor light transmittance of products. In order to solve the technical problems, the present application provides a method for preparing a hindered amine light stabilizer by a solvent method, wherein the method for preparing the hindered amine light stabilizer by the solvent method comprises: under the action of a catalyst, carrying out ester exchange reaction on a 2,2,6, 6-tetramethyl piperidyl parent body and dimethyl sebacate in an organic solvent to obtain an ester exchange product; and (3) sequentially washing, filtering and desolventizing the ester exchange product to obtain the hindered amine light stabilizer and wastewater, wherein the 2,2,6, 6-tetramethyl piperidyl matrix has the following structure:

r is HMethyl, ethyl, isopropyl, n-propyl, n-butyl or C₁-C₈Alkoxy, A is H or hydroxy; the organic solvent is selected from solvent oil, petroleum ether and C₅～C₁₂At least one of an alkane or a cycloalkane.

Researches show that when the hindered amine light stabilizer is synthesized in the presence of a solvent, the product quality is easy to control, the process is simple, the large-scale production is facilitated, and the light transmittance of the product is improved. Particularly, when the organic hydrocarbon solvent is selected, the reaction can be carried out at a lower reaction temperature, which is beneficial to ensuring the light transmittance of the product; further, it was found that solvent oil and C were selected₅～C₁₂The yield of the product can be further improved when alkane or cycloalkane is adopted; in the research process, the inventor tests various solvents including benzene solvents (such as toluene, xylene and the like) and high-boiling point solvents (such as undecane and dodecane), and finds that the benzene solvents are not beneficial to improving the light transmittance; the solvent with high boiling point is not beneficial to improving the light transmittance of the product and influencing the product quality.

Since the wastewater also contains a certain amount of unreacted raw materials, in order to improve the utilization rate of the raw materials and the environmental protection of the wastewater, preferably, the method for preparing the hindered amine light stabilizer by using the solvent method further comprises the following steps: before the step of washing with water, the transesterification product is washed with acid; and/or adding liquid alkali and solvent into the waste water for extraction to recover unreacted 2,2,6, 6-tetramethyl piperidyl precursor.

In the specific application process, the substituent in the 2,2,6, 6-tetramethyl piperidyl parent body can be optimized according to requirements, and preferably, when R in the 2,2,6, 6-tetramethyl piperidyl parent body is alkoxy, C is₁-C₁₀Alkoxy includes, but is not limited to, methoxy, ethoxy, isopropoxy, n-propoxy, n-butoxy or octoxy.

In a specific application process, the substituent in the 2,2,6, 6-tetramethylpiperidyl parent body can be optimized according to needs, preferably, when A is hydroxyl, R is H, methyl, ethyl, isopropyl, n-propyl or n-butyl.

In a preferred embodiment, the miscella includes, but is not limited to, at least one of miscella D30 and miscella D20; c₅～C₁₂The alkane or cycloalkane is selected from one or more of heptane, n-hexane, cyclohexane, n-octane and nonane, and the adoption of the solvents is more beneficial to improving the light transmittance and yield of the product.

In a preferred embodiment, the weight ratio of the 2,2,6, 6-tetramethylpiperidinyl precursor to the organic solvent is 1 (1.2-1.8), for example, in a specific embodiment, 1: 1.5.

In a preferred embodiment, the weight ratio of the 2,2,6, 6-tetramethylpiperidinyl precursor, dimethyl sebacate and catalyst is 1 (0.4-0.9) to (0.004-0.02). The weight ratio of the 2,2,6, 6-tetramethylpiperidinyl precursor, dimethyl sebacate and catalyst includes, but is not limited to, the above ranges, and limiting it to the above ranges is advantageous to further increase the yield of hindered amine light stabilizers.

In a preferred embodiment, the catalyst includes, but is not limited to, one or more of the group consisting of n-butyl titanate, tetraisopropyl titanate, sodium methoxide, aluminum isopropoxide, lithium amide, and dibutyltin oxide.

In a preferred embodiment, the temperature of the transesterification reaction is 110 to 160 ℃ and the reaction time is 4 to 24 hours. The reaction at the temperature is favorable for further improving the catalytic activity of the catalyst and the selectivity of the reaction, so that the reaction rate of the ester exchange reaction is further improved, and the yield of the hindered amine light stabilizer is also improved. Preferably, the temperature of the transesterification reaction is 120-150 deg.C, such as 120 deg.C, 130 deg.C, 140 deg.C, 150 deg.C.

In order to further improve the solubility of the 2,2,6, 6-tetramethylpiperidinyl precursor in water, it is preferred that the acid used in the acid washing process includes, but is not limited to, one or more of the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, p-toluenesulfonic acid, and the amount of acid added is 1 to 20 wt%, preferably 0.05 to 0.1%, of the 2,2,6, 6-tetramethylpiperidinyl precursor, generally calculated as 100% pure acid.

During the recovery of the 2,2,6, 6-tetramethylpiperidinyl precursor:

the extraction solvent is the same as the organic solvent of the transesterification reaction, i.e. the organic solvent is selected from the group consisting of mineral spirits, petroleum ether and C₅～C₁₂At least one of alkane or cycloalkane, and the amount of solvent used for extraction is 10-20 times (volume/weight ratio) of the theoretically recovered 2,2,6, 6-tetramethylpiperidyl precursor. The same organic solvent is adopted for the extraction solvent and the ester exchange reaction, which is more favorable for improving the purity and the quality of the recovered 2,2,6, 6-tetramethyl piperidyl parent substance, and the recovered 2,2,6, 6-tetramethyl piperidyl parent substance can be directly fed for the next batch reaction without influencing the yield, the purity and the light transmittance of the product.

In order to improve the recovery rate of the 2,2,6, 6-tetramethyl piperidyl parent, the method for preparing the hindered amine light stabilizer by adopting the solvent method simultaneously comprises an acid washing step and an extraction step, and the molar ratio of the addition amount of the liquid alkali to the addition amount of the acid is 1-2: 1. In a preferred embodiment, the liquid alkali may be selected from sodium hydroxide solvent, potassium hydroxide solution and other liquid alkali known in the art, and particularly, the sodium hydroxide solution or potassium hydroxide solution with a concentration of 10-30% is more favorable for improving the recovery rate of the 2,2,6, 6-tetramethylpiperidyl precursor, facilitating the treatment and being more environment-friendly.

In the reaction system, the ester exchange reaction is promoted by adopting the organic solvent, so that the light transmittance of the product can be improved, meanwhile, the solvent can dissolve the unreacted 2,2,6, 6-tetramethyl piperidyl parent material, and the waste water treatment can be used for efficiently recovering the 2,2,6, 6-tetramethyl piperidyl parent material by using the solvent which is the same as the reaction solvent, so that the production cost is saved, and the raw material consumption is reduced.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

Example 1

Adding 120.15g (0.7653mol) of 2,2,6, 6-tetramethyl piperidinol, 80.06g (0.3476mol) of dimethyl sebacate and 175.47g of solvent oil D20 (Yueyangjiaxin) into a four-neck flask in sequence, and introducing N₂Fully protecting, installing a condenser, starting magnetic stirring, and heating toReflux dehydration is carried out at 120 ℃ until no water drops exist, 1.74g of tetraisopropyl titanate is dripped in the reflux dehydration for 10-15 min, the temperature is raised to 150 ℃, the heat preservation reaction is carried out, methanol is continuously evaporated out in the reaction process, 24g of 80% acetic acid is added after the reaction is finished, pickling with ethyl alcohol and washing with water, filtering and desolventizing are carried out, and white crystalline powder bis (2,2,6, 6-tetramethylpiperidyl) sebacate is obtained, the product yield is 99.62 wt%, the GC content is 99.41%, and the light transmittance at 425nm is 99.25%. 50g of liquid caustic soda (containing 20 percent of sodium hydroxide) and 75.47g of solvent oil D20175 are added into the generated wastewater for extraction, about 10g of 2,2,6, 6-tetramethyl piperidinol is recovered, and the recovery rate is 90 percent.

Example 2

Adding 120.09g (0.7022mol) of 1,2,2,6, 6-pentamethyl-4-piperidinol, 85.38g (0.3707mol) of dimethyl sebacate and 200.65g of solvent oil D30 (Yueyangjiaxin) into a four-neck flask in sequence, and introducing N₂And (2) fully protecting, installing a condenser, starting magnetic stirring, heating to 125 ℃, refluxing and dehydrating until no water drops exist, dropwise adding 0.75g of tetraisopropyl titanate, dropwise adding for 10-15 min, heating to 150 ℃, carrying out heat preservation reaction, continuously evaporating methanol in the reaction process, adding 12g of 80% acetic acid after the reaction is finished, carrying out acid washing and water washing, filtering and desolventizing to obtain a light yellow liquid, namely a mixture consisting of bis (1,2,2,6, 6-pentamethylpiperidinol) sebacate and mono (1,2,2,6, 6-pentamethylpiperidinol) sebacate, wherein the product yield is 99.09 wt%, the GC content is 99.76%, and the light transmittance is 425nm and 99.9%. 22g of liquid alkali (containing 20 percent of sodium hydroxide) and D30200.65g of solvent oil are added into the generated wastewater for extraction, about 8g of 1,2,2,6, 6-pentamethyl-4-piperidinol is recovered, and the recovery rate is 88 percent.

Example 3

The differences from example 1 are: the solvent is petroleum ether.

The yield of bis (2,2,6, 6-tetramethylpiperidyl) sebacate was 97.2% by weight, the GC content was 99.6%, and the light transmittance at 425nm was 99.8%.

Example 4

The differences from example 1 are: the solvent is heptane.

The yield of bis (2,2,6, 6-tetramethylpiperidyl) sebacate was 99.5% by weight, the GC content was 99.5% and the light transmittance at 425nm was 99.5%.

Example 5

The differences from example 1 are: the raw materials are as follows: 110.15g of 2,2,6, 6-tetramethylpiperidinyl precursor, 10g of 2,2,6, 6-tetramethylpiperidinyl precursor recovered in the examples, totaling 120.15 g.

The yield of bis (2,2,6, 6-tetramethylpiperidyl) sebacate was 99.6% by weight, the GC content was 99.3%, and the light transmittance at 425nm was 99.4%.

Comparative example 1

The differences from example 1 are: no organic solvent is added during the transesterification reaction.

The yield of bis (2,2,6, 6-tetramethylpiperidyl) sebacate was 98.7% by weight, the GC content was 98.1% and the light transmittance at 425nm was 97.1%.

Comparative example 2

The differences from example 1 are: the transesterification process is not followed by an acid wash, but only by a water wash. The generated wastewater is directly extracted by solvent naphtha D20175.47g, and 2,2,6, 6-tetramethyl piperidinol is recovered.

The yield of bis (2,2,6, 6-tetramethylpiperidyl) sebacate was 98.9% by weight, the GC content was 99.4%, and the light transmittance at 425nm was 98.0%. The recovery rate of 2,2,6, 6-tetramethylpiperidinol was 30%.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: the hindered amine light stabilizer prepared by the preparation method is not only beneficial to reducing the process cost, but also beneficial to improving the purity, the recovery rate and the light transmittance of the hindered amine light stabilizer.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described or illustrated herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.