阅读说明：本技术 一种低气味聚醚多元醇的制备方法 (Preparation method of low-odor polyether polyol ) 是由 王艳丽 徐丹 金振宇 齐旺顺 蒋尧尧 孙永旭 贺信淳 张宏科 于 2019-10-09 设计创作，主要内容包括：本发明涉及一种低气味聚醚多元醇的制备方法,包括如下步骤：1)反应釜中加入起始剂和催化剂后,加入共沸溶剂,共沸脱除体系中的水分后,继续加热,脱除体系中的共沸溶剂；2)通入环氧化合物,优选环氧丙烷或环氧乙烷,温度为80-140℃,优选90-120℃下,先一次性投入环氧化合物总用量的5％～10％进行预聚合,反应生成聚醚多元醇a；3)待反应表压低于0.05MPa,氮气保护下加入自由基引发剂,搅拌均匀；4)继续通入环氧化合物,继续进行聚合反应,得到粗聚醚。本发明的制备方法能有效降低聚醚的不饱和度,采用强酸性聚合物吸附碱金属离子,避免常规使用的酸中和、过滤工艺,可获得极低的金属含量,降低气味,生产成本低。(The invention relates to a preparation method of low-odor polyether polyol, which comprises the following steps: 1) adding an initiator and a catalyst into a reaction kettle, adding an azeotropic solvent, removing water in a system through azeotropy, and continuously heating to remove the azeotropic solvent in the system; 2) introducing an epoxy compound, preferably propylene oxide or ethylene oxide, at the temperature of 80-140 ℃, preferably at the temperature of 90-120 ℃, firstly, adding 5-10 percent of the total amount of the epoxy compound for prepolymerization at one time, and reacting to generate polyether polyol a; 3) adding a free radical initiator under the protection of nitrogen when the reaction gauge pressure is lower than 0.05MPa, and uniformly stirring; 4) and continuously introducing the epoxy compound, and continuously carrying out polymerization reaction to obtain the crude polyether. The preparation method can effectively reduce the unsaturation degree of the polyether, adopts the strong acid polymer to adsorb alkali metal ions, avoids the conventional acid neutralization and filtration process, can obtain extremely low metal content, reduces the odor and has low production cost.)

1. A preparation method of low-odor polyether polyol is characterized by comprising the following steps:

1) adding an initiator and a catalyst into a reaction kettle, adding an azeotropic solvent, removing water in a system through azeotropy, and continuously heating to remove the azeotropic solvent in the system;

2) introducing an epoxy compound: at the temperature of 80-140 ℃, preferably at the temperature of 90-120 ℃, firstly, 5-10 wt% of the total amount of the epoxy compound is added at one time for prepolymerization, and polyether polyol a is generated after reaction;

3) adding a free radical initiator under the protection of nitrogen when the reaction gauge pressure is lower than 0.05MPa, and uniformly stirring;

4) and continuously introducing the epoxy compound, and continuously carrying out polymerization reaction to obtain the crude polyether.

2. The method of producing polyether polyol according to claim 1, further comprising the steps of:

5) passing the crude polyether through an adsorption tower filled with a strongly acidic polymer, the temperature of the adsorption tower being maintained at 90-120 ℃, preferably 100-110 ℃, the residence time of the polyether in the adsorption tower being maintained at 30-120min, preferably 90-120min,

6) then, after water and small molecular substances are removed under reduced pressure, a refined polyether polyol product b is obtained.

3. The method according to claim 1 or 2, wherein the radical initiator is a thermal initiator containing no water, preferably one or more of a peroxide initiator and an azo compound.

4. The production method according to any one of claims 1 to 3, wherein the epoxy compound is propylene oxide and/or ethylene oxide;

the catalyst is alkali metal catalyst or bimetallic catalyst, and the alkali metal catalystThe agent comprises potassium hydroxide and sodium hydroxide, and the double metal cyanide catalyst comprises Zn₂[Co(CN)₆]₂，Zn₂[Fe(CN)₆]₂；

The peroxide initiator comprises: one or more than two of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide, di-tert-butyl peroxide and potassium persulfate;

the azo compound comprises: azodiisobutyronitrile, azodiisoheptonitrile, dimethyl azodiisobutyrate, azodiisovaleronitrile and azodicyclohexyl formonitrile.

5. The process according to any one of claims 2 to 4, wherein the strongly acidic polymer is-SO₃H-type perfluorosulfonic acid resin.

6. The process according to any one of claims 1 to 5, wherein the radical initiator is added in an amount of 0.01 to 0.3 wt%, preferably 0.05 to 0.2 wt%, based on the total mass of the epoxy compound.

7. The production method according to any one of claims 1 to 6, wherein the azeotropic solvent is added in an amount of 2 to 6 times by mass of the initiator;

the addition amount of the catalyst is the total mass of the added epoxy compounds: 0.05 wt.% to 1.5 wt.%, preferably 0.1 wt.% to 1 wt.%.

8. The production method as claimed in any one of claims 1 to 7, wherein the polyether polyol a in the step (2) has a weight average molecular weight of 200-800.

9. The process according to any one of claims 1 to 8, wherein the polyether polyol product b has a weight average molecular weight of 300 to 12000, preferably 1000-12000, and is monofunctional or polyfunctional.

10. The refining method according to any one of claims 1 to 9,

the temperature of the decompression removing tower in the step 6) is 90-120 ℃, and the pressure is 0-1.5KPa gauge pressure.

Technical Field

The invention belongs to the technical field of polyether polyol production, and particularly relates to a preparation method of low-odor polyether polyol.

Background

Two production processes are generally adopted for industrial production of polyether polyol, one is a potassium hydroxide catalysis process, potassium alkoxide is formed by potassium hydroxide and an initiator, and then ethylene oxide or propylene oxide or a mixture of the ethylene oxide and the propylene oxide is introduced for anion ring-opening polymerization to generate polyether polyol; one is a bimetallic catalysis process, which uses dicyano metal compound as catalyst, and produces polyether polyol through ring-opening polymerization reaction with ethylene oxide or propylene oxide or their mixture in the form of complex.

In the polyether produced by the potassium hydroxide catalytic process, under the strong alkaline condition, isopropyl alcohol taking propylene oxide as a terminal group is easily isomerized into allyl alcohol, and allyl alcohol is further isomerized into allyl ether, so that unsaturated polyether with the terminal group of allyl is generated in a polyether long chain. The unsaturated polyether can reduce the hydroxyl value and functionality of the polyether, and allyl ether is easily broken during storage to form allyl alcohol, which is oxidized into aldehyde and further oxidized into acid, so that VOC in the polyether is increased, the VOC is an odor source of the polyether, and the reactivity of the polyether is influenced. In addition, in the polyether with allyl as a terminal group, the allyl of the terminal group cannot react with isocyanate and the like in the production process of foam, sponge and the like, so that the crosslinking degree of the foam is reduced, and the foam performance is affected.

The polyether produced by adopting the bimetallic catalysis process generally contains metals such as zinc, cobalt and the like in a catalyst, the metals have a catalytic effect on the reaction activity of the polyether polyol and the isocyanate, and the polyether polyol and the isocyanate can be gelled when the content of the metals is higher, so that production accidents are caused.

Currently, the more well-established process for industrial application is the neutralization-adsorption process, i.e. phosphoric acid neutralization-dehydration crystallization-adsorption and filtration-polyether end product. In the process, the content of potassium ions can meet the requirement, but the dehydration time is long, and the obtained polyether has impurities such as aldehydes, allyl alcohol and the like, so that the polyether has obvious sour taste. Patent CN 108059717 reports that the implementation of adding a compound antioxidant into crude polyether to inhibit the generation of byproducts can achieve obvious reduction of aldehydes, but the antioxidant introduced by the method reaches 0.1 percent, and the cost is improved to a certain extent. Along with the increasingly fierce competition of related industries and the increasingly strict control of downstream application on VOC of polyurethane foam, the refining process of polyether products is improved, the content of harmful substances is reduced, the smell of polyether is controlled, and the production efficiency is improved, so that the problems which are urgently needed to be solved by various polyether manufacturers are solved.

A great deal of work is also done by various large production enterprises and scientific research institutions at home and abroad around the odor problem of polyether polyol products. US6504062 reports a process for the preparation of odor-lean polyether polyols. A process for preparing a low-odor polyether polyol from a polyether polyol starting product obtained by reacting a starting compound having a plurality of active hydrogen atoms with one or more alkylene oxides, the process comprising the steps of: (a) contacting the neutralized or unneutralized polyether polyol product with an excess of an acid having a pKa value below 5 under hydrolysis conditions, (b) contacting the reaction mixture with water under hydrolysis conditions, and (c) recovering the odor-lean polyether polyol.

CN104130389 reports a method for reducing VOC content of polyether polyols. In a closed reaction kettle, an oxide is added into polyether polyol through a feeding pipeline extending into the bottom of the kettle, the mixture is mixed under certain pressure and temperature, and then the mixture is subjected to post-treatment to obtain a polyether polyol product with low VOC content.

CN 108059717 a reports a method of obtaining refined low odor polyether polyol by adding water and a compound antioxidant to crude polyether polyol, adding a neutralizing agent for neutralization, then adding an adsorbent for adsorption, and finally performing reduced pressure dehydration and filtration.

At present, the process of polyether polyol products is mature and stable, but with increasing attention of people on environmental protection, how to effectively reduce the odor of polyether polyol products becomes a very concerned problem for people, and the process is also the key point of future development of polyether polyol.

Disclosure of Invention

In view of the disadvantages of the prior art, the present invention aims to provide a method for preparing a low-odor polyether polyol, wherein a thermal-initiated free radical initiator is added to react allyl groups in a system to generate free radicals, so that the free radicals are polymerized to reduce the content of double bonds in the system; according to the invention, metal ions in the system are replaced by ion exchange resin instead of the original step of neutralization and salification filtration, so that the metal ions in polyether are removed, and the polyether product with low odor, low monool content and low metal content is obtained.

In order to solve the technical problems, the invention provides the following technical scheme:

a preparation method of low-odor polyether polyol is characterized by comprising the following steps:

1) adding an initiator and a catalyst into a reaction kettle, adding an azeotropic solvent, removing water in a system through azeotropy, and continuously heating to remove the azeotropic solvent in the system;

2) introducing an epoxy compound: at the temperature of 80-140 ℃, preferably 90-120 ℃, firstly, 5-10 percent of the total amount of the epoxy compound is added at one time for prepolymerization, and polyether polyol a is generated through reaction;

3) adding a free radical initiator under the protection of nitrogen when the reaction pressure is lower than 0.05MPa, and uniformly stirring;

4) and continuously introducing the epoxy compound, and continuously carrying out polymerization reaction to obtain the crude polyether.

Preferably, in the step (2), the internal pressure of the reaction apparatus is controlled to 0.4MPa or less.

The invention also comprises the following steps:

5) introducing the generated crude polyether into an adsorption tower filled with a strong acid polymer, maintaining the reaction temperature at 90-120 ℃, preferably 100-110 ℃, and keeping the residence time of the polyether in the adsorption tower at 30-120min, preferably 90-120 min;

6) then, after water and micromolecular substances are removed under reduced pressure, a refined polyether polyol product b is obtained;

the temperature of the decompression removing tower in the step 6) is 90-120 ℃, the pressure is 0-1.5KPa gauge pressure,

in the invention, the addition amount of the catalyst is the total mass of the added epoxy compound:

0.05 wt.% to 1.5 wt.%, preferably 0.1 wt.% to 1 wt.%.

In the present invention, the epoxy compound is propylene oxide and/or ethylene oxide.

In the invention, the catalyst is an alkali metal catalyst or a double-metal catalyst, the alkali metal catalyst comprises alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and the double-metal cyanide catalyst comprises Zn₂[Co(CN)₆]₂，Zn₂[Fe(CN)₆]₂Bimetallic compounds of like structure;

the addition of the initiator may be carried out by using the conventional initiators for preparing polyether polyols by the potassium hydroxide process or the bimetallic catalyst process, such as: propylene glycol, glycerol, ethylene glycol, mannitol, trimethylolpropane, sorbitol, pentaerythritol, sucrose, etc., and the amount of the initiator added may be conventionally selected by one of ordinary skill in the art depending on the relative molecular weight of the polyether polyol to be finally prepared, and may be, for example, but not limited to, 0.5 wt% to 1.5 wt%, 1.5 wt% to 5 wt%, 5 wt% to 10 wt%, 10 wt% to 20 wt%, 20 wt% to 30 wt%, or other ranges of the total mass of the epoxy compound added, and is not limited herein.

In the invention, the addition amount of the azeotropic solvent is 2-6 times of the mass of the initiator. The azeotropic solvent is preferably a low boiling point azeotropic solvent such as toluene or acetone.

In the present invention, the polyether polyol a in the step (2) is a low molecular weight polyether polyol having a weight average molecular weight of 200-800.

In the present invention, the radical initiator is a thermal initiator containing no water, and preferably one or more of a peroxide initiator and an azo compound. The amount of the radical initiator added is 0.01 to 0.3 wt%, preferably 0.05 to 0.2 wt% of the total mass of the epoxy compound.

In the present invention, the peroxide initiator includes: one or more than two of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide, di-tert-butyl peroxide and potassium persulfate;

in the present invention, the azo compound includes: one or more of azodiisobutyronitrile, azodiisoheptonitrile, dimethyl azodiisobutyrate, azodiisovaleronitrile and azodicyclohexyl formonitrile;

in the present invention, the strongly acidic polymer is-SO₃H-type perfluorosulfonic acid resin.

In the present invention, the weight average molecular weight of the polyether polyol product b is 300-12000, preferably 1000-12000, and is monofunctional or polyfunctional.

In the invention, the step 6) is carried out by adopting a decompression removing tower, and decompression dehydration and micromolecule substances can be carried out by adopting the prior art.

Description of the drawings: in the present invention, the pressure is gauge pressure.

The invention has the beneficial effects that:

1. adding a thermal-initiated free radical initiator to react allyl in the system to generate free radicals, so that free radical polymerization is carried out, and the content of double bonds in the system is reduced; the method provided by the invention can effectively reduce the unsaturation degree of polyether. By using-SO₃The H-type perfluorinated sulfonic acid resin can catalyze the residual allyl polyether in the polyether to react, further reduce the unsaturation degree in the polyether, and obtain a polyether product with low odor, low monool content and low metal content.

2. The invention passes through-SO₃The H-type perfluorinated sulfonic acid resin can also perform ion exchange reaction with metal ions in the polyether, and the metal ions in the system are replaced to replace the original step of neutralization and salification filtration, so that the metal ions in the polyether are removed, the content of the metal ions in the polyether is reduced to the maximum extent, and the polyether product with low odor, low monool content and low metal content is obtained.

3. SO adopted by the process₃H type perfluoroThe sulfonic acid resin can be regenerated by washing with water and used repeatedly.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Comparative example:

comparative example is a preparation of a conventional polyether: putting 38.5g of propylene glycol and 5g of potassium hydroxide into a stainless steel reaction kettle, reacting for 1h, vacuum dehydrating at 90 ℃, replacing nitrogen for three times, firstly putting 54g of propylene oxide at 140 ℃ for prepolymerization, continuously putting the rest 907.5g of propylene oxide into the kettle for reaction when the reaction pressure is lower than 0.05MPa, and vacuumizing after the reaction is finished to remove unreacted monomers to obtain the crude polyether polyol. After the crude polyether polyol is subjected to neutralization adsorption treatment, the pH value is 4.8, and refined polyether polyol is obtained.