阅读说明：本技术 一种废旧硬质聚氨酯泡沫回收制备聚醚多元醇的方法 (Method for preparing polyether polyol by recycling waste hard polyurethane foam ) 是由 王文博 杨小祥 张宏科 张金强 高振华 肖应鹏 杨径靖 陈盟 于 2021-10-29 设计创作，主要内容包括：本发明提供了一种废旧硬质聚氨酯泡沫回收制备聚醚多元醇的方法。所述的方法包括：将回收的硬质聚氨酯泡沫材料粉碎成颗粒,与醇解剂、碱复配成醇解液,加热得到醇解产物；将醇解产物过滤后转入反应釜中,加入碱金属催化剂,脱水后加入环氧化物进行聚合反应,降温,再加入磷腈催化剂,升温后继续加入环氧化物进行聚合反应,得到高分子量的聚醚多元醇；聚醚多元醇降温,加入中和剂、吸附剂,中和反应后脱水,再过滤得到目标聚醚多元醇。本发明克服了醇解产物分子量分布宽、胺值高的缺点,且回收产物所制得的聚氨酯泡沫具有导热系数低、压缩强度高的特点,可实现聚氨酯行业内物料的高质量循环利用,有效降低聚氨酯废料对环境的影响。(The invention provides a method for preparing polyether polyol by recycling waste hard polyurethane foam. The method comprises the following steps: crushing the recovered rigid polyurethane foam material into particles, compounding the particles with an alcoholysis agent and alkali to form an alcoholysis solution, and heating to obtain an alcoholysis product; filtering the alcoholysis product, transferring the alcoholysis product into a reaction kettle, adding an alkali metal catalyst, dehydrating, adding an epoxide for polymerization reaction, cooling, adding a phosphazene catalyst, heating, and continuing to add the epoxide for polymerization reaction to obtain high molecular weight polyether polyol; and cooling the polyether polyol, adding a neutralizing agent and an adsorbent, dehydrating after neutralization reaction, and filtering to obtain the target polyether polyol. The invention overcomes the defects of wide molecular weight distribution and high amine value of alcoholysis products, and the polyurethane foam prepared by recycling the products has the characteristics of low heat conductivity coefficient and high compression strength, can realize high-quality recycling of materials in the polyurethane industry, and effectively reduces the influence of polyurethane waste on the environment.)

1. A method for preparing polyether polyol by recycling waste hard polyurethane foam is characterized by comprising the following steps:

s1: crushing the recovered rigid polyurethane foam material into particles, compounding the particles with an alcoholysis agent and alkali to form an alcoholysis solution, and heating to obtain an alcoholysis product;

s2: filtering the alcoholysis product, transferring the alcoholysis product into a reaction kettle, adding an alkali metal catalyst, dehydrating, adding an epoxide for polymerization reaction, cooling, adding a catalyst A, heating, and continuing to add the epoxide for polymerization reaction to obtain polyether polyol with high molecular weight;

s3: and cooling the polyether polyol, adding a neutralizing agent and an adsorbent, dehydrating after neutralization reaction, and filtering to obtain the target polyether polyol.

2. The method according to claim 1, wherein the S1 pulverizes the polyurethane foam material into particles with a diameter of less than 5 mm;

and/or, S1, the alcoholysis agent is one or more of ethylene glycol, glycerol, diethylene glycol, 1, 4-butanediol, preferably diethylene glycol and/or dipropylene glycol, more preferably dipropylene glycol, and the base is one or more of sodium hydroxide, potassium hydroxide, magnesium hydroxide, cesium hydroxide, preferably potassium hydroxide and/or sodium hydroxide, more preferably potassium hydroxide;

preferably, the mass ratio of the alcoholysis agent to the base to the polyurethane foam is (50-500) to (1-20) to (60-800);

and/or the alcoholysis temperature is 170-220 ℃ and the time is 4-8 h.

3. The method of claim 1, wherein the epoxide of S2 is one or more of ethylene oxide, propylene oxide, tetrahydrofuran;

preferably, the epoxide to alcoholysis product mass ratio is (1-20) to 1;

and/or, the alkali metal catalyst of S2 is one or more of sodium hydroxide, potassium hydroxide and cesium hydroxide;

preferably, the amount of the alkali metal catalyst is 0.05-1% of the mass of the alcoholysis product;

and/or, S2 the a catalyst is a phosphazene catalyst, preferably one or more of aminotris (dimethylamino) phosphorochloridite, iminotris (dimethylamino) phosphoroshine, tetrakis (dimethylamino) phosphoroimino) phosphine oxide, dimethylaminotis (tris (dimethylamino) phosphoroimino) phosphine oxide;

preferably, the amount of the catalyst is 0.005-0.05% of the mass of the alcoholysis product;

and/or the polymerization reaction temperature of S2 is 100-120 ℃, the first epoxide adding reaction time is 2-3h, and the second epoxide adding reaction time is 2-6 h.

4. The method of claim 1, wherein the neutralizing agent of S3 is one or more of acetic acid, phosphoric acid, oxalic acid, formic acid, sulfurous acid, hypochlorous acid;

and/or the adsorbent of S3 is one or more of magnesium silicate, aluminum silicate, silica gel, diatomite and alumina;

and/or, the neutralization reaction temperature of S3 is 40-60 ℃, and the reaction time is 0.5-1 h.

5. Polyether polyol prepared by the method for recovering waste hard polyurethane foam as described in any one of claims 1-4, wherein the polyether polyol has a hydroxyl value of 330-513mg KOH/g, a viscosity of 1700-4200cp, an amine value of 0.1-0.5mg KOH/g, an average molecular weight of 910-3600, and a distribution coefficient of 1.15-1.25.

6. Use of a polyether polyol obtained by the method for recycling waste rigid polyurethane foams according to any one of claims 1 to 4 or the polyether polyol according to claim 5, for the preparation of rigid polyurethane foams for refrigerators and freezers.

7. A polyurethane foam prepared by using polyether polyol prepared by recycling of waste rigid polyurethane foam, the polyether polyol of the polyurethane foam being prepared by the method for recycling of waste rigid polyurethane foam as defined in any one of claims 1 to 4, or the polyether polyol of claim 5, or the polyether polyol used in the method for producing polyether polyol of claim 6, wherein the polyurethane foam has an apparent core density of 40 to 47mg/m³The compression strength is 210-.

Technical Field

The invention belongs to the technical field of waste polyurethane product recycling, and particularly relates to a method for preparing polyether polyol by recycling waste hard polyurethane foam.

Background

Polyurethane foam is widely applied to a plurality of fields such as buildings, automobile traffic, cold chains, pipeline heat insulation materials and the like by virtue of excellent physical properties and mechanical processing properties of the polyurethane foam. The application range of the polyurethane foam is continuously expanded, the yield is continuously increased, but meanwhile, the waste polyurethane foam is increased day by day, and how to treat the waste polyurethane foam is also a great problem. The waste polyurethane foam is conventionally disposed of by incineration and landfill, but the incineration process generates a large amount of toxic and harmful gas such as NO₂Hydrocyanic acid (HCN), environmental pollution; the landfill occupies a large amount of land resources, and the extremely long degradation time can cause serious damage to the soil quality. Therefore, both landfilling and incineration are not suitable disposal methods, and are neither environmentally friendly nor economical. Physical recycling, such as simple comminution for filler reprocessing, is only suitable for low end applications and has limited throughput.

The chemical recovery method can relatively effectively avoid the problems, mainly comprises an alkaline hydrolysis method, an amine hydrolysis method, a hydrolysis method, an alcoholysis method and the like, and the currently industrially mature chemical recovery method is the alcoholysis method. The recovery liquid obtained by alcoholysis mainly comprises hydroxyl-terminated oligomer (containing benzene ring and carbamate structure) and unreacted alcoholysis agent (polyalcohol micromolecule). However, the oligomer polyol mixture obtained by this method has some problems such as: the oligomer mixture obtained by alcoholysis is inevitably mixed with partial primary amine and secondary amine compounds, moisture and even partial solid inorganic filler particles, and meanwhile, because the oligomer in the alcoholysis product coexists with the small molecular polyol, the molecular weight distribution is wider, the average molecular weight is relatively lower, the product quality is poor when the oligomer is reused in the polyurethane foam industry, and the oligomer can only be used or applied to the low-end field after being mixed with the normal polyol product.

Currently, there are reports on alcoholysis recovery of polyurethane foams. The chemical recovery of polyurethanes mentioned in the patent CN102196279A does not address the above problems. One of the products of the recycling of waste polyurethane elastomers mentioned in CN104672414A is used directly in low-end insulation. The CN105399985A patent mentions that in the polyurethane foam chemical recovery method, an acid anhydride or phthalic anhydride deaminating agent is added to solve the problem of high amine value of the recovered product, but the patent does not relate to the solution of the problem of wide molecular weight distribution of the recovered product. In order to better recycle oligomer polyol obtained by recycling polyurethane foam into the polyurethane industry and realize green and high-quality recycling of waste polyurethane foam, the problems need to be effectively solved.

Disclosure of Invention

The invention aims to solve the problems and provides a method for preparing polyether polyol by recovering waste hard polyurethane foam.

Different from direct use or blending use of regenerated polyether by polyurethane foam alcoholysis, the invention adopts a mode of adding epoxide to a two-step catalytic polyurethane foam alcoholysis product, firstly uses an alkali metal catalyst to catalyze amine substances, residual alcoholysis agent, hydroxyl-terminated oligomer (containing benzene ring and carbamate structure) in the alcoholysis product to polymerize with epoxide, and converts the amine substances, the residual alcoholysis agent, the hydroxyl-terminated oligomer and the epoxide into an oligomer polyol mixture with low amine value; and then the selectivity of the nitrile catalyst is utilized to preferentially catalyze the polymerization of the low molecular weight polyol, so that the molecular weight of the regenerated polyether polyol product is more concentrated.

Compared with other polyurethane foam alcoholysis regeneration technologies, the regenerated polyether polyol prepared by the method effectively reduces adverse effects of residual alcoholysis agents and amine substances in recovered products on a subsequent foaming process, can be directly reused for preparing polyurethane rigid foam, fully utilizes rigid structures such as benzene rings in regenerated polyether and the like, and improves the heat resistance and the compression strength of foam products.

The invention realizes the aim through the following technical scheme:

a method for preparing polyether polyol by recycling waste hard polyurethane foam, which comprises the following steps:

s1: crushing the recovered rigid polyurethane foam material into particles, compounding the particles with an alcoholysis agent and alkali to form an alcoholysis solution, and heating to obtain an alcoholysis product;

s2: filtering the alcoholysis product, transferring the alcoholysis product into a reaction kettle, adding an alkali metal catalyst, dehydrating, adding an epoxide for polymerization reaction, cooling, adding a catalyst A, heating, and continuing to add the epoxide for polymerization reaction to obtain polyether polyol with high molecular weight;

s3: and cooling the polyether polyol, adding a neutralizing agent and an adsorbent, dehydrating after neutralization reaction, and filtering to obtain the target polyether polyol.

Firstly, catalyzing amine substances, residual alcoholysis agents, hydroxyl-terminated oligomers (containing benzene rings and carbamate structures) in the alcoholysis product by using an alkali metal catalyst to polymerize with the epoxide, and converting the amine substances, the residual alcoholysis agents, the hydroxyl-terminated oligomers and the epoxide into oligomer polyol mixtures with low amine values; and then the low molecular weight polyol is preferentially catalyzed to polymerize by utilizing the selectivity of the phosphazene catalyst, so that the molecular weight of the regenerated polyether polyol product is more concentrated.

In the present invention, the S1 pulverizes the polyurethane foam into particles having a diameter of less than 5 mm.

In the present invention, the alcoholysis agent of S1 is one or more of ethylene glycol, glycerol, diethylene glycol, 1, 4-butanediol, preferably diethylene glycol and/or dipropylene glycol, more preferably dipropylene glycol, and the base is one or more of sodium hydroxide, potassium hydroxide, magnesium hydroxide, and cesium hydroxide, preferably potassium hydroxide and/or sodium hydroxide, more preferably potassium hydroxide; preferably, the mass ratio of the alcoholysis agent to the base to the polyurethane foam is (50-500) to (1-20) to (60-800).

In the invention, the alcoholysis temperature is 170-220 ℃, and the time is 4-8 h.

In the invention, the epoxide in S2 is one or more of ethylene oxide, propylene oxide and tetrahydrofuran; preferably, the mass ratio of epoxide to alcoholysis product is (1-20): 1.

In the invention, the alkali metal catalyst of S2 is one or more of sodium hydroxide, potassium hydroxide and cesium hydroxide; preferably, the amount of the alkali metal catalyst is 0.05 to 1 percent of the mass of the alcoholysis product.

In the present invention, the catalyst a in S2 is a phosphazene catalyst, preferably one or more of aminotris (dimethylamino) phosphorochloridite, iminotris (dimethylamino) phosphoroshine, tetrakis (tris (dimethylamino) phosphoroamino) phosphine oxide, and dimethylaminotis (tris (dimethylamino) phosphoroamino) phosphine oxide; preferably, the catalyst is used in an amount of 0.005% to 0.05% by mass of the alcoholysis product.

In the invention, the polymerization temperature of S2 is 100-120 ℃, the first epoxide addition reaction time is 2-3h, and the second epoxide addition polymerization reaction time is 2-6 h.

In the invention, the neutralizer S3 is one or more of acetic acid, phosphoric acid, oxalic acid, formic acid, sulfurous acid and hypochlorous acid.

In the invention, the adsorbent of S3 is one or more of magnesium silicate, aluminum silicate, silica gel, diatomite and alumina.

In the invention, the neutralization reaction temperature of S3 is 40-60 ℃, and the reaction time is 0.5-1 h.

It is another object of the present invention to provide a polyether polyol.

The polyether polyol is prepared by the recovery method of the waste hard polyurethane foam, and has a hydroxyl value of 330-513mg KOH/g, a viscosity of 1700-4200cp, an amine value of 0.1-0.5mg KOH/g, an average molecular weight of 910-3600 and a distribution coefficient of 1.15-1.25.

It is a further object of the present invention to provide the use of a polyether polyol.

The polyether polyol is prepared by the recovery method of the waste hard polyurethane foam, or the polyether polyol is adopted, and the application of the polyether polyol is to prepare the hard polyurethane foam for refrigerators and freezers.

It is still another object of the present invention to provide a polyurethane foam.

The polyurethane foam is prepared from polyether polyol prepared by recycling waste rigid polyurethane foam, the polyether polyol of the polyurethane foam is prepared by the method for recycling the waste rigid polyurethane foam, or the polyether polyol is adopted, or the polyether polyol is used, and the apparent core density of the polyurethane foam is 40-47mg/m³The compression strength is 210-.

In one embodiment, the polyurethane foam is prepared by: weighing regenerated polyether, triethylene diamine and deionized water at room temperature, stirring and mixing, after uniform mixing, quickly pouring the mixture and PM-200 into a preheated aluminum open mold after stirring and mixing in a stirrer, and foaming the mixture. And after foaming is finished, taking out the foam to obtain the polyurethane foam.

Compared with the prior art, the invention has the advantages that:

according to the invention, two catalysts are added step by step to gradually catalyze the ring-opening polymerization of products such as micromolecule amine, residual alcoholysis agent, oligomer polyol and the like obtained after alcoholysis of the waste polyurethane material and the epoxide to generate polyether polyol. The method has the advantages that the prepared recovery product has low amine value (amine value is 0.1-0.5mg KOH/g), concentrated molecular weight distribution (distribution coefficient is 1.15-1.25), the foam product prepared from the recovery product has low heat conductivity coefficient (heat conductivity is 0.021-0.030W/(m.K)), and high compressive strength (210-.

Detailed Description

The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the following examples.

Raw materials:

rigid polyurethane foam: heat preservation foam of a hail waste refrigerator;

diethylene glycol, mcrine, 98%;

triethylenediamine, michelin, AR;

potassium hydroxide: mikelin, AR;

propylene oxide: warfarWis;

iminotris (dimethylamino) phosphorane: mclin, 97%;

phosphoric acid: shanghai Tantake Technique, Inc., 85%;

aluminum silicate: shanghai Tatan, GR;

polymeric MDI (PM-200), Wawa chemical;

the test instrument includes:

compression testing machine: shanghai Strength Instrument manufacturing Ltd, CTM2000 series Material testing machine;

thermal conductivity tester: HCDR-S transient planar heat source method thermal conductivity instrument, south beijing sincerity instruments and meters ltd.

The characterization method comprises the following steps:

hydroxyl value, Switzerland 905Titrando automatic potentiometric titrator, GB/T12008.3-2009;

amine value: titration by the perchloric acid method: weighing a certain mass M of sample to be detected by an analytical balance, adding the sample to be detected into a conical flask, adding 15ml of glacial acetic acid, 5ml of pure benzene and 1-2 drops of indicator crystal violet by using a pipette, and shaking up to fully dissolve the sample to be detected. Titration was carried out with a perchloric acid-acetic acid solution (concentration C) which had been calibrated. Upon the solution changing from violet to blue, the end of the titration is reached and the consumption volume V of perchloric acid-acetic acid solution is recorded. The amine value was calculated by the formula (56.1C V)/M;

the average molecular weight was measured by Gel Permeation Chromatography (GPC): 2 drops of the sample to be tested are added into a 2mL gas cylinder by using a pipette, 1.5mL dichloromethane is added, and the gas cylinder is placed into an Agilent 1260II type liquid chromatograph for testing.

Viscosity, Brookfield viscometer DV-II + Pro viscometer, GB/T12008.7-2010;

acid value, switzerland warong 905Titrando autopotentiometric titrator;

the physical properties of the foam product are measured according to GB/T26689-2011.

Example 1

Waste hard polyurethane foam is crushed into particles with the diameter less than 5mm, 300g of dipropylene glycol, 1g of potassium hydroxide and 300g of foam particles are added into a 2L reaction kettle, and an alcoholysis solution is compounded. Heating to 180 ℃ for 8h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. 300g of alcoholysis product is added into another 2L reaction kettle, 1.2g of potassium hydroxide as a catalyst is added, the temperature is raised to 110 ℃, and the vacuum dehydration is carried out for 1 h. Then 150g of liquid propylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 2 h. Cooling to 60 ℃, adding 0.06g of iminotris (dimethylamino) phosphorane, uniformly stirring, heating to 110 ℃, adding 300g of liquid propylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. And cooling to 60 ℃, sequentially adding 1.5g of phosphoric acid, 6g of pure water and 0.75g of aluminum silicate, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the yellowish-brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Example 2

Crushing waste hard polyurethane foam into particles with the diameter less than 5mm, adding 300g of ethylene glycol, 6g of magnesium hydroxide and 360g of foam particles into a 2L reaction kettle, and compounding to obtain an alcoholysis solution. Heating to 180 ℃ for 8h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. Adding 300g of alcoholysis product into another 2L reaction kettle, adding 3g of potassium hydroxide serving as a catalyst, heating to 110 ℃, and carrying out vacuum dehydration for 1 h. Then 150g of liquid propylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 2 h. Cooling to 60 ℃, adding 0.06g of amino tri (dimethylamino) phosphorane chloride, uniformly stirring, heating to 110 ℃, adding 150g of liquid propylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. Cooling to 60 ℃, sequentially adding 1.5g of phosphoric acid, 6g of pure water and 0.75g of aluminum silicate, stirring for neutralization reaction for 0.5h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the yellowish-brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Example 3

Waste hard polyurethane foam is crushed into particles with the diameter smaller than 5mm, 500g of dipropylene glycol, 20g of potassium hydroxide and 800g of foam particles are added into a 2L reaction kettle, and an alcoholysis solution is compounded. Heating to 220 ℃ for 4h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. Adding 300g of alcoholysis product into another 2L reaction kettle, adding 0.15g of potassium hydroxide catalyst, heating to 110 ℃, and carrying out vacuum dehydration for 1 h. 2000g of liquid propylene oxide is added according to the feeding speed of 20g/min, the adding process is synchronous, and the temperature is controlled to be 110 ℃ for polymerization reaction for 2 h. Cooling to 60 ℃, adding 0.03g of tetra (dimethylamino) phosphoroamino) phosphine oxide, uniformly stirring, heating to 110 ℃, adding 150g of liquid propylene oxide into the reaction kettle at a feeding speed of 2.5g/min, carrying out polymerization reaction for 3h at the temperature of 110 ℃, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. Cooling to 40 ℃, sequentially adding 1.5g of acetic acid, 6g of pure water and 0.75g of magnesium silicate, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the yellowish brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Example 4

Waste hard polyurethane foam is crushed into particles with the diameter less than 5mm, 200g of diethylene glycol, 1g of potassium hydroxide and 300g of foam particles are added into a 2L reaction kettle, and an alcoholysis solution is compounded. Heating to 220 ℃ for 4h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. 300g of alcoholysis product is added into another 2L reaction kettle, 1.5g of sodium hydroxide as a catalyst is added, the temperature is raised to 110 ℃, and the vacuum dehydration is carried out for 1 h. Then 300g of liquid ethylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 3 h. Cooling to 60 ℃, adding 0.15g of dimethylamino-tris (dimethylamino) phosphoranylidene) phosphine oxide, uniformly stirring, heating to 110 ℃, adding 150g of liquid ethylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. And cooling to 40 ℃, sequentially adding 1.5g of oxalic acid, 6g of pure water and 0.75g of silica gel, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the yellowish brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Example 5

Waste hard polyurethane foam is crushed into particles with the diameter smaller than 5mm, 300g of glycerol, 3g of sodium hydroxide and 500g of foam particles are added into a 2L reaction kettle, and an alcoholysis solution is compounded. Heating to 220 ℃ for 4h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. 300g of alcoholysis product is added into another 2L reaction kettle, 1.5g of sodium hydroxide as a catalyst is added, the temperature is raised to 110 ℃, and the vacuum dehydration is carried out for 1 h. Then 300g of liquid ethylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 3 h. Cooling to 60 ℃, adding 0.06g of iminotris (dimethylamino) phosphorane, uniformly stirring, heating to 110 ℃, adding 150g of liquid ethylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. And cooling to 40 ℃, sequentially adding 1.5g of formic acid, 6g of pure water and 0.75g of diatomite, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the yellowish-brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Comparative example 1

Comparative example 1 polyether was prepared without adding waste foam and with only alcoholysis agent, in comparison to example 1. Through comparison, the characteristics of low heat conductivity coefficient and high compressive strength of the polyurethane foam product obtained by the scheme disclosed by the invention are related to the alcoholysis structure of the waste foam.

300g of dipropylene glycol and 1g of potassium hydroxide are added into a 2L reaction kettle to be compounded into a solution. Heating to 180 ℃ for 8h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a colorless transparent product. 300g of the product is added into another 2L reaction kettle, 1.2g of potassium hydroxide as a catalyst is added, the temperature is raised to 110 ℃, and the vacuum dehydration is carried out for 1 h. Then 150g of liquid propylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 2 h. Cooling to 60 ℃, adding 0.06g of iminotris (dimethylamino) phosphorane, uniformly stirring, heating to 110 ℃, adding 300g of liquid propylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. Cooling to 60 ℃, sequentially adding 1.5g of phosphoric acid, 6g of pure water and 0.75g of aluminum silicate, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain colorless transparent polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Comparative example 2

Comparative example 2 foam degradation, polymerization, neutralization refining were carried out with solvent only, and comparison was made with example 1. The comparison shows that the alcoholysis agent is not added, and only self-degradation is carried out, so that the defects of low degradation degree, high amine value of degradation products, low hydroxyl value and wide molecular weight distribution are existed.

Waste hard polyurethane foam is crushed into particles with the diameter smaller than 5mm, 300g of methyl silicone oil serving as a solvent, 1g of potassium hydroxide and 300g of foam particles are added into a 2L reaction kettle, and reaction liquid is compounded. Heating to 180 ℃ for 8h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a dark wine red degradation product. Adding 300g of degradation product into another 2L reaction kettle, adding 1.2g of potassium hydroxide as a catalyst, heating to 110 ℃, and carrying out vacuum dehydration for 1 h. Then 150g of liquid propylene oxide is added according to the feeding speed of 2.5g/min, the addition process is synchronous, and the temperature is controlled at 110 ℃ for polymerization reaction for 2 h. Cooling to 60 ℃, adding 0.06g of iminotris (dimethylamino) phosphorane, uniformly stirring, heating to 110 ℃, adding 300g of liquid propylene oxide into the reaction kettle at a feeding speed of 2.5g/min, controlling the temperature to be 110 ℃ for polymerization reaction for 3 hours, and controlling the gauge pressure not to exceed 0.4MPa in the reaction process. Cooling to 60 ℃, sequentially adding 1.5g of phosphoric acid, 6g of pure water and 0.75g of aluminum silicate, stirring for neutralization reaction for 1h, heating to 110 ℃, vacuum dehydrating for 3h, and filtering at high temperature to obtain the dark brown regenerated polyether polyol. And in the reaction process, the nitrogen atmosphere is always kept in the reaction kettle. The polyether polyol characterization results are shown in table 1.

80g of regenerated polyether, 2.4g of triethylene diamine and 8g of deionized water are weighed at room temperature (25 ℃), stirred and mixed for 0.5h, after uniform mixing, the mixture and 120g of PM-200 are stirred and mixed for 6 seconds in a stirrer (rotating speed of 3000rpm), and then the mixture is quickly poured into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) which is preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

Comparative example 3

Comparative example 3 only underwent the alcoholysis step and did not go through the subsequent S2, S3 steps, comparable to example 1. By comparison, the S2 and S3 of the scheme of the invention reduce the amine value of the recovered polyether, narrow the molecular weight distribution and have no residual alcoholysis agent in the recovered polyether.

Waste hard polyurethane foam is crushed into particles with the diameter less than 5mm, 300g of dipropylene glycol, 1g of potassium hydroxide and 300g of foam particles are added into a 2L reaction kettle, and an alcoholysis solution is compounded. Heating to 180 ℃ for 8h, reducing the temperature in the reaction kettle to 80 ℃, and filtering to obtain a wine red alcoholysis product. The polyether polyol characterization results are shown in table 1.

80g of alcoholysis product, 2.4g of triethylenediamine and 8g of deionized water were weighed out at room temperature (25 ℃) and mixed with stirring for 0.5h, after mixing uniformly, the mixture was mixed with 120g of PM-200 in a stirrer (rotating at 3000rpm) for 6 seconds and then poured quickly into an aluminum open mold (size: 300mm in length, 300mm in width and 50mm in thickness) preheated to 60 ℃ to foam the mixture. And after 7 minutes, taking out the foam to obtain the polyurethane foam. The results of the characterization of the polyurethane foams are shown in Table 2.

TABLE 1 index analysis of regenerated polyether polyol of comparative example and example

From example 1 and comparative example 1 in Table 1, the regenerated polyether polyol obtained by the present invention has a larger average molecular weight and a smaller molecular weight distribution coefficient than the polyether polyol obtained by adding only the alcoholysis agent for alcoholysis, polymerization, neutralization and purification without adding the waste rigid foam. The foam products prepared from example 1 and comparative example 1 in Table 2 have lower thermal conductivity and higher compressive strength.

From example 1 and comparative example 2 in table 1, the regenerated polyether polyol obtained by the present invention has a lower amine value and a smaller molecular weight distribution coefficient than those obtained by subjecting polyurethane foam degradation, polymerization, neutralization and purification with a solvent alone;

from example 1 and comparative example 3 in table 1, the regenerated polyether polyol obtained by the present invention has a lower amine number, a larger molecular weight, a smaller molecular weight distribution coefficient, and no small molecule alcoholysis agent residue, compared to polyether polyols obtained by conducting only alcoholysis of polyurethane foams.

TABLE 2 index analysis of rigid polyurethane foams prepared from comparative examples, examples recycled polyether polyols

As can be seen from the results of the examples in Table 2, the polyurethane rigid foam prepared from the recycled polyether polyol obtained by the method of the present invention has the characteristics of low thermal conductivity and high compressive strength, and completely meets the performance requirements of the rigid polyurethane foam for refrigerators and freezers.

It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.