Green production method and application of vegetable oil polyol

Abstract

The invention belongs to the technical field of vegetable oil polyols, and provides a green production method and application of vegetable oil polyols, and the green production method comprises the following steps: carrying out epoxy bond ring-opening reaction on epoxidized vegetable oil and a nucleophilic reagent in the presence of an imidazole catalyst to generate the vegetable oil polyols; the imidazole catalyst is selected from one or more of imidazole, N-methylimidazole and dimethylimidazole; the nucleophilic reagent is one or more of ethanol, glycerol, diethylene glycol and diethanol amine. According to the production method provided by the invention, the soybean oil is subjected to ring-opening oxidation by using the low-molecular alcohol, and the imidazole compound is used as a catalyst, is retained in the vegetable oil polyol after reaction and can be continuously used as a reaction catalyst of polyurethane, so that the process is simple, the reaction condition is mild, a solvent is not needed in the production process, and waste water and waste residues are not generated.

Description

Technical Field

[0001] The present invention belongs to the technical field of vegetable oil polyols, and relates to a green production method and application of vegetable oil polyols. Background Art

[0002] With the increasing consumption of non-renewable resources such as petroleum and coal, the decreasing reserves of these resources, and the continuous increase in product prices, renewable bio-based raw materials have attracted more and more attention. Bio-based polyols are substitutes for petroleum-based polyols, with significant energy-saving and emission-reduction value, and are of great significance for carbon emission reduction and carbon neutrality.

[0003] The raw materials of vegetable oil polyols are cheap and easily available, and have been widely used in the production of polyurethane foam plastics. The most commonly used vegetable oils are palm oil and soybean oil, and there are mainly two different technical routes. The more common one is the transesterification reaction with polyhydroxy compounds to suspend the fatty acid chain on the traditional polyether polyol chain segment, which acts like an internal plasticizer, reducing the functionality of the polyether and having a certain impact on the properties of the foam. Another technical route is to open the double bond in the fatty acid chain segment and replace it with a hydroxyl group, and there are several different reaction paths, such as ozonation. This method first breaks the unsaturated double bond with ozone and then generates hydroxyl groups through hydrogenation and other reactions; aldehyde formation method, in which the double bond is first converted into an aldehyde group under the action of a catalyst and then the aldehyde is hydrogenated to alcohol; epoxidation method, in which the unsaturated double bond in vegetable oil is first oxidized into an epoxy bond and then polyols are prepared through ring-opening reaction.

[0004] Among them, the epoxy ring-opening method is the most common method to increase the hydroxyl content of vegetable oil, which is suitable for the preparation of polyurethane flexible foam or elastomers. At present, the industrial production of vegetable oil polyols mostly adopts this method. The main synthesis route is that the unsaturated double bond in vegetable oil undergoes an epoxidation reaction under the action of a peroxide to generate an epoxy group, and the epoxy group undergoes ring-opening under certain conditions to obtain vegetable oil polyols. Commonly used ring-opening reagents include water, ethanol, glycerol, propylene glycol, or acids, etc. When the degree of unsaturation of vegetable oil is relatively high, polyols with higher hydroxyl values can be obtained, which is beneficial to the improvement of the crosslinking density and tensile strength of polyurethane. For the vegetable oil polyols produced by the ring-opening of epoxy vegetable oil double bonds, traditional ring-opening catalysts are generally inorganic strong acids (such as sulfuric acid, nitric acid, hydrochloric acid, etc.) and strong bases (such as KOH, NaOH, etc.). These catalysts cause very serious corrosion to equipment, and the post-treatment process is cumbersome, with a large amount of wastewater discharge and very serious environmental pollution.

[0005] In the ozonation method, the ozonides obtained from the conversion of unsaturated double bonds in vegetable oil are reduced to polyols under the action of lithium aluminum hydride or sodium borohydride catalysts, and the double bond conversion rate is as high as 97%. The polyols obtained by this method have almost all primary hydroxyl groups located at the ends of the fatty chains, with high reactivity, and can be used as raw materials for rigid polyurethane foam materials. Generally speaking, the ozonation method has relatively complex steps, involves the use of toxic solvents, and the obtained polyols have relatively low molecular weights and functionalities, with a small range of product applications.

[0006] In the hydroformylation method, vegetable oil can undergo carbonylation reaction to obtain aldehyde groups under the action of noble metal catalysts, and then the aldehyde groups are hydrogenated to primary alcohols under the action of Raney nickel. The catalysts used in this method are relatively expensive, the process is relatively complex, and the conversion rate is low, making it difficult to achieve large-scale industrial applications.

[0007] In summary, it is of great significance to study the green production method of vegetable oil polyols at present. Summary of the Invention

[0008] The present invention provides a green production method and application of vegetable oil polyols. The process provided by the present invention is simple, the reaction conditions are mild, no solvent is required during the production process, and no wastewater and waste residue are generated.

[0009] The technical solution of the present invention is realized as follows: A green production method of vegetable oil polyols includes the following steps: The epoxy vegetable oil undergoes an epoxy ring-opening reaction with a nucleophile in the presence of an imidazole catalyst to generate vegetable oil polyols; the imidazole catalyst is selected from one or more of imidazole, N-methylimidazole, and dimethylimidazole; the nucleophile is one or more of ethanol, glycerol, diethylene glycol, and diethanolamine.

[0010] Preferably, the dosage relationship between the epoxy vegetable oil and the nucleophile is 300 - 330 g: 1 - 1.6 mol.

[0011] Preferably, the nucleophile is composed of glycerol and diethanolamine with a mass ratio of 55: 90 - 100.

[0012] Preferably, the epoxy vegetable oil can be one or a mixture of one or more vegetable oils such as soybean oil, safflower oil, sunflower oil, linseed oil, sesame oil, rapeseed oil, tung oil, castor oil, tall oil, and peanut oil, and its epoxy value is between 2 and 7.

[0013] Preferably, the dosage of the imidazole catalyst is 0.1 - 1% of the total mass of the reactants.

[0014] Preferably, the dosage relationship between the epoxy vegetable oil and the nucleophile is 300 - 330 g: 1.5 mol.

[0015] Preferably, the reaction temperature is 100 - 200 °C.

[0016] Preferably, the epoxy vegetable oil is epoxy soybean oil; Preferably, the reaction temperature is 140 - 180 °C; Preferably, the dosage of the imidazole catalyst is 0.3 - 0.8% of the total mass of the reactants.

[0017] The present invention also provides a vegetable oil polyol prepared by the green production method of the above vegetable oil polyol.

[0018] The present invention also provides the application of the vegetable oil polyol prepared by the green production method of the above vegetable oil polyol in the fields of thermal insulation materials and CASE.

[0019] The working principle and beneficial effects of the present invention are as follows: 1. The production method provided by the present invention uses low molecular weight alcohols to ring - open epoxy vegetable oil, and uses imidazole compounds as catalysts. After the reaction, they are retained in the vegetable oil polyol and can continue to be used as reaction catalysts for polyurethanes. Its process is simple, the reaction conditions are mild, no solvents are required during the production process, and no waste water or waste residue is generated.

[0020] 2. The production method of the vegetable oil polyol provided by the present invention obtains a vegetable oil polyol with a functionality of 2 - 10 and a hydroxyl value of 200 - 700 for the polyol. Description of the Drawings

[0021] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0022] Figure 1 It is the infrared spectrum diagram of the vegetable oil polyol prepared in Example 1 of the present invention. Specific Embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention. In the embodiments of the present invention, the production processes, experimental methods or detection methods involved, unless otherwise specified, are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the art, and are very clear and definite in the relevant application fields. Those skilled in the art can understand the conventional process steps according to the name and apply the corresponding equipment, and implement them under conventional conditions or conditions recommended by the manufacturer.

[0026] There are no special restrictions on the sources of various instruments, equipment, raw materials or reagents used in the embodiments of the present invention. They are all conventional products that can be obtained through regular commercial channels, and can also be prepared according to the conventional methods well-known to those skilled in the art.

[0027] In the following examples and comparative examples, the epoxidized soybean oil used was from Nantong Hairma Technology Co., Ltd., with an epoxy value of 6.22%, a viscosity of 380 mPa·s at 25°C, and an acid value of 0.52 mgKOH / g.

[0028] Example 1 A green production method of vegetable oil polyol includes the following steps: Put 315 g of epoxidized soybean oil, 137 g of glycerol and 1.5 g of N-methylimidazole into a 500 ML three-necked flask. After heating to 155°C, take samples during the period to detect the infrared spectrum. Keep the temperature constant for reaction for 9 hours and dehydrate at 110°C for 1 hour to obtain the finished product. As Figure 1 , the infrared spectrum shows that the epoxy characteristic peak at a wave number of 823 gradually weakens in intensity as the reaction time prolongs.

[0029] Example 2 A green production method of vegetable oil polyol includes the following steps: Put 315 g of epoxidized soybean oil, 55 g of glycerol, 94.5 g of diethanolamine and 2 g of N-methylimidazole into a 500 ML three-necked flask. After heating to 155°C, keep the temperature constant for reaction for 7 hours and dehydrate at 110°C for 1 hour to obtain the finished product.

[0030] Example 3 A green production method of vegetable oil polyol includes the following steps: Put 315 g of epoxidized soybean oil, 106 g of diethylene glycol and 2 g of N-methylimidazole into a 500 ML three-necked flask. After heating to 155°C, keep the temperature constant for reaction for 7 hours and dehydrate at 110°C for 1 hour to obtain the finished product.

[0031] Example 4 A green production method of vegetable oil polyol includes the following steps: Put 315 g of epoxidized soybean oil, 69 g of ethanol and 2 g of N-methylimidazole into a 500 ML three-necked flask. After heating to 155 °C, keep the temperature constant for reaction for 7 hours, and dehydrate at 110 °C for 1 hour to obtain the finished product.

[0032] Comparative Example 1 Put 315 g of epoxidized soybean oil, 137 g of glycerol and 6 g of 40 wt% aqueous dimethylamine solution into a 500 ML three-necked flask. After heating to 155 °C, keep the temperature constant for reaction for 9 hours, and dehydrate at 110 °C for 1 hour to obtain the finished product. The mid-infrared spectrum shows a strong epoxy characteristic peak at a wave number of 823.

[0033] Comparative Example 2 Put 315 g of epoxidized soybean oil, 55 g of glycerol and 2 g of N-methylimidazole into a 500 ML three-necked flask. After heating to 120 °C, keep the temperature constant for reaction for 7 hours, and remove low-boiling substances at 110 °C for 1 hour to obtain the finished product. The mid-infrared spectrum shows a strong epoxy characteristic peak at a wave number of 823.

[0034] The finished products of the above examples and comparative examples were tested as shown in Table 1 below.

[0035] Table 1 *Note: When calculating the functionality, the transesterification reaction of vegetable oil polyols and the influence of unreacted low-molecular-weight alcohols therein are not considered.

[0036] Method for calculating the epoxy ring-opening rate: Method for determining the hydroxyl value of polyols: Under the condition of constant-temperature heating and reflux, the hydroxyl group reacts with phthalic anhydride dissolved in pyridine for esterification reaction, and the excess phthalic anhydride is titrated with a standard sodium hydroxide solution. Phthalic anhydride can also react with epoxy groups. Therefore, when detecting the hydroxyl value of vegetable oil polyols by the national standard method, it not only includes the hydroxyl value from low-molecular-weight polyols, but also includes the epoxy groups that react with phthalic anhydride. As the ring-opening reaction proceeds and the content of epoxy groups decreases, the measured hydroxyl value of the reactants will continuously decrease. Dividing the number of moles of the decrease in the hydroxyl value of the reaction mixture by the number of moles of epoxy in epoxidized soybean oil can obtain the calculated epoxy ring-opening rate.

[0037] Method for calculating the functionality: The molecular weight and degree of epoxidation of epoxidized soybean oil are different, and the present invention does not make any restrictions. In the present invention, epoxidized soybean oil with a molecular weight of 1000 is taken as an example for the following description.

[0038] The molecular structure of epoxidized soybean oil is shown in Formula I below: Formula I; The average molecular weight is about 1000. When the epoxy value of epoxidized soybean oil is 6.2, on average, each epoxidized soybean oil molecule contains 3.88 epoxy groups. After the epoxy groups are ring-opened with glycerol, each epoxy group can form three hydroxyl groups (as shown in Formula II below). When all the epoxy groups are opened, theoretically, on average, each soybean oil molecule is grafted with 11.64 hydroxyl groups, that is, the highest functionality of the soybean oil polyol can reach 11.64. If the ring-opening rate of the epoxy groups reaches 60%, the average functionality of the soybean oil polyol can reach 11.64 * 60% = 7.

[0039] Formula II.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A green production method of vegetable oil polyols, characterized in that: The steps include: The epoxidized vegetable oil undergoes an epoxide ring-opening reaction with a nucleophilic reagent in the presence of an imidazole catalyst to generate a vegetable oil polyol; the imidazole catalyst is selected from one or more of imidazole, N-methylimidazole and dimethylimidazole; the nucleophilic reagent is one or more of ethanol, glycerol, diethylene glycol and diethanolamine.

2. The green production method of vegetable oil polyol according to claim 1, characterized in that: The usage ratio of the epoxidized vegetable oil and the nucleophilic reagent is 300-330 g: 1-1.6 mol.

3. The green production method of vegetable oil polyol according to claim 1, characterized in that: The nucleophilic reagent consists of glycerol and diethanolamine in a mass ratio of 55:90-100.

4. The green production method of vegetable oil polyol according to claim 1, characterized in that: The epoxidized vegetable oil can be one or more of soybean oil, safflower oil, sunflower oil, linseed oil, sesame oil, rapeseed oil, tung oil, castor oil, tall oil, and peanut oil, and the epoxidized vegetable oil has an epoxide value of 2-7.

5. The green production method of vegetable oil polyol according to claim 1, characterized in that: The amount of the imidazole catalyst used is 0.1-1% of the total amount of the reactants.

6. The green production method of vegetable oil polyol according to claim 1, characterized in that: The usage ratio of the epoxidized vegetable oil and the nucleophilic reagent is 300-330 g:1.5 mol.

7. The green production method of vegetable oil polyol according to claim 1, characterized in that: The reaction temperature is 100-200°C.

8. The green production method of vegetable oil polyol according to claim 1, characterized in that: The epoxidized vegetable oil is epoxidized soybean oil; The reaction temperature is 140-180°C; The amount of the imidazole catalyst used is 0.3-0.8% of the total amount of the reactants.

9. A vegetable oil polyol prepared by the green production method of vegetable oil polyol according to any one of claims 1 to 8.

10. Use of the vegetable oil polyol prepared by the green production method of the vegetable oil polyol according to any one of claims 1 to 8 in the field of thermal insulation materials and CASE.

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