阅读说明：本技术 纤维素聚醚多元醇的制备方法 (Preparation method of cellulose polyether polyol ) 是由 白维坤 孙露霞 张莉萍 周永振 郭怀泉 于 2020-12-28 设计创作，主要内容包括：本发明涉及一种纤维素聚醚多元醇的制备方法,属于聚醚多元醇改性技术领域。本发明所述的纤维素聚醚多元醇的制备方法,是在低温环境下将纤维素溶解在碱和尿素的水溶液中,以纤维素、尿素和液体小分子醇作为起始剂,在碱的催化作用下,与环氧丙烷进行聚合反应,得到所述的纤维素聚醚多元醇。本发明设计科学合理,降低了成本,安全环保,拓展了纤维素的应用范围,纤维素转化率高,无残留。(The invention relates to a preparation method of cellulose polyether polyol, belonging to the technical field of polyether polyol modification. The preparation method of the cellulose polyether polyol comprises the steps of dissolving cellulose in an aqueous solution of alkali and urea at a low temperature, taking the cellulose, the urea and liquid micromolecule alcohol as initiators, and carrying out polymerization reaction with propylene oxide under the catalysis of alkali to obtain the cellulose polyether polyol. The invention has scientific and reasonable design, reduces the cost, is safe and environment-friendly, expands the application range of cellulose, and has high cellulose conversion rate and no residue.)

1. A method for preparing cellulose polyether polyol is characterized in that: dissolving cellulose in aqueous solution of alkali and urea at low temperature, taking the cellulose, the urea and liquid micromolecule alcohol as initiator, and carrying out polymerization reaction with propylene oxide under the catalysis of alkali to obtain the cellulose polyether glycol.

2. The method for producing a cellulose polyether polyol according to claim 1, characterized in that: the method comprises the following steps:

(1) dissolution of cellulose: taking cellulose, putting the cellulose into an aqueous solvent system of alkali and urea, and dissolving the cellulose in a freezing environment at the temperature of between 10 ℃ below zero and 15 ℃ below zero to obtain an aqueous solution of the alkali, the urea and the cellulose;

(2) low-temperature polymerization: adding an alkali, urea and cellulose aqueous solution into a reaction kettle, adding a liquid small molecular alcohol initiator, replacing with nitrogen, heating, controlling the temperature to be 75-85 ℃, dropwise adding propylene oxide, and curing;

(3) removing solvent water: after the curing is finished, heating to 90-105 ℃, vacuumizing and bubbling nitrogen to remove water in the stub bar;

(4) high-temperature polymerization: controlling the temperature to be 105-110 ℃, continuously dripping the residual propylene oxide, and curing;

(5) and (3) carrying out aftertreatment on crude polyether: and neutralizing the crude polyether by using phosphoric acid until the pH value is neutral, and carrying out reduced pressure dehydration and filtration to obtain the cellulose polyether polyol.

3. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: the base is sodium hydroxide.

4. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: in the aqueous solvent system in the step (1), the mass ratio of the alkali is 5-10 wt%, and the mass ratio of the urea is 8-14 wt%.

5. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: the mass ratio of alkali to urea to cellulose in the aqueous solution of alkali to urea to cellulose is 6-8: 9-13: 5.

6. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: the liquid small molecular alcohol is glycerol, ethylene glycol, diethylene glycol or propylene glycol.

7. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: the mass ratio of the addition amount of the cellulose and the liquid small molecular alcohol to the total addition amount of the propylene oxide is 1: 0.5-5: 10 to 30.

8. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: the mass and dosage ratio of the propylene oxide in the step (2) to the propylene oxide in the step (4) is 1: 0.1-10.

9. The process for preparing a cellulose polyether polyol according to claim 2, characterized in that: cellulose having a molecular mass of < 3 x 10⁵The natural cellulose of (1).

Technical Field

The invention relates to a preparation method of cellulose polyether polyol, belonging to the technical field of polyether polyol modification.

Background

The cellulose is a renewable biomass resource with the largest reserve on the earth, has wide sources, biodegradability and biocompatibility, is expected to become one of the main chemical raw materials in the future, and has wide application prospects in the field of materials. Cellulose as a polymer raw material mainly has the following applications: such as application as wood in building materials, application of cotton and hemp fibers and the like in textile materials, application in papermaking and the like; cellulose is subjected to a series of chemical reactions and transformations to obtain cellulose derivative materials in the form of cellulose-based filaments or films for industrial or consumer use. The cellulose is degraded into small molecular organic compounds, such as saccharides or alcohols, which can be used for producing bioethanol or biodiesel and the like, and can be used as a substitute of petroleum raw materials. However, since the structure of the cellulose derivative has high crystallinity and contains complex hydrogen bonds, the cellulose is difficult to dissolve in general solvents, and the development and application of the cellulose are greatly restricted by the difficult solubility of the cellulose.

Polyether polyol is an important raw material in the polyurethane industry, and is widely used in the fields of household appliance heat insulation, pipeline heat insulation, sandwich boards, automotive interiors, coatings and the like. Polyether polyol is prepared by the addition polymerization reaction of an initiator (a compound with an active hydrogen group) and an epoxy compound (ethylene oxide and propylene oxide). The initiators that are widely used at present include sucrose, glycerin, mannitol, sorbitol, monoethanolamine, diethanolamine, and the like.

Due to the extremely difficult solubility of cellulose, no literature document is available on the direct liquefaction of cellulose for the synthesis of polyether polyols.

Disclosure of Invention

The invention aims to provide a preparation method of cellulose polyether polyol, which has the advantages of scientific and reasonable design, cost reduction, safety, environmental protection, expansion of the application range of cellulose, high cellulose conversion rate and no residue.

The preparation method of the cellulose polyether polyol comprises the steps of dissolving cellulose in an aqueous solution of alkali and urea at a low temperature, taking the cellulose, the urea and liquid micromolecule alcohol as initiators, and carrying out polymerization reaction with propylene oxide under the catalysis of alkali to obtain the cellulose polyether polyol.

The preparation method of the cellulose polyether polyol specifically comprises the following steps:

(1) dissolution of cellulose: taking cellulose, putting the cellulose into an aqueous solvent system of alkali and urea, and dissolving the cellulose in a freezing environment at the temperature of between 10 ℃ below zero and 15 ℃ below zero to obtain an aqueous solution of the alkali, the urea and the cellulose;

(2) low-temperature polymerization: adding an alkali, urea and cellulose aqueous solution into a reaction kettle, adding a liquid small molecular alcohol initiator, replacing with nitrogen, heating, controlling the temperature to be 75-85 ℃, dropwise adding propylene oxide, and curing;

(3) removing solvent water: after the curing is finished, heating to 90-105 ℃, vacuumizing and bubbling nitrogen to remove water in the stub bar;

(4) high-temperature polymerization: controlling the temperature to be 105-110 ℃, continuously dripping the residual propylene oxide, and curing;

(5) and (3) carrying out aftertreatment on crude polyether: and neutralizing the crude polyether by using phosphoric acid until the pH value is neutral, and carrying out reduced pressure dehydration and filtration to obtain the cellulose polyether polyol.

Preferably, the base is sodium hydroxide.

Preferably, in the aqueous solvent system in the step (1), the alkali accounts for 5-10 wt%, and the urea accounts for 8-14 wt%.

Preferably, the mass ratio of the alkali to the urea to the cellulose in the aqueous solution of the alkali to the urea to the cellulose is 6-8: 9-13: 5.

Preferably, the liquid small molecule alcohol is glycerol, ethylene glycol, diethylene glycol or propylene glycol.

Preferably, the mass ratio of the addition amount of the cellulose and the liquid small molecular alcohol to the total addition amount of the propylene oxide is 1: 0.5-5: 10 to 30.

Preferably, the mass ratio of the propylene oxide in the step (2) to the propylene oxide in the step (4) is 1: 0.1-10.

Preferably, the cellulose has a molecular mass of < 3 x 10⁵The natural cellulose of (1).

At low temperature, urea and cellulose macromolecules in a solvent are self-assembled by hydrogen bond driving to form a pipeline inclusion compound, so that cellulose molecules are brought into an aqueous solution; under the condition of low temperature, the sodium hydroxide/urea/water solution may form large solvent molecule groups, so that hydrogen bonds in cellulose molecules and between cellulose molecules are weakened, and (-NH-) in urea forms hydrogen bonds with cellulose molecules, so that the cellulose molecules are dissolved. The invention uses cellulose and urea as initiator to synthesize cellulose polyether glycol simply.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention selects a solvent system for efficiently dissolving cellulose, and the solvent has low cost, simple preparation, safety and environmental protection;

(2) the solute in the solvent selected by the invention is simultaneously used as a catalyst and an initiator in the polyether synthesis process;

(3) the invention effectively expands the application range of the cellulose and has certain economic value;

(4) the cellulose polyether polyol prepared by the method has high cellulose conversion rate and no residue;

(5) the cellulose polyether glycol prepared by the method is used for preparing the polyurethane rigid foam plastic, so that the polyurethane rigid foam can be effectively prevented from being pulverized and has low shrinkage; the prepared polyurethane soft foam can improve the hardness and tensile property of the product.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the practice of the invention.

The starting materials used in the examples are all commercial products.

Example 1

Adding 25g of cellulose (molecular weight 0.7 x 10^5) into 500g of aqueous solvent system of 8 wt% of NaOH and 12 wt% of urea, and dissolving at 10 +/-5 ℃ in a freezing environment to obtain aqueous solution of NaOH, urea and cellulose. Adding the solution into a 2.5L polymerization reaction kettle, adding 26g of diethylene glycol, performing stamping detection on the polymerization reaction kettle to ensure good sealing performance, vacuumizing to the lowest vacuum degree of-0.093 MPa after nitrogen replacement, controlling the temperature to be 80 +/-5 ℃, dropwise adding propylene oxide until the added propylene oxide amount is 360g, stopping adding the propylene oxide, heating to 100 +/-5 ℃ after curing, vacuumizing and bubbling nitrogen to remove water in a stub bar; after the dehydration is finished, controlling the temperature to be 108 +/-2 ℃, continuously dropwise adding 220g of propylene oxide, and curing after the dropwise adding is finished to obtain crude polyether; then neutralizing the crude polyether with phosphoric acid until the pH value is neutral, decompressing, dehydrating and filtering to obtain the cellulose polyether polyol.

The cellulose polyethers synthesized are indicated in Table 1.

Example 2

20g of cellulose (molecular weight 0.7 x 10^5) is put into a 500g aqueous solvent system of 8 wt% of NaOH and 12 wt% of urea and dissolved at 5 +/-5 ℃ in a freezing environment to obtain NaOH, urea and cellulose aqueous solution. Adding the solution into a 2.5L polymerization reaction kettle, adding 26g of diethylene glycol, performing stamping detection on the polymerization reaction kettle to ensure good sealing performance, vacuumizing to the lowest vacuum degree of-0.093 MPa after nitrogen replacement, controlling the temperature to be 80 +/-5 ℃, dropwise adding propylene oxide until the added propylene oxide amount is 360g, stopping adding the propylene oxide, heating to 95 +/-5 ℃ after curing, vacuumizing and bubbling nitrogen to remove water in a stub bar; after the dehydration is finished, controlling the temperature to be 108 +/-2 ℃, continuously dropwise adding 220g of propylene oxide, and curing after the dropwise adding is finished to obtain crude polyether; then neutralizing the crude polyether with phosphoric acid until the pH value is neutral, decompressing, dehydrating and filtering to obtain the cellulose polyether polyol.

The cellulose polyethers synthesized are indicated in Table 1.

Example 3

15g of cellulose (molecular weight 0.7 x 10^5) is put into a 500g aqueous solvent system of 8 wt% of NaOH and 12 wt% of urea and dissolved at the temperature of minus 5 +/-5 ℃ to obtain NaOH, urea and cellulose aqueous solution. Adding the solution into a 2.5L polymerization reaction kettle, adding 26g of diethylene glycol, performing stamping detection on the polymerization reaction kettle to ensure good sealing performance, vacuumizing to the lowest vacuum degree of-0.093 MPa after nitrogen replacement, controlling the temperature to be 80 +/-5 ℃, dropwise adding propylene oxide until the added propylene oxide amount is 360g, stopping adding the propylene oxide, heating to 95 +/-5 ℃ after curing, vacuumizing and bubbling nitrogen to remove water in a stub bar; after the dehydration is finished, controlling the temperature to be 108 +/-2 ℃, continuously dropwise adding 520g of propylene oxide, and curing after the dropwise adding is finished to obtain crude polyether; then neutralizing the crude polyether with phosphoric acid until the pH value is neutral, decompressing, dehydrating and filtering to obtain the cellulose polyether polyol.

The cellulose polyethers synthesized are indicated in Table 1.

Example 4

20g of cellulose (molecular weight 0.7 x 10^5) is put into a 500g aqueous solvent system of 8 wt% of NaOH and 12 wt% of urea and dissolved at the temperature of minus 5 +/-5 ℃ to obtain NaOH, urea and cellulose aqueous solution. Adding the solution into a 2.5L polymerization reaction kettle, adding 23g of glycerol, performing stamping detection on the polymerization reaction kettle to ensure good sealing performance, vacuumizing to the lowest vacuum degree of-0.093 MPa after nitrogen replacement, controlling the temperature to be 80 +/-5 ℃, dropwise adding propylene oxide until the added propylene oxide amount is 360g, stopping adding the propylene oxide, heating to 95 +/-5 ℃ after curing, vacuumizing and bubbling nitrogen to remove water in a stub bar; after the dehydration is finished, controlling the temperature to be 107 +/-2 ℃, continuously dropwise adding 520g of propylene oxide, and curing after the dropwise adding is finished to obtain crude polyether; then neutralizing the crude polyether with phosphoric acid until the pH value is neutral, decompressing, dehydrating and filtering to obtain the cellulose polyether polyol.

The cellulose polyethers synthesized are indicated in Table 1.

Comparative example 1

Adding 20g of cellulose (molecular weight 0.7 x 10^5), 26g of diethylene glycol, 60g of urea and 40g of NaOH into a 2.5L polymerization reaction kettle, stamping and detecting the polymerization reaction kettle to ensure good sealing property, vacuumizing to the lowest vacuum degree of-0.093 MPa after nitrogen replacement, controlling the temperature to be 80 +/-5 ℃, dropwise adding propylene oxide, stopping adding the propylene oxide when the amount of the added propylene oxide is 360g, heating to 107 +/-2 ℃ after curing, continuously dropwise adding 220g of propylene oxide, and curing after finishing dropwise adding to obtain crude polyether; then neutralizing the crude polyether with phosphoric acid until the pH value is neutral, decompressing, dehydrating and filtering to obtain the cellulose polyether polyol.

The cellulose polyethers synthesized are indicated in Table 1.

TABLE 1 polyether indexes obtained in examples and comparative examples

As can be seen from the examples 1-4, the preparation method well designs and synthesizes the cellulose polyether polyols with different hydroxyl values; as can be seen from examples 1-4 and comparative example 1, the method can effectively solve the problem of cellulose dissolution, and enables cellulose and alkylene oxide to react well, so that the appropriate cellulose polyether polyol is prepared finally. Comparative example 1 it is theoretically possible to synthesize a polyether polyol, but since the cellulose did not participate in the reaction, the polyether polyol was cloudy in appearance, and the index deviated completely from the expected one, and was a failed sample.

The cellulose polyether polyol prepared by the method can be used in the fields of polyurethane hard foam heat preservation, soft foam, CASE polyether polyol and the like.