CN114262420B

CN114262420B - Preparation method of recyclable bio-based polyester polyurethane

Info

Publication number: CN114262420B
Application number: CN202111637091.6A
Authority: CN
Inventors: 沈勇; 李志波; 严钦; 颜婷
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2023-06-20
Anticipated expiration: 2041-12-29
Also published as: CN114262420A

Abstract

The invention provides a new method for preparing recyclable bio-based polyester polyurethane by a one-pot method under the condition of no solvent. Compared with the traditional method, the method provided by the invention has the following advantages: 1) The polyurethane is prepared by using a one-pot method, the process is simple, the preparation process does not need a solvent, and the cost is saved while the environment-friendly chemical principle is met; 2) The catalyst system is an organic catalyst system, has low biological toxicity and is easy to remove from the product, and experiments prove that the obtained product has no obvious cytotoxicity and can be used in the field of biological medicine; 3) The polyurethane can be recovered in high yield under bulk conditions to give delta-caprolactone monomers.

Description

Preparation method of recyclable bio-based polyester polyurethane

Technical Field

The invention relates to the fields of high polymer materials and chemistry and chemical engineering, in particular to recyclable polyester polyurethane and a preparation method thereof.

Background

Polyurethane materials have the advantages of low cost, high performance, wide application and the like, and are applied to the aspects of society. However, most of the raw materials of polyurethane are extracted from petroleum at present and are not easy to degrade, so that great environmental challenges exist in the mass production and treatment process of the polyurethane. In recent years, consumer preference and government policy changes have increased the need for bio-based polymers, including polyurethanes. As sustainable raw materials to meet this demand, low cost and rich natural bio-based polyols have attracted considerable attention because they have great potential to be degradable and recyclable, and the preparation process has less environmental pollution and resource waste.

Poly (delta-caprolactone) is an important class of aliphatic polyester polyols with excellent biocompatibility and recyclability. In addition, delta-caprolactone is a widely available and low-cost bio-based monomer, which can be obtained from biomass raw materials and is a renewable raw material. Compared with the existing polyester polyurethane material, the novel bio-based recyclable polyurethane material constructed by using poly (delta-caprolactone) as a soft segment has the advantages of lower price, recyclability and the like.

In view of this, the present invention provides a novel method for preparing recyclable bio-based polyester polyurethane in a one-pot process without solvent. Compared with the traditional method, the method provided by the invention has the following advantages: 1) The polyurethane is prepared by using a one-pot method, the process is simple, the preparation process does not need a solvent, and the cost is saved while the environment-friendly chemical principle is met; 2) The catalyst system is an organic catalyst system, has low biological toxicity and is easy to remove from the product, and experiments prove that the obtained product has no obvious cytotoxicity and can be used in the field of biological medicine; 3) The polyurethane can be depolymerized and recovered in high yield under bulk conditions to obtain delta-caprolactone monomers.

Disclosure of Invention

The invention aims to provide a method for preparing polyester polyurethane with poly (delta-caprolactone) as a soft segment by a one-pot method under the condition of no solvent, which comprises the following steps:

(1) Uniformly mixing a polyol initiator, strong alkali, a cocatalyst and delta-caprolactone, and reacting for 1-30 min at 10-50 ℃;

(2) Adding diphenyl phosphate into the system, stirring for 1min, adding isocyanate and polyurethane catalyst, and reacting at 30-100 deg.c for 0.1-24 hr to obtain polyurethane.

The chemical structural formula of the polyurethane is shown as formula (I):

wherein m is a natural number of 5 or more and n is a natural number of 5 or more.

Wherein R is ₁ The structure can be as follows:

R ₂ the structure can be as follows:

in the preparation method, the cocatalyst is at least one of urea and has a structure of one of the following:

in the preparation method, the polyol initiator in the step (1) can be concretely ethylene glycol, propylene glycol, butanediol, 1, 4-cyclohexanediol, glycerol and pentaerythritol; the strong base may be alkali metal, alkali metal compound or organic phosphazene base catalyst, and specifically sodium, potassium hydride, sodium hydride, hexa [ tri (dimethyl amine) phosphazene]Triphosphazene ({ [ (NMe) ₂ ) ₃ P＝N] ₂ P＝N} ₃ ) P4-tert-butyl ([ (NMe) phosphazene ligand ₂ ) ₃ P＝N] ₃ P＝NtBu，tert-Bu-P ₄ ) P2-tert-butyl ([ (NMe) phosphazene ligand ₂ ) ₃ P＝N](NMe ₂ ) ₂ P＝NtBu，tert-Bu-P ₂ )。

In the preparation method, the molar ratio of the strong base to the polyol initiator in the step (1) is 1/3-20/1; the molar ratio of the alkali to the urea is 1/0.5-1/10. The molar ratio of the polyol initiator to delta-caprolactone is 1/10-1/300; the mole ratio of the diphenyl phosphate to the strong alkali is 1/1-10/1.

In the preparation method, the polyurethane catalyst in the step (2) is N, N-dimethylcyclohexylamine, bis (2-dimethylaminoethyl) ether, N, N, N ' -tetramethyl alkylenediamine, triethylamine, N, N-dimethylbenzylamine, N-ethylmorpholine, N-methylmorpholine, N, N ' -diethyl piperazine, pyridine, N, N ' -dimethylpyridine, dibutyltin dilaurate and stannous octoate. The isocyanate is toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 1, 5-naphthalene diisocyanate.

In the preparation method, the molar ratio of the isocyanate to the polyol initiator in the step (2) is 1/1-2/1; the molar ratio of the polyurethane catalyst to the isocyanate is 1/500-1/10.

Drawings

FIG. 1 is a polyurethane prepared in example 1 ¹ H NMR spectrum.

FIG. 2 is a schematic diagram of the polyurethane produced in example 1 ¹³ C NMR spectrum.

FIG. 3 is an infrared spectrum of the polyurethane prepared in example 1.

FIG. 4 is a GPC chart of polyurethanes produced in examples 1-3.

FIG. 5 is a drawing graph of the polyurethane of example 2 at a draw rate of 50mm/min.

FIG. 6 shows delta-caprolactone and the original monomer obtained by bulk depolymerization and recovery of example 5 ¹ H NMR superimposed spectrum.

Detailed Description

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Comparative example 1

(4 mmol,360 mg) 1, 4-butanediol, (0.08 mmol,29.4 mg) phosphazene ligand P2-tert-butyl, cocatalyst U2 (0.24 mmol,50.9 mg) was added to the reaction tube, and then (40 mmol,4.4 mL) delta-caprolactone was added to the reaction tube with stirring by syringe. After the reaction was carried out under nitrogen protection for 10 minutes, the reaction tube was placed in an oil bath at 50℃and stirred for 5 minutes, and after addition of (4.4 mmol,1.1 g) diphenylmethane diisocyanate and (0.05 mmol,31.6 mg) dibutyltin dilaurate, the reaction was carried out for 4 hours to obtain polyurethane. The polyurethane is crosslinked, insoluble in solvents and cannot be tested and reprocessed.

Example 1

(4 mmol,360 mg) 1, 4-butanediol, (0.08 mmol,29.4 mg) phosphazene ligand P2-tert-butyl, cocatalyst U2 (0.24 mmol,50.9 mg) was added to the reaction tube, and then (40 mmol,4.4 mL) delta-caprolactone was added to the reaction tube with stirring by syringe. After the reaction was carried out under nitrogen for 10min, diphenyl phosphate (0.088 mmol,22 mg) was added thereto and stirred at room temperature for 5min. The reaction tube was then placed in an oil bath at 50℃with stirring for 5min, and after addition of (4.4 mmol,1.1 g) diphenylmethane diisocyanate and (0.05 mmol,31.6 mg) dibutyltin dilaurate, the reaction was carried out for 4h to give polyurethane. In comparison with comparative example 1, diphenyl phosphate was added to neutralize the strong base of the phosphazene ligand P2-t-butylHigh activity strong base catalyzed polyurethane crosslinking is avoided. GPC measured a weight average molecular weight of 267.1kg/mol, a number average molecular weight of 130.0kg/mol, a molecular weight distribution of 2.06, and a polyurethane obtained ¹ The H NMR spectrum of the obtained polyurethane is shown in FIG. 1 ¹³ The C NMR spectrum is shown in FIG. 2, and the GPC spectrum is shown in FIG. 4.

Example 2

(2 mmol,276.4 mg) 1, 4-phenyl dimethanol, (0.08 mmol,96 mg) hexa [ tris (dimethylamine) phosphazene ] triphosphazene, cocatalyst U1 (0.24 mmol,83.6 mg) was added to the reaction tube, and then (40 mmol,4.4 mL) delta-caprolactone was added to the reaction tube with stirring by syringe. After the reaction was carried out under nitrogen for 10min, diphenyl phosphate (0.088 mmol,22 mg) was added thereto and stirred at room temperature for 5min. The reaction tube was then placed in an oil bath at 50℃with stirring for 5min, and after addition of (2.2 mmol,550 mg) diphenylmethane diisocyanate and (0.05 mmol,31.6 mg) dibutyltin dilaurate, the reaction was carried out for 4h to give polyurethane. GPC showed that weight average molecular weight was 192.8kg/mol, number average molecular weight was 83.9kg/mol, molecular weight distribution was 2.30, and C=O bond characteristic peak infrared spectrum of the obtained polyurethane was shown in FIG. 3, GPC spectrum was shown in FIG. 4, and stretching curve diagram was shown in FIG. 5.

Example 3

(2 mmol,124 mg) ethylene glycol, (0.08 mmol,3.2 mg) potassium hydride, co-catalyst U3 (0.24 mmol,90.8 mg) were added to the reaction tube, and then (40 mmol,4.4 mL) delta-caprolactone was added to the reaction tube with a syringe and stirred. After the reaction was carried out under nitrogen for 10min, diphenyl phosphate (0.088 mmol,22 mg) was added thereto and stirred at room temperature for 5min. The reaction tube was then placed in an oil bath at 80℃with stirring for 5min, and after addition of (2.2 mmol,449 mg) isophorone diisocyanate and (0.05 mmol, 660 mg) stannous octoate, the reaction was carried out for 6h to give polyurethane. The GPC showed that the weight average molecular weight was 120.6kg/mol, the number average molecular weight was 60.5kg/mol, the molecular weight distribution was 2.50, and the GPC chart was shown in FIG. 4.

Example 4

(2 mol,180 g) 1, 4-butanediol, (0.6 mol,13.8 g) sodium, cocatalyst U4 (1.8 mmol,558.5 g) was added to the reaction vessel, and then (20 mol,2.28 kg) delta-caprolactone was added to the reaction vessel and stirred. After the reaction was carried out under nitrogen for 2 hours, diphenyl phosphate (0.66 mmol,165 g) was added thereto and stirred at room temperature for 10 minutes. The reaction vessel was then heated to 50℃and stirred for 10min, after which (2.2 mol,550 g) of diphenylmethane diisocyanate and (3 mmol,201.3 mg) of pyrrole were added and reacted for 12h to give polyurethane. GPC showed a number average molecular weight of 200.0kg/mol and a molecular weight distribution of 2.25.

Example 5

(30 g) of polyurethane (polyurethane sample in example 1) was cut into pieces and (300 mg) stannous octoate was added to the reaction flask and the mixture was stirred. Using a reduced pressure distillation apparatus, the reaction flask was heated to 170℃for 4 hours, and pure delta-caprolactone (20.9 g, yield: 97%) was recovered. Bulk depolymerization of recovered delta-caprolactone with original monomer ¹ The H NMR spectrum is shown in fig. 6.

Claims

1. A method for preparing polyester polyurethane with poly (delta-caprolactone) as a soft segment by a one-pot method under the condition of no solvent, which comprises the following steps:

(1) Adding a polyol initiator, strong alkali, a cocatalyst and delta-caprolactone into a reaction vessel, and reacting for 1-30 min at 10-50 ℃;

(2) Adding diphenyl phosphate into the system, stirring for 1min, adding isocyanate and a polyurethane catalyst, and reacting at 30-100 ℃ for 0.1-24h to obtain polyurethane;

the cocatalyst has a structure of one of the following:

2. the method of claim 1, wherein the poly (δ -caprolactone) is a soft segment polyester polyurethane having the chemical structural formula of formula (i):

the method is characterized in that m is a natural number greater than or equal to 5, and n is a natural number greater than or equal to 5;

wherein R is ₁ Has one of the following structures:

R ₂ has one of the following structures:

3. the method according to claim 1, characterized in that:

in the preparation method, the polyol initiator in the step (1) is one of ethylene glycol, propylene glycol, butanediol, 1, 4-cyclohexanediol, glycerol and pentaerythritol; the strong base is sodium, potassium hydride, sodium hydride, hexa [ tri (dimethyl amine) phosphazene]Triphosphazene ({ [ (NMe) ₂ ) ₃ P＝N] ₂ P＝N} ₃ ) P4-tert-butyl ([ (NMe) phosphazene ligand ₂ ) ₃ P＝N] ₃ P＝NtBu，tert-Bu-P ₄ ) P2-tert-butyl ([ (NMe) phosphazene ligand ₂ ) ₃ P＝N](NMe ₂ ) ₂ P＝NtBu，tert-Bu-P ₂ ) One of them.

4. The method according to claim 1, characterized in that:

in the preparation method, the molar ratio of the strong base to the initiator in the step (1) is 1/3-20/1; the molar ratio of the strong alkali to the urea is 1/0.5-1/10; the molar ratio of the polyol initiator to delta-caprolactone is 1/10-1/300.

5. The method according to claim 1, characterized in that:

in the preparation method, the polyurethane catalyst in the step (2) is one of N, N-dimethyl cyclohexylamine, bis (2-dimethylaminoethyl) ether, N, N, N ' -tetramethyl alkylene diamine, triethylamine, N, N-dimethyl benzylamine, N-ethylmorpholine, N-methylmorpholine, N, N ' -diethyl piperazine, pyridine, N, N ' -dimethylaminopyridine, dibutyltin dilaurate and stannous octoate; the isocyanate is one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate and 1, 5-naphthalene diisocyanate.

6. The method according to claim 1, characterized in that:

in the preparation method, the molar ratio of the diphenyl phosphate to the strong alkali in the step (2) is 1/1-10/1; the molar ratio of the isocyanate to the polyol initiator is 1/1-2/1; the molar ratio of the polyurethane catalyst to the isocyanate is 1/500-1/10.