TW202405073A - A self-healable recycling material and its preparing method - Google Patents

Abstract

The invention discloses a self-healable recycling material and its preparing method. The invented self-healable recycling material is self-healing thermoset polyurethane. In particular, the self-healing thermoset polyurethane is prepared from waste polycarbonate.

Description

A self-healing recycling material and its preparation method

The present invention relates to a self-healing cyclic material and a preparation method thereof. In particular, the self-healing cyclic material is a self-healing thermosetting polyurethane derived from polycarbonate or waste composite materials.

The degree of extreme climate in the world today has become much stronger than in the past. If carbon emissions are not reduced in time to slow down global warming, the intensity and frequency of extreme climates such as heavy rains, droughts, and tropical cyclones will continue to increase in the future. However, polymer waste is currently mainly disposed of through incineration or landfilling, which not only increases carbon emissions and exacerbates global warming, but the leakage of pollutants from landfills is also a major concern for the environment.

At present, the conventional technology field only has established systematic recycling and reuse technology for polyethylene terephthalate (PET). However, for other polymers, such as polycarbonate, there is still no waste treatment method with economic value established. The material treatment method allows related products to be recycled through chemical recycling methods after reaching the end of their service life, achieving the concept of circular economy.

In summary, in the current field of polymer plastic recycling technology, it is still a big challenge to research and develop an innovative polymer chemical recycling method while recycling and producing high-value products. There is an urgent need for relevant industries to come up with innovative solutions to achieve recycling. economic purpose.

In view of the above invention background, in order to meet the industrial requirements, the present invention One purpose is to reveal a self-healing recycling material. Specifically, the self-healing recycled material is a self-healing thermosetting polyurethane derived from polycarbonate or waste composite materials.

Specifically, the structure of the self-repairable recycling material includes a plurality of polysiloxane segments, a plurality of polyurethane segments and a plurality of isocyanurate heterocyclic structures, and the plurality of polysiloxane segments are borrowed from The plurality of polyurethane segments and the plurality of isocyanurate heterocyclic structures are connected by phenol-urethane bonds, thereby forming a self-healing thermosetting polyurethane.

More specifically, the polysiloxane segment is derived from an amine-based polysiloxane, the polyurethane segment is derived from a diisocyanate, the isocyanurate heterocyclic structure is derived from a diisocyanate trimer, and the The phenol-urethane bond is derived from the aminolysis reaction of the amino polysiloxane and polycarbonate and the condensation reaction of the residue of bisphenol A of polycarbonate and the diisocyanate.

Specifically, the self-healing thermosetting polyurethane has a chemical structural formula shown in formula (1).

Formula 1).

Specifically, R ₁ represents the polysiloxane segment and has a structure shown in formula (2).

(2) Formula (2).

(2)

Specifically, n is an integer from 1 to 100 and p is an integer from 2 to 4.

Specifically, R ₂ is a linear alkyl group, a cyclic alkyl group, or a polyethylene glycol group having 2 to 16 carbon atoms.

More specifically, _R2 is a residue of a diisocyanate constituting the polyurethane segment. Preferably, the diisocyanate is hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (4,4'-Methylene diphenyl diisocyanate, MDI) or dicyclohexylmethane diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI).

Specifically, R ₃ is a linear alkyl group or a cyclic alkyl group having 2 to 10 carbon atoms. More specifically, the isocyanurate heterocyclic structure with _R3 is derived from hexamethylene diisocyanate trimer (tri-HDI) or isophorone diisocyanate trimer (tri-IPDI).

Specifically, R ₄ is a residue of bisphenol-A (bis-A). Preferably, the residue of bisphenol-A (bis-A) is derived from polycarbonate.

More specifically, R ₄ is the residue of bisphenol-A (bis-A) constituting the phenol-urethane linkage.

Specifically, m is an integer from 0 to 10, and o is an integer from 0 to 10.

More specifically, the Fourier transform infrared spectrum of the self-healing thermosetting polyurethane includes characteristic peaks at the following positions: 3330±10cm ^-1 , 1720±10cm ^-1 , 1690±10cm ^-1 , 1257±10cm ^-1 , 1076± 10cm ^-1 , 1013±10cm ^-1 and 790±10cm ^-1 .

In particular, the cross-linking density of the self-healing thermosetting polyurethane ranges from 40 to 800 mol/m ³ , and the thermal cracking temperature of the self-healing thermosetting polyurethane is greater than 200°C.

More specifically, the phenol-urethane bond of the self-healing thermosetting polyurethane is a dynamic covalent bond of the reversible bond addition type, and the phenol-urethane bond is triggered through cyclic heating or temperature rising procedures. Dynamic covalent bonding mechanism, thereby achieving the technical effect of material self-healing. Accordingly, the self-healing thermosetting polyurethane is a temperature-responsive self-healing cyclic material.

The second object of the present invention is to disclose a method for preparing self-healing thermosetting polyurethane, the steps of which are as follows.

Step 1: Conduct an aminolysis reaction between polycarbonate and monoaminopolysiloxane to generate a phenol-urethane intermediate. The phenol-urethane intermediate has the formula ( 3) The chemical structural formula shown.

Formula (3).

Specifically, p is an integer from 2 to 4, n is an integer from 1 to 100, and m is an integer from 0 to 10.

Step 2: react the phenolic-urethane intermediate with a composition including diisocyanate, diisocyanate trimer and catalyst to prepare a self-healing thermosetting polyurethane. The solid polyurethane has a chemical structural formula represented by formula (1) described in the first embodiment.

Specifically, the functional group equivalent weight of the aminopolysiloxane is 200-3000g/mol.

Specifically, the proton nuclear magnetic resonance spectrum of the phenolic-urethane intermediate contains characteristic peaks at the following positions: 0.30±0.20ppm, 0.85±0.20ppm, 1.70±0.20ppm, 3.40±0.2 ppm,7.00±0.20ppm,7.20±0.2ppm,7.50±0.2ppm,7.80±0.2ppm,9.50±0.2ppm.

Specifically, the diisocyanate is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (4,4'-Methylene diphenyl diisocyanate, MDI) and dicyclohexylmethane diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI).

Specifically, the diisocyanate trimer is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate trimer (Tri-HDI) and isophorone diisocyanate trimer (Tri-IPDI) .

Specifically, the catalyst includes dibutyltin dilaurate, stannous isooctate, zinc acetate or combinations thereof.

In particular, the above-mentioned preparation method of self-repairing thermosetting polyurethane can also use waste polycarbonate as raw material, and convert the carbonate functional group composed of carbon dioxide in its structure into urethane, and re-fix it in the present invention. The self-healing thermosetting polyurethane extends the carbon cycle of carbon dioxide. Therefore, the self-healing thermosetting polyurethane described in the second object of the present invention is a preparation method for self-healing thermosetting polyurethane that is both environmentally friendly and highly atomically efficient.

In summary, the present invention at least includes the following technical features and effects. (1) The self-healing thermosetting polyurethane of the present invention introduces phenol-urethane dynamic covalent bonds into the structure, so that it has excellent mechanical strength, high thermal stability and self-healing characteristics; (2) The present invention The polysiloxane segment in the self-healing thermosetting polyurethane structure has a high degree of segment mobility, thereby further improving its optical properties and self-healing properties; (3) The self-healing thermosetting polyurethane of the present invention system The preparation method is to recover PC through aminolysis to produce a reaction intermediate containing polysiloxane segments, and use it as an alcohol monomer to react and polymerize with a multifunctional isocyanate monomer and a diisocyanate trimer to prepare the above-mentioned The self-healing thermosetting polyurethane does not release carbon dioxide during the manufacturing process, and innovatively converts the carbonate functional groups of the recycled PC structure directly into urethane, which is then re-fixed to the self-healing thermosetting polyurethane of the present invention, extending the The carbon cycle of carbon dioxide.

[Figure 1] is a flow chart of the synthesis steps of the self-healing thermosetting polyurethane of the present invention.

[Figure 2] is the FT-IR spectrum of the S4-Xβ series polyurethane of the present invention.

[Figure 3] is the FT-IR spectrum of the S8-Xβ series polyurethane of the present invention.

[Figure 4] is the FT-IR spectrum of the S20-Xβ series polyurethane of the present invention.

[Figure 5] is a thermogravimetric loss curve of the S4-Xβ series polyurethane of the present invention.

[Figure 6] is a thermogravimetric loss curve of the S8-Xβ series polyurethane of the present invention.

[Figure 7] is a thermogravimetric loss curve of the S20-Xβ series polyurethane of the present invention.

[Figure 8] is the DSC spectrum of the S4-Xβ series polyurethane of the present invention.

[Figure 9] shows the DSC spectrum of the S8-Xβ series polyurethane of the present invention.

[Figure 10] is the DSC spectrum of the S20-Xβ series polyurethane of the present invention.

[Fig. 11] (a) is a tensile test analysis diagram of the S4-Xβ series samples of the present invention; (b) is a tensile test analysis diagram of the S8-Xβ series samples of the present invention.

[Figure 12] is an optical microscope image and schematic diagram of the self-healing behavior of S4-X25 of the present invention.

[Figure 13] is the infrared spectrum of S8-X50 of the present invention, in which (a) is the FT-IR analysis spectrum of S8-X50 at different temperatures, and (b) is the local FT-IR spectrum of S8-X50 in the first heating cycle. IR spectrum, (c) It is the FR-IR spectrum of the second heating cycle of S8-X50, and (d) is the FR-IR spectrum of the third heating cycle of S8-X50.

According to a first embodiment of the present invention, a self-repairable recycling material is disclosed. Specifically, the self-healing recycled material is a self-healing thermosetting polyurethane derived from polycarbonate or waste composite materials.

In a specific embodiment, the structure of the self-repairable recycling material includes a plurality of polysiloxane segments, a plurality of polyurethane segments and a plurality of isocyanurate heterocyclic structures, and the plurality of polysiloxanes The segments connect the plurality of polyurethane segments and the plurality of isocyanurate heterocyclic structures through phenol-urethane bonds, thereby forming a self-healing thermosetting polyurethane.

More specifically, the polysiloxane segment is derived from an amine-based polysiloxane, the polyurethane segment is derived from a diisocyanate, the isocyanurate heterocyclic structure is derived from a diisocyanate trimester, and the phenol - The urethane bond is derived from the aminolysis reaction of the amino polysiloxane and polycarbonate and the condensation reaction of the residue of bisphenol A of polycarbonate and the diisocyanate.

In particular, the phenol-urethane bond of the self-healing thermosetting polyurethane is a dynamic covalent bond of the reversible bond addition type, and the dynamics of the phenol-urethane bond is triggered through cyclic heating or temperature rising procedures. The covalent bond mechanism achieves the technical effect of material self-healing. Accordingly, the self-healing thermosetting polyurethane is a temperature-responsive self-healing cyclic material.

In a specific embodiment, the self-healing thermosetting polyurethane has a chemical structural formula shown in formula (1).

Formula 1).

In a specific embodiment, R ₁ represents the polysiloxane segment and has a structure shown in formula (2).

Formula (2).

In a specific embodiment, n is an integer from 1 to 100 and p is an integer from 2 to 4.

In a specific embodiment, R ₂ is a linear alkyl group with 2 to 16 carbon atoms, a cyclic alkyl group, or a polyethylene glycol group.

In another specific embodiment, R ₂ is a residue of diisocyanate constituting the polyurethane segment. Preferably, the diisocyanate is hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (4,4'-Methylene diphenyl diisocyanate, MDI) or dicyclohexylmethane diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI).

In a specific embodiment, R ₃ is a linear alkyl group or a cyclic alkyl group having 2 to 10 carbon atoms. More specifically, the isocyanurate heterocyclic structure with _R3 is derived from hexamethylene diisocyanate trimer (tri-HDI) or isophorone diisocyanate trimer (tri-IPDI).

In a specific embodiment, R ₄ is a residue of bisphenol-A (bis-A). Preferably, the residue of bisphenol-A (bis-A) is derived from polycarbonate.

In another specific embodiment, R ₄ is a residue of bisphenol-A (bis-A) constituting the phenol-urethane bond.

In a specific embodiment, m is an integer from 0 to 10, and o is an integer from 0 to 10.

In another specific embodiment, the Fourier transform infrared spectrum of the self-healing thermosetting polyurethane includes characteristic peaks at the following positions: 3330±10cm ^-1 , 1720±10cm ^-1 , 1690±10cm ^-1 , 1257±10cm ^-1 , 1076±10cm ^-1 , 1013±10cm ^-1 and 790±10cm ^-1 .

In another specific embodiment, the cross-linking density of the self-healing thermosetting polyurethane ranges from 40 to 800 mol/m ³ .

In another specific embodiment, the thermal cracking temperature of the self-healing thermosetting polyurethane is greater than 200°C.

According to a second embodiment of the present invention, the present invention discloses a preparation method of self-healing thermosetting polyurethane, the steps of which are as follows.

Step 1: Conduct an aminolysis reaction between polycarbonate and monoaminopolysiloxane to generate a phenol-urethane intermediate. The phenol-urethane intermediate has the formula ( 3) The chemical structural formula shown.

Formula (3).

Specifically, p is an integer from 2 to 4, n is an integer from 1 to 100, and m is an integer from 0 to 10.

Step 2: react the phenolic-urethane intermediate with a composition including diisocyanate, diisocyanate trimer and catalyst to prepare a self-healing thermosetting polyurethane. The solid polyurethane has a chemical structural formula represented by formula (1) described in the first embodiment.

In a specific embodiment, the proton nuclear magnetic resonance spectrum of the phenolic-urethane intermediate includes characteristic peaks at the following positions: 0.30±0.20ppm, 0.85±0.20ppm, 1.70±0.20ppm, 3.40±0.2ppm, 7.00±0.20ppm, 7.20±0.2ppm, 7.50±0.2ppm, 7.80±0.2ppm, 9.50±0.2ppm.

In a specific embodiment, the functional group equivalent weight of the aminopolysiloxane is 200-3000g/mol.

In a specific embodiment, the diisocyanate is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenyl Methane diisocyanate (4,4'-Methylene diphenyl diisocyanate, MDI) and dicyclohexylmethane diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI).

In a specific embodiment, the diisocyanate trimer is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate trimer (Tri-HDI) and isophorone diisocyanate trimer (Tri -IPDI).

In a specific embodiment, the catalyst includes dibutyltin dilaurate, stannous isooctate, zinc acetate or a combination thereof.

In a representative embodiment, please refer to the flow chart of the synthesis steps of self-healing thermosetting polyurethane shown in Figure 1. The present invention uses an aminolysis method to convert polycarbonate (PC) into aminopolysiloxane. (Amino polysiloxane) is digested into phenolic-carbamate intermediates (DP-biscarbamates), which are also alcohol monomers, and then the phenolic-carbamates The intermediate product is further polymerized with isocyanate monomer (HDI) and diisocyanate trimer (Tri-HDI) under the action of catalyst dibutyltin dilaurate (DBTDL) to form the cross-linked thermosetting type with self-healing properties Polyurethane (Self-healable crosslinked PU).

The following specific experimental examples serve as detailed explanations of the technical features and effects of the present invention.

Experimental Example 1: Preparation of phenolic-urethane intermediates by recovering polycarbonate by aminolysis method

Use KF-8010 aminopolysiloxane (S4, EW 430/mol) to recover the PC as the phenolic-urethane intermediate through the aminolysis method. This series of phenol-urethane intermediates Referred to as PC-S4 . The detailed process of the reaction is as follows. Dissolve PC (30g, 117.9mmol) in 90°C anisole (150mL) under nitrogen environment. After the solution becomes homogeneous, the temperature is cooled to 75°C and 1.02 times the equivalent of diluted S4 (51.77g, 62.4mmol) and use FT-IR to monitor the reaction. When the carbonate C=O characteristic peak at 1775cm ^-1 disappears; the carbamate C=O characteristic peak at 1715cm ^-1 is generated, it is judged. Digestion is complete. Anisole was removed by distillation under reduced pressure and the product structure was identified by NMR.

FT-IR (KBr, cm ^-1 ): 1775 (C=O, Carbonate), 1715 (C=O, Carbamate); ¹ H-NMR (DMF-d ₇ , δ, ppm): 0.35 (m, 72H) ,0.84(m,4H),1.78-1.87(m,18H),3.37(q,4H),6.95(m,5H),7.25(m,9H),7.44(t,5H),7.79(t,2H ),9.53(s,2H).

Use X-22-161A aminopolysiloxane (S8, EW 800g/mol) to recover PC as the phenolic-urethane intermediate through aminolysis method. This series of phenolic-urethane intermediates The intermediate is referred to as PC-S8 . The detailed process of the reaction is as follows. Dissolve PC (30g, 117.9mmol) in 90°C anisole (150mL) under nitrogen environment. After the solution becomes homogeneous, the temperature is cooled to 75°C and 1.02 times the equivalent of diluted S8 (96.32g, 96.32g, 60.2mmol) was reacted and FT-IR was used to monitor the reaction. When the C=O characteristic peak of carbonate at 1775cm ^-1 disappeared; the C=O characteristic peak of carbamate at 1715cm ^-1 was generated, it was judged that the digestion was complete. Anisole was removed by distillation under reduced pressure and the product structure was identified by NMR.

FT-IR (KBr, cm ^-1 ): 1775 (C=O, Carbonate), 1715 (C=O, Carbamate); ¹ H-NMR (DMF-d ₇ , δ, ppm): 0.33 (m, 96H) ,0.82(m,5H),1.77-1.86(m,24H),3.35(q,4H),6.94(m,8H),7.23(m,13H),7.43(t,5H),7.78(t,2H ),9.51(s,4H).

Use KF-8012 aminopolysiloxane (S20, EW 2200g/mol) to recover PC as the phenolic-urethane intermediate through the aminolysis method. This series of phenol-urethane intermediates Referred to as PC-S20. The detailed process of the reaction is as follows. Dissolve PC (30g, 117.9mmol) in 90°C anisole (150mL) in a nitrogen environment. After the solution becomes homogeneous, the temperature is cooled to 75°C and 1.02 times the equivalent of diluted S20 (264.89g, 60.2mmol) to react and use FT-IR to monitor the reaction. When the carbonate C=O characteristic peak at 1775cm ^-1 disappears; the carbamate C=O characteristic peak at 1715cm ^-1 is generated, it is judged that the digestion is complete. Anisole was removed by distillation under reduced pressure and the product structure was identified by NMR.

FT-IR (KBr, cm ^-1 ): 1775 (C=O, Carbonate), 1715 (C=O, Carbamate); ¹ H-NMR (DMF-d ₇ , δ, ppm): 0.34 (m, 352H) ,0.84(m,5H),1.78-1.87(m,58H),3.37(q,4H),6.94(m,29H),7.26(m,34H),7.43(t,5H), 7.80(t,2H ),9.53(s,14H).

Experimental Example 2: Preparation of self-healing thermosetting polyurethane

At room temperature, isocyanate monomer (HDI) and diisocyanate trimer (Tri) with the same functional group equivalent (Equivalent weight, EW) as the phenolic-urethane intermediate (DP-biscarbamates) prepared above -HDI) and 0.5wt% DBTDL (5wt% in anisole) were mixed evenly at room temperature through mechanical stirring. During the process, the solid content of the reactant was adjusted to 80wt% with anisole, and finally a vacuum pump was used to remove air bubbles. Then the reactants were poured into a Teflon plate and reacted in a 60°C oven for 24 hours to obtain a series of self-healing thermosetting polyurethane films. The sample names are named according to the percentage of the aminopolysiloxane used during the aminolysis and the Tri-HDI added during the polymerization. They are generally called Sα-Xβ. The sample names of each formula are detailed in Table 1. Among them, Sα represents the amino polysiloxane used, α=4 represents the functional group equivalent of the amino polysiloxane is 430g/mol; α=8 represents the functional group equivalent of 800g/mol; α=20 represents the functional group equivalent of 2200g. /mol. Xβ represents the percentage of Tri-HDI in the isocyanate monomer. For example, when β=75, it means that Tri-HDI accounts for 75% of the total isocyanate functional group equivalents, and the remaining 25% is HDI. The crosslink density of each sample is a theoretical value calculated through the Scanlan formula. The calculation formula is as follows, and the preparation method of each sample is detailed in Table 1.

Scanlan formula

為DP-biscarbamates的莫耳數(mol)；

為HDI的莫耳數(mol)；

代表Tri-HDI的莫耳數(mol)；

為DP-biscarbamates的分子量(g/mol)；

為HDI的分子量(g/mol)；

為Tri-HDI的分子量(g/mol)。 υ represents the cross-linking density of the material (mol/m ³ ); ρ is the density of the polymer (g/m ³ );

is the mole number (mol) of DP-biscarbamates;

is the mole number of HDI (mol);

Represents the mole number (mol) of Tri-HDI;

is the molecular weight of DP-biscarbamates (g/mol);

is the molecular weight of HDI (g/mol);

is the molecular weight of Tri-HDI (g/mol).

Table 1

The S4 series FT-IR analysis results are shown in Figure 2. The -NCO stretching vibration signal peak at 2260cm ^-1 has completely disappeared, indicating that the polymerization reaction is complete and no isocyanate monomer remains; 3326cm ^-1 is the OH stretching vibration peak of polyurethane and The signal peak generated by the overlapping of the stretching vibration peak of NH; 1720cm ^-1 is the C=O stretching vibration peak of urethane; and 1690cm ^-1 is the C=O in the heterocyclic structure of isocyanurate (Isocyanurate) Stretch vibration absorption peak. In addition, the FT-IR spectrum results also have characteristic peaks of polysiloxane segments, such as: 1257cm ^-1 is Si-CH ₃ ; 1076 and 1013cm ^-1 are Si-O-Si; 790cm ^-1 is Si-CH ₃ , proving that this experiment successfully prepared polyurethane containing polysiloxane segments.

In the ¹ H-NMR (CDCl ₃ ) spectrum of S4-X0, the signal peaks at 7.20 and 7.02 ppm respectively represent the hydrogens at the ortho and meta positions of the benzene ring in the structure; 6.70 ppm is presumed to be the reaction by-product urea NH; 5.15 ppm is NH peak of urethane; 3.26ppm is -CH ₂ - next to -CO-NH-; 1.66ppm is -CH ₃ in the BPA structure, -CH ₂ - in the HDI carbon chain and the polysiloxane structure The broad spectrum band produced by the overlap of the three -CH ₂ - in it; 0.60ppm is -Si-CH ₂ -; 0.10ppm is Si-CH ₃ . It shows that this experiment successfully polymerized DP-biscarbamates and isocyanate monomers into polyurethane, and successfully introduced polysiloxane segments into the material structure.

The FT-IR spectrum of S8-Xβ series polyurethane is shown in Figure 3. The -NCO tensile vibration signal peak located at 2260cm ^-1 completely disappeared, indicating that the polymerization reaction is complete and no isocyanate monomer remains; 3340cm ^-1 is the OH and OH of polyurethane. The signal peak generated by the overlap of the stretching vibration peak of NH; 1720cm ^-1 is the C=O stretching vibration peak of urethane; and 1690cm ^-1 is the C=O stretching vibration absorption in the isocyanurate heterocyclic structure peak. In addition, 1257cm ^-1 is Si-CH ₃ ; 1076 and 1013cm ^-1 are Si-O-Si; 790cm ^-1 is the characteristic peak of Si-CH ₃ , which preliminarily proves that this experiment successfully prepared polyurethane containing polysiloxane segments. .

In the ¹ H-NMR (CDCl ₃ ) spectrum of S8-X0, the signal peaks at 7.20 and 7.02 ppm respectively represent the hydrogens at the ortho and meta positions of the benzene ring in the structure; 6.70 ppm is presumed to be the reaction by-product urea NH; 5.13 ppm is NH peak of urethane; 3.26ppm is -CH ₂ - next to -CO-NH-; 1.66ppm is -CH ₃ in the BPA structure, -CH ₂ - in the HDI carbon chain and the polysiloxane structure _{The broad spectrum band produced by the overlap of -CH 2 - in} In this experiment, DP-biscarbamates and isocyanate monomers were successfully polymerized into polyurethane, and polysiloxane segments were successfully introduced into the material structure.

The FT-IR spectrum of S20 series polyurethane is shown in Figure 4. The -NCO stretching vibration signal peak located at 2260cm ^-1 has completely disappeared, indicating that the polymerization reaction is complete and no isocyanate monomer remains; 3340cm ^-1 is the OH stretching vibration peak of polyurethane. The signal peak generated by overlapping the stretching vibration peak of NH; 1720cm ^-1 is the C=O stretching vibration peak of urethane; and 1690cm ^-1 is the C= in the heterocyclic structure of isocyanurate (Isocyanurate) O stretching vibration absorption peak. In addition, the FT-IR spectrum results also have characteristic peaks of polysiloxane segments, such as: 1257cm ^-1 is Si-CH ₃ ; 1076 and 1013cm ^-1 are Si-O-Si; 790cm ^-1 is Si-CH ₃ , proving that this experiment successfully prepared polyurethane containing polysiloxane segments.

In the ¹ H-NMR (CDCl ₃ ) spectrum of S20-X0, the signal peaks at 7.20 and 7.02 ppm respectively represent the hydrogens at the ortho and meta positions of the benzene ring in the structure; 6.70 ppm is presumed to be the reaction by-product urea NH; 5.10 ppm is NH peak of urethane; 3.26ppm is -CH ₂ - next to -CO-NH-; 1.65ppm is -CH ₃ in the BPA structure, -CH ₂ - in the HDI carbon chain and the polysiloxane structure The broad spectrum band produced by the overlap of _{-CH 2 - in} the The chemical shifts show that these three series of samples have quite similar chemical structures, and also indicate that this experiment successfully polymerized DP-biscarbamates and isocyanate monomers into polyurethane containing polysiloxane segments.

In order to determine the degree of cross-linking of the sample, this experiment selected the S8-Xβ series polyurethane with a relatively low cross-linking density for solubility analysis. The sample was cut into test pieces weighing about 50 mg and soaked in different solvents at room temperature for 24 hours. The solubility analysis results are shown in Table 2, which shows that the sample S8-X0 without Tri-HDI was completely dissolved after 24 hours of solvent immersion, proving that S8-X0 is a thermoplastic polyurethane with a linear structure.

Table II

Thermal properties of self-healing thermosetting polyurethane were measured through TGA, such as: decomposition temperature (T _d5 ) and coke residual rate (Char yield). T _d5 is defined as the temperature at which the sample loses 5wt% of its original weight; the coke residual rate is defined as the proportion of the sample's residual weight at 700°C. The TGA measurement was performed in a nitrogen environment with a heating rate of 10°C/min. Figure 5 is the thermogravimetric loss curve of the S4-Xβ series polyurethane. It shows that the T _d5 of this series of polyurethane is between 200-240°C. Among them, S4-X100 has the highest coke residual rate (7%). The results show that as the samples As the connection density increases, the T _d5 and coke residual rate of the sample will also increase. Figure 6 shows the thermogravimetric loss curve of the S8-Xβ series samples. The T _d5 of this series of samples is between 215-240°C, and T _d5 is also positively correlated with the cross-linking density. S8-X100 in this series also has the highest The coke residual rate (4%) shows similar results to the S4-Xβ series samples. The thermogravimetric loss curve in Figure 7 is for S20-Xβ series polyurethane samples. T _d5 is between 230-240°C and the coke residual rate is about 2%. However, the relationship between the thermal stability and cross-linking density of this series of samples is There is no obvious trend. The data related to thermal properties of all samples are summarized in Table 3. The results show that S4-Xβ and S8-Xβ series polyurethanes can improve thermal stability by increasing cross-linking density. In addition, the T _d5 of all samples is higher than 200°C, indicating that the thermosetting polyurethane in this study has good thermal stability. .

The glass transition temperature (T _g ) of the material is obtained through DSC, and the internal state of the material is analyzed. For polyurethane, polymer segments can be divided into soft segments and hard segments according to their properties. For the purposes of the present invention, polysiloxane segments are soft segments due to the large free volume of Si atoms and the asymmetry of the structure. segment; isocyanate monomers HDI and Tri-HDI are hard segments due to their regular structure. Figure 8 shows the DSC measurement results of S4-Xβ series polyurethane. From the results, it can be found that this series of samples all have two _Tg , indicating phase separation behavior of forming soft segment region and hard segment region, and the cross-linking density of the sample is 0 mol. /m ³ S4-X0 polyurethane has a higher T _{g, SS} (-3℃) and a lower T _{g, HS} (61℃) in this series; as the cross-linking density increases, the T _g of the sample _{, SS} decreases, while T _{g, HS} has an upward trend; the T _{g, SS} and T _{g, HS} of S4-X100 with a cross-linking density of 567 mol/m ³ are -26°C and 73°C respectively. Figure 9 shows the DSC measurement results of S8-Xβ series polyurethane. It also shows that as the cross-linking density of the sample increases, the T _{g, SS} and T _{g, HS} of the soft and hard segments show a decreasing and increasing trend respectively. T _{g, SS} dropped from -27°C for S8-X0 (crosslinking density = 0mol/m ³ ) to -46°C for S8-X100 (crosslinking density = 399mol/m ³ ). Figure 10 is the DSC measurement result of S20-Xβ series polyurethane. It can be observed that there is no obvious trend in the relationship between T _{g, SS} and cross-linking density of the sample. It is speculated that it may be because the polysiloxane used is of high The molecular weight (MW=4400g/mol) makes the cross-linking density of this system lower than that of the other two systems. In addition, all samples have no obvious crystallization peaks and T _m , indicating that the polyurethane in this experiment does not have an obvious crystallization zone. The temperature range of T _{g and HS} increases from 61°C of Sα-X0 without cross-linking to the system after cross-linking. To the T _g,HS above 70°C, it shows that the T _g of the hard segment of the sample can be significantly improved by increasing the cross-linking density of the sample. In summary, the DSC results show that as the functional group equivalent of the polysiloxane segment within the polyurethane increases, at the same Tri-HDI addition ratio, the product tends to have a lower T _g,SS (of the soft segment). _Tg from low temperature to high temperature are S20-Xβ, S8-Xβ, S4-Xβ), showing that the chemical configuration of the soft segment of samples with lower siloxane functional group equivalents is more susceptible to structural restrictions. Therefore, it has a higher T _g,SS .

The present invention evaluates the mechanical properties of the samples through tensile tests, which are summarized in Table 3. Among them, the S20-Xβ series samples cannot be tested because they are too soft, so subsequent exploration is not carried out. Discuss. Figure 11(a) shows the tensile test analysis results of S4-Xβ series samples. The tensile strength of this series of samples is positively related to the hard segment contents (HS) and cross-linking density. Among them, S4-X100 has It has the highest HS and cross-link density among all samples, with a tensile strength as high as 14.49MPa and an elongation at break of 479%; while S4-X0 has the lowest HS and cross-link density in this series, with a tensile strength of only 0.09MPa. , but the elongation at break is as high as 1495%. The results of the S8-Xβ series samples are shown in Figure 11(b). The HS of this series of samples is lower than that of S4-Xβ, so the tensile strength of the material is lower. Although S8-X100 has the highest tensile strength among the S8-Xβ series samples, HS and cross-link density, but the tensile strength of this sample is only 3.99MPa, and the elongation at break is 642%, showing that the tensile strength of this series of samples is also positively correlated with HS and cross-link density.

Table 3

This study used the PC digestion process to introduce polysiloxane segments to prepare polyurethane containing polysiloxane segments to improve the optical properties of the overall material. The optical properties of the sample were quantified through UV-Vis. The results showed that S4-Xβ had all The transmittance of the samples at the 550nm wavelength remains above 70%, and the visible light transmittance of both series of samples is negatively correlated with the cross-linking density.

Experimental Example 3: Analysis of Self-Repair Behavior

This experiment uses an optical microscope (Optical Microscope, OM) to evaluate the repair behavior of self-healing thermosetting polyurethane after surface damage. The detailed experimental process is as follows. First, a scalpel is used to scratch the sample, and then the dynamic bonding mechanism of the phenol-urethane covalent bond of the sample is triggered by heating in a circulating oven, thereby repairing the sample. This experiment selected S4-X25 (cross-linking density: 156.36 mol/m ³ ) as a representative test sample. The results show that after scratching, the material only needs to be placed in a 120°C oven for 10 minutes to completely repair the damaged surface. As shown in Figure 12, its self-healing speed is fast and the process is simple. Analysis of the repair properties of other samples shows that sample S4-X75 with a high cross-linking density (439.03 mol/m ³ ) also has a very good self-healing ability. It can also repair the damaged surface in 10 minutes at 120°C.

Experimental Example 4: Variable Temperature Infrared Spectroscopy Analysis

This study uses variable temperature FT-IR to compare the spectrum changes of sample S8-X50 at different temperatures to verify the self-healing mechanism of the material. The temperature-variable FT-IR spectrum shows that the sample has a tensile vibration absorption peak of -NCO at 2260 cm ^-1 at 80°C, and the absorption intensity of this characteristic peak increases as the temperature increases, indicating that the sample has more isocyanates in a high temperature environment. The generation of functional groups preliminarily proves that the phenol-urethane covalent bond can be broken at high temperatures and the reaction tends to break the bond to generate isocyanate functional groups as the temperature increases, as shown in Figure 13; In addition, this experiment also revealed that The variable temperature FT-IR test of heating and cooling cycles further verified the reversible nature of the phenol-urethane dynamic bond. Figure 13(b) shows the local FT-IR spectrum of sample S8-X50 in the first heating cycle, showing that it is located at 2260cm The absorption intensity of the -NCO stretching vibration absorption peak of ^-1 increases as the temperature increases, and the -NCO absorption peak obviously disappears after cooling; Figure 13(c) is the FR-IR spectrum of the second heating cycle, It also shows the same results as the first heating cycle. The intensity of the -NCO stretching vibration absorption peak located at 2260 cm ^-1 increases as the temperature increases and disappears after cooling; the FT-IR spectrum of the third heating cycle It also shows the same trend as the first two heating cycles, showing that -NCO functional groups are still generated, as shown in Figure 13(d).

Temperature-changing FT-IR analysis results prove that the phenol-urethane bond will break at high temperatures to generate -NCO and -OH functional groups, indicating that this dynamic covalent bonding belongs to the DCC reaction of the reversible bond addition category. Finally, the FT-IR spectrum of the temperature cycle also showed that the reversible reaction could be cycled at least three times. It is proved that the dynamic bonding is reversible through multiple cycles.

The present invention successfully recovers PC as a phenol-urethane intermediate containing polysiloxane segments through the aminolysis method, and polymerizes it as an alcohol monomer with a multifunctional isocyanate monomer to prepare a series of self-contained Restorative thermoset polyurethane. By introducing phenol-urethane dynamic covalent bonds into the structure through molecular design, the finished product not only has the excellent mechanical strength and thermal stability of thermosetting plastics, but also has the characteristics of easy recycling of thermoplastic plastics; and the polymer structure The high degree of segment mobility of the polysiloxane chain segment also further improves the optical properties and self-healing properties of polyurethane. Tensile tests and optical property analysis show that the cross-linking density and soft-hard segment ratio of the sample have a significant impact on the mechanical properties, optical properties, and self-healing properties of the material. The optimal tensile strength of the sample is as high as 14.5MPa, and the fracture The elongation is greater than 1200% and has excellent visible light penetration (87%); and the self-healing experimental results show that S4-X25 can completely repair surface damage in only 10 minutes under oven heating at 120°C, and can be repaired repeatedly. Three times, and the reversibility and reaction mechanism of the phenol-urethane bond were verified through temperature-variable Fourier transform infrared spectroscopy, which showed that the phenol-urethane bond will react reversibly at 80°C.

In summary, the present invention recovers PC through aminolysis to produce a phenol-urethane intermediate containing polysiloxane segments, and polymerizes it as an alcohol monomer with a multifunctional isocyanate monomer to prepare a phenolic-urethane intermediate. A series of thermosetting polyurethanes with self-healing properties. By introducing phenol-urethane dynamic covalent bonds into the structure through molecular design, the finished product has excellent mechanical strength, thermal stability and easy recycling characteristics; and the high degree of segment mobility of the polysiloxane segments in the structure , also further improves the optical properties and self-healing properties of the self-healing thermosetting polyurethane of the present invention. Tensile tests and optical property analysis show that the cross-linking density and soft-to-hard segment ratio of the sample have a significant impact on the mechanical properties, optical properties, and self-healing properties of the material. The optimal tensile strength of the sample Up to 14.5MPa, elongation at break greater than 1200% and excellent visible light penetration (87%); and self-healing experimental results show that S4-X25 can completely repair surface damage in only 10 minutes under oven heating at 120°C , and can be repaired three times repeatedly, and the reversibility and reaction mechanism of the phenol-urethane bond are verified through temperature-variable Fourier transform infrared spectroscopy, which shows that the phenol-urethane bond will react reversibly at 80°C.

In summary, this study successfully recovered PC into phenol-urethane intermediates through chemical recycling methods, and prepared a recyclable self-healing thermosetting polyurethane, giving the recycled products new uses, and at the same time Retains the excellent properties of thermoset and thermoplastic plastics. The above are all technical effects of the present invention.

Although the present invention has been described above with specific experimental examples, this does not limit the scope of the present invention. As long as it does not deviate from the gist of the present invention, those skilled in the art will understand that various modifications or changes can be made without departing from the intention and scope of the present invention. In addition, the abstract section and title are only used to assist in searching patent documents and are not intended to limit the scope of the invention.

Claims (10)

A self-repairable recycling material whose structure includes a plurality of polysiloxane segments, a plurality of polyurethane segments and a plurality of isocyanurate heterocyclic structures. The plurality of polysiloxane segments are formed by phenol-amine The polyurethane linkage connects the plurality of polyurethane segments and the plurality of isocyanurate heterocyclic structures, thereby forming a self-healing thermosetting polyurethane. As for the self-healing recycling material described in claim 1, the self-healing thermosetting polyurethane has a chemical structural formula as shown in formula (1):

Wherein, R ₁ represents the polysiloxane segment and has the structure shown in formula (2);

n is an integer from 1 to 100 and p is an integer from 2 to 4; R ₂ is a linear alkyl group, cyclic alkyl group, or polyethylene glycol group having 2 to 16 carbon atoms; R ₃ is a linear alkyl group or cyclic alkyl group with 2 to 10 carbon atoms; R ₄ is a residue of bisphenol-A (bis-A); and m is an integer from 0 to 10, and o is an integer from 0 to 10. For the self-healing cyclic material described in claim 1, the Fourier transform infrared spectrum of the self-healing thermosetting polyurethane includes characteristic peaks at the following positions: 3330±10cm ^-1 , 1720±10cm ^-1 , 1690±10cm ^-1 , 1257±10cm ^-1 , 1076±10cm ^-1 , 1013±10cm ^-1 and 790±10cm ^-1 . As for the self-healing recycling material described in claim 1, the thermal cracking temperature of the self-healing thermosetting polyurethane is greater than 200°C. A preparation method of self-healing thermosetting polyurethane, including the following steps: Step 1: Conduct an aminolysis reaction between polycarbonate and an aminopolysiloxane to generate a phenol-urethane intermediate. The phenol-urethane intermediate has the formula ( 3) The chemical structural formula shown:

p is an integer from 2 to 4, n is an integer from 1 to 100, and m is an integer from 0 to 10; and Step 2: react the phenolic-urethane intermediate with a composition including diisocyanate, diisocyanate trimer and catalyst to prepare a self-healing thermosetting polyurethane. The solid polyurethane has a chemical structural formula represented by formula (1) described in Claim 2. As for the preparation method of self-healing thermosetting polyurethane described in claim 5, the functional group equivalent weight of the amino polysiloxane is 200-3000g/mol. As for the preparation method of self-healing thermosetting polyurethane described in claim 5, the diisocyanate is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate (HDI), isophorone diisocyanate Isocyanate (isophorone diisocyanate, IPDI), diphenylmethane diisocyanate (4,4'-Methylene diphenyl diisocyanate, MDI) and dicyclohexylmethane diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI). As claimed in claim 5, the preparation method of self-healing thermosetting polyurethane, the diisocyanate trimer is selected from one of the following groups or a combination thereof: hexamethylene diisocyanate trimer and isophorone diisocyanate. Isocyanate trimer. As for the preparation method of self-healing thermosetting polyurethane described in claim 5, the catalyst includes dibutyltin dilaurate, stannous isooctate, zinc acetate or a combination thereof. As for the preparation method of self-healing thermosetting polyurethane as described in claim 5, the proton nuclear magnetic resonance spectrum of the phenolic-urethane intermediate contains characteristic peaks at the following positions: 0.30±0.20ppm, 0.85±0.20ppm ,1.70±0.20ppm,3.40±0.2ppm,7.00±0.20ppm,7.20±0.2ppm,7.50±0.2ppm,7.80±0.2ppm,9.50±0.2ppm.

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