METHOD FOR RECYCLING AND REUSING POLYURETHANE FOAM

Abstract

The invention discloses a method for recycling and reusing polyurethane foam. The method includes: (1) The functionalized oligomers are obtained by adding solvent and catalyst to the polyurethane foam. (2) The functionalized oligomers are chemically modified, and the photosensitive group is introduced through the functional group reaction. The diluent, photoinitiator, and light absorber, etc. are introduced into the obtained oligomers to prepare photocurable resin. It can be used for photocurable coatings or 3D printing. This method has a fast reaction time, easy recovery of solvent and catalyst, higher value-added recycled product, good economic benefits, and social value.

Claims

1. A method for recycling and reusing polyurethane foam comprising the following steps: (1) obtaining functionalized oligomers by adding a solvent and a catalyst to the polyurethane foam; and (2) chemically modifying the functionalized oligomers, introducing a photosensitive group through the functional group reaction, and introducing a diluent, a photoinitiator, and a light absorber into the obtained oligomers to prepare photocurable resin.

2. The method of claim 1, wherein the solvent comprises one or more of formamide, dimethylformamide, dimethylacetamide, dimethylsulfoxide, trifluoroacetic acid, acetonitrile, hexamethylphosphoramide, alcohol, pyridine, furan, chloroform, toluene, tetramethylethylenediamine, N-methylpyrrolidone; and the catalyst comprises one or more of guanidines, amidines, tins, and amines.

3. The method of claim 2, wherein the guanidines comprise tetramethylguanidine, 1,5,7-triazidebicyclo(4.4.0)dec-5-ene, 2-tert-butyl-1,1,3,3-tetramethylguanidi, 7-methyl-1,5,7-triazabis[4.4.0]dec-5-ene; the amidines include 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene; the tins include dibutyltin dilaurate, stannous octoate; and the amines include triethylamine, bisdimethylaminoethyl ether, etc.

4. The method of claim 1, wherein the functional groups of the oligomers in step (1) comprises one or more of hydroxyl groups, amino groups, aldehyde groups, amidine bonds, and isocyanate groups.

5. The method of claim 1, wherein the content of the solvent is 0.1-50 times of the foam; the content of the catalyst is 0.01-50 wt % of the foam; the reaction temperature is 25-180° C. and the reaction time is 1 min-10 hours.

6. The method of claim 1, wherein the solvent and catalyst in step (1) are separated and recycled.

7. The method of claim 1, wherein the photosensitive group in step (2) comprises acrylate/methacrylate, vinyl, thiol, allyl, and epoxy group.

8. The method of claim 1, wherein in step (2), the monomer diluent is monofunctional monomers and low-viscosity multifunctional crosslinking agents; the photoinitiator is a visible light initiator or an ultraviolet light initiator; the light absorber is a dye.

9. The method of claim 1, wherein the content of recycled polyurethane foam accounts for 50% to 90% of the photocurable resin.

10. The method of claim 1, wherein the photocurable resin is used as photocurable coatings or 3D printing resins.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a schematic diagram of recycling in Example 1.

[0034] FIG. 2 shows the product obtained by 3D printing in Example 1.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will be further described in detail with the examples below. It should be noted that the examples described below are intended to help understand the details of this invention. And the method should not be limited to these examples.

Example 1 (Use TBD/DMF to Recycle High-Resilience 35-Density Polyurethane Foam for 3D Printing)

Raw Material:

[0036] High resilience 35-density polyurethane foam, Yongyi Company; N,N-Dimethylformamide (DMF), Sinopharm; Dimethyl Sulfoxide (DMSO), Sinopharm; 1,5,7-Triazide Bicyclic (4.4.0) Dec-5-ene (TBD), TCI; Isocyanate Ethyl Acrylate, TCI; Dibutyltin Dilaurate, TCI; 2-Phenoxyethyl Acrylate, TCI; Photoinitiator 819, TCI.

Recycling of Polyurethane:

[0037] 5 g of polyurethane foam was weighed and pulverized with a pulverizer. 0.15 g of TBD and 50 ml of DMF were added to the polyurethane foam. After mixing uniformly, thermal treatment was conducted at 120° C. for 5 minutes to break the cross-linked network and obtain a uniform transparent solution. The DMF was recycled after vacuum distilling at 120° C. for 10 minutes. The oligomers terminated with amine groups and hydroxyl groups were obtained. The content of functional groups was determined by NMR (Nuclear Magnetic Resonance) spectroscopy and titration.

Preparation of Photocurable Resin:

[0038] 3 times of DMSO was added to the above product to obtain a yellow solution. After Adding equimolar isocyanate ethyl acrylate, the reaction was conducted at room temperature for 4 hours and a followed 2 hours after the addition of dibutyltin dilaurate catalyst. The solvent DMSO was removed by rotary evaporation. Subsequently, the product was compounded with 2-phenoxyethyl acrylate at a mass ratio of 4:1, and 3 wt % of photoinitiator 819 was added to obtain a photocurable resin.

3D Printing and Characterization:

[0039] DLP (Digital Light Processing) was used as the light source to print out a sample that meets the ASTM (American Society for Testing and Materials) D412 standard and tested the mechanical properties in a universal testing machine. The material's modulus was 10 MPa, the strain at break was 50%, and the breaking strength was 10 MPa.

Example 2 (Utilize DBU/DMF to Recycle High-Resilience 35-Density Polyurethane Foam for 3D Printing)

Raw Material:

[0040] High resilience 35 density polyurethane foam, Yongyi Company; N,N-Dimethylformamide (DMF), Sinopharm; 1,8-Diazabicycloundec-7-ene (DBU), TCI; Imidazole, Sinopharm; Epoxy resin, Baling Petrochemical; Isobornyl acrylate, TCI; Photoinitiator 819, TCI.

Recycling of Polyurethane:

[0041] 5 g of polyurethane foam was weighed and pulverized with a pulverizer. 1.5 g of DBU and 50 ml of DMF were added to the polyurethane foam. After mixing uniformly, thermal treatment was conducted at 120° C. for 10 minutes to break the cross-linked network and obtain a uniform transparent solution. The DMF and DBU were recycled after vacuum distilling at 120° C. for 10 minutes. The oligomers terminated with amine groups and hydroxyl groups were obtained. The content of functional groups was determined by NMR spectroscopy and titration.

Preparation of Photocurable Resin:

[0042] 3 times of DMF was added to the above product to obtain a yellow solution. After adding two molar equivalents of epoxy resin and 0.5 wt % of imidazole catalyst, the reaction was conducted at 160° C. for 4 hours. The solvent DMF was removed by rotary evaporation. Subsequently, the product was compounded with isobornyl acrylate at a mass ratio of 6:1, and 3 wt % of photoinitiator 819 was added to obtain a photocurable resin.

3D Printing and Characterization:

[0043] SLA (Stereolithography Appearance) was used as the light source to print out a sample that meets the ASTM D412 standard and tested the mechanical properties in a universal testing machine. The material's modulus was 500 MPa, the strain at break was 40%, and the breaking strength was 30 MPa.

Example 3 (Use DBTDL/DMF to Recycle High-Resilience 35-Density Polyurethane Foam for Coating)

Raw Material:

[0044] High resilience 35-density polyurethane foam, Yongyi Company; N,N-Dimethylformamide (DMF), Sinopharm; Dibutyltin Dilaurate (DBTDL), TCI; Acrylic Isocyanate, TCI; Benzoin Dimethyl Ether (DMPA), TCI; Eosin Y, Anaiji company.

Recycling of Polyurethane:

[0045] 5 g of polyurethane foam was weighed and pulverized with a pulverizer. 0.1 g of DBTDL and 50 ml of DMF were added to the polyurethane foam. After mixing uniformly, thermal treatment was conducted at 150° C. for 1 hour to break the cross-linked network and obtain a uniform transparent solution. The DMF was recycled after vacuum distilling at 120° C. for 10 minutes. The oligomers terminated with amine groups and hydroxyl groups were obtained. The content of functional groups was determined by NMR spectroscopy and titration.

Preparation of Photocurable Resin:

[0046] 3 times of DMF was added to the above product to obtain a yellow solution. After Adding two molar equivalents of acrylic isocyanate, the reaction was conducted at 80° C. for 2 hours. The solvent DMF was removed by rotary evaporation. Subsequently, 1% of DMPA and Eosin Y was added to obtain a red photocurable resin.

Photocurable Coating:

[0047] The photocurable resin was spin-coated on the glass substrate, and a 200 nm ultraviolet light source was used for light polymerization to obtain a polymer coating.

Example 4 (Use TMG/DMF to Recycle Ordinary 35-Density Polyurethane Foam for Coating)

Raw Material:

[0048] Ordinary 35-density polyurethane foam, Yongyi Company; N,N-Dimethylformamide (DMF), Sinopharm; Tetramethylguanidine (TMG), TCI; Acrylic Isocyanate, TCI; Photoinitiator 819, TCI.

Recycling of Polyurethane:

[0049] 5 g of polyurethane foam was weighed and pulverized with a pulverizer. 5 g of TMG and 50 ml of DMF were added to the polyurethane foam. After mixing uniformly, thermal treatment was conducted at 120° C. for 20 minutes to break the cross-linked network and obtain a uniform transparent solution. The DMF and TMG were recycled after vacuum distilling at 120° C. for 10 minutes. The oligomers terminated with amine groups and hydroxyl groups were obtained. The content of functional groups was determined by NMR spectroscopy and titration.

Preparation of Photocurable Resin:

[0050] 3 times of DMF was added to the above product to obtain a yellow solution. After Adding two molar equivalents of acrylic isocyanate, the reaction was conducted at 80° C. for 2 hours. The solvent DMF was removed by rotary evaporation. Subsequently, 1% of photoinitiator 819 was added to obtain a photocurable resin.

Photocurable Coating:

[0051] The photocurable resin was spin-coated on the glass substrate, and the visible light source was used for light polymerization to obtain a polymer coating.

Example 5 (Use TBD/DMF to Recycle Shaped Cotton 60-Density Polyurethane Foam for 3D Printing)

Raw Material:

[0052] Shaped cotton 60-density polyurethane foam, Yongyi Company; N,N-Dimethylformamide (DMF), Sinopharm; 1,5,7-Triazidebicyclo(4.4.0)dec-5-ene (TBD), TCI; Acrylic Isocyanate, TCI; Photoinitiator 819, TCI.

Recycling of Polyurethane:

[0053] 5 g of polyurethane foam was weighed and pulverized with a pulverizer. 0.15 g of TBD and 50 ml of DMF were added to the polyurethane foam. After mixing uniformly, thermal treatment was conducted at 120° C. for 15 minutes to break the cross-linked network and obtain a uniform transparent solution. The DMF was recycled after vacuum distilling at 120° C. for 10 minutes. The oligomers terminated with amine groups and hydroxyl groups were obtained. The content of functional groups was determined by NMR spectroscopy and titration.

Preparation of Photocurable Resin:

[0054] Two molar equivalents of acrylic isocyanate were added to the above product and reacted at 80° C. for 2 hours. Subsequently, 1% photoinitiator 819 was added to obtain a high-viscosity photocurable resin.

3D Printing and Characterization:

[0055] Inject printing was used to extrude a sample that meets the ASTM D412 standard and was cured by visible light. The mechanical properties were tested in a universal testing machine. The material's modulus was 50 MPa, the strain at break was 200%, and the breaking strength was 50 MPa.