DEGRADABLE POLYURETHANES AND COMPOSITES THEREOF

Abstract

Among others, the present invention provides isocyanate resin compositions which include an isocyanate compound containing two or more isocyanate functional groups; a chain extender comprising a degradable diamine and optionally a dihydric alcohol, a polyether diol, a polyester diol, a diamine, a dimercaptan, or a bisphenol; and a cross-linker comprising a degradable polyamine and optionally a trifunctional, tetrafunctional or polyfunctional polyhydric alcohol, polyether polyol, polyester polyol, polyamine, polymercaptan, or polyphenol.

Claims

1. An isocyanate resin composition comprising: an isocyanate compound containing two or more isocyanate functional groups; and a chain extender comprising a degradable diamine and optionally a dihydric alcohol, a polyether diol, a polyester diol, a diamine, a dimercaptan, or a bisphenol; wherein the degradable diamine is of the structure of ##STR00020## in which R is ##STR00021## each of Ra and Rb is independently hydrogen, alkylene, cycloalkylene, heterocyclic alkylene, arylene and heteroarylene; or Ra and Rb, together with the carbon atom to which they are bonded, form a 3-7 membered ring optionally containing 1-5 heteroatoms each of which is independently S, O, or N; and each of R.sub.1 and R.sub.2 is independently alkylene, cycloalkylene, heterocyclic alkylene, arylene, heteroarylene, or aralkylene; and a cross-linker comprising a degradable polyamine and optionally a trifunctional, tetrafunctional or polyfunctional polyhydric alcohol, polyether polyol, polyester polyol, polyamine, polymercaptan, or polyphenol; and the degradable polyamine is of Formula 1, ##STR00022## wherein each of m, n, and P, independently, is an integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; the sum of m, n and p is 3 or greater; R, R.sub.1, and R.sub.2 are the same as defined above for the degradable diamine in the chain extender; each of R.sub.3, R.sub.4, R.sub.5 and R.sub.6, independently, is alkylene, cycloalkylene, heterocyclic alkylene, arylene, heteroarylene, or aralkylene.

2. The isocyanate resin composition of claim 1, wherein the isocyanate compound comprises m-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate, tetramethylene diisocyanate, cyclohexane 1,4-diisocyanate, hexahydrotoluene diisocyanate, 1,5-naphthalene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 2,2-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 4,4-biphenylene diisocyanate, 3,3-dimethoxy-4,4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, 4,4,4-triphenylmethane triisocyanate, toluene 2,4,6-triisocyanate, 4,4-dimethyldiphenylmethane 2,2-5,5-tetraisocyanate, polymethylene polyphenylene polyisocyanate, or an isomer thereof.

3. The isocyanate resin composition of claim 1, wherein the degradable diamine in the chain extender comprises: ##STR00023## ##STR00024## ##STR00025## ##STR00026##

4. The isocyanate resin composition of claim 1, wherein the degradable polyamine in the cross-linker comprises: ##STR00027## ##STR00028##

5. A degradable three-dimensional reticulated polyurethane matrix, wherein the polyurethane matrix is obtained by curing an isocyanate resin composition of claim 1 and possesses cross-linking points that are derived from reacting the cross-linker comprising a degradable polyamine and an optional trifunctional, tetrafunctional or polyfunctional polyhydric alcohol, polyether polyol, polyester polyol, polyamine, polymercaptan, or polyphenol, with a polyisocyanate.

6. The polyurethane matrix of claim 5, wherein, between each two cross-linking points, there is at least one cleavable moiety of structure ##STR00029## each of Ra and Rb is independently hydrogen, alkylene, cycloalkylene, heterocyclic alkylene, arylene and heteroarylene; or Ra and Rb, together with the carbon atom to which they are bonded, form a 3-7 membered ring optionally containing 1-4 heteroatoms each of which is independently S, O, or N.

7. The polyurethane matrix of claim 5, wherein the curing process is conducted at a temperature in the range from ambient temperature to 250 C.

8. The polyurethane matrix of claim 5, wherein the curing process is conducted under a pressure in the range from ambient pressure to 10 atmospheric pressure.

9. The polyurethane matrix of claim 5, wherein the curing process is conducted for a time period ranging from 10 second to 1 month.

10. A reinforced composite material comprising: a degradable three-dimensional reticulated polyurethane matrix of claim 5; a reinforcing material comprising carbon nanotubes, boron nitride nanotubes, carbon black, metal nanoparticles, metal oxide nanoparticles, organic nanoparticles, iron oxide, glass fiber, carbon fiber, natural fiber, chemical fiber, or fabrics made therefrom; and an auxiliary material comprising an accelerator, a diluent, a plasticizer, a toughening agent, an adhesion promoter, a thickening agent, a coupling agent, a defoamer, a flatting agent, an ultraviolet absorber, an antioxidant, an optical brightener, a fluorescent agent, a gloss additive, a pigment, or a filler.

11. The reinforced composite material of claim 10, wherein the reinforced composite material is prepared by a process comprising wet lay-up, infusion, vacuum assisted infusion, RTM (resin transfer molding), HPRTM (high pressure resin transfer molding), filament winding, pultrusion, compression molding, or prepreg.

12. A method for degrading and recycling a degradable three-dimensional reticulated polyurethane matrix of claim 5, comprising the steps of: (1) immersing the degradable three-dimensional reticulated polyurethane matrix of claim 5 or the reinforced composite material of claim 10 in a degradation system comprising an acid and optionally a peroxide or peroxyacid with or without a solvent for 1600 hours to give a degradation mixture, wherein the degradation system is maintained at a temperature in the range of 15400 C. with agitating and the mass concentration of the acid in the degradation system is 0.01100%; (2) recovering the reinforcing material, liberated from the reinforced composite material of claim 10 from the degradation mixture after the degradable three-dimensional reticulated polyurethane polymer matrix is fully degraded in step (1) by separating, washing and drying; (3) neutralizing the degradation mixture from step (1) or (2) by using an alkali solution to above pH 6 while maintaining the temperature within the range of 0200 C. during neutralization, wherein the mass concentration of alkali solution is 0.0199%; and (4) recovering the precipitates formed during neutralization in step (3) by separating, washing and drying.

13. The method of claim 12, wherein the acid comprises hydrochloric acid, hydrobromic acid, hydrofluoric acid, acetic acid, trifluoroacetic acid, lactic acid, formic acid, propionic acid, citric acid, methanesulfonic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, sulfurous acid, phosphoric acid, perchloric acid, benzoic acid, salicylic acid, or phthalic acid; the peroxide or peroxyacid comprises hydrogen peroxide, performic acid, peroxyacetic acid, peroxypropionic acid, 2-butanone peroxide, bis(t-butyl)peroxide, perbenzoic acid, sodium peroxide, potassium peroxide, calcium peroxide, magnesium peroxide, or potassium persulfate; the solvent, if present, comprises methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, benzyl alcohol, phenethyl alcohol, p-hydroxymethyl benzene, m-hydroxymethyl benzene, o-hydroxy benzene, p-hydroxyethyl benzene, m-hydroxyethyl benzene, o-hydroxyethyl benzene, water, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, methyl tetrahydrofuran, glycerol, or dioxane; the alkali comprises lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, or ammonia; and the solvent of the alkali solution comprises methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, benzyl alcohol, phenethyl alcohol, p-hydroxymethyl benzene, m-hydroxymethyl benzene, o-hydroxy benzene, p-hydroxyethyl benzene, m-hydroxyethyl benzene, o-hydroxyethyl benzene, water, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, methyl tetrahydrofuran, glycerol, dioxane, or combinations thereof.

14. The method of claim 12, wherein in step (1), the degradation system is maintained at a temperature in the range of 80150 C., the polyurethane polymer matrix or the reinforced composite material is immersed in the heated degradation system for 116 hours, and the mass concentration of the acid in the solvent is preferably 199%; and in step (2), the temperature is within the range of 550 C., the final pH value after neutralization is in the range of 712, and the mass concentration of alkali solution is in the range of 530%.

15. A method for degrading and recycling a reinforced composite material of claim 10, comprising the steps of: (1) immersing the degradable three-dimensional reticulated polyurethane matrix of claim 5 or the reinforced composite material of claim 10 in a degradation system comprising an acid and optionally a peroxide or peroxyacid with or without a solvent for 1600 hours to give a degradation mixture, wherein the degradation system is maintained at a temperature in the range of 15400 C. with agitating and the mass concentration of the acid in the degradation system is 0.01100%; (2) recovering the reinforcing material, liberated from the reinforced composite material of claim 10 from the degradation mixture after the degradable three-dimensional reticulated polyurethane polymer matrix is fully degraded in step (1) by separating, washing and drying; (3) neutralizing the degradation mixture from step (1) or (2) by using an alkali solution to above pH 6 while maintaining the temperature within the range of 0200 C. during neutralization, wherein the mass concentration of alkali solution is 0.0199%; and (4) recovering the precipitates formed during neutralization in step (3) by separating, washing and drying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0061] The following examples are provided for illustration of the present invention only, and not intended to be limiting in any aspect.

EXAMPLE 1

Synthesis of Cross-Linker I

[0062] 296 g aqueous ammonia and 32 g ammonium chloride were added into the reaction flask and stirred to dissolve, then 50 g bis (2-chloroethoxy) methane was added at room temperature. Then heated up to 80 C., the reaction was stirred for 6 hours, detecting the end of the reaction by TLC. After the reaction, most of solution was concentrated under reduced pressure, the residue was transferred to a reaction flask, adjusted pH with 30% sodium hydroxide solution to pH10 at less than 25 C., extracted the aqueous phase by 300 ml mixture of chloroform and ethanol (volume ratio 3: 1) for 3 times, the organic phases was combined and dried by anhydrous sodium sulfate, filtered, and the filter cake was washed with a small amount of solvent for 1 time. The filtrate was concentrated to dry to give 20 g cross-linker I, the value of total amine was 5.9 mmol/g.

EXAMPLE 2

Synthesis of Cross-Linker II

[0063] 69.4 g ethanediamine was added into the reaction flask with stirring, then 10 g bis (2-chloroethoxy) methane was dropwise added at room temperature for 1 hour. Then heated up to 120 C., the reaction was stirred for 20 hours, detecting the end of the reaction by TLC. After the reaction, most of solution was concentrated under reduced pressure, the residue was transferred to a reaction flask, adjusted pH with 30% sodium hydroxide solution to pH10 at less than 25 C., extracted the aqueous phase by 90 ml dichloromethane for 3 times, the organic phases was combined and dried by anhydrous sodium sulfate, filtered, and the filter cake was washed with a small amount of solvent for 1 time. The filtrate was concentrated to dry to give 12 g cross-linker II, the value of total amine was 9.7 mmol/g.

EXAMPLE 3

Synthesis of Cross-Linker III

[0064] 500 g aqueous ammonia and 1 g urotropin were added into the reaction flask and stirred to dissolve, then 50 g bis (2-chloroethoxy) methane was added at room temperature. Then heated up to 80 C., the reaction was stirred for 6 hours, detecting the end of the reaction by TLC. After the reaction, most of solution was concentrated under reduced pressure, the residue was transferred to a reaction flask, adjusted pH with 30% sodium hydroxide solution to pH10 at less than 25 C., extracted the aqueous phase by 300 ml mixture of chloroform and ethanol (volume ratio 3: 1) for 3 times, the organic phases was combined and dried by anhydrous sodium sulfate, filtered, and the filter cake was washed with a small amount of solvent for 1 time. The filtrate was concentrated to dry to give 14 g cross-linker III, the value of total amine was 5.2 mmol/g.

EXAMPLE 4

Preparation of the Curing Agent A

[0065] ##STR00015##

[0066] Curing agent A was synthesized according methods described in WO 2013007128.

EXAMPLE 5

Preparation of the Curing Agent B

[0067] ##STR00016##

[0068] Curing agent B was synthesized according methods described in WO 2014169846.

EXAMPLE 6

Preparation of the Curing Agent C

[0069] ##STR00017##

[0070] 89 g 2-nitropropane, 30 g paraformaldehyde and 100 mL triethylamine were placed in a 250 mL round bottom flask and stirred at 45 C. for 0.5 h. The reaction mixture was filtered to obtain 60 g 2-methyl-2-nitropropan-1-ol.

[0071] 11.9 g 2-methyl-2-nitropropan-1-ol, 5.7 g 2,2-dimethoxy propane, and 0.3 g p-toluene sulfonic acid and 500 mL of cyclohexane were mixed in a 1 L round bottom flask equipped with Dean-Stark apparatus to distill evolved methanol. After 6 h, the solution was cooled to room temperature, a moderate amount of sodium carbonate was added into the reaction bottle, then the reaction solution was concentrated at reduced pressure to give 5.7 g 2-methyl-1-((2-(2-methyl-2-nitropropoxy) propan-2-yl)oxy)-2-nitropropane.

[0072] 1 g 2-methyl-1-((2-(2-methyl-2-nitropropoxy)propan-2-yl)oxy)-2-nitropropane, 0.1 g Raney nickel and 25 mL methanol were mixed in a 50 mL round bottom and reduced by hydrogen gas at 55 C. for 12 h. The reaction mixture was filtered and the filtrate was concentrated at reduced pressure to give 0.7 g curing agent C.

EXAMPLE 7

Preparation of the Curing Agent D

[0073] ##STR00018##

[0074] Curing agent D was synthesized according methods described in WO 2014169847.

EXAMPLE 8

Preparation of Degradable Polyurethane

[0075] Polyethylene glycol 1000, MDI and curing agent A were mixed at the mass ratio of 100/20/1. After quickly defoamed under vacuum with vigorous stirring, the mixture was cured at the room temperature, followed by postcured in an 80 C. oven for 2 hours to give a degradable polyurethane.

EXAMPLE 9

Preparation of Degradable Polyurethane

[0076] Polyethylene glycol 1000, MDI, curing agent C were mixed at the mass ratio of100/13/1. After quickly defoamed under vacuum with vigorous stirring, the mixture was cured at the room temperature, followed by postcured in an 80 C. oven for 2 hours to give a degradable polyurethane.

EXAMPLE 10

Preparation of Degradable Polyurethane

[0077] Polyethylene glycol 1000, MDI and curing agent D were mixed at the mass ratio of 100/20/1.5. After quickly defoamed under vacuum with vigorous stirring, the mixture was cured at room temperature, followed by postcured in an 80 C. oven for 2 hours to give a degradable polyurethane.

EXAMPLE 11

Preparation of Degradable Polyurethane

[0078] Polyethylene glycol 1000, Isocyanate TDI and curing agent A were mixed at the mass ratio of 100/20/10. After quickly defoamed under vacuum with vigorous stirring, the mixture was cured at room temperature, followed by postcured in an 80 C. oven for 2 hours to give a degradable polyurethane.

EXAMPLE 12

Degradation of Degradable Polyurethane

[0079] In a round-bottomed flask, a piece of the degradable polyurethane sample (1.0 g) from Example 8 was immerged in a mixture of 10 mL concentrated hydrochloric acid and 90 mL ethylene glycol. The degradation solution was stirred at 100 C. for 4 hours to give a clear solution which was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered, and the collected solid was washed with water and dried, giving a mass recovery yield of 96.5%.

EXAMPLE 13

Degradation of Degradable Polyurethane

[0080] In a round-bottomed flask, a piece of the degradable polyurethane sample (1.0 g) from Example 9 was immerged in a mixture of 1 mL concentrated hydrochloric acid and 90 mL ethylene glycol. The degradation solution was stirred at 180 C. for 2 hours to give a clear solution which was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered, and the collected solid was washed with water and dried, giving a mass recovery yield of 96%.

EXAMPLE 14

Degradation of Degradable Polyurethane

[0081] In a round-bottomed flask, a piece of the degradable polyurethane sample (1.0 g) from Example 10 was immerged in a mixture of 10 mL concentrated hydrochloric acid and 90 mL ethylene glycol. The degradation solution was stirred at 100 C. for 4 hours giving a clear solution which was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered, and the collected solid was washed with water and dried, giving a mass recovery yield of 97%.

EXAMPLE 15

Degradation of Degradable Polyurethane

[0082] In a round-bottomed flask, a piece of degradable polyurethane sample (1.0 g) from Example 11 was immerged in a mixture of 1 mL concentrated hydrochloric acid and 90 mL ethylene glycol. The degradation solution was stirred at 180 C. for 2 hours giving a clear solution which was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered, and the collected solid was washed with water and dried, giving a mass recovery yield of 98%.

EXAMPLE 16

Preparation of Recyclable Carbon Fiber Polyurethane Composite

[0083] Polyethylene glycol 1000, MDI and curing agent A were mixed at the mass ratio of 100/28.2/10. After quickly defoamed under vacuum with vigorous stirring, the mixture was evenly applied over three layers of 2x2 twill carbon fiber (3 K) fabric sheets. The resultant stack was then cured on a flat hot-pressing machine at 80 C. under a pressure of 10 atms for 2 hours, giving a recyclable carbon fiber polyurethane composite laminate.

EXAMPLE 17

Preparation of Recyclable Carbon Fiber Polyurethane Composite

[0084] Polyethylene glycol 1000, isocyanate TDI, curing agent A were mixed at the mass ratio of 100/20/10. After quickly defoamed under vacuum with vigorous stirring, the mixture was evenly applied over three layers of 2x2 twill carbon fiber (3 K) fabric sheets. The resultant stack was then cured on a flat hot-pressing machine at 80 C. under a pressure of 10 atms for 2 hours, giving a recyclable carbon fiber polyurethane composite laminate.

EXAMPLE 18

Degradation of Recyclable Carbon Fiber Polyurethane Composite Panel

[0085] In a round-bottomed flask, a piece of recyclable carbon fiber polyurethane composite sample (1.0 g) from Example 16 was immerged in a mixture of 10 mL concentrated hydrochloric acid and 90 mL ethylene glycol. After heated at 100 C. for 4 hours, the degradation solution was filtered to separate the carbon fibers, and the filtrate was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered again, and the collected solid was washed with water and dried, giving a mass recovery yield of 96%.

EXAMPLE 19

Degradation of Recyclable Carbon Fiber Polyurethane Composite Panel

[0086] In a round-bottomed flask, a piece of recyclable carbon fiber polyurethane composite sample (1.0 g) from Example 17 was immerged in a mixture of 1 mL concentrated hydrochloric acid and 90 mL ethylene glycol. After heated at 180 C. for 2 hours, the degradation solution was filtered to separate the carbon fibers, and the filtrate was neutralized with a 20% aqueous sodium hydroxide solution. The resultant suspension was filtered again, and the collected solid was washed with water and dried, giving a mass recovery yield of 96%.

EXAMPLE 20

Preparation of the Curing Agent E

[0087] ##STR00019##

[0088] Curing agent E was synthesized according methods described in WO 2014169847.

EXAMPLE 21

Preparation of Degradable Polyurethane

[0089] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.3 g curing agent D was added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 130 C. for 6 hours to give polyurethane elastomer.

EXAMPLE 22

Preparation of Degradable Polyurethane

[0090] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.3 g curing agent D were added with stirring, vacuumed for 30 minutes at 70 C., then cured at 130 C. for 6 hours to give polyurethane elastomer.

EXAMPLE 23

Preparation of Degradable Polyurethane

[0091] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.3 g curing agent E was added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 110 C. for 6 hours to give polyurethane elastomer.

EXAMPLE 24

Preparation of Degradable Polyurethane

[0092] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.3 g curing agent E were added with stirring, vacuumed for 30 minutes at 70 C., then cured at 110 C. for 6 hours to give polyurethane elastomer 4.

EXAMPLE 25

Preparation of Degradable Polyurethane

[0093] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.2 g curing agent A was added with stirring, vacuumed for 30 minutes at 70 C., then cured at 80 C. for 6 hours to give polyurethane elastomer 5.

EXAMPLE 26

Preparation of Degradable Polyurethane

[0094] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.2 g curing agent A were added with stirring, vacuumed for 30 minutes at 70 C., then cured at 80 C. for 6 hours to give polyurethane elastomer 6.

EXAMPLE 27

Degradation of Degradable Polyurethane

[0095] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 21 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 5 hours.

EXAMPLE 28

Degradation of Degradable Polyurethane

[0096] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 21 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 3 hours.

EXAMPLE 29

Degradation of Degradable Polyurethane

[0097] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 22 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 3 hours.

EXAMPLE 30

Degradation of Degradable Polyurethane

[0098] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 22 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 3 hours.

EXAMPLE 31

Degradation of Degradable Polyurethane

[0099] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 23 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 4.5 hours.

EXAMPLE 32

Degradation of Degradable Polyurethane

[0100] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 23 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 2.5 hours.

EXAMPLE 33

Degradation of Degradable Polyurethane

[0101] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 24 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 3 hours.

EXAMPLE 34

Degradation of Degradable Polyurethane

[0102] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 24 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 3 hours.

EXAMPLE 35

Degradation of Degradable Polyurethane

[0103] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 25 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 2 hours.

EXAMPLE 36

Degradation of Degradable Polyurethane

[0104] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 25 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1 hours.

EXAMPLE 37

Degradation of Degradable Polyurethane

[0105] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 26 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 1.5 hours.

EXAMPLE 38

Degradation of Degradable Polyurethane

[0106] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g polyurethane elastomer from example 26 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1.5 hours.

EXAMPLE 39

Preparation of Degradable Polyurethane

[0107] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.72 g cross-linker I from Example 1 was added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 80 C. for 6 hours to give sample 1.

EXAMPLE 40

Preparation of Degradable Polyurethane

[0108] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.72 cross-linker I from Example 1 were added with stirring, vacuumed for 30 minutes at 70 C., then cured at 80 C. for 6 hours to give sample 2.

EXAMPLE 41

Preparation of Degradable Polyurethane

[0109] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.43 g cross-linker II from Example 2 was added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 120 C. for 6 hours to give sample 3.

EXAMPLE 42

Preparation of Degradable Polyurethane

[0110] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.43 cross-linker II from Example 2 were added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 120 C. for 6 hours to give sample 4.

EXAMPLE 43

Preparation of Degradable Polyurethane

[0111] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI was added dropwise with stirring. After the addition, the mixture was held at 70 C. for 2 hours under vacuum to obtain the prepolymer. Into the prepolymer, 0.8 g cross-linker III from Example 3 was added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 120 C. for 6 hours to give sample 5.

EXAMPLE 44

Preparation of Degradable Polyurethane

[0112] 20 g HKP-244 (polyester diol, mol. wt. 2000) was dehydrated for 1.5 hours at 50 C. under vacuum, 4 g MDI and 0.8 g cross-linker III from Example 3 were added with stirring, vacuumed for 30 minutes at 70 C., and then cured at 120 C. for 6 hours to give sample 6.

EXAMPLE 45

Degradation of Degradable Polyurethane

[0113] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 1 from Example 39 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 3 hours.

EXAMPLE 46

Degradation of Degradable Polyurethane

[0114] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 1 from Example 39 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 3 hours.

EXAMPLE 47

Degradation of Degradable Polyurethane

[0115] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 2 from Example 40 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 3 hours.

EXAMPLE 48

Degradation of Degradable Polyurethane

[0116] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 2 from Example 40 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 3 hours.

EXAMPLE 49

Degradation of Degradable Polyurethane

[0117] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 3 from Example 41 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 1 hours.

EXAMPLE 50

Degradation of Degradable Polyurethane

[0118] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 3 from Example 41 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1 hours.

EXAMPLE 51

Degradation of Degradable Polyurethane

[0119] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 4 from Example 42 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 1 hours.

EXAMPLE 52

Degradation of Degradable Polyurethane

[0120] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 4 from Example 42 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1 hours.

EXAMPLE 53

Degradation of Degradable Polyurethane

[0121] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 5 from Example 43 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 1.5 hours.

EXAMPLE 54

Degradation of Degradable Polyurethane

[0122] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 5 from Example 43 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1.5 hours.

EXAMPLE 55

Degradation of Degradable Polyurethane

[0123] 95 g ethylene glycol, 5 g concentrated hydrochloric acid and 1 g sample 6 from Example 44 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get light yellow solution. The time was 1.5 hours.

EXAMPLE 56

Degradation of Degradable Polyurethane

[0124] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 6 from Example 44 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 130138 C. until degraded completely to get colorless solution. The time was 1.5 hours.

EXAMPLE 57

Degradation of Degradable Polyurethane

[0125] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 1 from Example 39 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 20 hours.

EXAMPLE 58

Degradation of Degradable Polyurethane

[0126] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 2 from Example 40 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 20 hours.

EXAMPLE 59

Degradation of Degradable Polyurethane

[0127] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 3 from Example 41 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 16 hours.

EXAMPLE 60

Degradation of Degradable Polyurethane

[0128] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 4 from Example 42 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 16 hours.

EXAMPLE 61

Degradation of Degradable Polyurethane

[0129] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 5 from Example 43 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 18 hours.

EXAMPLE 62

Degradation of Degradable Polyurethane

[0130] 90 g ethylene glycol, 10 g concentrated hydrochloric acid and 1 g sample 6 from Example 44 (thickness is 2 mm, width is 2-3 mm) were mixed and stirred at 9095 C. until degraded completely to get colorless solution. The time was 18 hours.

[0131] WO 2015/081610 A1 described degradable isocyanates and their reactions with diamine or polyamines, and diol or polyols to form one kind of recyclable polyurethane network. W02015/081610 A1 disclosed recyclable polyurethane formed by reaction of degradable isocyanates with diols or polyols, and diamines or polyamines, including degradable diamine curing agents described in WO 2012/071896, WO 2013/007128, WO 2014/169846, and WO 2014/169847. The degradable curing agent can include an acetal or ketal aliphatic amine (see, e.g., WO 2012/071896, WO 2013/007128, and CN 103249712A), an acetal or ketal aromatic amine or salt thereof (see, e.g., CN 103254406A, and WO 2014/169847 A), a cyclic acetal or ketal amine (see, e.g., CN 103242509A, and WO 2014/169846 A), an acetal or ketal hydrazide (see, e.g., CN 103193959A and WO 2014/169847 A), or hydrazone (see, e.g., CN103483554 B and WO 2015/043462 A). All references referred to herein are incorporated by reference in their entireties.

Other Embodiments

[0132] The invention has been described above with the reference to specific examples and embodiments, not to be constructed as limiting the scope of this invention in any way. It is understood that various modifications and additions can be made to the specific examples and embodiments disclosed without departing from the spirit of the invention, and such modifications and additions are contemplated as being part of the present invention.