# US 10,501,600 B2 · Process for recycling materials containing benzoxazine resin, especially fiber composite plastics containing benzoxazine resin

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- Number: US 10,501,600 B2
- Document ID: US10501600B2
- Status: Granted
- Kind: B2
- Application number: 15/745,948
- Filed: 2016-07-14
- Published: 2018-07-26
- Granted: 2019-12-10
- Earliest claimed: 2015-07-22
- Assignees: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
- Applicants: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
- Inventors: Dominik Soethje; Christian Dreyer; Monika Bauer
- Web page: https://patentgrep.com/patent/US10501600B2

## CPC

- C08J 11/28: by treatment with organic compounds containing nitrogen, sulfur or phosphorus
- B29B 17/02: Separating plastics from other materials
- C08G 18/64: Macromolecular compounds not provided for by groups C08G18/42 - C08G18/63
- C08G 18/6511: {compounds of group C08G18/3203}
- B29K 2039/00: Use of polymers with unsaturated aliphatic radicals and with a nitrogen or a heterocyclic ring containing nitrogen in a side chain or derivatives thereof as moulding material
- B29K 2277/00: Use of {PA, i.e.} polyamides, e.g. polyesteramides {or derivatives thereof,} as reinforcement
- B29K 2307/04: Carbon
- B29K 2309/08: Glass
- B29K 2311/10: Natural fibres, e.g. wool or cotton
- C08G 2101/00: Manufacture of cellular products
- C08J 2377/00: Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J 2379/00: Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates to a process for chemically degrading materials containing benzoxazine resin, in particular benzoxazine resins, benzoxazine resin pre-polymers and benzoxazine resin-containing plastics, that enables a high quality recycling process for used up benzoxazine resin-containing materials, in particular the separation of composite materials, such as duromer-based fiber composite plastics containing a benzoxazine resin matrix, and reuse of the benzoxazine-containing materials.

## Claims

### Claim 1

A process for degrading benzoxazine resin-containing materials, wherein the benzoxazine resin-containing material is subjected to aminolysis with an agent containing at least one reactive NH2 group and/or NH group.

### Claim 2 (depends on 1)

The process as recited in claim 1, wherein the agent containing the at least one reactive NH2 group and/or NH group is an aliphatic or aromatic amine or hydrazine that can comprise other functional groups.

### Claim 3 (depends on 1)

The process as recited in claim 1, wherein the agent containing the at least one reactive NH2 group and/or NH group is an amino alcohol having the formula NH2—Y—OH, where Y is a divalent aliphatic or aromatic residue.

### Claim 4 (depends on 1)

The process as recited in claim 1, wherein the agent containing the at least one reactive NH2 group and/or NH group is a diamine of formula NH2—Y—NH2, where Y is a divalent aliphatic or aromatic residue.

### Claim 5 (depends on 1)

The process as recited in claim 1, wherein the reaction is performed in a solvent.

### Claim 6 (depends on 5)

The process as recited in claim 5, wherein the solvent is tetrahydrofuran, dimethyl sulfoxide, ethanol, water, dioxane, dichloromethane, chloroform, dimethylformamide, or N-methyl-2-pyrrolidone.

### Claim 7 (depends on 1)

The process as recited in claim 1, wherein the agent containing the at least one reactive NH2 group and/or NH group is used as solvent, if needed under pressure in the condensed state, or after melting.

### Claim 8 (depends on 1)

The process as recited in claim 1, wherein the process is performed at elevated temperature and/or elevated pressure.

### Claim 9 (depends on 1)

The process as recited in claim 1, wherein the benzoxazine-containing material is reinforced with fibers.

### Claim 10 (depends on 9)

The process as recited in claim 9, wherein the fibers are selected from carbon fibers, glass fibers, aramide fibers, basalt fibers, ceramic fibers, synthetic fibers and natural fibers, wherein after the breakdown of the benzoxazine-containing material the fibers are present in solid form in the solution of the agent containing the at least one NH2 group and/or NH group and the degradation products of the benzoxazine-containing material.

### Claim 11 (depends on 9)

The process as recited in claim 9, wherein the fibers are polyamide fibers.

### Claim 12 (depends on 11)

The process as recited in claim 11, wherein the agent containing the reactive NH2 groups and/or NH groups is selected from a primary amine and a diamine having two primary amino groups that do not contain any additional reactive substituents, preferably from an amine of formula R*NH2, wherein R* is an unsubstituted hydrocarbon residue with preferably at least 6 carbon atoms or an alkylene diamine such as ethylene diamine, whereby after the degradation of the benzoxazine-containing material the fibers are present in solid form in the solution of the agent containing at least one NH2 group and/or NH group and the degradation products of the benzoxazine-containing material.

### Claim 13 (depends on 11)

The process as recited in claim 11, wherein the agent containing the reactive NH2 groups and/or NH groups is selected from amino alcohols, in particular amino ethanol, whereby after the breakdown of the benzoxazine-containing material the breakdown product of the fibers are also present in solubilized form in the agent containing at least one NH2 group and/or NH group.

### Claim 14 (depends on 1)

A process for recycling a benzoxazine resin-containing material, comprising the degradation of the material as defined in claim 1, the removal of volatile products, preferably under reduced pressure and/or at elevated temperature, and the mixing of the material with one or more substances that react with the resultant degradation products under formation of a polymer network.

### Claim 15 (depends on 14)

The process as recited in claim 14, wherein the material is mixed with an at least bifunctional isocyanate.

### Claim 16 (depends on 5)

The process as recited in claim 5, wherein the reaction is performed in a cyclic ether, an alcohol, a chlorinated hydrocarbon or an N-containing solvent.

### Claim 17 (depends on 15)

The process as recited in claim 15, wherein the bifunctional isocyanate is hexamethylene-1,6-diisocyanate-based (HDI-) trimer.