Boron-containing thermoplastic polymer, method for recycling boron-containing thermoplastic polymer, precursor, and raw material set

Abstract

To provide a boron-containing thermoplastic polymer having a new crosslinked structure.SOLUTION: The boron-containing thermoplastic polymer of the present invention contains a main chain, and the main chain contains repeating units linked to each other via a boron atom.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to boron-containing thermoplastic polymers, methods for recycling boron-containing thermoplastic polymers, precursors, and raw material sets. [Background technology]

[0002] Various developments have been made on boron-containing polymers. One such technique is described in Patent Document 1. Patent Document 1 describes a technique for forming a gel using a polyvinyl alcohol resin as a crosslinking agent and boric acid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-043826 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gel described in Patent Document 1, two adjacent hydroxyl groups present in the main chain are bonded by boron ester bonding, thereby forming a structure in which polyvinyl alcohol molecules are three-dimensionally crosslinked with each other. The present inventors have investigated polymers having a crosslinked structure different from the above-mentioned three-dimensional crosslinked structure. [Means for solving the problem]

[0005] After further investigation, the present inventors found that the precursor of the monomer or oligomer can constitute the main chain of the polymer via boron crosslinking, thereby completing the present invention.

[0006] According to one aspect of the present invention, there are provided the following boron-containing thermoplastic polymer, a method for recycling a boron-containing thermoplastic polymer, a precursor, and a raw material set.

[0007] 1. A boron-containing thermoplastic polymer comprising a backbone, the main chain comprises repeat units linked to each other via boron atoms; Boron-containing thermoplastic polymers. 2. The boron-containing thermoplastic polymer according to 1., A boron-containing thermoplastic polymer, wherein each of both ends of the repeating unit contains a crosslinking moiety chemically bonded to the boron atom. 3. The boron-containing thermoplastic polymer according to 2., The boron-containing thermoplastic polymer has a crosslinking site having a plurality of groups formed by removing a hydrogen atom from a group consisting of a hydroxyl group, an amino group, and a carboxyl group. 4. The boron-containing thermoplastic polymer according to 3., the crosslinking moiety contains an aromatic ring, A boron-containing thermoplastic polymer having a structure in which at least two of the plurality of groups are bonded to adjacent carbon atoms in the aromatic ring at the crosslinking site. 5. The boron-containing thermoplastic polymer according to any one of 1. to 4., A boron-containing thermoplastic polymer having at least one of thermal decomposition, acid decomposition, and alkali decomposition properties. 6. A method for recycling boron-containing thermoplastic polymers, comprising: The method includes a step of recovering at least one of boron atoms, boron components containing boron atoms, and monomers or oligomers derived from repeating units constituting the main chain of the boron-containing thermoplastic polymer by subjecting the boron-containing thermoplastic polymer according to any one of 1. to 5. to at least one of thermal decomposition, acid decomposition, and alkali decomposition. Method for recycling boron-containing thermoplastic polymers. 7. A precursor to a boron-containing thermoplastic polymer, comprising: A precursor that is a monomer or oligomer having multiple crosslinkable groups that can be chemically bonded with a boron-based crosslinker. 8. The precursor according to item 7, A precursor, wherein the plurality of crosslinkable groups include one or more types selected from the group consisting of a hydroxyl group, an amino group, and a carboxyl group. 9. A precursor according to 7. or 8., A precursor having a structure in which at least two of the plurality of crosslinkable groups are bonded to adjacent carbon atoms in an aromatic ring. 10. A raw material set for use in forming a boron-containing thermoplastic polymer, comprising: a boron-based crosslinking agent; a monomer or oligomer having a plurality of crosslinkable groups, which is capable of chemically bonding with the boron-based crosslinking agent; Including raw material set. [Effects of the Invention]

[0008] According to the present invention, there are provided a boron-containing thermoplastic polymer having a novel crosslinked structure, a method for recycling the boron-containing thermoplastic polymer, a precursor, and a raw material set. DETAILED DESCRIPTION OF THE INVENTION

[0009] The boron-containing thermoplastic polymer of this embodiment will be described.

[0010] The boron-containing thermoplastic polymer of this embodiment is 1. A boron-containing thermoplastic polymer comprising a backbone, The backbone comprises repeating units linked to each other through boron atoms.

[0011] According to the findings of the present inventors, it has been found that monomers or oligomers (precursors) can be polymerized with each other via boron crosslinks, thereby forming the main chain of a polymer.

[0012] In this specification, the precursor means a precursor of a boron-containing thermoplastic polymer. The precursor of this embodiment contains at least one of a monomer and an oligomer having a plurality of crosslinkable groups that can be chemically bonded to a boron-based crosslinking agent.

[0013] The boron-containing thermoplastic polymer can be used in a variety of applications, for example, as a replacement for known thermoplastic resins. Examples of applications include vehicles, aircraft, sports, leisure, logistics, buildings, medical care, electronic devices, space, and industrial applications. In any of the above applications, a composite material containing the boron-containing thermoplastic polymer and other materials, such as known fillers, may be provided.

[0014] The boron-containing thermoplastic polymer may have at least one of thermal decomposition, acid decomposition, and alkali decomposition properties. When decomposed under relatively mild conditions, the boron-containing thermoplastic polymer can be highly recyclable.

[0015] An example of a method for producing a boron-containing thermoplastic polymer may include crosslinking a plurality of precursors using a boron-based crosslinking agent.

[0016] The boron-based crosslinking agent is specifically a compound or salt thereof containing at least two, preferably three or more BOH groups (boronic acid groups), which may be contained alone or in any combination of two or more.

[0017] The compound having a BOH group may be either an inorganic boron compound or an organic boron compound. Inorganic boron compounds include boric acid (B(OH)3), borates, borate esters, polyborates, and the like. The salt is not particularly limited, but examples thereof include alkali metal salts such as sodium salts, alkaline earth metal salts such as calcium salts and magnesium salts, aluminum salts, and organic amine salts such as triethylamine, triethanolamine, morpholine, piperazine, and pyrrolidine. Examples of borate esters include alkyl borates and aryl borates. For example, borates, borate esters, polyborates, and the like may be hydrolyzed to produce compounds containing at least two or more BOH groups (boronic acid groups). Among these, boric acid, borate salts, and borate esters are preferred, and boric acid and borate esters are more preferred.

[0018] The precursor monomers are monomers that constitute the repeating units of known thermoplastic resins such as polyamide (PA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherimide (PEI), polyethersulfone (PES), polyester (PET), thermoplastic polyurethane elastomer (TPU), polycarbonate (PC), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polyacryl ether ketone (PAEK), polyether ketone ketone (PEKK), polyethylene (PE), polyethylene terephthalate (PET), ABS resin, polystyrene (PS), and polypropylene (PP). The precursor oligomer may be a low molecular weight compound in which several of the above-mentioned monomers are bonded. The oligomer may be a dimer, trimer, tetramer, etc. The number of monomers bonded in the oligomer may be determined taking into consideration the intended use, the above-mentioned decomposability, etc.

[0019] The precursor monomer and oligomer each have a plurality of crosslinkable groups in the molecule that can chemically bond with the boron-based crosslinking agent.

[0020] The multiple crosslinkable groups may include one or more types selected from the group consisting of hydroxyl groups, amino groups, and carboxyl groups. For example, the multiple crosslinkable groups may include two or more crosslinkable groups of the same type, such as hydroxyl groups, or two or more crosslinkable groups of different types, such as hydroxyl groups and carboxyl groups.

[0021] The precursor monomer and oligomer may each have, as a group containing a crosslinkable group, at least one aromatic ring to which the above-mentioned crosslinkable group is bonded, and preferably two or more aromatic rings. The aromatic ring may be a hydrocarbon aromatic ring or a heteroaromatic ring, but is preferably a hydrocarbon aromatic ring such as a benzene ring.

[0022] The precursor monomer may include a monomer having two or more, preferably three or more, more preferably four or more of the above-mentioned crosslinkable groups in one molecule, and may include a compound represented by the following chemical formula [1]: L-X1-L [1] In the above chemical formula [1], L represents a group containing an aromatic ring to which one or more of the above crosslinkable groups are bonded, and X1 represents the above monomer, provided that the total number of crosslinkable groups in the molecule in the above chemical formula [1] is preferably 3 or more, more preferably 4 or more.

[0023] The precursor oligomer may also contain a linked product of monomers having, at each of both ends, a group containing an aromatic ring to which one or more of the above-mentioned crosslinkable groups are bonded, or may contain a compound represented by the following chemical formula [2]: L-X2-L [2] In the above chemical formula [2], L represents a group containing an aromatic ring to which one or more of the above crosslinkable groups are bonded, and X2 represents a bond of two or more of the above monomers, provided that the total number of crosslinkable groups in the molecule in the above chemical formula [2] is preferably 3 or more, more preferably 4 or more.

[0024] In L in the above chemical formula [1] and the above chemical formula [2], the two bridging groups bonded to the same aromatic ring may be located at positions two atoms apart from each other on the ring atoms, preferably one atom apart, and more preferably adjacent to each other. Each of the precursor monomers and oligomers may have a structure in which at least two of the multiple crosslinkable groups are bonded to adjacent carbon atoms in an aromatic ring.

[0025] Crosslinkable groups can be introduced into monomers or oligomers using known methods for introducing functional groups. Examples include simultaneous or sequential addition of a compound containing a crosslinkable group (a crosslinkable component) during synthesis of X2 in the oligomer's chemical formula [2], a method utilizing a condensation reaction, and a method utilizing an amine-aldehyde reaction. Using these methods, multiple crosslinkable groups can be introduced into the monomer or oligomer by reacting functional group A of the monomer or oligomer with functional group B of the compound containing a crosslinkable group. Alternatively, crosslinkable groups can be introduced during oligomer synthesis. Examples of compounds containing crosslinkable groups include aromatic compounds in which one or more crosslinkable groups and functional group B are bonded to an aromatic ring.

[0026] The crosslinking reaction between the boron-based crosslinking agent and the precursor may be carried out in a suitable solvent, and if necessary, known accelerating treatments such as heating, stirring, and catalysts may be added. As a result of the above, a boron-containing thermoplastic polymer is obtained which includes a main chain formed by a plurality of precursors being linked together via crosslinking sites containing boron atoms.

[0027] The boron-containing thermoplastic polymer may have crosslinking sites in the main chain, where both ends of the repeating unit are chemically bonded to boron atoms. When the boron-containing thermoplastic polymer contains a plurality of main chains, the main chains may not be crosslinked to each other.

[0028] The crosslinking moiety may have a plurality of groups obtained by removing a hydrogen atom from any one of the group consisting of a hydroxyl group, an amino group, and a carboxyl group. Three or more, preferably four, of these groups obtained by removing a hydrogen atom may be bonded to a boron atom present in one crosslinking moiety. Furthermore, the plurality of groups obtained by removing a hydrogen atom may be the same or different.

[0029] Furthermore, when the crosslinked moiety contains an aromatic ring, the crosslinked moiety may have a structure in which at least two of the multiple groups are bonded to adjacent carbon atoms in the aromatic ring.

[0030] The present embodiment can provide a set of raw materials used to form a boron-containing thermoplastic polymer. An example of this raw material set may include a boron-based crosslinking agent and a monomer or oligomer (precursor) having a plurality of crosslinkable groups that can chemically bond with the boron-based crosslinking agent. In the raw material set, the boron-based crosslinking agent and the precursor may be stored in separate containers.

[0031] The present embodiment also provides a method for recycling boron-containing thermoplastic polymers. One example of this recycling method may include a step of subjecting the boron-containing thermoplastic polymer to at least one of thermal decomposition, acid decomposition, and alkali decomposition to recover at least one of boron atoms, boron components containing boron atoms, and monomers or oligomers derived from repeating units constituting the main chain of the boron-containing thermoplastic polymer. The recovered materials may be reused to produce a boron-containing thermoplastic polymer, or may be used as another material.

[0032] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0033] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0034] <Preparation of precursor> m-Phenylenediamine and 3,4-dihydroxybenzaldehyde were added to dimethylacetamide (DMAc) and stirred overnight at room temperature to obtain a reaction product, which was then reprecipitated in pure water, filtered, and vacuum-dried to obtain a precursor having the following structural formula:

[0035] [ka]

[0036] In the above <Preparation of Precursor>, NMR and FT-IR confirmed that the amino group in the diamine monomer reacted with the aldehyde group in the catechol in a 1:1 ratio. This result suggests that a structure in which catechol (a group with two crosslinkable groups) is bonded to each end of the diamine monomer was synthesized.

[0037] <Production of boron-containing thermoplastic polymer> [Example 1] The precursor obtained above and boronic acid (B(OH)3) were added to dimethyl sulfoxide (DMSO) and stirred overnight at room temperature to obtain a solution containing a boron-containing thermoplastic polymer having the following repeating unit:

[0038] [ka]

[0039] [Comparative Example 1] A solution containing the above precursor was obtained in the same manner as in Example 1, except that boronic acid (B(OH)3) was not added.

[0040] It was confirmed that a film could be formed by drying the solution of Example 1. On the other hand, it was confirmed that powder was generated when the solution of Comparative Example 1 was dried.

[0041] The viscosity of each solution was measured using a rheometer at a room temperature of 25°C and a shear rate of 50 rpm. As a result, it was confirmed that the viscosity of Example 1 was higher than that of Comparative Example 1, i.e., an increase in the viscosity of the solution. This result suggests that the boron-containing thermoplastic polymer was a precursor having a high molecular weight due to the formation of boron crosslinking sites.

[0042] The solutions of Example 1 and Comparative Example 1 were subjected to TG-DTA measurement using a simultaneous differential thermal and thermogravimetric analyzer in a nitrogen atmosphere at a temperature rise rate of 5°C / min at temperatures from 25 to 800°C. The TG curves showed that in the temperature range of about 100 to about 300°C, Example 1 had a larger weight loss (%) than Comparative Example 1. This result suggests that in Example 1, the boron crosslinking sites of the boron-containing thermoplastic polymer were decomposed.

[0043] The solubility of a film formed by drying the solution of Example 1 was evaluated. This film (test piece) was immersed in a solvent at a liquid temperature of 25°C, and the solvent was heated to 65°C on a hot plate, and then the solvent was allowed to stand at room temperature. Water and 2 mol hydrochloric acid were used as the solvent. As a result, no coloring of the liquid was observed in water at a temperature of 25°C, but the liquid turned brown within a few minutes in water at a temperature of 65°C, and a precipitate was observed in the water after standing at room temperature. On the other hand, with 2M hydrochloric acid, the liquid turned brown within a few minutes at temperatures of 25°C, 65°C, and after cooling to room temperature, and no precipitate was observed.

[0044] From Example 1, it was confirmed that a boron-containing thermoplastic polymer can be obtained from the above precursor and boronic acid. It was also found that the boron-containing thermoplastic polymer of Example 1 decomposed under relatively mild temperature conditions.

Claims

1. 1. A boron-containing thermoplastic polymer comprising a backbone, the main chain comprises repeat units linked to each other via boron atoms; Boron-containing thermoplastic polymers.

2. 2. The boron-containing thermoplastic polymer of claim 1, A boron-containing thermoplastic polymer, wherein each of both ends of the repeating unit contains a crosslinking moiety chemically bonded to the boron atom.

3. 3. The boron-containing thermoplastic polymer of claim 2, The boron-containing thermoplastic polymer has a crosslinking site having a plurality of groups formed by removing a hydrogen atom from a group consisting of a hydroxyl group, an amino group, and a carboxyl group.

4. 4. The boron-containing thermoplastic polymer of claim 3, the crosslinking moiety contains an aromatic ring, A boron-containing thermoplastic polymer having a structure in which at least two of the plurality of groups are bonded to adjacent carbon atoms in the aromatic ring at the crosslinking site.

5. 3. The boron-containing thermoplastic polymer according to claim 1 or 2, A boron-containing thermoplastic polymer having at least one of thermal decomposition, acid decomposition, and alkali decomposition properties.

6. 1. A method for recycling a boron-containing thermoplastic polymer, comprising: The method comprises a step of recovering at least one of boron atoms, boron components containing boron atoms, and monomers or oligomers derived from repeating units constituting the main chain of the boron-containing thermoplastic polymer by subjecting the boron-containing thermoplastic polymer according to claim 1 or 2 to at least one of thermal decomposition, acid decomposition, and alkali decomposition. Method for recycling boron-containing thermoplastic polymers.

7. A precursor to a boron-containing thermoplastic polymer, comprising: A precursor that is a monomer or oligomer having multiple crosslinkable groups that can be chemically bonded with a boron-based crosslinker.

8. 8. The precursor of claim 7, A precursor, wherein the plurality of crosslinkable groups include one or more types selected from the group consisting of a hydroxyl group, an amino group, and a carboxyl group.

9. 9. A precursor according to claim 7 or 8, A precursor having a structure in which at least two of the plurality of crosslinkable groups are bonded to adjacent carbon atoms in an aromatic ring.

10. A raw material set used to form a boron-containing thermoplastic polymer, comprising: a boron-based crosslinking agent; a monomer or oligomer having a plurality of crosslinkable groups capable of chemically bonding with the boron-based crosslinking agent; Including raw material set.

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