Polyester synthesis based on aspartic acid modification

Abstract

Provided in the present invention is polyester synthesis based on aspartic acid modification. A monomer of a unique structure of an imide ring is obtained based on aspartic acid and a dibasic acid likely to be cyclized, the monomer is based on the aspartic acid, can be derived from biomass, is low in cost and renewable, meets the requirement of sustainable development, and the unique structure of the monomer can regulate and control various properties of polyester materials, such as the mechanics, temperature resistance, hydrophilicity and hydrophobicity, and crystallization.

Description

Synthesis of a polyester modified with aspartic acid Technical Field

[0001] The invention belongs to the technical field of polymer synthesis, in particular to the synthesis of polyester based on aspartic acid modification. Background Art

[0002] Currently, resin materials on the market still face the challenge of balancing cost and performance, especially for bio-based materials. PBS (polybutylene succinate), as a biodegradable plastic, has excellent heat resistance and is widely used, but the material suffers from poor mechanical strength and high cost. PLA (polylactic acid), which exhibits good degradation properties and good mechanical strength, is brittle, exhibits poor high and low temperature resistance, and lacks toughness. PET (polymethyl terephthalate), currently the primary research target for recyclable materials and widely used in food packaging, also suffers from unsatisfactory heat resistance. While the recently popular PEF (polyethylene furandicarboxylate) material has improved heat resistance, its currently high monomer cost limits its large-scale application.

[0003] Researching high-performance bio-based materials with great cost advantages and green monomer sources is a feasible way to solve the current problems of pure petroleum-based resin materials, such as poor environmental protection, high recycling costs and poor performance. Summary of the Invention

[0004] The present invention first provides a dibasic acid monomer containing an imide ring structure as shown in (Formula I), an ester or a prepolymer of the monomer:

[0005] wherein R1 is a derivative group of aspartic acid, and X is a residue that easily forms a cyclic dibasic acid or -C=C-;

[0006] n is an integer of 0 or greater; preferably, n is any integer from 0 to 7;

[0007] Or, the ring-opened structure of the dibasic acid monomer containing an imide ring structure represented by the monomer (Formula I), the ester of the monomer, or the prepolymer, for example:

[0008] or a combination of the ring-opening modes of (Formula II) and (Formula III), wherein n1 and n2 are non-negative integers less than n, preferably n1 and n2 are any integers from 0 to 6; the N value is an independent value of n, n1 or n2; preferably, the content of the monomer having the N value greater than 0 is greater than 0;

[0009] X is preferably -C=C-; or X is preferably at least one of an alkylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, an alkylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl and is interrupted by one or more O atoms, an alkenylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkylene group or a heterocycloalkyl group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkenylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, an arylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a heteroarylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, or a bridged ring group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro;

[0010] Preferably, the alkylene group in the definition of X is C1-C10 alkylene group, preferably C1-C6 alkylene group, more preferably C1-C5 alkylene group, most preferably methylene, ethylene, 1-methylethylene, 1,1-dimethylethylene, 1,2-dimethylethylene, 1,1,2,2-tetramethylethylene, 1-phenylethylene, 1-benzylethylene, 1,1-diphenylethylene, 1,1-dibenzylethylene, 1,2 -diphenylethylene, 1,2-dibenzhydrylethylene, propylene, 1-methylpropylene, 2-methylpropylene, 1,1-dimethylpropylene, 1,2-dimethylpropylene, 2,2-dimethylpropylene, 1,3-dimethylpropylene, 1-phenylpropylene, 2-phenylpropylene, 1,2-diphenylpropylene, 2,2-diphenylpropylene or 1,3-diphenylpropylene; the alkenylene group in the definition of X is C2-C10 Alkenylene is preferably C2-C6 alkenylene, more preferably C2-C3 alkenylene, most preferably vinylene, 1-methylvinylene, 1,2-dimethylvinylene or propenylene; the alkylene group defined in X, which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, is interrupted by one or more O atoms and is interrupted by 1-3 oxygen atoms, such as 2-oxa-1,3-ethylene; the cycloalkylene group defined in X is C3-C8 cycloalkylene, preferably C4-C6 cycloalkylene, most preferably cyclobutylene or cyclohexylene; the cycloalkenylene group defined in X may be C4-C8 cycloalkenylene, preferably C4-C6 cycloalkenylene, most preferably 3-cyclohexene-1,6-diyl; the arylene group defined in X is C6-C10 arylene, preferably phenylene, such as 1,6-phenylene; the cyclized group defined in X is norbornenylene;

[0011] Most preferably, X is -C=C-, ethylene, 1,2-cyclohexylene or 1,2-phenylene.

[0012] Preferably, the aspartic acid in the monomer is of biological origin; preferably, the aspartic acid has a 14 C / 12 C ratio.

[0013] In a second aspect, the present invention provides a monomer composition, which contains a dibasic acid monomer containing an imide cyclic structure as shown in (Formula I) in claim 1, or (Formula I) further contains (Formula II) and / or (Formula III), an ester or prepolymer of the monomer, and contains two or more monomers with different N values, wherein the N value is an independent value of n, n1 or n2, and the content of the monomer with an N value greater than 0 is greater than 0.

[0014] Preferably, the monomer composition is a dibasic acid monomer containing an imide ring structure represented by Formula I, or a mixture of Formula I and Formula II, an ester or a prepolymer of the monomer, more preferably a mixture of monomers having at least one N value of 0 and n of 1-7, or more preferably a mixture of monomers having at least two N values ​​of 1-7.

[0015] Alternatively, the monomer composition is a dibasic acid monomer containing an imide cyclic structure represented by Formula I and Formula III, or a mixture of Formula I, Formula II and Formula III, an ester or a prepolymer of the monomer, more preferably comprising a mixture of at least one monomer having an N value of 0-7 and at least one monomer having an N value of 0-6, and most preferably comprising at least one monomer having an N value greater than 0 among n, n1 and n2.

[0016] The third aspect of the present invention provides a copolymer, comprising a polymer main structural unit and a first modified structural unit, wherein the first modified structural unit comprises a structure represented by Formula VI:

[0017] Preferably, the first modified structural unit is a polyester structure represented by (Formula VI-1):

[0018] R3 is a diol residue used for polymer synthesis, preferably, selected from C1-C12 alkylene groups, alicyclic groups, or heterocyclic groups containing at least one N, O, or S atom, which are unsubstituted or substituted by substituents selected from halogen, alkyl, aryl, arylalkyl, or alkylaryl groups; preferably, R3 is selected from at least one of C2-C8 alkylene groups, alicyclic groups, or C5-C8 heterocyclic groups containing oxygen atoms, which are unsubstituted or substituted by substituents selected from halogen, alkyl, aryl, arylalkyl, or alkylaryl groups; more preferably, R3 is C2-C6 alkylene groups.

[0019] Preferably, the first modified structural unit further comprises a structure represented by Formula VII and / or Formula VIII:

[0020] n is an integer of 0 or greater than 0, preferably n is any integer from 0 to 7; n1 and n2 are non-negative integers less than n, preferably n1 and n2 are any integers from 0 to 6; preferably, the N value is an independent value of n, n1 or n2, and the content of the monomer with an N value greater than 0 is greater than 0;

[0021] Preferably, the first modified structural unit further comprises a polyester structure represented by (Formula VII-1) and / or (Formula VIII-1):

[0022] Preferably, the first modified structural unit forms a branched and / or cross-linked structure through double bonds and / or carboxyl groups on the side chains.

[0023] In a specific embodiment of the present invention, the main structural unit is polyester; preferably, the main structural unit is polyester such as one or more of aliphatic polyester, aliphatic-aromatic polyester, and aromatic polyester; further preferably, the main structural unit comprises two or more different structural units;

[0024] Preferably, it is a structural unit of one or more polyesters selected from PBS, PES, PBA, PET, PBT, PTT, PBAT, PBST, PEAT or PEST.

[0025] In a specific embodiment of the present invention, the first modified structural unit accounts for 0.5-99.5% of the total structural units of the polymer, preferably 1-90 mol%, and more preferably 5%-30 mol%.

[0026] In a specific embodiment of the present invention, the copolymer further comprises a second modified structural unit.

[0027] The present invention also provides a polymer alloy comprising the above copolymer.

[0028] The present invention also provides a polymer composition or a molded article comprising the above copolymer or the above polymer alloy.

[0029] The present invention also provides uses of the above-mentioned copolymer, polymer alloy, or composition or molded body, such as food containers, food packaging films, disposable tableware such as spoons or straws, transparent boxes for daily necessities, cosmetics, home appliances, etc., transparent windows for cartons, and other packaging containers, transparent folders, ID holders and other stationery, industrial films or agricultural films, and chemical fibers for clothing or industry.

[0030] The present invention also provides the use of any of the aforementioned monomers, esters or prepolymers of the monomers, or the monomer compositions, or precursor compositions of the monomers or monomer compositions, for synthesizing polymers, wherein the precursor composition comprises aspartic acid and an easily cyclic dibasic acid.

[0031] Preferably, the monomer or monomer composition comprises at least two, three, four, five or six monomers with N values ​​of 0, 1, 2, 3, 4 or 5.

[0032] Preferably, the monomer or monomer composition includes monomers with N values ​​of 0, 1 and 2; preferably, the monomer with N value of 0 has the largest content.

[0033] Preferably, the monomer or monomer composition includes monomers with N values ​​of 1, 2, 3, 4 and 5; preferably, the monomer with N value of 2 has the largest content.

[0034] Preferably, the monomer or monomer composition includes monomers with N values ​​of 2, 3, 4 and 5; preferably, the monomer with N value of 3 has the largest content.

[0035] The present invention also provides a method for synthesizing the above-mentioned monomer or monomer composition, comprising a reaction step of aspartic acid and a readily cyclic dicarboxylic acid or its anhydride; preferably, the molar ratio of aspartic acid to the readily cyclic dicarboxylic acid is 1:50-50:1, preferably 1:10-10:1, and further preferably 1:3-1:1.

[0036] Preferably, the reaction is carried out under melt conditions.

[0037] The present invention also provides a method for synthesizing the above copolymer, comprising:

[0038] Providing the above-mentioned monomer or monomer composition;

[0039] Providing polyester prepolymers of dibasic acids and diols;

[0040] The monomer or monomer composition of step 1 and the prepolymer of step 2) and optionally newly added dibasic acid and / or diol are subjected to a condensation reaction.

[0041] Beneficial technical effects

[0042] The modified monomer used in the present invention is based on aspartic acid, which can be derived from biomass, is low-cost and renewable, and meets the needs of sustainable development; and the monomer with a unique structure of the present invention can regulate various properties of polyester materials such as mechanics, temperature resistance, hydrophilicity and hydrophobicity, and crystallization properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 shows the NMR spectrum of a dibasic acid monomer containing an imide ring structure.

[0044] FIG2 shows the monomer self-polymerization (aspartic acid:succinic acid=1:3) analyzed by NMR spectrum.

[0045] FIG3 shows the monomer self-polymerization (aspartic acid:succinic acid=1:5) analyzed by NMR spectrum.

[0046] FIG4 is an NMR spectrum of the product obtained in Monomer Synthesis Example 3 of the present invention.

[0047] FIG5 is an NMR spectrum of the product obtained in Monomer Synthesis Example 4 of the present invention.

[0048] Figure 6 XRD curve of PBS modified with 10% aspartic acid modification units.

[0049] Figure 7 FTIR spectrum of PBS modified with 10% aspartic acid modification units.

[0050] Figure 8 Mass spectrum of the product of aspartic acid:succinic anhydride 1:1.

[0051] Figure 9 Mass spectrum of the product of aspartic acid:succinic anhydride 1:3.

[0052] Figure 10 Mass spectrum of the product of aspartic acid:succinic anhydride 1:10. DETAILED DESCRIPTION

[0053] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art are not described to avoid confusion with the present invention.

[0054] The following describes the implementation of the present invention in detail with reference to the definitions of terms:

[0055] I. Aspartic acid monomers containing imide ring structures and their synthesis

[0056] The present invention first provides an aspartic acid monomer containing an imide ring structure, wherein the monomer has the following structure:

[0057] Wherein R1 is a derivative group of aspartic acid, X is a residue of a dicarboxylic acid that easily forms a ring or -C=C-, and n is 0 or an integer greater than 0.

[0058] The derivative group of aspartic acid of the present invention is the residual group except dicarboxyl group and amino group after the reaction of aspartic acid and easily cyclic dibasic acid, namely: -CH(-)-CH2-.

[0059] The present invention has discovered that when an easily cyclizable dibasic acid is used to block the amino group of aspartic acid, the aspartic acid itself will undergo self-polymerization, ring opening, or formation of a terminal double bond, resulting in a side chain having a unique structure with one or more succinimide rings or an open ring structure and an easily cyclizable dibasic acid end-blocking or aspartic acid terminal double bond side chain, and the structure affects the properties of the polymer.

[0060] Therefore, the monomer of the present invention may include one or more ring-opened structures of imide (Formula I), for example:

[0061] or a combination of the ring-opening modes of (Formula II) and (Formula III).

[0062] For the structure of (Formula III), since the carbon atoms between the amino group and the two carboxyl groups in aspartic acid are different, there are two different open-ring structures:

[0063] As exemplified by (Formula IV), the ring-opening form in which the carboxyl group is closer to the amino group to form an amide bond is referred to as an α-ring-opening structure in the present invention; as exemplified by (Formula V), the ring-opening form in which the carboxyl group is farther away from the amino group to form an amide bond is referred to as a β-ring-opening structure in the present invention.

[0064] Exemplary aspartic acid monomers containing an imide ring structure include:

[0065] Exemplarily, a typical monomer containing at least one aspartic acid deamination double bond of the present invention has the following structure:

[0066] Synthesis of aspartic acid monomer containing imide ring structure:

[0067] The monomer can be obtained by mixing aspartic acid and a readily cyclic dicarboxylic acid in a certain ratio and performing an amidation reaction. The reaction conditions can be selected by those skilled in the art according to the aspartic acid and the readily cyclic dicarboxylic acid. For example, the reaction can be carried out under anaerobic hot melt conditions. The NMR spectrum of a typical monomer is shown in Figure 1. There is no absorption peak of amino and imino H near 8, indicating that the amino group of aspartic acid is completely protected.

[0068] The N value is an independent value of n, n1 or n2, that is, the values ​​of n, n1 or n2 can be the same or different, and Formula I, Formula II or Formula III can each contain multiple monomers with different N values.

[0069] Typical electrospray mass spectra of monomers or monomer compositions with N values ​​greater than 0 are shown in Figures 8 to 10. Analysis shows that monomers or monomer compositions with different N values ​​can be obtained by changing the feed ratio of aspartic acid and easily cyclic dicarboxylic acid.

[0070] Taking the reaction of aspartic acid and succinic anhydride at 180°C for 2 hours as an example, when the aspartic acid:succinic anhydride ratio is 1:1, N = 2, 3, 4, and 5 are predominant, with N = 3 being the most common, followed by N = 2 (as shown in Figure 8). When the aspartic acid:succinic anhydride ratio is 1:3, N = 1, 2, 3, 4, and 5 are predominant, with N = 2 being the most common, followed by N = 3 (as shown in Figure 9). When the aspartic acid:succinic anhydride ratio is 1:10, N = 0, 1, and 2 are predominant, with N = 0 being the most common, followed by N = 1 (as shown in Figure 10). The above N value analysis is obtained through spectral curve integration analysis.

[0071] In the practice of polymer synthesis, the dibasic acid can be converted into an ester of its lower alcohol (such as C1-C6 alkyl alcohol) or a prepolymer of the diol, and then the polymer synthesis is carried out; therefore, the ester or prepolymer of the dibasic acid monomer shown in Formula I or the reaction mixture of the dibasic acid monomer shown in Formula I and the lower alcohol and / or diol also falls within the scope of protection of the present invention.

[0072] II. First Modifying Structural Unit

[0073] The aspartic acid monomer containing the imide ring structure is introduced into the polymer to form a first modified structural unit. In a specific aspect of the present invention, the first modified structural unit is a polyester: or a combination thereof.

[0074] wherein R3 is the residue of a diol used in polymer synthesis.

[0075] When the aspartic acid monomer containing an imide ring structure has an open ring structure (carboxyl group) and / or a double bond structure, the first modified structural unit also contains the same open ring structure (carboxyl group) and / or double bond structure and forms branching and / or crosslinking in the polymer.

[0076] In a further embodiment of the present invention, the main chain structural unit of the modified polymer is also polyester:

[0077] Wherein R2 is the residue of a dibasic acid used for polymer synthesis, R3 is the residue of a diol used for polymer synthesis, and R3 in the main chain structural unit and the first modified structural unit are the same or different.

[0078] In a further embodiment of the present invention, the polymer is branched and / or cross-linked through the ring-opening carboxyl groups and / or double bonds of the side chains of the first modifying monomer.

[0079] In certain aspects of the present invention, the aspartic acid of the first modified structural unit is derived from biomass, which is low in cost and renewable, thus meeting the needs of sustainable development.

[0080] In another aspect of the present invention, the first modified structural unit improves the rigidity of the polymer; in another aspect, it improves the temperature resistance of the polymer.

[0081] III. Polymers containing a second modifying structural unit

[0082] The polymer of the present invention may optionally include a second modified unit that is heat-resistant, transparent or has a high barrier property. The second modified unit may be composed of a polymerized repeating unit consisting of a dibasic acid, a diamine or an amino acid (one or more of isophthalic acid, furandicarboxylic acid, camphoric acid, adipic acid, proline, and m-xylenediamine) and a diol (one or more of ethylene glycol, butanediol, and 1,4-cyclohexanedimethanol).

[0083] IV. Alloy

[0084] The polymers of the present invention may form alloys with each other or optionally with other polymers.

[0085] V. Composition and Molded Article

[0086] The present invention also provides a composition or a molded body of the above polymer. Methods for processing or molding various types of polymers are known in the art.

[0087] Taking polyester copolymers as an example, the polyester composition of the present invention further comprises a plasticizer, a crystal nucleating agent or a hydrolysis inhibitor in addition to the aforementioned strength-enhancing polymer.

[0088] The polyester composition of the present invention may contain, as other components besides those mentioned above, fillers (inorganic fillers, organic fillers), flame retardants, antioxidants, hydrocarbon waxes or anionic surfactants (i.e., lubricants), ultraviolet absorbers, antistatic agents, anti-corona agents, light stabilizers, pigments, mildewproofing agents, antibacterial agents, foaming agents, etc., within a range that does not impair the effects of the present invention. Similarly, other polymer materials and other resin compositions may be added within a range that does not impair the effects of the present invention.

[0089] The polyester composition of the present invention can be prepared into a molded body such as a sheet by extrusion molding or press molding; the obtained sheet can also be further thermoformed in a temperature range above the glass transition temperature (Tg) and below the melting point (Tm) of the polyester resin composition, for example, stretched into a film or fiber.

[0090] VI. Products and Applications

[0091] The polymer, alloy thereof, or composition or molded article of the present invention is suitable for use in food containers, food packaging films, disposable tableware such as spoons or straws, transparent boxes for daily necessities, cosmetics, home appliances, etc., transparent windows for cardboard boxes, etc., transparent folders, ID holders and other stationery, industrial films or agricultural films, and chemical fibers for clothing or industry.

[0092] VII. Technical Terms

[0093] Structural units and segments

[0094] The structural unit, also known as the monomer unit, is the smallest indivisible structural unit included in the polymer. It has the same structure as the monomer except for the functional group that undergoes polymerization. In a binary copolymer, two different structural units are contained and can be divided into random copolymers, alternating copolymers or block copolymers, etc. The polymer of the present invention is preferably a random copolymer.

[0095] Melt flow index

[0096] The melt flow index of the present invention is tested according to ASTM-D1238, with a unit of g / 10 min and an error range of ±5.

[0097] Dicarboxylic acids that are easily cyclized HOOC-X-COOH

[0098] The HOOC-X-COOH is a dicarboxylic acid that readily cyclizes, i.e., a dicarboxylic acid that readily forms a cyclic anhydride in the absence of a catalyst or under catalytic conditions. Dicarboxylic acids that readily cyclize are known to those skilled in the art, for example, see CN110790906B. HOOC-X-COOH may be selected from an alkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, an alkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl and is interrupted by one or more O atoms, an alkenedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen or alkyl, a cycloalkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkenedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, an aromatic dicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, or a bridged cyclic dicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro. Preferably, HOOC-X-COOH can be selected from at least one of succinic acid, 2-methylsuccinic acid, 2-phenylsuccinic acid, 2-benzylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,3-diphenylsuccinic acid, 1,2-cyclobutanedicarboxylic acid, 2,2,3,3-tetramethylsuccinic acid, methylmaleic acid, dimethylmaleic acid, phthalic acid, hexahydrophthalic acid, norbornenic acid, tetrahydrophthalic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-phenylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, diglycolic acid, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, 2,3-pyridinedicarboxylic acid, and 3,4-pyridinedicarboxylic acid. The cyclic anhydride of HOOC-X-COOH can be preferably selected from succinic anhydride, 2-methylsuccinic anhydride, 2-phenylbutyric anhydride, 2-benzylsuccinic anhydride, 2,2-dimethylsuccinic anhydride, 2,3-dimethylsuccinic anhydride, 2,3-diphenylsuccinic anhydride, 1,2-cyclosuccinic anhydride, 2,2,3,3-tetramethylsuccinic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, phthalic acid At least one of dihydrophthalic anhydride, hexahydrophthalic anhydride, nadic anhydride, tetrahydrophthalic anhydride, glutaric anhydride, 2-methylglutaric anhydride, 3-methylglutaric anhydride, 3-phenylglutaric anhydride, 2,2-dimethylglutaric anhydride, 3,3-dimethylglutaric anhydride and diglycolic anhydride, 2,3-furandicarboxylic anhydride, 3,4-furandicarboxylic anhydride, 2,3-pyridinedicarboxylic anhydride and 3,4-pyridinedicarboxylic anhydride.

[0099] Dicarboxylic acids for polymer synthesis

[0100] The dicarboxylic acid used for polymer synthesis in the present invention can be used for the synthesis of polymer bulk structural units, and can also be used for the synthesis of structural units for improving polymer strength. When used for the synthesis of structural units for improving polymer strength, that is, HOOC-R2-COOH defined in the present invention, it can be any dicarboxylic acid different from HOOC-X-COOH, for example, it can be the easily cyclized dicarboxylic acid described above for HOOC-X-COOH; or it can be a dicarboxylic acid that is not easily cyclized, such as terephthalic acid, 2,5-furandicarboxylic acid, oxalic acid, malonic acid, 1,6-hexanediol, 1,10-decanedioic acid, and 1,18-octadecanediol. Preferably, HOOC-R2-COOH can be selected from an alkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, an alkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl and is interrupted by one or more O atoms, an alkenedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen or alkyl, a cycloalkanedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkenedicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, an aromatic dicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, or a bridged cyclic dicarboxylic acid which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro. Preferably, HOOC-R2-COOH can be selected from succinic acid, 2-methylsuccinic acid, 2-phenylsuccinic acid, 2-benzylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,3-diphenylsuccinic acid, 1,2-cyclobutanediol, 2,2,3,3-tetramethylsuccinic acid, oxalic acid, malonic acid, 1,6-hexanediol, 1,10-decanedioic acid, 1,18-octadecanedioic acid, maleic acid, methylmaleic acid, dioctadecanedioic ...6-hexanediol, 1,10-decanedioic acid, 1,18-octadecanedioic acid, 1,6-hexanediol, 1,6-hexanediol, 1,18-octadecanedioic acid, 1,6-hexanediol, 1,6-hexanediol, 1, At least one of methylmaleic acid, phthalic acid, hexahydrophthalic acid, norbornenic acid, tetrahydrophthalic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-phenylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, diglycolic acid, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, 2,3-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, terephthalic acid, and 2,5-furandicarboxylic acid.

[0101] Diol HO-R3-OH for polymer synthesis

[0102] The diol used for polymer synthesis can be selected from alkylene glycols that are unsubstituted or substituted with substituents selected from halogen, alkyl or nitro groups, OH-alkylene-cycloalkylene-alkylene-OH that are unsubstituted or substituted with substituents selected from halogen, alkyl or nitro groups, polyether glycols, or alkylene glycols interrupted by one or more nitrogen atoms; preferably, at least one selected from alkylene glycols containing 2 to 18 carbon atoms, polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, N-methyldiethanolamine, and N-ethyldiethanolamine. Preferably, at least one selected from ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,18-octadecanediol, polyethylene glycol, and 1,4-cyclohexanedimethanol.

[0103] Polyester structural unit

[0104] The polyester structural unit used in the present invention has the common meaning in the art, and is preferably formed by polycondensation of the above-mentioned dicarboxylic acid used for polymer synthesis and diol used for polymer synthesis.

[0105] The present invention will be further described below with reference to the embodiments. The examples of the embodiments are intended to explain the present invention but should not be construed as limiting the present invention.

[0106] Example

[0107] Monomer Synthesis Example 1

[0108] Aspartic acid:succinic acid = 1:3 molar ratio was reacted in a reactor, and 200 ppm of antioxidant and heat stabilizer were added. The temperature was raised and melted under nitrogen protection to react. The NMR spectrum of the obtained product is shown in Figure 2.

[0109] Monomer Synthesis Example 2

[0110] Aspartic acid:succinic acid = 1:5 molar ratio was reacted in a reactor, and 200 ppm of antioxidant and heat stabilizer were added. The temperature was raised and melted under nitrogen protection to react. The NMR spectrum of the obtained product is shown in Figure 3.

[0111] As can be seen from Figures 2 and 3, 2.9 is the methylene absorption peak when aspartic acid is not self-polymerized, and the peaks near 3.08 and 2.84 are the methylene absorption peaks on the ring when aspartic acid is self-polymerized. The ratio is determined by integration as the proportion of aspartic acid increases, that is, the number of self-polymerized rings increases. It can be seen that the products obtained in Monomer Synthesis Examples 1 and 2 are a mixture of compounds of Formula I-1 with different n values, that is, the proportion of compounds of Formula I-1 in which n is greater than 0 is greater than 0, and as the proportion of aspartic acid increases, the proportion increases.

[0112] Monomer Synthesis Example 3

[0113] Aspartic acid: 1,2-cyclohexanedicarboxylic acid = 1:3 molar ratio was reacted in a reactor, and 200 ppm of antioxidant and heat stabilizer were added. The temperature was raised and melted under nitrogen protection to react. The NMR spectrum of the obtained product is shown in Figure 4.

[0114] Monomer Synthesis Example 4

[0115] Aspartic acid:phthalic acid = 1:3 molar ratio was reacted in a reactor, and 200 ppm of antioxidant and heat stabilizer were added. The temperature was raised and melted under nitrogen protection to react. The NMR spectrum of the obtained product is shown in Figure 5.

[0116] As shown in Figures 4 and 5, the hydrogen absorption peaks on the cyclohexanedicarboxylic acid and phthalic acid rings are shifted, and the aspartic acid amino peak disappears, indicating that compounds of formula I-2 and formula I-3 with cyclohexanedicarboxylic acid and phthalic acid end-chains are produced.

[0117] Polymer Synthesis Example 1

[0118] Step 1: While the monomers are being synthesized, succinic acid and butanediol are added to another reactor to control the ratio of succinic acid to butanediol to be 1:1.2. 200 ppm of antioxidant and heat stabilizer are also added. The mixture is heated and melted under nitrogen protection to carry out esterification reaction.

[0119] Step 2: Blend the materials from the two kettles, heat to 160°C, add 200ppm of anhydrous zinc acetate, add butanediol, control the system's diol:diacid ratio to 1.2:1, and esterify for 1h-2h.

[0120] Step 3: After the esterification is completed, 200ppm of tetrabutyl titanate is added as a catalyst to carry out polycondensation reaction. The vacuum degree in the reactor is slowly reduced, and the temperature is further raised to 250°C. The vacuum degree is maintained below 50Pa and the reaction is terminated after 4-6 hours to obtain the modified product. Its structure is:

[0121] Polymer Synthesis Example 2

[0122] Step 1: While the monomers are being synthesized, terephthalic acid, ethylene glycol, 200 ppm each of antioxidant, heat stabilizer and anhydrous zinc acetate are added to another reactor. During the stirring process, nitrogen is gradually introduced to 150 kPa and the temperature is raised to 220°C for pressure esterification.

[0123] Step 2: After esterification, the two kettles are mixed and ethylene glycol is added to adjust the diol:diacid ratio to 1.2:1. 200 ppm of antimony trioxide is added at 200°C. When the reaction water output reaches 99% of the theoretical value, the pressure is returned to normal for polycondensation. The vacuum level in the kettle is slowly reduced, and the temperature is further raised to 250°C. The vacuum level is maintained below 50 Pa for 2-4 hours before the reaction is terminated. The modified PET resin is then discharged. The structure is shown below:

[0124] Polymer Synthesis Example 3 (One-pot Random Copolymerization)

[0125] Step 1: Monomer synthesis;

[0126] Step 2: After monomer synthesis is complete, add the remaining succinic acid and butanediol to control the aspartic acid modified segment to 10%. Control the system's diol:diacid ratio to be 1.2:1. Add 200ppm of zinc acetate and conduct the esterification reaction at 180°C for 2-4 hours.

[0127] Step 3: After the esterification is completed, 200ppm of tetrabutyl titanate is added as a catalyst to carry out polycondensation reaction, slowly reduce the vacuum degree in the kettle, and further increase the temperature to 250℃, maintain the vacuum degree below 50Pa, and react for 4-6 hours before ending the reaction.

[0128] Effect Examples

[0129] Effect Example 1: Effect of different modified unit ratios on the properties of PBS polyester

[0130] PBS polyesters with different modified unit ratios were synthesized (Examples 1-1 to 1-7) by referring to the method of Polymer Synthesis Example 1, and the polymers of Examples 1-8 were synthesized by referring to Polymer Synthesis Example 3. A conventional method was used to synthesize PBS as a control. The XRD curve of PBS modified with 10% aspartic acid modified units is shown in Figure 6: the diffraction peaks at 19.7, 21.88, and 22.52 correspond to the 020, 021, and 110 crystal planes of α-crystalline PBS, respectively. The characteristic peaks are obvious, indicating that the main crystalline body of the material is PBS; the FTIR spectrum is shown in Figure 7, with a wavelength of 3050-3500 cm -1 、1660-1640cm -1There is no absorption peak at the end, that is, there is no absorption of primary amine and secondary amide groups, indicating that the aspartic acid in the polymer has been completely ring-closed. Referring to Table 1 Examples 1-7, when the aspartic acid modified unit content is 5%, the material heat resistance temperature is 115.3°C (Example 1-1); when the aspartic acid modified unit accounts for 10%, the material heat resistance reaches the best of 120.5°C (Example 1-2), and the tensile strength is also significantly improved. As the amount of modified addition increases, the regularity of the material is greatly damaged, the heat resistance is reduced, but it can maintain a high elongation at break (>300%) while maintaining a high tensile strength. The semi-crystallization time is longer and can be controlled by the ratio, making it more suitable for preparing membrane materials. Moreover, due to the reduction in the amount of succinic acid used, the cost can be effectively reduced. After the aspartic acid modified unit content is >70%, the material regularity is improved and the heat resistance returns to above 90°C. In addition, more imide rings can provide better hydrophilic properties, which can expand the application in the field of hydrophilic polymer materials while reducing costs.

[0131] Effect Example 2: Effect of the ratio of precursors of modified monomers (aspartic acid: succinic acid) on the properties of modified polymers

[0132] Monomers with different precursor ratios were synthesized with reference to Monomer Synthesis Example 1 or 2, and modified polymers were synthesized with reference to Polymer Synthesis Example 1 (see Table 2). The results show that as the aspartic acid:succinic acid ratio increases from 1:5 to 1:3, the melting point of the material is significantly improved. After the ratio is further increased to 1:1, the heat resistance of the material decreases but is close to that of the PBS comparative example. Analysis of Figures 2 and 3 shows that when the aspartic acid ratio increases, more self-polyimide rings are formed, that is, a moderate number of imide rings can make the material have both good heat resistance and mechanical strength.

[0133] Effect Example 3: Effect of modified monomers with different precursors (cyclohexanedicarboxylic acid and phthalic acid) on the properties of modified polymers

[0134] Refer to Monomer Synthesis Example 3 or 4 to synthesize monomers with different precursors, and refer to Polymer Synthesis Example 1 to synthesize modified polymers (see Table 3). The results show that the tensile strength of the synthesized materials is greatly improved. At the same time, the introduction of cyclohexanedicarboxylic acid and phthalic acid will destroy some regularity, resulting in a lower melting point than the polymer modified by the monomer with succinic acid end-chain.

[0135] Effect Example 4: Study on the modification of different polyesters

[0136] Referring to Polymer Synthesis Example 2, various modified polyesters were synthesized. See Table 4. The results show that the introduction of the modified units increased the elongation at break of the various polyester materials compared to the control examples, effectively improving toughness. Crystallization performance testing also showed that the introduction of the modified units reduced the half-crystallization time of PBT, increasing it from 54s to 180s.

Claims

1. A dibasic acid monomer containing an imide ring structure as shown in (Formula I), an ester or a prepolymer of the monomer, wherein R1 is a derivative group of aspartic acid, and X is a residue of a dibasic acid that is easily cyclic-formed or -C=C-; n is an integer of 0 or greater than 0; preferably, n is any integer from 0 to 7; Or, the monomer includes one or more dibasic acid monomers containing an imide ring structure as shown in (Formula I), an ester of the monomer or a ring-opened structure of a prepolymer, for example: Or a combination of (Formula II) and (Formula III) in the ring-opening manner, wherein n1 and n2 are non-negative integers less than n, preferably n1 and n2 are any integers from 0 to 6; The N value is an independent value of n, n1 or n2; preferably, the monomer content of the N value greater than 0 is greater than 0; X is preferably -C=C-; or X is preferably at least one of an alkylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, an alkylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl and is interrupted by one or more O atoms, an alkenylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkylene group or a heterocycloalkyl group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a cycloalkenylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, an arylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, a heteroarylene group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro, or a bridged ring group which is unsubstituted or substituted with a substituent selected from halogen, alkyl or nitro; Preferably, the alkylene group in the definition of X is C1-C10 alkylene group, preferably C1-C6 alkylene group, more preferably C1-C5 alkylene group, and most preferably methylene, ethylene, 1-methylethylene, 1,1-dimethylethylene, 1,2-dimethylethylene, 1,1,2,2-tetramethylethylene, 1-phenylethylene, 1-benzylethylene, 1,1-diphenylethylene, 1,1-dibenzylethylene, 1,2 -diphenylethylene, 1,2-dibenzhydrylethylene, propylene, 1-methylpropylene, 2-methylpropylene, 1,1-dimethylpropylene, 1,2-dimethylpropylene, 2,2-dimethylpropylene, 1,3-dimethylpropylene, 1-phenylpropylene, 2-phenylpropylene, 1,2-diphenylpropylene, 2,2-diphenylpropylene or 1,3-diphenylpropylene; the alkenylene in the definition of X is C2-C10 Alkenylene, preferably C2-C6 alkenylene, more preferably C2-C3 alkenylene, most preferably vinylene, 1-methylvinylene, 1,2-dimethylvinylene or propenylene; the alkylene group in the definition of X, which is unsubstituted or substituted by a substituent selected from halogen, alkyl, aryl, arylalkyl or alkylaryl, is interrupted by 1-3 oxygen atoms, such as 2-oxa-1,3-ethylene; the cycloalkylene group in the definition of X is C3-C8 cycloalkylene, preferably C4-C6 cycloalkylene, most preferably cyclobutylene or cyclohexylene; the cycloalkenylene group in the definition of X may be C4-C8 cycloalkenylene, preferably C4-C6 cycloalkenylene, most preferably 3-cyclohexene-1,6-diyl; the arylene group in the definition of X is C6-C10 arylene, preferably phenylene, such as 1,2-phenylene; the bridging ring group in the definition of X is norbornene; Most preferably, X is -C=C-, a succinic acid residue (ethylene), a 1,2-cyclohexanedicarboxylic acid residue (1,2-cyclohexylene) or a phthalic acid residue (1,2-phenylene); Preferably, the aspartic acid in the monomer is of biological origin; preferably, the aspartic acid has a 14 C / 12 C ratio.

2. A monomer composition, comprising a dibasic acid monomer containing an imide ring structure as shown in (Formula I) in claim 1, or (Formula I) further comprising (Formula II) and / or (Formula III), an ester or prepolymer of the monomer, and comprising two or more monomers with different N values, wherein the N value is an independent value of n, n1 or n2, and the content of the monomer with an N value greater than 0 is greater than 0; Preferably, the monomer composition is a dibasic acid monomer containing an imide ring structure represented by formula I, or a mixture of formula I and formula II, an ester or a prepolymer of the monomer, more preferably a mixture of monomers having at least one N value of 0 and n of 1-7, or more preferably a mixture of monomers having at least two N values ​​of 1-7; Or, the monomer composition is a dibasic acid monomer containing an imide ring structure represented by Formula I and Formula III, or a mixture of Formula I, Formula II and Formula III, an ester or a prepolymer of the monomer, more preferably comprising a mixture of at least one monomer having an N value of 0-7 and at least one monomer having an N value of 0-6 among n1 and n2, and most preferably comprising at least one monomer having an N value greater than 0 among n, n1 and n2; Preferably, the monomer or monomer composition comprises at least two, three, four, five or six monomers having N values ​​of 0, 1, 2, 3, 4 or 5; Preferably, the monomer or monomer composition includes monomers with N values ​​of 0, 1 and 2; preferably, the monomer with N value of 0 has the largest content; Preferably, the monomer or monomer composition includes monomers with N values ​​of 1, 2, 3, 4, and 5; preferably, the monomer with N value of 2 has the largest content; Preferably, the monomer or monomer composition comprises monomers with N values ​​of 2, 3, 4 and 5; preferably, the monomer with N value of 3 has the largest content.

3. A copolymer, comprising a polymer main structural unit and a first modified structural unit, wherein the first modified structural unit comprises a structure shown in Formula VI: wherein R1 is a derivative group of aspartic acid, and X is a residue of a dibasic acid that is easily cyclic-formed or -C=C-; Preferably, the first modified structural unit is a polyester structure shown in (Formula VI-1): R3 is a diol residue for polymer synthesis, preferably, selected from C1-C12 alkylene groups, alicyclic groups, or heterocyclic groups containing at least one N, O, or S atom, which are unsubstituted or substituted by substituents selected from halogen, alkyl, aryl, arylalkyl, or alkylaryl groups; preferably, R3 is selected from at least one of C2-C8 alkylene groups, alicyclic groups, or C5-C8 heterocyclic groups containing oxygen atoms, which are unsubstituted or substituted by substituents selected from halogen, alkyl, aryl, arylalkyl, or alkylaryl groups; more preferably, C2-C6 alkylene groups; Preferably, the first modified structural unit further comprises a structure represented by Formula VII and / or Formula VIII: n is an integer of 0 or greater than 0, preferably n is any integer of 0-7; n1 and n2 are non-negative integers less than n, preferably n1 and n2 are any integers of 0-6; preferably, the N value is an independent value of n, n1 or n2, and the content of the monomer with an N value greater than 0 is greater than 0; Preferably, the first modified structural unit further comprises a polyester structure represented by (Formula VII-1) and / or (Formula VIII-1): Preferably, the first modified structural unit forms a branched and / or cross-linked structure through double bonds and / or carboxyl groups on the side chains.

4. The copolymer according to claim 3, wherein the main structural unit is polyester; Preferably, the main structural unit is a polyester such as one or more of aliphatic polyester, aliphatic-aromatic polyester, and aromatic polyester; further preferably, the main structural unit comprises two or more different structural units; Preferably, it is a structural unit of one or more polyesters selected from PBS, PES, PBA, PET, PBT, PTT, PBAT, PBST, PEAT or PEST.

5. The copolymer according to any one of claims 3 to 4, characterized in that The first modified structural unit accounts for 0.5-99.5% of the total structural units of the polymer, preferably 1-90 mol%, and more preferably 5%-30 mol%.

6. The copolymer according to any one of claims 3 to 5, further comprising a second modifying structural unit.

7. A polymer alloy comprising the copolymer according to any one of claims 3 to 6.

8. A polymer composition or a molded article comprising the copolymer according to any one of claims 3 to 6 or the polymer alloy according to claim 7.

9. Use of the copolymer according to any one of claims 3 to 6, the polymer alloy according to claim 7, or the composition or molded body according to claim 8 for food containers, food packaging films, disposable tableware such as spoons or straws, packaging containers such as transparent boxes for daily necessities, cosmetics, and household appliances, transparent windows for cartons, transparent folders, stationery such as document holders, industrial films or agricultural films, and chemical fibers for clothing or industry.

10. Use of the monomer according to claim 1, the ester or prepolymer of the monomer, or the monomer composition according to claim 2, or the precursor composition of the monomer or monomer composition for synthesizing a polymer, wherein the precursor composition comprises aspartic acid and an easily cyclized dibasic acid; Preferably, the monomer or monomer composition includes monomers with N values ​​of 0, 1 and 2; preferably, the monomer with N value of 0 has the largest content; Preferably, the monomer or monomer composition includes monomers with N values ​​of 1, 2, 3, 4, and 5; preferably, the monomer with N value of 2 has the largest content; Preferably, the monomer or monomer composition comprises monomers with N values ​​of 2, 3, 4 and 5; preferably, the monomer with N value of 3 has the largest content.

11. A method for synthesizing the monomer according to claim 1 or the monomer composition according to claim 2, comprising a reaction step of aspartic acid and a readily cyclizable dibasic acid or its anhydride; preferably, the molar ratio of aspartic acid to the readily cyclizable dibasic acid is 1:50-50:1, preferably 1:10-10:1, and more preferably 1:3-1:

1.

12. A method for synthesizing a copolymer according to any one of claims 3 to 6, comprising: 1) Providing the monomer according to claim 1 or the monomer composition according to claim 2; 2) providing a polyester prepolymer of a dibasic acid and a diol; 3) subjecting the monomer or monomer composition of step 1 and the prepolymer of step 2) and optionally newly added dibasic acid and / or diol to a condensation reaction; Preferably, the method of claim 11 is used to provide the monomer of claim 1 or the monomer composition of claim 2.

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