Galactoxyloglucan derivative

Abstract

Provided is a galactoxyloglucan derivative in which hydrogen in at least some of a plurality of hydroxyl groups of galactoxyloglucan are substituted with an acyl group, said galactoxyloglucan derivative having one kind of the acyl group that is represented by R1-CO- (where R1 is an alkyl group having 3-17 carbon atoms).

Description

Galactoxyloglucan derivatives CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2024-115165, the disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a galactoxyloglucan derivative.

[0003] In order to provide materials that can replace petroleum-derived plastics, attempts have been made to impart thermoplasticity to polysaccharides derived from plants and the like.

[0004] For example, Patent Document 1 describes that esterified starch having thermoplastic properties is obtained by esterifying starch.

[0005] Furthermore, Patent Documents 2 and 3 describe that a thermoplastic β-1,3-glucan derivative can be obtained by esterifying at least one of the multiple hydroxyl groups of a β-1,3-glucan called paramylon, which is synthesized by Euglena (green algae).

[0006] Japanese Patent Publication No. 2018-53192 Japanese Patent Publication No. 2014-98095 Japanese Patent Publication No. 2017-218566

[0007] However, if starch, which is widely used in food, were to be used as a substitute for plastic, there is a risk that the substitute would compete with food ingredients.Similarly, if paramylon, which has been attracting attention for its various functional possibilities, were to be used as a substitute for plastic, there is a risk that the substitute would compete with materials used in many products other than plastic products.

[0008] Furthermore, paramylon cannot be used as a resource material because it requires the artificial cultivation of Euglena to obtain industrially viable amounts.

[0009] Therefore, the present inventors focused on galactoxyloglucan extracted from the seeds of tamarind fruit. The pulp of tamarind fruit is often used in various foods such as sweets and sauces. On the other hand, a considerable amount of tamarind seeds are discarded. Therefore, if galactoxyloglucan could be used as an alternative material to plastics, it would lead to the utilization of tamarind seeds as a resource.

[0010] In view of the above circumstances, an object of the present invention is to provide a galactoxyloglucan derivative having thermoplasticity.

[0011] The galactoxyloglucan derivative according to the present invention is as follows: (1) A galactoxyloglucan derivative in which at least some hydrogen atoms of a plurality of hydroxyl groups of a galactoxyloglucan are substituted with acyl groups, wherein the galactoxyloglucan derivative is represented by the formula: R １ -CO-(R １ A galactoxyloglucan derivative having one of the acyl groups represented by the formula (I): an alkyl group having 3 to 17 carbon atoms.

[0012] (2) The galactoxyloglucan derivative according to (1) above, wherein the degree of substitution of the plurality of hydroxyl groups with the acyl groups is 40% or more.

[0013] (3) The galactoxyloglucan derivative according to (1) or (2) above, which is used for producing a molded article by thermoforming.

[0014] (4) The galactoxyloglucan derivative according to (3) above, wherein the heating temperature for the thermoforming is 80°C to 230°C.

[0015] As described above, the present invention can provide a galactoxyloglucan derivative having thermoplastic properties.

[0016] A galactoxyloglucan derivative according to an embodiment of the present invention will be described.

[0017] In the galactoxyloglucan derivative of this embodiment, at least some of the hydrogen atoms in the hydroxyl groups of the galactoxyloglucan are substituted with acyl groups. In other words, in the galactoxyloglucan derivative of this embodiment, at least some of the hydroxyl groups of the galactoxyloglucan are converted to ester groups by acylation. The galactoxyloglucan derivative of this embodiment can be used as a molding material for various containers, films, fibers, and the like produced by thermoforming. The molding material may be used to produce molded articles by injection molding or extrusion molding, or may be used to produce films, etc. by hot press molding, or may be used to produce fibers by melt spinning or solution spinning.

[0018] The galactoxyloglucan is a polysaccharide contained in tamarind (Tamarindus Indica L.) seeds. As shown in the following chemical formula (1), the galactoxyloglucan contains a repeating structure having a main chain composed of three D-glucose molecules linked by β-(1-4) bond and two side chains linked to the main chain. The first side chain is composed of D-xylose linked by α-(6-1) bond to one of the three D-glucose molecules in the main chain, and D-galactose linked by β-(2-1) bond to the D-xylose. The second side chain is composed of D-xylose linked by α-(6-1) bond to one of the three D-glucose molecules in the main chain. In the repeating structure of the following chemical formula (1), the number of protons in the sugar backbone (the total number of protons in the main chain and the side chains) is 40, and the total number of hydroxyl groups that can be substituted by acyl groups is 16.

[0019]

[0020] The galactoxyloglucan maintains substantially the same molecular weight as when it existed in nature. In other words, the main chain or side chain of the galactoxyloglucan has not been artificially decomposed by enzymatic degradation, acid or alkali hydrolysis, or the like. Such galactoxyloglucan typically exhibits a viscosity of 300 to 600 mPa·s at 25°C in a 1.5% by mass aqueous solution (galactoxyloglucan:water=1.5:98.5). The viscosity here refers to a value measured using a Brookfield viscometer (B-type viscometer) at a rotation speed of 30 rpm.

[0021] The galactoxyloglucan derivative is R １ -CO-(R １ R: an alkyl group having 3 to 17 carbon atoms). That is, the galactoxyloglucan derivative has only one type of the acyl group. １ The number of carbon atoms in R is preferably 4 or more, and more preferably 5 or more. １ The number of carbon atoms is preferably 16 or less, and more preferably 15 or less.

[0022] R １ The alkyl group represented by is preferably acyclic. １ The alkyl group represented by the formula (I) is preferably linear, but may be branched. Examples of linear alkyl groups include an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, and an n-heptadecyl group. Examples of branched alkyl groups include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 2,2-dimethylpropyl group, a 3-methylbutyl group, a 2-methylbutyl group, a 1-methylbutyl group, a 1,1-dimethylpropyl group, a 1-ethylpropyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 2,2-dimethylpentyl group, and a 2,3-dimethylbutyl group.

[0023] The stress-strain curve of the molded body produced using the galactoxyloglucan derivative is１ As the number of carbon atoms in the alkyl group represented by R decreases, the tensile stress tends to increase and the elongation tends to decrease. １ As the number of carbon atoms in the alkyl group indicated by ┌┘ ...

[0024] The stress-strain curve also shows a tendency that the tensile stress increases and the elongation decreases as the degree of substitution of the hydroxyl groups with the one type of acyl group decreases. In other words, the stress-strain curve shows a tendency that the tensile stress decreases and the elongation increases as the degree of substitution of the hydroxyl groups with the one type of acyl group increases.

[0025] The degree of substitution of the plurality of hydroxyl groups with the one type of acyl group may be 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, thereby providing the galactoxyloglucan derivative with even more excellent thermoplasticity.

[0026] The degree of substitution is １ The measurement can be performed by H-NMR. The measurement conditions are as follows: ３ ) to prepare a 10 mg / mL sample, and the number of accumulations is 8. １ According to H-NMR measurements, it has been found that for galactoxyloglucan derivatives having only one type of acyl group, the chemical shift value (near 0.9 ppm) of the proton of the methyl group of the acyl group does not overlap with the chemical shift values ​​of other protons, and therefore the degree of substitution, which serves as an index for performance evaluation, can be determined. When determining the degree of substitution of such a galactoxyloglucan derivative, the integral value of 40 protons (approximately in the range of 3 ppm to 6 ppm) in the sugar skeleton of the galactoxyloglucan derivative is defined as Is, the integral value of the protons of the methyl group of the alkyl group of the only type of acyl group is defined as Ia, and the number of methyl groups in the alkyl group is defined as n, the degree of substitution can be calculated using the following formula (m1): Degree of substitution (%) = [Ia / (3 × n)] / [(Is / 40) × 16] × 100 ... (m1)

[0027] The galactoxyloglucan derivative has thermal properties that can be measured using a capillary rheometer (flow tester). Specifically, the capillary rheometer is a constant test force extrusion type capillary rheometer (CFT-500EX, piston diameter 11.282 mm (area 1 cm) manufactured by Shimadzu Corporation). ２ The measurement conditions are as follows: a 1 cm diameter die hole in the cylinder of the capillary rheometer; a 1 mm diameter die hole; and a 1 mm length die. ３ A sample of 10 ...

[0028] The galactoxyloglucan derivative may constitute the entire molding material, or may constitute a part of the molding material. For example, the galactoxyloglucan derivative may be mixed with a petroleum-derived plastic material to form the molding material.

[0029] The molded article obtained by thermoforming the galactoxyloglucan derivative exhibits a tensile breaking strength of 5 MPa to 50 MPa, preferably 5 MPa to 40 MPa, as measured according to the method specified in JIS K7161. The molded article also exhibits a tensile breaking strain of 2% to 20%, preferably 5% to 20%, as measured according to the method specified in JIS K7161.

[0030] The galactoxyloglucan derivative may also constitute the molding material together with a plasticizer. By including a plasticizer in the molding material, the outflow initiation temperature and the offset method temperature are lowered, and the molding material has thermoformability that allows it to be thermoformed at 80°C to 230°C.

[0031] Next, a method for producing the galactoxyloglucan derivative will be described.

[0032] The production method according to this embodiment includes a reaction step of reacting the galactoxyloglucan with an acylating agent to obtain the galactoxyloglucan derivative. １ (R １ An acylating agent having an alkyl group represented by the formula (as defined above) is used.

[0033] The acylating agent is R １ The acylating agent is represented by R １ The acylating agent may be a vinyl ester of a carboxylic acid having an alkyl group represented by the formula (I), a halide of the carboxylic acid, or an acid anhydride of the carboxylic acid. In order to obtain a galactoxyloglucan derivative with a high degree of substitution, it is preferable to use a vinyl ester as the acylating agent and to mix the galactoxyloglucan with an ionic liquid such as 1-ethyl-3-methylimidazolium acetate.

[0034] Although the embodiments have been shown as examples, the galactoxyloglucan derivative of the present invention is not limited to the configuration of the above-mentioned embodiments. Furthermore, the galactoxyloglucan derivative of the present invention is not limited by the above-mentioned effects. The galactoxyloglucan derivative of the present invention can be modified in various ways without departing from the spirit and scope of the present invention.

[0035] The present invention will be further explained below with reference to examples, but the present invention is not limited to these examples.

[0036] Example 1 Galactoxyloglucan (10 g, 0.011 mol, 1 equivalent) was mixed with 1-ethyl-3-methylimidazolium acetate (30 mL) and DMSO (170 mL) and stirred at 70°C for 2 hours to obtain a galactoxyloglucan solution. After cooling to room temperature, vinyl butyrate (40 g, 0.35 mol, 32 equivalents) was added to the galactoxyloglucan solution while stirring, and an acylation reaction was carried out at 70°C to obtain a crude product containing a galactoxyloglucan derivative. Methanol was added to the crude product to form a precipitate containing the galactoxyloglucan derivative, which was then collected by filtration. The precipitate was recrystallized using methanol as a solvent to obtain a purified galactoxyloglucan derivative.

[0037] Example 2 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl hexanoate.

[0038] Example 3 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl octanoate.

[0039] Example 4 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl decanoate.

[0040] Example 5 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl laurate.

[0041] Example 6 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl palmitate.

[0042] Example 7 A galactoxyloglucan derivative was obtained in the same manner as in Example 3, except that the equivalent of vinyl octanoate was changed to 0.7 equivalents.

[0043] Example 8 A galactoxyloglucan derivative was obtained in the same manner as in Example 3, except that the equivalent of vinyl octanoate was changed to 0.5 equivalents.

[0044] Example 9 A galactoxyloglucan derivative was obtained in the same manner as in Example 5, except that the equivalent of vinyl laurate was changed to 0.5 equivalents.

[0045] Reference Example 1 A galactoxyloglucan derivative was obtained in the same manner as in Example 5, except that the equivalent of vinyl laurate was changed to 0.3 equivalents.

[0046] Comparative Example 1 A galactoxyloglucan derivative was obtained in the same manner as in Example 1, except that the acylating agent was changed to vinyl propionate.

[0047] (Measurement of Physical Properties) The degree of substitution, flow-out starting temperature, and offset temperature were measured according to the above-mentioned measurement methods. The results are shown in Tables 1 and 2.

[0048] (Method for evaluating injection moldability) A pneumatic injection molding machine (IMC-5705, manufactured by Imoto Machinery Co., Ltd.) was used to prepare Type A12 test pieces as specified in JIS K7139, and the injection moldability of each galactoxyloglucan derivative was evaluated according to the following evaluation criteria. The injection molding pressure was 97.2 MPa (air pressure 0.6 MPa), and the mold heating temperature was 60°C. The results are shown in Tables 1 and 2. (Evaluation criteria for injection moldability) ○: High fluidity, with the molten material permeating the entire mold. ×: Poor fluidity, with the molten material not permeating the entire mold.

[0049] (Method for evaluating heat press moldability) A film was produced using a heat press (IMC-180C, manual hydraulic heating press, manufactured by Imoto Machinery Co., Ltd.) and the heat press moldability of each galactoxyloglucan derivative was evaluated according to the following evaluation criteria. The heating temperature was the heat press temperature shown in Tables 1 and 2, the pressure was 60 kN, and the pressing time was 10 minutes. The results are shown in Tables 1 and 2. (Evaluation criteria for heat press moldability) ○: A smooth film was obtained. ×: A film with cracks or holes was obtained.

[0050] In addition to the above, the test pieces obtained by injection molding were measured for tensile stress at break and tensile strain at break according to the method specified in JIS K 7161. The results are shown in Tables 1 and 2.

[0051]

[0052]

Claims

1. A galactoxyloglucan derivative in which at least some of the hydrogen atoms of a plurality of hydroxyl groups of a galactoxyloglucan are substituted with acyl groups, wherein the galactoxyloglucan derivative is represented by the formula: R １ -CO-(R １ A galactoxyloglucan derivative having one of the acyl groups represented by the formula (I): an alkyl group having 3 to 17 carbon atoms.

2. The galactoxyloglucan derivative according to claim 1, wherein the degree of substitution of said plurality of hydroxyl groups with said acyl groups is 40% or more.

3. The galactoxyloglucan derivative according to claim 1 or 2, which is used for producing a molded body by thermoforming.

4. The galactoxyloglucan derivative according to claim 3, wherein the heating temperature for said thermoforming is 80°C to 230°C.

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