Β-1,3-glucan ester derivative, resin composition, molded product, electronic part, and electronic apparatus

Abstract

To provide a β-1,3-glucan ester derivative that is free from odor and coloration.SOLUTION: The present invention provides a β-1,3-glucan ester derivative comprising a structure represented by the following structural formula (1) as the main chain, wherein the content of carboxylic acid in the β-1,3-glucan ester derivative is 0.1 mass% or less (where R's independently represent a hydrogen atom or an alkylcarbonyl group, with at least some of R's being alkylcarbonyl groups, and n represents a natural number).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a β-1,3-glucan ester derivative, a resin composition, a molded article, an electronic component, and an electronic device. [Background technology]

[0002] In recent years, bio-based polymers synthesized from renewable resources have been attracting attention. Paramylon, produced by photosynthesis in microalgae such as Euglena, and curdlan, produced by bacteria in a culture medium through fermentation, are linear polymeric polysaccharides composed of β-1,3-glucan.

[0003] Previous research has shown that new fibers and resins can be obtained by introducing ester groups and synthesizing paramylon ester derivatives through chemical modification for the purpose of applying them as plastics.

[0004] Patent Document 1 discloses a resin composition containing a β-1,3-glucan derivative resin and a phosphorus-based flame retardant, the phosphorus-based flame retardant having an average particle size of 5 μm or less in the resin, for the purpose of providing a resin composition having excellent mechanical strength and flame retardancy.

[0005] Patent Document 2 discloses a paramylon resin in which the weight-average molecular weight, substituent, degree of substitution, impact strength, and MFE of paramylon are specified, with the aim of providing a paramylon resin with excellent mechanical properties and thermoplasticity. Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional β-1,3-glucan ester derivatives had problems such as odor and coloration. An object of the present invention is to provide a β-1,3-glucan ester derivative that is odorless and colorless. [Means for solving the problem]

[0007] The above problems can be solved by the present invention described below. A β-1,3-glucan ester derivative having at least a structure represented by the following structural formula (1) as its main chain, characterized in that the amount of carboxylic acid in the β-1,3-glucan ester derivative is 0.1 mass% or less. [ka] (In the formula, each R is independently a hydrogen atom or an alkylcarbonyl group, at least a part of R is an alkylcarbonyl group, and n is a natural number.) Effect of the Invention

[0008] According to the present invention, a β-1,3-glucan ester derivative that is odorless and colorless can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present invention will be described. The present invention was completed based on the discovery during the development of a resin formulation for a β-1,3-glucan ester derivative that the odor of the β-1,3-glucan ester derivative is caused by the residual carboxylic acid content in the β-1,3-glucan ester derivative. The β-1,3-glucan ester derivative can be obtained by reacting β-1,3-glucan with a carboxylic acid to esterify at least a portion of the hydroxyl groups in the β-1,3-glucan with the carboxylic acid. Although the carboxylic acid, which is the raw material for the reaction, remains in the β-1,3-glucan ester derivative, the present invention is characterized in that the amount of carboxylic acid remaining in the β-1,3-glucan ester derivative is kept to 0.1 mass% or less, thereby preventing odor and discoloration caused by the carboxylic acid. The present invention will now be described. Hereinafter, the amount of carboxylic acid remaining in the β-1,3-glucan ester derivative is referred to as the "residual carboxylic acid amount."

[0010] <β-glucan> β-Glucan refers to a group of polysaccharides in which β-glucose units are linked by (1→3), (1→4), and (1→6) bonds, and includes cellulose, laminaran, lichenan, cereal β-glucans, β-glucans derived from yeast cell walls such as callose and zymosan, β-glucans derived from krestin, lentinan, dizophyllan, grifolan, pachyman, β-glucans derived from mushrooms such as Ganoderma lucidum, Agaricus blazei, Yamabushitake, Obliquus obliquus, Kawariharatake, and Meshimakobu, curdlan, and paramylum derived from Euglena.

[0011] <β-1,3-glucan> β-1,3-glucan is a polysaccharide produced mainly by algae, fungi, etc. β-1,3-glucan has a glucose bond that is linked by β-1,3-bonds, which is similar to cellulose, in that glucose is linked by β-1,4-bonds. They also share the lack of thermoplasticity.

[0012] However, the polymer chains of β-1,3-glucan can take on a triple helix structure, which differs from the sheet-like structure of cellulose. Due to this difference in structure, β-1,3-glucan has unique physical properties and reaction characteristics that are different from those of cellulose.

[0013] β-1,3-glucan is easy to purify, and the purification process can be carried out under milder conditions than for cellulose. That is, cellulose in plants exists in a form tightly bound to lignin and hemicellulose, and in order to isolate the cellulose, a complex and harsh purification process using strong acids and the like is required. In contrast, β-1,3-glucan from algae and fungi often exists alone, making it easy to purify and not requiring the use of strong acids and the like. Therefore, β-1,3-glucan is resistant to depolymerization even during the purification process, and can be isolated while roughly maintaining the monodisperse state with a narrow distribution of molecular chain lengths that is characteristic of natural polymers.

[0014] When β-1,3-glucan is used as a raw material for resins, this monodispersity is a major feature. In other words, since this monodispersity is maintained throughout the acylation reaction, the resulting β-1,3-glucan ester derivative is less likely to have defects due to differences in melting points. In addition, since β-1,3-glucan can be isolated with a higher purity than cellulose, the resulting β-1,3-glucan ester derivative tends to have higher transmittance and other properties than cellulose derivatives.

[0015] The β-1,3-glucan may or may not have a side chain. Examples of β-1,3-glucans having side chains include schizophyllan, lentinan, etc. Examples of β-1,3-glucans not having side chains include curdlan, paramylon, etc.

[0016] (Paramylon) Paramylon is a storage polysaccharide β-glucan contained in Euglena and is derived from Euglena. It is a polymer formed by polymerizing approximately 700 glucose units through β-1,3-bonds.

[0017] (Cardran) Curdlan is a polysaccharide produced by soil bacteria in a medium through fermentation. It is also a linear β-1,3-glucan, and has a molecular weight three times that of paramylon.

[0018] The β-1,3-glucan may be of biological origin or synthetic origin. From the viewpoint of reducing the environmental load, those of biological origin are preferred, and those of plant origin are more preferred. Among them, β-1,3-glucan separated from microalgae that synthesize β-1,3-glucan within cells is preferred, from the viewpoint of ease of isolation and purification of β-1,3-glucan.

[0019] As the microalgae, Euglena (a microalgae belonging to the phylum Euglenophyta) is preferable because Euglena is easy to culture, has a fast growth cycle, and accumulates a large amount of paramylon particles as a photosynthetic product within the cells.

[0020] Paramylon synthesized and accumulated by Euglena is a β-1,3-glucan that is usually composed of 1500 to 2000 glucose units linked together by β-1,3-bonds. β-1,3-glucans such as paramylon can be separated from microalgae by standard methods.

[0021] <β-1,3-glucan ester derivative> In the β-1,3-glucan ester derivative, some of the hydroxyl groups in the glucose constituting the main chain of β-1,3-glucan are acylated with acyl groups. That is, the β-1,3-glucan ester derivative has an acyl group. The presence of acyl groups (i) weakens the interactions between molecular chains by disrupting the molecular chain arrangement, and (ii) weakens the interactions between molecular chains by reducing the formation of hydrogen bonds between the main chains by hydroxyl groups. As a result, it is believed that the material has excellent thermoplasticity as well as adhesive and tackiness.

[0022] Examples of the β-1,3-glucan ester derivative include a β-1,3-glucan ester derivative represented by the following structural formula (2).

[0023] [ka] (wherein, each R is independently a hydrogen atom or an acyl group, at least a part of R is an acyl group, and n is a natural number.)

[0024] The acyl group is R 1 C(O)-(where R 1 is a hydrocarbon group. The hydrocarbon group includes an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be linear, branched, or have a ring structure. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group (alkyl group) or an unsaturated aliphatic hydrocarbon group (alkenyl group or alkynyl group). The aliphatic hydrocarbon group is selected from the group consisting of the ease of synthesis, R 1 From the viewpoint of the high degree of freedom in the structure, etc., an alkyl group is preferred, a linear or branched alkyl group is more preferred, and a linear alkyl group is further preferred.

[0025] Examples of the acyl group include an acetyl group, a propionyl group, an isopropionyl group, a butyryl group, an isobutyryl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a lauroyl group, a myristoyl group, a palmitoyl group, a stearoyl group, an oleoyl group, a linoleoyl group, and a linolenoyl group. From the viewpoint of moldability, an acetyl group, a propionyl group, an isopropionyl group, a butyryl group, an isobutyryl group, a pentanoyl group, and a hexanoyl group are more preferred.

[0026] The weight average molecular weight Mw of the β-1,3-glucan ester derivative is 2.0×10 3 Da or more 1.0×10 6 Da or less is preferable, 5.0×10 3 Da or more 5.0×10 5 The number average molecular weight Mn of the β-1,3-glucan ester derivative is preferably 2.0×10 Da or less. 3 Da or more 1.0×10 6 Da or less is preferable, 5.0×10 3 Da or more 5.0×10 5 If the molecular weight of the β-1,3-glucan ester derivative is within the above range, appropriate adhesiveness and tackiness are exhibited, and the solubility in organic solvents when used as a solvent-based adhesive is excellent.

[0027] The polydispersity Mw / Mn of the β-1,3-glucan ester derivative is preferably 1.0 or more and 1.6 or less. If the dispersity Mw / Mn is within the above range, the monodispersity of the β-1,3-glucan used as the raw material is better maintained, and a β-1,3-glucan ester derivative can be obtained that is less susceptible to defects caused by differences in melting points.

[0028] An example of a method for producing a β-1,3-glucan ester derivative is a synthesis method in which some or all of the hydroxyl groups in glucose constituting β-1,3-glucan are acylated with fatty acids (Japanese Patent No. 6029155). If the carboxylic acid concentration (mass%) in the β-1,3-glucan ester derivative is 0.1 mass% or less, a resin that is free from coloration and odor can be obtained. In terms of coloration and odor, it is more preferable that the carboxylic acid concentration in the resin is 0.01 mass% or less.

[0029] <Resin composition> The resin composition of the present invention can be obtained by blending the β-1,3-glucan ester derivative of the present invention with a resin, talc, a flame retardant, and the like.

[0030] (talc) In order to impart rigidity to the resin composition, talc can be blended into the resin composition. Talc is a hydrous magnesium silicate (Mg 3 S 4 O 10 (OH) 2 ). Talc is mined in the form of rock, and the powder obtained after crushing can be added to a resin to improve the rigidity of the resin composition. The talc to be added may be one type or two or more types. Talc may be added when the β-1,3-glucan ester derivative is kneaded, or a mixture obtained by kneading a part of the β-1,3-glucan ester derivative or another resin in advance may be added when the β-1,3-glucan ester derivative is kneaded.

[0031] The content of talc may be an appropriate amount, but is preferably 1 part by mass or more and 10 parts by mass or less. In the preferred range, talc is less likely to aggregate, dispersion is improved, and a decrease in toughness can be suppressed. In the examples of the present invention, fine powder talc PAOG-3 and RA-3 manufactured by Nippon Talc Co., Ltd. were used as the talc, but other talcs may also be used.

[0032] (Flame retardant) In order to impart flame retardancy to the resin composition, talc can be blended into the resin composition. Examples of the flame retardant include halogen-based flame retardants, phosphorus-based flame retardants, and hydrated metal flame retardants, and these may be used alone or in combination of two or more. The flame retardant may be added when the β-1,3-glucan ester derivative is kneaded, or the flame retardant may be previously kneaded with a part of the β-1,3-glucan ester derivative or with another resin, and the resulting mixture may be added when the β-1,3-glucan ester derivative is kneaded. In the examples of the present invention, a phosphorus-based flame retardant PX-200 manufactured by Daihachi Chemical Industry Co., Ltd. is used as the flame retardant, but other flame retardants may also be used.

[0033] (resin) The resin composition of the present invention may contain PP resin, PE resin, PC resin, PS resin, ABS resin, etc., to the extent that the flame retardancy, impact resistance, etc. are not significantly reduced. The content of the other resin may be 5 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the resin contained in the resin composition. (Other additives) The resin composition of the present invention may contain other additives such as phosphorus-based stabilizers, phenol-based stabilizers, dyes and pigments, and fillers, within the range that does not significantly reduce the flame retardancy, impact resistance, and the like.

[0034] (Method of producing resin composition) The resin composition of the present invention can be obtained by kneading the β-1,3-glucan ester derivative with the above-mentioned resin or additive. One example of a method for producing the resin composition of the present invention (hereinafter also referred to as "one example of the production method") includes, for example, a melt-kneading step in which a β-1,3-glucan ester derivative, a flame retardant, and optionally added components, as well as other additives added as necessary, are melt-kneaded.

[0035] (Melting and kneading process) In one example of the production method, first, the components necessary for the present invention, the components that are added optionally, and other additives that are added as necessary are melt-kneaded (melt-kneading step). According to the above process, each component can be mixed uniformly. In this step, the above-mentioned components are kneaded using a kneading machine known in the art, such as a tumbler, a Henschel mixer, a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader, while appropriately adjusting conditions such as the kneading speed, kneading temperature, and kneading time.

[0036] For example, the above components may be mixed in advance using a tumbler, Henschel mixer, or the like, and then melt-kneaded using a kneader such as a Banbury mixer, roll, Brabender, single-screw kneading extruder, twin-screw kneading extruder, or kneader. Alternatively, for example, the components may not be mixed in advance, but may be fed into an extruder using a feeder and melt-kneaded. Furthermore, for example, only some of the components may be mixed in advance, and then melt-kneaded to obtain a resin composition, which is used as a master batch, and the remaining components may be melt-kneaded again. Here, in this step, there is no particular limitation, and it is also preferable that the arbitrarily selected components are melt-mixed in advance and then added to the twin-screw kneading extruder.

[0037] <Molded body> The molded article of the example of the present invention (hereinafter also referred to as "an example molded article") contains the flame-retardant resin composition of the example of the present invention. Examples of the molded article include components for information and mobile devices such as computers, notebook computers, tablet terminals, smartphones, and mobile phones, and office automation devices such as printers and copiers. In particular, the molded article is preferably used for exterior components that require heat resistance. The example molded article can be obtained, for example, by injection molding the example flame-retardant resin composition according to a conventional method.

[0038] <Electronic components, electronic devices> An electronic device according to one embodiment of the present invention has the molded article according to the present invention. An electronic device according to one embodiment of the present invention has the molded article according to the present invention. Examples of the electronic components include electronic components of information and mobile devices such as computers, notebook personal computers, tablet terminals, smartphones, and mobile phones, office automation devices such as printers and copiers, etc. Examples of the electronic devices include information and mobile devices such as computers, notebook personal computers, tablet terminals, smartphones, and mobile phones, office automation devices such as printers and copiers, and home appliances such as televisions, refrigerators, and vacuum cleaners. EXAMPLES

[0039] The present invention will be described in more detail below based on examples, but the technical scope of the present invention is not limited to the following examples in any way. In the following description, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0040] [Example 1] According to the procedure described below, β-1,3-glucan, trifluoroacetic anhydride, and hexanoic acid were reacted to obtain a β-1,3-glucan ester derivative. Procedure 1: 200 g of β-1,3-glucan, 8,000 ml of trifluoroacetic anhydride, and 8,000 ml of carboxylic acid were reacted at 50° C. for 2 hours. Step 2: A mixed solution of methanol / water was added to the reaction solution to obtain a precipitate. Step 3: The precipitate was washed with a mixed solution of methanol / water. Step 4: The washed material obtained in step 3 was washed with ethanol for 1 hour. Step 5: The washed product obtained in step 4 was vacuum dried for 24 hours to obtain [β-1,3-glucan ester derivative 1].

[0041] [Examples 2 to 6] The procedure of Example 1 was repeated except that the carboxylic acids in Example 1 were changed to those shown in Table 1, thereby obtaining [β-1,3-glucan ester derivative 2] to [β-1,3-glucan ester derivative 6].

[0042] [Example 7] The procedure of Example 1 was repeated except that the washing time with ethanol in step 4 was changed to 0.5 hours to obtain [β-1,3-glucan ester derivative 7].

[0043] [Comparative Example 1] In step 2 of Example 1, instead of adding a mixed solution of methanol / water to the reaction solution to obtain a precipitate, the reaction solution was dissolved in chloroform and then a mixed solution of methanol / water was used to obtain a precipitate. The procedure was the same as in Example 1, except that [β-1,3-glucan ester derivative 8] was obtained.

[0044] [Comparative Example 2] The procedure of Example 1 was repeated except that the washing steps 3 and 4 were not carried out to obtain [β-1,3-glucan ester derivative 9]. Table 1 shows the combinations of β-1,3-glucans and carboxylic acids used as raw materials for synthesizing β-1,3-glucan ester derivatives in the examples and comparative examples.

[0045] The raw materials used in Table 1 were as follows: Propionic acid: Special grade (Kanto Chemical Co., Ltd.) Butyric acid: Deer special grade (Kanto Chemical Co., Ltd.) Valeric acid: Deer special grade (Kanto Chemical Co., Ltd.) Hexanoic acid: Grade 1 (Kanto Chemical Co., Ltd.) Talc: PAOG-3 (manufactured by Nippon Talc Co., Ltd.) Phosphorus compounds: PX-200 (manufactured by Daihachi Chemical Industry Co., Ltd.)

[0046] [Table 1]

[0047] The β-1,3-glucan ester derivatives obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for the amount of residual carboxylic acid, odor, and coloring by the evaluation methods described below. The evaluation results are shown in Table 2.

[0048] [Evaluation method] (Evaluation of Residual Carboxylic Acid Amount) The amount of residual carboxylic acid is evaluated as follows. First, each carboxylic acid is sampled and injected into a gas chromatograph (hereinafter abbreviated as GC) to measure the peak area, and a calibration curve is created from the GC peak areas of different concentrations. Similarly, the synthesized β-1,3-glucan ester derivative is measured, and the carboxylic acid peak area is determined. The amount of carboxylic acid (m) is calculated from the obtained carboxylic acid peak area, and the amount of residual carboxylic acid (mass%) is calculated from the total mass (W) of the β-1,3-glucan ester derivative. In the present invention, the GC device used is not particularly limited, and GC and GCMS devices from various manufacturers can be used.

[0049] (Odor evaluation method) The odor evaluation is carried out as follows: The obtained β-1,3-glucan ester derivative was dried at 60° C. for 3 hours, and the odor was evaluated according to the following criteria. <Evaluation criteria> ◎: No odor 〇: Slightly odorous ×: Odor is present.

[0050] (Coloring evaluation) For the color evaluation, strips for a Charpy impact tester were prepared as test pieces in accordance with ISO179-1, and the test pieces were measured using a spectrophotometer eXact manufactured by X-Rite. The evaluation method is L * a * b * Color space L * Using the value (brightness), * Value and L of sample placed on white paper * The absolute value of the difference between the values ​​was taken as the lightness change ΔL, and the lightness change was evaluated according to the following evaluation criteria based on the value of ΔL. <Evaluation criteria> ◎: Less than 30 ○: 30 to under 40 ×:40 or more

[0051] [Table 2]

[0052] [Example 8] 100 parts of the [β-1,3-glucan ester derivative 1] obtained in Example 1 was mixed with 5 parts of PAOG-3 and kneaded at a temperature of 185°C using a small kneader (Mini-Labo: manufactured by Thermo Fisher Scientific) to obtain a resin composition.

[0053] [Example 9] A resin composition was obtained in the same manner as in Example 8, except that PAOG-3 was changed to 20 parts of PX200.

[0054] The flame retardancy and toughness of the resin compositions obtained in Examples 8 and 9 were evaluated by the following evaluation methods. The evaluation results are shown in Table 3.

[0055] (Charpy impact strength evaluation) Impact tests were performed using a Charpy impact tester in accordance with ISO179-1. The test pieces were notched. Charpy impact test value (kJ / m 2) and evaluated according to the following criteria. <Evaluation criteria> ◎: 6 or more ○: 4 or more and less than 6 ×: Less than 4

[0056] (Flame retardancy evaluation) Flame retardancy tests were conducted in accordance with the UL94 test (combustion test for plastic materials for equipment parts) established by Underwriters Laboratories (UL) of the United States, and the products were evaluated according to the following criteria. The thickness t of the test piece was 1.5 mm. <Evaluation criteria> UL94V testing was conducted and the rating was "V-0", "V-1", or "V-2". V-2 or above was considered a pass.

[0057] [Table 3]

[0058] For example, aspects of the present invention are as follows. (1) A β-1,3-glucan ester derivative having at least a structure represented by the following structural formula (1) as its main chain, characterized in that the amount of carboxylic acid in the β-1,3-glucan ester derivative is 0.1 mass% or less. [ka] (In the formula, each R is independently a hydrogen atom or an alkylcarbonyl group, at least a part of R is an alkylcarbonyl group, and n is a natural number.) (2) The β-1,3-glucan ester derivative according to (1) above, wherein the carboxylic acid is at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, decanoic acid, and lauric acid. (3) A resin composition comprising the β-1,3-glucan ester derivative according to (1) or (2) above and talc. (4) The resin composition according to (3) above, which contains a flame retardant. (5) A molded article comprising the resin composition according to (3) or (4) above. (6) An electronic component comprising the molded article according to (5) above. (7) An electronic device comprising the molded article according to (6) above. [Prior art documents] [Patent documents]

[0059] [Patent Document 1] JP 2022-003113 A [Patent Document 2] International Publication No. 2020 / 013232

Claims

1. A β-1,3-glucan derivative having at least a structure represented by the following structural formula (1) as a main chain, characterized in that the amount of carboxylic acid in the β-1,3-glucan ester derivative is 0.1 mass% or less. 【Chemistry 1】 (In the formula, each R is independently a hydrogen atom or an alkylcarbonyl group, at least a part of R is an alkylcarbonyl group, and n is a natural number.)

2. The β-1,3-glucan ester derivative according to claim 1, wherein the carboxylic acid is at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, decanoic acid, and lauric acid.

3. A resin composition comprising the β-1,3-glucan ester derivative according to claim 1 and talc.

4. The resin composition according to claim 3 , further comprising a flame retardant.

5. A molded article comprising the resin composition according to claim 3 or 4.

6. An electronic component comprising the molded article according to claim 5 .

7. An electronic device comprising the molded article according to claim 6.

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