WO2022085120A1

WO2022085120A1 - Cellulose mixed fatty acid ester and cellulose mixed fatty acid ester composition

Info

Publication number: WO2022085120A1
Application number: PCT/JP2020/039574
Authority: WO
Inventors: 匡章楠本; 暁浩樋口; 知弘橋爪; 旭東賀
Original assignee: 株式会社ダイセル
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2022-04-28

Abstract

This cellulose mixed fatty acid ester has an acetyl group and an acyl group having 3 or more carbon atoms. The degree of acetyl substitution DSa is at least 1.5 and less than 2.6. The degree of acyl group substitution DSb by the acyl group having 3 or more carbon atoms is more than 0 and not more than 0.30. The total degree of substitution DS, which is the sum of the degree of acetyl substitution DSa and the degree of acyl substitution DSb, is not more than 2.6. This cellulose mixed fatty acid ester composition contains this cellulose mixed fatty acid ester and an additive. The additive is selected from the group consisting: of (a) a substance having a pH of 8 or more at 20°C when in the form of a 1 wt% aqueous solution; (b) a substance whose solubility in water at 20ºC is 2 wt% or more; and (c) a substance that is biodegradable in seawater.

Description

Cellulose mixed fatty acid ester and cellulose mixed fatty acid ester composition

The present disclosure relates to a cellulose mixed fatty acid ester. More specifically, the present invention relates to a cellulose mixed fatty acid ester acylate and a cellulose mixed fatty acid ester acylate composition.

In recent years, due to growing interest in the global environment, biodegradable molded products have been demanded. Cellulose acetate is a typical biodegradable resin.

For example, cellulose acetate having a degree of substitution of about 2.5 is used as a material for a cigarette filter used in a cigarette containing an electronic cigarette, a material for an absorber for sanitary goods, and the like. Cellulose acetate having a degree of substitution of about 2.5 is known to decompose in soil or activated sludge. However, its biodegradability is not as good as that of cellulose or cellulose acetate with a degree of substitution of 1.8.

Patent Document 1 discloses a technique for improving the biodegradability of a polymer such as a cellulose ester by adding a basic additive having a pH of 13 or less and 7 or more in a 1% aqueous solution (20 ° C.). Has been done.

In Patent Document 2, the total degree of acyl substitution at the 2-position, 3-position and 6-position is 2.67 or more, and the total of the acyl substitution degrees at the 2-position and 3-position is 1.97 or more. In, a technique for reducing the viscosity of the cellulose acylate solution used in the solvencast method by setting −0.1 ≦ (degree of acyl substitution at the 3-position to the degree of acyl substitution at the 2-position) ≦ 0.3 is disclosed. There is.

In Patent Document 3, in a composition containing a cellulose ester and a plasticizer as main components, a cellulose ester having an average of 0.5 or more esters per glucose unit having 3 or more carbon atoms in the acyl portion is used. A technique for improving thermal fluidity and reducing coloration due to thermal history is disclosed.

Special Table 2018-500416 Gazette Japanese Unexamined Patent Publication No. 2002-265501 Japanese Unexamined Patent Publication No. 2005-247911

Cellulose acetate has poor thermal meltability due to hydrogen bonds caused by the hydroxyl groups remaining in the molecular chain. From the viewpoint of improving biodegradability, it is preferable that the degree of substitution of cellulose acetate is low, but the lower the total degree of substitution, the higher the melting temperature tends to be. If the melting temperature exceeds 200 ° C., there is a problem that coloring occurs due to thermal decomposition of cellulose acetate. On the other hand, the higher the total degree of substitution of cellulose acetate, the higher the crystallinity, and therefore the solubility and the meltability tend to decrease. The techniques disclosed in Patent Documents 1 and 2 are both used for film formation by a casting method, and do not mention melt molding.

Further, as described above, cellulose acetate is known to be decomposed in soil or activated sludge. However, there is a problem that a satisfactory decomposition rate cannot be obtained in an aqueous system having a smaller number of bacteria than activated sludge, for example, in seawater.

The cellulose mixed fatty acid ester disclosed in Patent Document 3, for example, cellulose acetate propionate, improves moldability but further lowers biodegradability. In particular, the degradability in water systems such as the ocean is reduced. This is because the cellulose mixed fatty acid ester becomes more hydrophobic by containing a substituent having 3 or more carbon atoms.

An object of the present disclosure is to provide a cellulose mixed fatty acid ester and a cellulose mixed fatty acid ester composition which can be melt-molded and have excellent biodegradability in an aqueous system, particularly marine biodegradability.

The present inventors lower the glass transition temperature of the cellulose mixed fatty acid ester by lowering the degree of acyl group substitution of the cellulose mixed fatty acid ester having an acetyl group and an acyl group having 3 or more carbon atoms. It was found that the fluidity at the time of melting is improved. Furthermore, we have found that the biodegradability in the ocean is unexpectedly improved, and completed this disclosure.

That is, the cellulose mixed fatty acid ester according to the present disclosure has an acetyl group and an acyl group having 3 or more carbon atoms. The degree of acetyl substitution DSa of this cellulose mixed fatty acid ester is 1.5 or more and less than 2.6. The degree of acyl substitution DSb by the acyl group having 3 or more carbon atoms of this cellulose mixed fatty acid ester is more than 0 and 0.30 or less. The total degree of substitution DS, which is the sum of the acetyl substitution degree DSa and the acyl substitution degree DSb, is 2.6 or less.

Preferably, the number of carbon atoms of the acyl group having 3 or more carbon atoms is 3 or more and 10 or less. The acyl group having 3 or more carbon atoms is preferably a propionyl group or a butyryl group.

Preferably, the degree of acyl substitution DSb of this cellulose mixed fatty acid ester is 0.01 or more and 0.20 or less. Preferably, the total degree of substitution DS of this cellulose mixed fatty acid ester is 2.0 or more and 2.6 or less.

The cellulose mixed fatty acid ester composition according to the present disclosure contains any of the above-mentioned cellulose mixed fatty acid esters and additives. This additive is (a) a substance having a pH of 8 or more at 20 ° C. in a 1 wt% aqueous solution, (b) a substance soluble in 2 wt% or more in water at 20 ° C., and (c) biodegradable in seawater. It is selected from the group consisting of substances showing.

Preferably, the content of the cellulose mixed fatty acid ester in this composition is 50% by weight or more. Preferably, the total amount of additives added to this composition is 3% by weight or more and 40% by weight or less.

Preferably, the substance (a) having a pH of 8 or more at 20 ° C. of a 1 wt% aqueous solution is selected from the group consisting of the following (a1)-(a3).
(A1) Inorganic compound containing an oxygen atom that binds to any metal element of Na, K, Ca or Mg (a2) With one or more metal ions selected from Na ⁺ , K ⁺ , Ca ²⁺ or Mg ²⁺ . , A metal salt comprising one or more anions selected from carbonate ion, hydrogen carbonate ion, silicate ion or aluminate ion, and (a3) an inorganic compound containing magnesium.

Preferably, the main component of the inorganic compound (a3) containing magnesium is magnesium oxide.

Preferably, the substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more is selected from the group consisting of the following (b1)-(b3).
(B1) Glycerin ester (b2) Citric acid ester and (b3) Polyethylene glycol having a number average degree of polymerization of 20 or less

Preferably, the substance (c) that exhibits biodegradability in seawater is polyester having a weight average molecular weight of 50,000 or less. Preferably, the polyester is selected from the group consisting of polyhydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate, polybutylene succinate, polycaprolactone and polyglycolic acid.

Preferably, the cellulose mixed fatty acid ester composition contains an additive selected from magnesium oxide, magnesium aluminometasilicate and triacetin. Preferably, the cellulose mixed fatty acid ester composition comprises an additive consisting of a combination of magnesium oxide and triacetin.

The cellulose mixed fatty acid ester and the cellulose mixed fatty acid ester composition according to the present disclosure are excellent in biodegradability, particularly biodegradability in seawater. Further, the cellulose mixed fatty acid ester and the cellulose mixed fatty acid ester composition can be melt-molded in a relatively low temperature region. Moreover, the melt viscosity of this cellulose mixed fatty acid ester and the cellulose fatty acid composition is low. Further, according to the cellulose mixed fatty acid ester and the cellulose fatty acid composition, a high melt tension can be obtained.

Hereinafter, the present disclosure will be described in detail based on a preferred embodiment. The scope of the present disclosure is not bound by these explanations, and other than those exemplified below, it is possible to appropriately change and implement the present disclosure within a range that does not impair the purpose of the present disclosure. Further, the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the claims. Other embodiments obtained by appropriately combining the technical means disclosed for each of the plurality of embodiments are also included in the technical scope of the present disclosure.

In the specification of the present application, "XY" indicating the range means "X or more and Y or less". Further, unless otherwise specified, "ppm" means "weight ppm".

[Cellulose mixed fatty acid ester]
The cellulose mixed fatty acid ester of the present disclosure has an acetyl group and an acyl group having 3 or more carbon atoms. The degree of substitution DSa (hereinafter, acetyl substitution degree) by an acetyl group in this cellulose mixed fatty acid ester is 1.5 or more and less than 2.6, and the degree of substitution DSb (hereinafter, acyl substitution degree) by an acyl group having 3 or more carbon atoms. Is greater than 0 and less than or equal to 0.30. The total degree of substitution DS, which is the sum of the acetyl substitution degree DSa and the acyl substitution degree DSb, is 2.6 or less. The cellulose mixed fatty acid ester according to the present disclosure may contain a cellulose sulfate ester in which some substituents are sulfate groups and salts thereof, and salts thereof.

The cellulose mixed fatty acid ester of the present disclosure has an acyl group having 3 or more carbon atoms together with an acetyl group, so that the glass transition temperature is lowered and the melt fluidity is improved, so that melt molding at a relatively low temperature is possible. It becomes. On the other hand, an acyl group having 10 or less carbon atoms is preferable because it does not inhibit the biodegradability of the cellulose fatty acid ester. From the viewpoint of improving biodegradability, the number of carbon atoms of the acyl group is more preferably 7 or less, further preferably 5 or less, and particularly preferably 4 or less.

The number of carbon atoms of the acyl group is preferably 3 or more and 10 or less from the viewpoint of achieving both melt moldability and biodegradability. The number of carbon atoms of the acyl group may be 3 to 7, may be 3 to 5, and may be 3 to 4. As long as the degree of substitution described later is satisfied, the cellulose mixed fatty acid ester of the present disclosure may have two or more kinds of acyl groups having different carbon atoms together with an acetyl group.

In the cellulose mixed fatty acid ester of the present disclosure, particularly preferable acyl groups are propionyl group and butyryl group. Cellulose mixed fatty acid esters having an acetyl group and a propionyl group are referred to as cellulose acetate propionates (CAP). Cellulose mixed fatty acid esters having an acetyl group and a butyryl group are referred to as cellulose acetate butyrate (CAB). Further, it may be a cellulose acetate butyrate propionate having an acetyl group, a propionyl group and a butyryl group.

A cellulose mixed fatty acid ester having an acyl substitution degree DSb of an acyl group having 3 or more carbon atoms of more than 0 and 0.30 or less can obtain high melt fluidity at a temperature of 200 ° C. or less. From this viewpoint, the degree of acyl substitution DSb is preferably 0.01 or more, more preferably 0.05 or more, and particularly preferably 0.10 or more. From the viewpoint of not inhibiting the biodegradability of the cellulose fatty acid ester, the acyl substitution degree DSb is preferably 0.20 or less. The degree of acyl substitution DSb may be more than 0 and 0.20 or less, may be 0.01 to 0.30, may be 0.01 to 0.20, and may be 0.05 to 0.30. It may be 0.05 to 0.20, 0.10 to 0.30, or 0.10 to 0.20.

Cellulose mixed fatty acid ester having an acetyl substitution degree DSa of 1.5 or more and less than 2.6 is excellent in biodegradability, particularly biodegradability in seawater. From the viewpoint of improving biodegradability, the degree of acetyl substitution DSa is preferably 2.4 or less, and more preferably 2.2 or less. From the viewpoint of easy molding, the degree of acetyl substitution DSa of the cellulose mixed fatty acid ester is preferably 1.6 or more, and more preferably 1.8 or more. The degree of acetyl substitution DSa of the cellulose mixed fatty acid ester may be 1.5 to 2.4, 1.5 to 2.2, 1.6 or more and less than 2.6. It may be 6 to 2.4, 1.6 to 2.2, 1.8 or more and less than 2.6, 1.8 to 2.4, and 1.8. It may be ~ 2.2.

In a cellulose mixed fatty acid ester in which the acetyl substitution degree DSa and the acyl substitution degree DSb satisfy the above-mentioned numerical ranges and the total substitution degree DS, which is the sum of the acetyl substitution degree DSa and the acyl substitution degree DSb, is 2.6 or less. , Good melt fluidity and excellent biodegradability are compatible. From this point of view, the preferable total degree of substitution DS is 2.0 or more and 2.6 or less. The total degree of substitution DS of the cellulose mixed fatty acid ester may be 2.0 to 2.5, 2.2 to 2.6, 2.2 to 2.5, and 2.3. It may be ~ 2.6 and may be 2.3 ~ 2.5.

The degree of acetyl substitution DSa and the degree of acyl substitution DSb of the cellulose mixed fatty acid ester can be calculated by measuring the amount of bound fatty acid per constituent unit weight of cellulose. The specific measurement method is carried out according to ASTM-D817-91. Further, according to ASTM-817-96, after measuring the cellulose mixed fatty acid ester (s) having a known degree of substitution to prepare a calibration line, 2, 3, 6 of the glucose ring of the cellulose mixed fatty acid ester as a sample. Each degree of substitution of the place can also be obtained by the NMR method according to the method of Tezuka (Tezuka, Carbonydr. Res. 273, 83 (1995)).

That is, the sample is dissolved in deuterated chloroform and the ¹³ C-NMR spectrum is measured. Taking the case where the substituent is an acetyl group, a propionyl group, or a butyryl group, the carbon signal of the acetyl group is a propionyl group in the region of 169 ppm to 171 ppm in the order of the 2-position, 3-position, and 6-position from the high magnetic field. The carbonyl carbon signal appears in the same order in the 172 ppm to 174 ppm region, and the butyryl group carbon signal appears in the 171 ppm to 173 ppm region in the same order from the high magnetic field side to the 2-position, 3-position, and 6-position. To give another example, when analyzing the degree of propionyl substitution in a cellulose mixed fatty acid ester having a propionyl group or a cellulose mixed fatty acid ester having no propionyl group treated with propionic anhydride for the purpose of analysis, a propionyl group is used. The carbonyl carbon signals of are appearing in the same order in the region from 172 ppm to 174 ppm.

Substitution degree Using the acyl substitution degree of a known cellulose mixed fatty acid ester, the area of the carbonyl signal of the acyl group is standardized, and the abundance ratio of the acetyl group and the acyl group at the corresponding positions (area ratio of each signal) can be obtained. For example, the degree of acyl substitution at the 2, 3 and 6 positions of the glucose ring in the original cellulose mixed fatty acid ester can be obtained.

[Viscosity average degree of polymerization (DPv) of cellulose mixed fatty acid ester]
The viscosity average degree of polymerization (DPv) of the cellulose mixed fatty acid ester of the present disclosure is not particularly limited, but is preferably 400 or less, more preferably 300 or less, still more preferably 200 or less, from the viewpoint of improving degradability. From the viewpoint of easy molding, the viscosity average degree of polymerization is preferably 10 or more, more preferably 15 or more, and particularly preferably 20 or more. The viscosity average degree of polymerization (DPv) may be 10 to 400, 10 to 300, 10 to 200, 15 to 40, 15 to 300, and 15 It may be up to 200, 20 to 400, 20 to 300, and 20 to 200.

The viscosity average degree of polymerization (DPv) is determined based on the limit viscosity number ([η], unit: cm ³ / g) of the cellulose mixed fatty acid ester.

The ultimate viscosity number ([η], unit: cm ³ / g) is determined according to JIS-K-7367-1 and ISO1628-1. Specifically, a sample solution using dimethyl sulfoxide (DMSO) as a solvent is prepared, and the logarithmic relative viscosity at 25 ° C. measured using a Ubbelohde viscometer of size 1C is divided by the concentration of the sample solution. Desired.

Using the obtained limit viscosity number [η], the viscosity average molecular weight was calculated by the following formula according to the literature of Kamide et al. (Polymer Journal, 13, 421-431 (1981)).
Viscosity average molecular weight = (extreme viscosity number [η] /0.171) (1 / 0.61)

Using the calculated viscosity average molecular weight, the viscosity average degree of polymerization (DPv) was determined by the following formula.
Viscosity Average Degree of Polymerization (DPv) = Viscosity Average Molecular Weight / (162.14 + 42.037 × DS)
In the formula, DS is the above-mentioned total degree of acetyl substitution.

[Alkaline metal / alkaline earth metal]
The cellulose mixed fatty acid ester of the present disclosure may contain an alkali metal and an alkaline earth metal. Examples of the alkali metal include Na (sodium) and K (potassium). Examples of alkaline earth metals include Ca (calcium) and Mg (magnesium).

In order to improve the biodegradability and heat resistance stability of the cellulose mixed fatty acid ester of the present disclosure, it is preferable that the alkali metal and the alkaline earth metal are mainly composed of Mg. Specifically, the alkali metal and the alkaline earth metal are preferably composed mainly of Mg and supplementarily containing Na, K and Ca.

Alkaline metals and alkaline soils are added as aqueous solutions to the washing water in the step of precipitating and separating the cellulose mixed fatty acid ester of the present disclosure from the reaction solution and washing. A cellulose mixed fatty acid ester containing a similar metal may be obtained.

For example, the cellulose mixed fatty acid ester of the present disclosure can be obtained by acylating raw pulp using a sulfuric acid catalyst. In this case, sulfuric acid remains as a sulfate ester bonded to cellulose. The remaining sulfuric acid ester is decomposed by heat and water to produce sulfuric acid. The generated sulfuric acid decomposes the cellulose mixed fatty acid ester. Therefore, the cellulose mixed fatty acid ester containing sulfuric acid ester causes quality defects such as browning due to sulfuric acid in the process of applying heat such as extrusion molding.

In order to prevent quality defects caused by sulfuric acid, it is preferable that the sulfuric acid ester bonded to cellulose is a salt of an alkali metal or an alkaline earth metal. In this case, Ca is known as a metal element that is most effective for stabilization as a salt. However, in the cellulose mixed fatty acid ester of the present disclosure, it is preferable to mainly use Mg and complementarily use Ca, Na and K.

By containing these alkali metals or alkaline earth metals in the cellulose mixed fatty acid ester, the sulfate ester in the cellulose mixed fatty acid ester is neutralized. Further, the sulfate ester neutralized with an alkali metal or an alkaline earth metal in the cellulose mixed fatty acid ester is hydrolyzed in an aqueous system to produce sulfuric acid. Therefore, the biodegradability is improved by containing an alkali metal or an alkaline earth metal. Furthermore, by containing Ca, which is most effective for thermal stability, discoloration of the cellulose mixed fatty acid ester during heat molding can be suppressed.

The content of the alkali metal and the alkaline earth metal is preferably 1 to 4 having a median Mg of 3 as 1 × ^10-6 equivalents with respect to 1 equivalent of the sulfuric acid catalyst in the reaction system. The contents of Ca, Na and K are much smaller than those of Mg, and the equivalents are preferably 1.0 to 5.0% with a median of 2% of the content of Mg, and 1.5 to 3 respectively. .0% is more preferable. By adding in this ratio, the thermal stability of the cellulose mixed fatty acid ester is improved and excellent biodegradability can be obtained, although the reason is unknown.

The content of alkali metal and alkaline earth metal in the cellulose mixed fatty acid is measured by the following method. For example, in the case of the cellulose mixed fatty acid ester composition described later, the cellulose mixed fatty acid ester composition is dissolved in an appropriate organic solvent and filtered with a glass filter or the like. Alternatively, remove insoluble matter such as inorganic salts with a centrifuge or the like. Next, high performance liquid chromatography is used to remove small molecule components other than the cellulose mixed fatty acid ester. Then, the obtained cellulose mixed fatty acid ester solution is dried and completely burned. After performing a pretreatment to dissolve the ash after combustion in hydrochloric acid, the contents of alkali metal and alkaline earth metal are measured by atomic absorption spectroscopy. From the obtained measured values, the content of each element in 1 g of the cellulose mixed fatty acid ester in an absolutely dry state is determined in ppm units (based on weight).

[Amount of sulfuric acid]
In the cellulose mixed fatty acid ester of the present disclosure, some substituents may be a sulfate ester or a salt thereof. Sulfuric acid esters are derived from sulfuric acid added as a catalyst during the production of cellulose mixed fatty acid esters. The median amount of sulfuric acid contained in the cellulose mixed fatty acid ester is preferably 10 ppm or more and 100 ppm or less, more preferably 20 ppm or more and 80 ppm or less, and particularly preferably 20 ppm or more and 50 ppm or less. The amount of sulfuric acid in the cellulose mixed fatty acid ester may be 10 to 80 ppm, 10 to 50 ppm, or 20 to 100 ppm.

The amount of sulfuric acid varies depending on the amount of sulfuric acid catalyst used during the production of the cellulose mixed fatty acid ester, the acylation time, the hydrolysis time, the temperature at the time of precipitation, the washing time, the temperature of the washing water, and the like. It is preferable to adjust the amount of alkali metal or alkaline earth metal according to the amount of sulfuric acid in the cellulose mixed fatty acid ester. The equivalent ratio of the total amount of the alkali metal and the alkaline earth metal to the amount of sulfuric acid is preferably 1 or more and 10 or less, more preferably 2 or more and 8 or less, and particularly preferably 3 or more and 7 or less, with 5 as the median. This equivalent ratio may be 1 to 8, may be 1 to 7, may be 2 to 10, may be 2 to 7, may be 3 to 10, and may be 3 to 8. It's okay.

The amount of sulfuric acid in the cellulose mixed fatty acid ester is measured by the following method. First, the dried cellulose mixed fatty acid ester is weighed and then baked in an electric furnace at 1300 ° C., and the generated sulfite gas is trapped in a 10% hydrogen peroxide solution. This trap solution is titrated with a specified aqueous solution of sodium hydroxide. From the obtained titration value, it is obtained as an amount in terms of H ₂ SO ₄ per absolute dry cellulose mixed fatty acid ester, and the amount of sulfuric acid in the cellulose mixed fatty acid ester is indicated in ppm unit (weight basis).

[Manufacturing method of cellulose mixed fatty acid ester]
The obtained cellulose mixed fatty acid ester has an acetyl group and an acyl group having 3 or more carbon atoms, has an acetyl substitution degree DSa of 1.5 or more and less than 2.6, and is acyl substituted with an acyl group having 3 or more carbon atoms. The production method is not particularly limited as long as the degree DSb is more than 0 and 0.30 or less, and the total degree of substitution DS, which is the sum of the acetyl substitution degree DSa and the acyl substitution degree DSb, is 2.6 or less.

For example, (1) a pretreatment step of disintegrating and crushing a pulp raw material (dissolved pulp) having a relatively high α-cellulose content and then spraying and mixing an acylating solvent, and (2) an acylating agent and an acylating solvent. And an acylation step of reacting the pretreated pulp of (1) with an acid mixture consisting of an acylation catalyst (for example, sulfuric acid), and (3) hydrolysis of the cellulose mixed fatty acid ester to obtain a cellulose mixed fatty acid ester having a desired degree of substitution. Examples thereof include a production method including a post-treatment step of separating, purifying, stabilizing, and drying the cellulose mixed fatty acid ester having been hydrolyzed from the reaction solution. In the acylation step, an acylating agent containing at least an acylating agent corresponding to an acyl group having 3 or more carbon atoms is used.

Acetic anhydride is essential as the composition of the acylating agent. Other acylating agents also need to be anhydrous carboxylic acids. The carboxylic acid anhydride is obtained by adding acetic anhydride to the corresponding carboxylic acid and distilling off the carboxylic acid anhydride, acetic anhydride, acetic acid and the carboxylic acid.

As an example of another production method, a cellulose acetate having a predetermined degree of acetyl substitution is acylated with an acylating agent corresponding to an acyl group having 3 or more carbon atoms to obtain the cellulose mixed fatty acid ester of the present disclosure. May be obtained. Further, the cellulose mixed fatty acid ester of the present disclosure can also be produced by dissolving cellulose acetate in a solvent such as pyridine, then adding the corresponding aliphatic carboxylic acid, hydrolyzing the ester, and exchanging the ester.

[Cellulose mixed fatty acid ester composition]
The cellulose mixed fatty acid ester composition according to the present disclosure contains the above-mentioned cellulose mixed fatty acid ester and additives. This additive is selected from the group consisting of the following (a)-(c).
(A) A substance having a pH of 8 or more at 20 ° C. of a 1% by weight aqueous solution (b) A substance that dissolves 2% by weight or more in water at 20 ° C. and (c) A substance that exhibits biodegradability in seawater.

A substance (a) having a pH of 8 or more at 20 ° C. of a 1 wt% aqueous solution promotes hydrolysis (particularly deacetylation) of a cellulose mixed fatty acid ester in weakly basic seawater. This is considered to contribute to the improvement of biodegradability of the cellulose mixed fatty acid ester composition.

Further, the substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more dissolves when the cellulose mixed fatty acid ester composition is put into seawater and elutes from the cellulose mixed fatty acid ester composition. The substance (c) exhibiting biodegradability in seawater is gradually eluted from the cellulose mixed fatty acid ester composition by biodegrading from the time when the cellulose mixed fatty acid ester composition is put into seawater. Due to these elutions, structural voids are formed in the molded product composed of the cellulose mixed fatty acid ester composition, and the substantial surface area of the molded product is increased. The increase in the surface area promotes the hydrolysis (particularly, deacetylation) of the cellulose mixed fatty acid ester in seawater, and also facilitates the invasion of microorganisms from the voids, so that the cellulose mixed fatty acid ester composition is biodegraded. It is thought that the sex will improve.

It is preferable that the action of the additive in the cellulose mixed fatty acid ester composition is not expressed when it is used as a product, but is rapidly expressed after contact with seawater. Therefore, if the additive is a solid, it is preferably dispersed in the cellulose mixed fatty acid ester composition in the form of particles, the particle size is preferably as small as possible, and the specific surface area thereof is preferably large.

[Contents of cellulose mixed fatty acid ester]
From the viewpoint of exhibiting high biodegradability in seawater, the content of the cellulose mixed fatty acid ester of the present disclosure in the cellulose mixed fatty acid ester composition is preferably 50% by weight or more with respect to the entire composition. 55% by weight or more is more preferable, and 60% by weight or more is particularly preferable. From the viewpoint that the decomposition promoting effect of the additive is effectively exhibited, the content of the cellulose mixed fatty acid ester is preferably 90% by weight or less, more preferably 85% by weight or less. The content of the cellulose mixed fatty acid ester in the composition of the present disclosure may be 50 to 90% by weight, may be 50 to 85% by weight, may be 55 to 90% by weight, and may be 55 to 85% by weight. It may be 60 to 90% by weight, and may be 60 to 85% by weight. When two or more kinds of cellulose mixed fatty acid esters having different physical characteristics are used in combination, the total amount thereof is adjusted to the above-mentioned numerical range.

[Amount of additives added]
From the viewpoint of contributing to the improvement of biodegradability, the total amount of additives added to the cellulose mixed fatty acid ester composition according to the present disclosure is preferably 3% by weight or more, preferably 5% by weight, based on the entire composition. The above is more preferable. From the viewpoint of easy molding, the total amount of the additive added is preferably 40% by weight or less, more preferably 35% by weight or less. The total amount of the additive added in the composition of the present disclosure may be 3 to 40% by weight, may be 3 to 35% by weight, may be 5 to 40% by weight, and may be 5 to 35% by weight. It may be there. When a plurality of additives are used in combination, the total amount is adjusted within the above-mentioned numerical range.

[Contents of cellulose mixed fatty acid ester and additives]
From the viewpoint of obtaining excellent biodegradability, the total content of the cellulose mixed fatty acid ester and the additive in the cellulose mixed fatty acid ester composition according to the present disclosure is preferably 85% by weight or more, preferably 90% by weight or more. Is more preferable, and 95% by weight or more is particularly preferable. The upper limit of the total content is not particularly limited and may be 100% by weight.

[A substance (a) having a pH of 8 or more at 20 ° C. of a 1 wt% aqueous solution]
A substance having a pH of 8 or more at 20 ° C. of a 1 wt% aqueous solution is also referred to as a basic additive. As this basic additive, the pH of the 1 wt% aqueous solution at 20 ° C. is preferably 8.5 or more, and more preferably 8.5 to 11. The pH of a 1 wt% aqueous solution is measured according to known procedures, for example with a glass pH electrode.

In the present disclosure, the "aqueous solution" does not mean only a state in which all the solutes are dissolved in water, but is a concept including a suspension. This "suspension" includes a slurry and a colloidal solution, which are dispersions in which solid particles are dispersed in a liquid. Further, in the present disclosure, in the "1 wt% aqueous solution", when the basic additive is added to water so as to have a concentration of 1 wt%, a part of the basic additive is dissolved to become an aqueous solution, and the rest. It also includes those in which the portion of the basic additive is a turbid liquid.

Preferably, the substance (a) having a pH of 8 or more at 20 ° C. of a 1 wt% aqueous solution is selected from the group consisting of the following (a1)-(a3).
(A1) Inorganic compound containing an oxygen atom that binds to any metal element of Na, K, Ca or Mg (a2) With one or more metal ions selected from Na ⁺ , K ⁺ , Ca ²⁺ or Mg ²⁺ . , A metal salt containing one or more anions selected from carbonate ion, hydrogen carbonate ion, silicate ion or aluminate ion and (a3) an inorganic compound containing magnesium. a1)-(a3) are defined as substances added as additives to the cellulose mixed fatty acid ester, separately from the alkali metal and the alkaline earth metal compounded at the time of producing the cellulose mixed fatty acid ester.

In particular, in the cellulose mixed fatty acid ester composition containing an additive selected from the inorganic compound (a1) and the metal salt (a2), its seawater biodegradability is remarkably improved. It is considered that this is because the inorganic compound (a1) and the metal salt (a2) remarkably promote the hydrolysis of the cellulose mixed fatty acid ester by exhibiting basicity in seawater. From this viewpoint, a composition containing at least one selected from (a1) and (a2) as an additive is preferable. The cellulose mixed fatty acid ester composition of the present disclosure may contain basic polymers and oligomers; basic amino acids and proteins; and basic saccharides as other basic substances.

Examples of the inorganic compound (a1) containing an oxygen atom bonded to any of the metal elements of Na, K, Ca or Mg include oxides, hydroxides and composites of the metal elements of Na, K, Ca or Mg. Oxides are exemplified. From the viewpoint of improving biodegradability and ease of handling, preferable inorganic compounds (a1) are magnesium oxide, magnesium hydroxide, talc, hydrotalcite, bentonite, calcium oxide, and calcium hydroxide.

Contains one or more metal ions selected from Na ⁺ , K ⁺ , Ca ²⁺ or Mg ²⁺ and one or more anions selected from carbonate ion, hydrogen carbonate ion, silicate ion or aluminate ion. As the metal salt (a2) consisting of, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, calcium hydrogencarbonate, magnesium hydrogencarbonate, calcium silicate, magnesium silicate, magnesium aluminate, Examples thereof include magnesium aluminometasilicate.

The sodium aluminate includes sodium aluminum dioxide (aluminum dioxide) which is a compound oxide: NaAlO ₂ and sodium tetrahydroxydoaluminate which is a hydroxy complex: Na [Al (OH) ₄ ] and the like. Magnesium aluminometasilicate is a substance represented by the general formula Al _2O ₃ , MgO, 2SiO ₂ , xH ₂ O (where x indicates the number of water of crystallization and 1 ≦ x ≦ 10). As the magnesium aluminometasilicate, for example, magnesium aluminometasilicate according to a pharmaceutical standard outside the Japanese Pharmacopoeia can be preferably used. Further, silicic acid is a general term for compounds of silicon, oxygen, and hydrogen represented by the general formula [SiO _x (OH) _4-2x ] _n .

From the viewpoint of obtaining high biodegradability and good moldability, preferable metal salts (a2) are calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, magnesium aluminate, and magnesium aluminometasilicate. ..

Examples of the inorganic compound (a3) containing magnesium include magnesium oxide. The main component of the inorganic compound (a3) containing magnesium is preferably magnesium oxide.

Magnesium oxide is an oxide of magnesium represented by the chemical formula MgO, and is also called magnesia milk. Magnesium oxide may contain a trace amount of each element of Al, Si, P, Mn, Fe, Ni, Cu and Zn. The minute amount referred to here means less than 1000 ppm, preferably less than 100 ppm.

In the present disclosure, the method for producing magnesium oxide is not particularly limited. It may be a method of firing and crushing natural magnesium carbonate ore (MgCO ₃ ) in dolomite (CaCO ₃ / MgCO ₃ ), and magnesium ions in seawater are used as hydroxide (Mg (OH) ₂ ). It may be produced by precipitating and dehydrating it at a high temperature.

[Substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more]
The substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more may be a high molecular weight substance or a low molecular weight substance as long as it is water-soluble. Preferably, the substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more is selected from the group consisting of the following (b1)-(b3).
(B1) Glycerin ester (b2) Citric acid ester and (b3) Polyethylene glycol having a number average degree of polymerization of 20 or less

Glycerin ester (b1), citric acid ester (b2) and polyethylene glycol (b3) having a number average degree of polymerization of 20 or less also act as a plasticizer for a cellulose mixed fatty acid ester. Therefore, the cellulose mixed fatty acid ester composition containing these as an additive is easy to melt-mold.

The glycerin ester (b1) is a compound in which at least one hydroxyl group of glycerin is esterified, and is preferably a compound esterified with a carboxylic acid having a molecular weight of 150 or less, more preferably 130 or less. The glycerin ester (b1) may be one in which all three hydroxyl groups of glycerin are esterified with the same carboxylic acid, two hydroxyl groups may be esterified with the same carboxylic acid, and three of glycerin. All of the hydroxyl groups of the above may be esterified with different carboxylic acids.

The carboxylic acid may be an aliphatic carboxylic acid (fatty acid) or an aromatic carboxylic acid. Fatty acids are preferable from the viewpoint of reducing the burden on the environment. It may be a saturated fatty acid or an unsaturated fatty acid. Preferred is a glycerin ester (b1) esterified with saturated fatty acids. Specific examples of saturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid and the like. A more preferable glycerin ester (b1) is glycerin acetate having an acetyl substitution degree of 0 or more and 3 or less, and triacetin (glycerol triacetate) in which all three hydroxyl groups of glycerin are esterified (in other words, acetylated) with acetic acid is used. Especially preferable.

Triacetin is a component that is recognized as safe even if ingested by humans, and because it is easily biodegraded, it has a small impact on the environment. Further, the cellulose mixed fatty acid ester composition obtained by adding triacetin to the cellulose mixed fatty acid ester has improved biodegradability as compared with the case where the cellulose mixed fatty acid ester is used alone. Further, by adding triacetin to the cellulose mixed fatty acid ester, the glass transition temperature of the cellulose mixed fatty acid ester can be efficiently lowered. Therefore, excellent thermoformability can be imparted to the raw material.

The citric acid ester (b2) is a compound in which at least one carboxyl group of citric acid is esterified. The citrate ester (b2) may be one in which all three carboxyl groups of citrate are esterified with the same hydrocarbon group, or two carboxyl groups are esterified with the same hydrocarbon group. Often, all three carboxyl groups of glycerin may be esterified with different hydrocarbon groups.

The hydrocarbon group may be linear, branched, or cyclic. An aliphatic hydrocarbon group is preferable, and a saturated aliphatic hydrocarbon group (alkyl group) is more preferable. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group and the like. Examples of the preferred citric acid ester (b2) include triethyl citrate and acetyltriethyl citrate.

Polyethylene glycol (b3) having a number average degree of polymerization of 20 or less has an ethyleneoxy group as a repeating unit. The degree of polymerization is the number of repeating units. Polyethylene glycol (b) having a number average degree of polymerization of 20 or less is easily dissolved in seawater and can contribute to the improvement of biodegradability. From this viewpoint, the number average degree of polymerization of polyethylene glycol is more preferably 18 or less, and particularly preferably 15 or less. From the viewpoint of suppressing bleed-out in the case of a molded product, the number average degree of polymerization of polyethylene glycol is preferably 2 or more, and more preferably 3 or more. The number average degree of polymerization is calculated from the number average molecular weight measured by size exclusion chromatography (GPC) using polystyrene as a standard substance.

[Substance showing biodegradability in seawater (c)]
The substance (c) showing biodegradability in seawater is, for example, a substance that decomposes by 50% by weight or more with respect to the cellulose to be compared after 120 days by the method specified by ASTM D6691, preferably 70. Examples thereof include a substance that decomposes by weight% or more, and more preferably a substance that decomposes by 90% by weight or more.

As the substance (c) exhibiting biodegradability in seawater, for example, polyester having a weight average molecular weight of 50,000 or less is exemplified. Polyesters selected from the group consisting of polyhydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate, polybutylene succinate, polycaprolactone, polyglycolic acid) are preferred.

[Preferable combination of additives]
From the viewpoint of improving biodegradability, the cellulose mixed fatty acid ester composition of the present disclosure preferably contains an additive selected from magnesium oxide, magnesium aluminometasilicate and triacetin. From the viewpoint of improving biodegradability and ease of molding, the cellulose mixed fatty acid ester composition of the present disclosure preferably contains at least one selected from magnesium oxide and magnesium aluminometasilicate, and triacetin. Additives consisting of a combination of magnesium oxide and triacetin are more preferred.

[Method for producing cellulose mixed fatty acid ester composition]
The cellulose mixed fatty acid ester composition of the present disclosure has an acetyl group and an acyl group having 3 or more carbon atoms, has an acetyl substitution degree DSa of 1.5 or more and less than 2.6, and has an acyl group having 3 or more carbon atoms. With a cellulose mixed fatty acid ester in which the acyl substitution degree DSb by the group is more than 0 and 0.30 or less, and the total substitution degree DS, which is the total of the acetyl substitution degree DSa and the acyl substitution degree DSb, is 2.6 or less. , The above-mentioned additives are mixed in a solvent such as acetone, and then the solvent is removed. The cellulose mixed fatty acid ester composition of the present disclosure may be obtained by melt-kneading. Preferably, this composition is obtained by mixing a cellulose mixed fatty acid ester and an additive, and then melt-kneading. By mixing before melt-kneading, the additive and the cellulose mixed fatty acid ester are more uniformly blended in a short time, so that the obtained kneaded product is homogenized, so that the composition with improved melt fluidity and processing accuracy can be obtained. can get.

A known mixer such as a Henschel mixer can be used for mixing the cellulose mixed fatty acid ester and the additive. Dry mixing may be used, or wet mixing may be used. When a mixer such as a Henschel mixer is used, the temperature inside the mixer is preferably a temperature at which the cellulose mixed fatty acid ester does not melt, for example, 20 ° C or higher and lower than 200 ° C.

An extruder such as a twin-screw extruder may be used for melt-kneading the cellulose-mixed fatty acid ester and the additive, or for melt-kneading after mixing the cellulose-mixed fatty acid ester and the additive. From the viewpoint of uniformity of the kneaded product and suppression of heat deterioration, the kneading temperature (cylinder temperature) by the extruder is preferably 170 ° C. or higher and 230 ° C. or lower. Since the cellulose mixed fatty acid ester of the present disclosure has a low glass transition temperature and a low plasticization temperature, a sufficiently uniform kneaded product can be obtained at a temperature of 230 ° C. or lower, preferably 200 ° C. or lower. For example, when melt-kneading using a twin-screw extruder, the kneading temperature (also referred to as cylinder temperature) may be 200 ° C. The kneaded product may be extruded into a strand shape from a die attached to the tip of a twin-screw extruder and then hot-cut to form pellets. At this time, the die temperature may be about 220 ° C.

The amount of the additive added to the entire obtained cellulose mixed fatty acid ester composition is preferably 3% by weight or more and 40% by weight or less. When two or more kinds of additives are blended, the total amount is adjusted to be 3% by weight or more and 40% by weight or less.

The blending amount of the cellulose mixed fatty acid ester with respect to the entire obtained cellulose mixed fatty acid ester composition is preferably 50% by weight or more, more preferably 50% by weight or more and 90% by weight or less. When two or more kinds of cellulose mixed fatty acid esters are blended, the total amount is adjusted so as to be preferably 50% by weight or more, more preferably 50% by weight or more and 90% by weight or less.

Other additives different from the above-mentioned additives may be added to this composition as long as the biodegradability of the cellulose mixed fatty acid ester composition is not impaired. Examples of other additives include colorants, ultraviolet absorbers, light stabilizers, antioxidants, heat stabilizers, optical property adjusters, fluorescent whitening agents, flame retardants and the like. In this case, it is preferable to blend the cellulose mixed fatty acid ester composition so that the total content of the cellulose mixed fatty acid ester and the additive is 85% by weight or more.

The cellulose mixed fatty acid ester composition of the present disclosure is also suitable for melt molding because it has excellent melt moldability. The shape of the molded body obtained by molding the cellulose mixed fatty acid ester composition of the present disclosure is not particularly limited, and includes, for example, a one-dimensional molded body such as a fiber; a two-dimensional molded body such as a film; and pellets. Examples thereof include three-dimensional molded bodies such as particles, tubes, and hollow cylinders.

Since the cellulose mixed fatty acid ester or the cellulose mixed fatty acid ester composition of the present disclosure has excellent biodegradability in seawater, it is a product that is easily disposable such as containers such as straws and cups, packaging materials, binders, and tobacco filters. ; Fiber for clothing; Non-woven fabric; Products that partially flow into the natural world with water when used, such as cosmetic beads and scrubs; be.

Hereinafter, the effects of the present disclosure will be clarified by the examples. Each configuration and a combination thereof in each embodiment are examples, and the configurations can be added, omitted, replaced, and other changes as appropriate without departing from the gist of the present disclosure. The present disclosure is not limited by embodiments, but only by the scope of the claims. Unless otherwise specified, all test temperatures are room temperature (20 ° C ± 5 ° C).

[Example 1]
20 g of cellulose acetate (total degree of acetyl substitution 2.15) was added to 180 g of pyridine and heated to 80 ° C. to dissolve it. After cooling the obtained solution to 5 ° C., 5.5 g of propionic anhydride was added while stirring, and stirring was continued for 30 minutes while maintaining the liquid temperature at 5 ° C. Then, the obtained reaction solution was heated to 80 ° C. with stirring. After 5 hours, 1.1 L of methanol was added to precipitate the reactants, and the precipitate was separated by filtration. The obtained precipitate was dissolved in 500 mL of a mixed solvent (volume ratio CH ₂ Cl ₂ / MeOH = 9/1), and 4.5 L of methanol was added for reprecipitation for purification. Then, the precipitate was separated by filtration, washed with methanol and pure, and vacuum dried at 80 ° C. for 3 hours to obtain a cellulose mixed fatty acid ester of Example 1. ¹ The acetyl substitution degree DSa and the acyl substitution degree DSb were measured by 1 H-NMR measurement, and the total substitution degree DSa + DSb was determined. In addition, the glass transition temperature Tg (° C.) was measured using a differential scanning calorimeter (manufactured by TA Instruments). The obtained results are shown in Table 1 below.

[Examples 2-3 and Comparative Examples 1-3]
Examples 2-3 and Comparative Example 1 are the same as in Example 1 except that the amount of each reagent added is changed so that the degree of acetyl substitution DSa and the degree of acyl substitution DSb are as shown in Table 1 below. A cellulose mixed fatty acid ester of -3 was obtained.

[Example 4]
95 parts by weight of the cellulose mixed fatty acid ester of Example 1 and 5 parts by weight of magnesium aluminometasilicate (manufactured by Fuji Chemical Industry Co., Ltd.) as an additive were blended in a dry state, dried at 80 ° C. for 3 hours or more, and further. The mixture was stirred and mixed using a Henschel mixer to obtain a mixture of a cellulose mixed fatty acid ester and an additive. The obtained mixture is supplied to a twin-screw extruder (manufactured by Ikekai Co., Ltd., trade name "PCM30", cylinder temperature: 180 ° C., die temperature: 180 ° C.), melt-kneaded, and then extruded into a strand shape. The cellulose mixed fatty acid ester composition of Example 3 was obtained. The extruded material was hot-cut to make pellets. ¹ The acetyl substitution degree DSa and the acyl substitution degree DSb were measured by 1 H-NMR measurement, and the total substitution degree DSa + DSb was determined. The results obtained are shown in Table 2 below.

[Example 5-8]
The cellulose mixed fatty acid ester composition of Example 5-8 was obtained in the same manner as in Example 4 except that the composition was as shown in Table 2 below.

[Example 9-13]
Example 9-13 in the same manner as in Example 4 except that the cellulose mixed fatty acid ester of Example 2 was used instead of the cellulose mixed fatty acid ester of Example 1 and the composition was as shown in Table 2 below. A cellulose mixed fatty acid ester composition was obtained.

[Evaluation of seawater biodegradation]
The degree of seawater biodegradation of Examples 1-13 and Comparative Example 1-3 was evaluated. In Example 4-13, pellets obtained by melt extrusion were each pulverized to an average particle size of about 20 μm and then subjected to the following biodegradation test.

60 mg of each sample was put into 250 g of seawater and stirred at a temperature of 30 ° C. The amount of carbon dioxide generated 90 days and 120 days after the sample was charged was measured. The theoretical carbon dioxide generation amount was calculated from the total organic carbon amount (TOC) measured for each sample used in the test, and the measured value of the blank (seawater only) was subtracted from the measured value for this theoretical carbon dioxide generation amount. The ratio of the values was taken as the degree of biodegradation (%). The obtained results are shown in Tables 1 and 2 below.

As shown in Table 1, the cellulose mixed fatty acid ester of Example 1-3 containing an acyl group having 3 or more carbon atoms has a lower glass transition temperature than the cellulose acetate containing no acyl group having 3 or more carbon atoms. bottom. The cellulose mixed fatty acid ester of Example 1-3 could be molded without any trouble by melt extrusion at a temperature of 180 ° C. or lower. On the other hand, in Comparative Example 3 containing an acyl group having 3 or more carbon atoms but having a total degree of substitution exceeding 2.6, the glass transition temperature was lowered, but the biodegradability in seawater was inferior.

Further, as shown in Table 2, the cellulose mixed fatty acid ester composition of the example contained an additive, and the decomposition rate in seawater was improved as compared with the corresponding cellulose mixed fatty acid ester. From this evaluation result, the superiority of the present disclosure is clear.

The cellulose mixed fatty acid ester and composition described above can be applied as a biodegradable material in various fields using melt molding and further melt forming.

Claims

It has an acetyl group and an acyl group having 3 or more carbon atoms.
The degree of acetyl substitution DSa is 1.5 or more and less than 2.6.
The degree of acyl substitution DSb by the acyl group having 3 or more carbon atoms is more than 0 and 0.30 or less.
A cellulose mixed fatty acid ester having a total substitution degree DS of 2.6 or less, which is the sum of the acetyl substitution degree DSa and the acyl substitution degree DSb.
The cellulose mixed fatty acid ester according to claim 1, wherein the acyl group has 3 or more and 10 or less carbon atoms.
The cellulose mixed fatty acid ester according to claim 1 or 2, wherein the acyl group is a propionyl group or a butyryl group.
The cellulose mixed fatty acid ester according to any one of claims 1 to 3, wherein the acyl substitution degree DSb is 0.01 or more and 0.20 or less.
Cellulose mixed fatty acid ester having a total degree of substitution DS of 2.0 or more and 2.6 or less.
The cellulose mixed fatty acid ester according to any one of claims 1 to 5 and an additive are contained.
The additive is (a) a substance having a pH of 8 or more at 20 ° C. in a 1 wt% aqueous solution, (b) a substance soluble in 2 wt% or more in water at 20 ° C., and (c) biodegradable in seawater. A cellulose mixed fatty acid ester composition selected from the group consisting of substances showing the above.
The cellulose mixed fatty acid ester composition according to claim 6, wherein the content of the cellulose mixed fatty acid ester is 50% by weight or more.
The cellulose mixed fatty acid ester composition according to claim 6 or 7, wherein the total amount of the additives added is 3% by weight or more and 40% by weight or less.
The substance (a) having a pH of 8 or more at 20 ° C. of the 1% by weight aqueous solution is
(A1) Inorganic compound containing an oxygen atom that binds to any of the metal elements of Na, K, Ca or Mg (a2) With one or more metal ions selected from Na + , K + , Ca 2+ or Mg 2+ . , A metal salt comprising one or more anions selected from carbonate ion, hydrogen carbonate ion, silicate ion or aluminate ion and (a3) selected from the group consisting of an inorganic compound containing magnesium. Item 6. The cellulose mixed fatty acid ester composition according to any one of Items 6 to 8.
The cellulose mixed fatty acid ester composition according to claim 9, wherein the main component of the inorganic compound (a3) containing magnesium is magnesium oxide.
The substance (b) that dissolves in water at 20 ° C. in an amount of 2% by weight or more is
The cellulose mixed fatty acid ester composition according to any one of claims 6 to 10, selected from the group consisting of (b1) glycerin ester (b2) citric acid ester and (b3) polyethylene glycol having a number average degree of polymerization of 20 or less. thing.
The cellulose mixed fatty acid ester composition according to any one of claims 6 to 11, wherein the substance (c) exhibiting biodegradability in seawater is a polyester having a weight average molecular weight of 50,000 or less.
12. The polyester according to claim 12, wherein the polyester is selected from the group consisting of polyhydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate, polybutylene succinate, polycaprolactone and polyglycolic acid. Cellulose mixed fatty acid ester composition.
The cellulose mixed fatty acid ester composition according to any one of claims 6 to 13, wherein the additive is selected from magnesium oxide, magnesium aluminometasilicate and triacetin.
The cellulose mixed fatty acid ester composition according to any one of claims 6 to 13, wherein the additive comprises a combination of magnesium oxide and triacetin.