Cellulose ester composition

Abstract

To provide a cellulose ester composition excellent in mechanical characteristics which can be thermally molded.SOLUTION: There is provided a cellulose ester composition which comprises a cellulose ester, an aliphatic polyester and a metal catalyst. The metal catalyst is a salt and / or a complex of a metal selected from Group 4 and Group 14 of the periodic table. A content of the metal catalyst is 3000 ppm or more as a metal element amount in the metal catalyst based on total amount of the cellulose ester, the aliphatic polyester and the metal catalyst. There is provided a method for producing the cellulose ester composition which comprises a mixing step of heating and mixing an aliphatic polyester with a cellulose ester and a metal catalyst. Preferably, the mixing step comprises a first step of heating and mixing an aliphatic polyester with a cellulose ester to obtain a base material and a second step of adding a metal catalyst to the base material, followed by heating and mixing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to cellulose ester compositions. In particular, the present disclosure relates to compositions comprising a cellulose ester and an aliphatic polyester. [Background technology]

[0002] In recent years, growing concern about the global environment has led to a demand for biodegradable molded products in various technical fields. Furthermore, from the perspectives of carbon neutrality and zero emissions, there is a demand for the development of materials derived from biomass resources as an alternative to petroleum-derived materials.

[0003] Cellulose esters are biomass-derived materials obtained by esterifying cellulose, a main component of wood, cotton, etc., and are known to be decomposed by activated sludge. Furthermore, a manufacturing method has been developed for inexpensive mass production of polylactic acid, a representative biodegradable resin, from biomass resources such as corn.

[0004] Japanese Patent No. 4600278 (Patent Document 1) discloses a polylactic acid resin composition comprising a polylactic acid resin having a weight-average molecular weight of 50,000 or more, a cellulose ester, and a compatibilizer. The compatibilizer used is an organometallic compound such as an organotitanium compound or an organoaluminum compound, and / or a polymer compound containing a methacrylic resin unit by grafting or copolymerization.

[0005] Japanese Patent Laid-Open Publication No. 2003-82160 (Patent Document 2) discloses a thermoplastic cellulose ester composition containing at least a cellulose ester and a polylactic acid having a weight-average molecular weight of 1,000 to 20,000 as a plasticizer, and a fiber made from the same. Patent Document 2 states that the polylactic acid is preferably one that does not contain a tin compound used as a polymerization catalyst. Therefore, the polylactic acid used necessarily has a low molecular weight.

[0006] Japanese Patent Laid-Open Publication No. 11-241008 (Patent Document 3) discloses a polylactic acid resin composition comprising a polymer component (A) containing polylactic acid (a1) and an aliphatic polyester (a2) having a melting point of 80 to 250°C, a plasticizer (B), and a natural product (C), of which acetylcellulose is exemplified. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4600278 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-82160 [Patent Document 3] Japanese Patent Application Publication No. 11-241008 Summary of the Invention [Problem to be solved by the invention]

[0008] Cellulose esters exhibit thermoplasticity depending on the introduced substituents and the degree of substitution, and are therefore used to produce molded articles by melt molding, injection molding, etc. However, many cellulose esters have poor thermal melting properties due to the closeness of their melting point (thermoforming temperature) and decomposition temperature, making them difficult to apply to thermoforming. For this reason, when thermoforming cellulose esters, a considerable amount of plasticizer must be added. Furthermore, cellulose esters having a substituent with a small number of carbon atoms or cellulose esters with a low degree of substitution tend to have even poorer thermoformability.

[0009] For example, in the case of cellulose acetate, a low degree of substitution is preferable from the viewpoint of improving biodegradability, but the lower the degree of substitution, the higher the melting temperature tends to be. In particular, when the melting temperature exceeds 200°C, it approaches the thermal decomposition temperature of cellulose acetate, which can cause discoloration in the resulting molded product. On the other hand, polylactic acid has the disadvantage of being difficult to crystallize during molding. Specifically, uncrystallized polylactic acid has a deflection temperature under load of 60°C or less, resulting in insufficient heat resistance. By crystallizing polylactic acid, its deflection temperature under load increases to approximately 140°C, making it usable as an engineering plastic for injection molding. However, the crystallization rate is very slow, which limits the number of shots required for thermoforming by injection molding. Furthermore, molded products obtained using polylactic acid have the problems of high brittleness and low flexibility, and furthermore, reduced mechanical properties due to a decrease in molecular weight caused by heating.

[0010] In Patent Document 1, an attempt is made to make polylactic acid compatible with cellulose ester in order to improve its heat resistance, but the amount of cellulose ester blended is less than 50 parts by weight of the total, and cellulose ester is not the main component. In Patent Document 2, a relatively low-molecular-weight polylactic acid is added to cellulose ester as a plasticizer to lower the melting temperature, thereby improving its processability, but the compatibility between cellulose ester and polylactic acid is insufficient.

[0011] An object of the present disclosure is to provide a cellulose ester composition having improved thermoformability and excellent mechanical properties. [Means for solving the problem]

[0012] To overcome the drawbacks of single polymers, "polymer blends" have been studied. However, it is impossible to blend different polymers at the nanometer level. In most polymer blends, each polymer forms a region (phase) on the order of a few microns, resulting in phase separation. This phase-separation interface is known to affect the fracture strength of molded products. Attempts to suppress this phase separation have been made by blending the two polymers with the addition of a compound (compatibilizer) that has high affinity with both polymers. However, this compatibilizer remains as an impurity in the resulting blend. Furthermore, previously proposed compatibilizers have the problem of being unable to uniformly compatibilize cellulose esters and aliphatic polyesters. After extensive research, the present inventors discovered that by melting an aliphatic polyester and mixing it with a cellulose ester in the presence of a specific metal catalyst, their compatibility is significantly improved, leading to the completion of the present invention.

[0013] That is, the cellulose ester composition according to the present disclosure comprises a cellulose ester, an aliphatic polyester, and a metal catalyst. The metal catalyst is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table. The content of the metal catalyst is 3,000 ppm or more in terms of the amount of metal element in the metal catalyst relative to the total amount of the cellulose ester, the aliphatic polyester, and the metal catalyst.

[0014] Preferably, the cellulose ester composition further comprises a modified cellulose ester, which is a transesterification reaction product of a cellulose ester and an aliphatic polyester.

[0015] Preferably, the glass transition temperature of this cellulose ester composition measured in accordance with the standard of JIS K7121 is in the range of 170°C or higher and 200°C or lower.

[0016] A preferred cellulose ester is cellulose acetate. A preferred aliphatic polyester is one or more selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycolic acid, polyethylene adipate, and polybutylene succinate.

[0017] A preferred metal catalyst is a salt of a metal selected from Group 14 of the periodic table. Preferably, the salt of this metal is a salt of a carboxylic acid having 1 to 10 carbon atoms.

[0018] A preferred metal catalyst is stannous octoate. Preferably, the cellulose ester composition has a tin content of 3,000 ppm or more and 50,000 ppm or less.

[0019] In another aspect, the present disclosure relates to a compatibilizer for cellulose esters and aliphatic polyesters, including any of the cellulose ester compositions described above.

[0020] From yet another viewpoint, the present disclosure relates to a molded article obtained by melt molding or injection molding any of the above-described cellulose ester compositions.

[0021] The method for producing a cellulose ester composition according to the present disclosure includes a mixing step of heating and mixing an aliphatic polyester with a cellulose ester and a metal catalyst, the metal catalyst being a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table.

[0022] Preferably, the mixing step comprises: (1) The first step is to heat-mix an aliphatic polyester with a cellulose ester to obtain a substrate. and (2) The second step involves adding a metal catalyst to the base material and further heating and mixing. Contains:

[0023] Preferably, in the first step, the cellulose ester is added to the melt of the aliphatic polyester and mixed in. Preferably, the heating temperature in this first step is 50°C or higher and 190°C or lower.

[0024] Preferably, in the second step, the heating temperature when the metal catalyst is added to the base material and mixed under heating is 70°C or higher and 200°C or lower.

[0025] Furthermore, this production method may include a third step after the second step in which a cellulose ester and / or an aliphatic polyester is added to the composition obtained in the second step and mixed under heating. [Effects of the Invention]

[0026] In the cellulose ester composition according to the present disclosure, the cellulose ester and the aliphatic polyester are uniformly compatibilized. The thermoformability of this composition is good. Molded articles obtained by thermoforming this composition have excellent mechanical properties such as breaking elongation and breaking strength. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a photograph showing the appearance of a dumbbell-shaped test piece of the cellulose ester composition of the example. [Figure 2] FIG. 2 is a photograph showing the state of the cellulose ester composition of the comparative example after hot pressing. [Figure 3] FIG. 3 is a photograph of a test piece obtained by injection molding the cellulose ester composition of the example. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present disclosure will be described in detail below based on preferred embodiments. Each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments, but only by the scope of the claims. Furthermore, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification.

[0029] In this specification, the range "X to Y" means "X or more and Y or less," and "ppm" means "ppm by weight." Unless otherwise noted, all tests were conducted at room temperature (20°C ± 5°C).

[0030] [Cellulose ester composition] The cellulose ester composition according to the present disclosure comprises a cellulose ester, an aliphatic polyester, and a metal catalyst. The metal catalyst is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table. These metal catalysts may be used as polymerization catalysts in the synthesis of aliphatic polyesters. In the cellulose ester composition, the metal catalyst is present in an amount of 3,000 ppm or more, calculated as the amount of metal element in the metal catalyst, relative to the total amount of the cellulose ester, the aliphatic polyester, and the metal catalyst.

[0031] In a cellulose ester composition (hereinafter sometimes simply referred to as "composition") containing the above-mentioned amount of salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table, the cellulose ester and the aliphatic polyester are compatibilized. Here, "compatibilization" refers to a state in which at least a portion of the segments of the cellulose ester and the aliphatic polyester are fused together in the segment dimension to form a single phase. "Complete compatibilization" refers to a state in which the entire composition is completely compatibilized. For example, when different polymers are mixed, multiple glass transition temperatures originating from each polymer are observed in the mixture. However, in a completely compatibilized mixture, the glass transition temperatures originating from each polymer disappear, and a single new glass transition temperature is essentially observed.

[0032] The composition in which the cellulose ester and the aliphatic polyester are compatibilized can be easily thermoformed by extrusion molding, injection molding, etc. The molded article obtained by thermoforming this composition exhibits biodegradability and good mechanical properties derived from the cellulose ester and the aliphatic polyester. Furthermore, the composition of the present disclosure can be thermoformed to obtain molded articles such as films and sheets.

[0033] In the cellulose ester composition of the present disclosure, when the aliphatic polyester and the cellulose ester are heated and mixed in the production method described below, it is considered that the action of the metal catalyst causes a transesterification reaction between them. This transesterification reaction produces a modified cellulose ester (for example, a copolymer of the cellulose ester and the aliphatic polyester), and this copolymer is present at the interface between the segments of the cellulose ester and the aliphatic polyester, thereby compatibilizing them.

[0034] In other words, the cellulose ester composition of the present disclosure further comprises the transesterification reaction product of cellulose ester and aliphatic polyester.In the composition of the present disclosure, this transesterification reaction product acts as a compatibilizer between cellulose ester and aliphatic polyester, and is therefore considered to approach complete compatibilization.Therefore, the composition of the present disclosure that comprises this transesterification reaction product can also be used as a masterbatch to be used as a compatibilizer between cellulose ester and aliphatic polyester.

[0035] [Glass transition temperature] The glass transition temperature of the cellulose ester composition of the present disclosure is appropriately selected depending on the type and ratio of cellulose ester and aliphatic polyester.In this composition in which cellulose ester and aliphatic polyester are compatibilized, the glass transition temperature can be lower than the glass transition temperature of cellulose ester and lower than the glass transition temperature of aliphatic polyester.This allows thermoforming at a temperature lower than the thermal decomposition temperature of cellulose ester.

[0036] Preferably, the cellulose ester composition of the present disclosure has a glass transition temperature measured by a differential scanning calorimeter (DSC) in the range of 170°C or higher and 200°C or lower in accordance with the provisions of JIS K7121. The composition of the present disclosure may have a plurality of glass transition temperatures in the range of 170°C or higher and 200°C or lower. From the viewpoint of suppressing thermal decomposition during molding, the glass transition temperature is more preferably 195°C or lower, and even more preferably 190°C or lower. From the viewpoint of the heat resistance of the resulting molded article, the glass transition temperature of the composition is more preferably 175°C or higher, and even more preferably 180°C or higher.

[0037] [Compatibility] Usually, a composition in which two components are completely compatible has a single glass transition temperature.Therefore, in the composition of the present disclosure, the complete compatibility of the cellulose ester and the aliphatic polyester can be confirmed, for example, by obtaining a DSC curve with a single glass transition point peak in the above-mentioned DSC measurement.However, as long as the composition can be thermoformed and has desired mechanical properties, the composition of the present disclosure may further have a glass transition point derived from the cellulose ester and / or the aliphatic polyester.

[0038] [Cellulose ester] The cellulose ester has an acyl group as a substituent. Examples of the acyl group include an acetyl group, a propionyl group, a butyryl group, a carboxyl group, a carboxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, and a methyl group. From the viewpoint of easily obtaining good biodegradability, the substituent of the cellulose ester is preferably an acetyl group, a propionyl group, or a butyryl group, and more preferably an acetyl group. The cellulose ester may have two or more types of acyl groups. The cellulose ester may contain a substituent other than an acyl group, as long as the effects of the present disclosure are not impaired.

[0039] Specific examples of the cellulose ester contained in the composition of the present disclosure include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, etc. Cellulose acetate is preferred because it can give a molded product with excellent strength.

[0040] [Total substitution degree] From the viewpoint of obtaining good biodegradability, the total degree of substitution of the cellulose ester is preferably 2.6 or less, more preferably 2.5 or less, even more preferably 2.4 or less, even more preferably 2.3 or less, and particularly preferably 2.2 or less. From the viewpoint of high melt fluidity and easy molding, the total degree of substitution of the cellulose ester is preferably 1.8 or more, more preferably 1.9 or more, and even more preferably 2.0 or more. Cellulose esters having a total degree of substitution of 1.8 or more and 2.2 or less are preferred.

[0041] [Method for measuring degree of substitution] The degree of substitution of cellulose ester can be measured by the following method. For example, it can be measured by NMR according to the method of Tezuka (Tezuka, Carbonydr. Res. 273, 83 (1995)). That is, the free hydroxyl groups of cellulose ester are acylated with a carboxylic acid anhydride in pyridine. The type of carboxylic acid anhydride used here should be selected depending on the purpose of analysis. For example, butyric anhydride is suitable for analyzing the degree of butyric substitution of cellulose acetate, and acetic anhydride is suitable for analyzing the degree of butyryl substitution of cellulose butyrate. The obtained sample is dissolved in deuterated chloroform and 13C-NMR spectrum is measured. For example, when the substituent is an acetyl group, the carbon signals of the acetyl group appear in the region from 169 ppm to 171 ppm in the order of 2nd, 3rd, and 6th positions from the high magnetic field. For another example, when a cellulose ester having a propionyl group or a cellulose ester not having a propionyl group is treated with propionic anhydride to analyze the degree of propionyl substitution, the signals of the carbonyl carbon of the propionyl group appear in the same order in the region from 172 ppm to 174 ppm. The total degree of substitution of cellulose ester treated with carboxylic anhydride by Tezuka's method or a method similar thereto is 3.0, so if the sum of the areas of the carbonyl carbon signals of the acyl groups originally possessed by the cellulose ester and the carbonyl signals of the acyl groups introduced by the carboxylic anhydride treatment is normalized to 3.0, and the abundance ratio of each acyl group at the corresponding positions (in other words, the area ratio of each signal) is calculated, this can be determined as the degree of acyl substitution at the 2nd, 3rd, and 6th positions of the glucose ring in the cellulose ester. Needless to say, the only substituents containing acyl groups that can be analyzed by this method are those that do not correspond to the carboxylic anhydride used in the treatment for analysis. In addition, 13 In addition to C-NMR, 1 It can also be analyzed by H-NMR.

[0042] [Weight average molecular weight of cellulose ester] The weight-average molecular weight of cellulose ester is not particularly limited, but from the viewpoint of obtaining a molded product with excellent tensile properties, it is preferably 10,000 or more, more preferably 100,000 or more, even more preferably 200,000 or more, even more preferably 300,000 or more, and particularly preferably 350,000 or more.From the viewpoint of obtaining suitable fluidity when melted, the weight-average molecular weight of cellulose ester is preferably 1,500,000 or less, more preferably 1,200,000 or less, even more preferably 800,000 or less, even more preferably 700,000 or less, particularly preferably 600,000 or less, and most preferably 500,000 or less.Preferably, the weight-average molecular weight of cellulose ester is 10,000 or more and 1,500,000 or less.

[0043] The weight-average molecular weight of the cellulose ester can be determined by a known method. Specifically, the weight-average molecular weight of the cellulose ester is determined by size exclusion chromatography (GPC) measurement using the following apparatus and conditions (GPC-light scattering method). Equipment: Shodex GPC "SYSTEM-21H" Solvent: Acetone Columns: 2 GMHxl (Tosoh), guard column (TSKgel guard column HXL-H manufactured by Tosoh) Flow rate: 0.8ml / min Temperature: 29℃ Sample concentration: 0.25% (wt / vol) Injection volume: 100μl Detection: MALLS (multi-angle light scattering detector) (Wyatt, "DAWN-EOS") MALLS correction standard material: PMMA (molecular weight 27600)

[0044] [Cellulose ester content] In the composition of the present disclosure, the content of cellulose ester is not particularly limited and is appropriately selected within the range compatible with aliphatic polyester.In the production method described below, from the viewpoint of easy miscibility with aliphatic polyester, the content of cellulose ester is preferably 50% by weight or more, more preferably 60% by weight or more, and particularly preferably 70% by weight or more based on the total composition.From the viewpoint of low melt fluidity and easy molding, the content of cellulose ester is preferably 95% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less.When two or more kinds of cellulose esters are used in combination, it is preferable that the total amount thereof is adjusted to the above-mentioned numerical range.

[0045] [Aliphatic polyester] The aliphatic polyester contained in the composition of the present disclosure is not particularly limited, and any biodegradable polyester can be suitably used. In addition, from the viewpoint of polymer structure, the polyester may be a polyester having, as a repeating unit, a structural unit formed by polycondensation of a hydroxycarboxylic acid, or a polyester having, as a repeating unit, a structural unit formed by dehydration condensation of a dicarboxylic acid and a diol.

[0046] Examples of polyesters having as repeating units structural units formed by polycondensation of hydroxycarboxylic acids include polyglycolic acid, polylactic acid, poly(β-hydroxybutyric acid), poly(β-hydroxyvaleric acid), poly(lactic acid-co-glycolic acid), poly(β-hydroxybutyric acid-co-β-hydroxyvaleric acid), poly(β-propiolactone), poly(ε-caprolactone), etc. Examples of polyesters having as repeating units structural units formed by dehydration condensation of dicarboxylic acids and diols include polyethylene succinate, polybutylene succinate, poly(butylene succinate-co-butylene adipate), etc.

[0047] From the viewpoints of availability and imparting good tensile properties to the resulting molded article, one or more aliphatic polyesters selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycolic acid, polyethylene adipate, and polybutylene succinate are preferred. From the viewpoint of compatibility with cellulose ester, polylactic acid is particularly preferred aliphatic polyester. Two or more aliphatic polyesters may be used in combination. Other polyesters may also be blended within a range that does not impair the effects of the present disclosure.

[0048] [Weight average molecular weight of aliphatic polyester] From the viewpoint of obtaining molded articles with excellent strength, the weight-average molecular weight of the polyester is preferably 1,000 or more, 3,000 or more, 5,000 or more, 9,000 or more, 15,000 or more, 50,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, 500,000 or more, and 600,000 or more, in that order. From the viewpoint of easy blending with cellulose ester, the weight-average molecular weight of the aliphatic polyester is preferably 3,000,000 or less, 2,500,000 or less, 2,000,000 or less, 1,000,000 or less, 900,000 or less, and 800,000 or less, in that order. The weight-average molecular weight of the aliphatic polyester is measured by the method described above for cellulose ester.

[0049] [Aliphatic polyester content] In the composition of the present disclosure, the amount of aliphatic polyester is appropriately selected depending on its type. From the viewpoint of facilitating thermoforming, the amount of aliphatic polyester is preferably 20 parts by weight or more, more preferably 25 parts by weight or more, and particularly preferably 30 parts by weight or more, relative to 100 parts by weight of cellulose ester. From the viewpoint of good compatibility with cellulose ester, the amount of aliphatic polyester is preferably 50 parts by weight or less, more preferably 45 parts by weight or less, and particularly preferably 40 parts by weight or less. When two or more types of aliphatic polyesters are used, the total amount thereof is adjusted to be within the above-mentioned range.

[0050] [Metal catalyst] The metal catalyst contained in the composition of the present disclosure is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table. These metal catalysts are known to promote the thermal decomposition of polyesters. The present inventors have discovered that adding a metal catalyst that causes thermal decomposition, which should be avoided, during the melt-mixing process of cellulose ester and aliphatic polyester significantly improves the compatibility of the two materials. As mentioned above, the details of this mechanism are still under investigation, but it is believed that heating during melt-mixing causes the metal catalyst to act as a transesterification reaction between the cellulose ester and the aliphatic polyester, and the reaction product acts as a type of compatibilizer, resulting in more uniform compatibilization.

[0051] Examples of metal elements in Group 4 include titanium (Ti) and zirconium (Zr). Examples of metal elements in Group 14 include tin (Sn) and germanium (Ge). From the viewpoint of easily compatibilizing the cellulose ester and the aliphatic polyester, salts and / or complexes of metals in Group 14 of the periodic table are preferred, and salts of metals in Group 14 are more preferred. Two or more metal catalysts may be used in combination.

[0052] The metal salt may be a salt of an inorganic acid such as hydrochloric acid, nitric acid, or sulfuric acid, or a salt of an organic acid such as carboxylic acid or sulfonic acid. From the viewpoint of easy miscibility with cellulose ester and aliphatic polyester, a salt of an organic acid is preferred, a salt of a carboxylic acid is more preferred, and a salt of a carboxylic acid having 1 to 10 carbon atoms is even more preferred. A particularly preferred metal catalyst is tin octoate because of its high catalytic activity.

[0053] There are no particular limitations on the metal complex, and for example, acetylacetone metal complexes, salicylic acid metal complexes, metal phthalocyanine complexes, β-diketone complexes, etc. may be appropriately selected and used.

[0054] [Metal catalyst content] The content of the metal catalyst in the composition of the present disclosure is 3000 ppm or more as the amount of metal element in this metal catalyst relative to the total amount of the composition (i.e., the total amount of cellulose ester, aliphatic polyester, and metal catalyst). From the viewpoint of easily compatibilizing the cellulose ester and the aliphatic polyester, it is preferably 5000 ppm or more, more preferably 8000 ppm or more, and even more preferably 10000 ppm or more. From the viewpoint of suppressing thermal degradation due to the metal catalyst remaining in the composition, the amount of the metal catalyst is preferably 1,000,000 ppm or less, more preferably 500,000 ppm or less, even more preferably 100,000 ppm or less, and particularly preferably 50,000 ppm or less. When two or more metal catalysts are used in combination, the total amount is adjusted to be within the above-mentioned range. The content of the metal catalyst in the composition of the present disclosure may be 3,000 to 1,000,000 ppm, 3,000 to 500,000 ppm, 3,000 to 100,000 ppm, 3,000 to 50,000 ppm, 5,000 to 1,000,000 ppm, 5,000 to 500,000 ppm, 5,000 to 100,000 ppm, or 5 It may be 8,000 to 50,000 ppm, 8,000 to 1,000,000 ppm, 8,000 to 500,000 ppm, 8,000 to 100,000 ppm, 8,000 to 50,000 ppm, 10,000 to 1,000,000 ppm, 10,000 to 500,000 ppm, 10,000 to 100,000 ppm, or 10,000 to 50,000 ppm.

[0055] The cellulose ester composition of the present disclosure may contain metals derived from the metal catalyst. The amount of this metal can be measured, for example, by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using an ICP emission spectrometer (Agilent 5110 manufactured by Agilent Technologies). The measurement conditions are a carrier gas of 0.7 L / min and an auxiliary gas of 1.0 L / min, and the metal can be quantified using a calibration curve method. In the production process of cellulose ester, hydroxides or salts of alkali metals or alkaline earth metals may be added as neutralizers for the acid catalyst. Furthermore, hydroxides or salts of alkali metals or alkaline earth metals may be added as stabilization treatments after precipitation of the cellulose ester. The amounts of these alkali metals and alkaline earth metals are not included in the metal content in the present disclosure.

[0056] When tin octylate is used as the metal catalyst, the tin content in the composition of the present disclosure is preferably 3,000 ppm or more, more preferably 5,000 ppm or more, even more preferably 8,000 ppm or more, and particularly preferably 10,000 ppm or more.From the viewpoint of suppressing deterioration during thermoforming, the tin content in the composition is preferably 1,000,000 ppm or less, more preferably 500,000 ppm or less, even more preferably 100,000 ppm or less, and particularly preferably 50,000 ppm or less.A cellulose ester composition having a tin content of 3,000 ppm or more and 50,000 ppm or less is preferred.

[0057] [Method of producing cellulose ester composition] The method for producing a cellulose ester composition of the present disclosure includes a mixing step in which a cellulose ester, an aliphatic polyester, and a metal catalyst, which is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table, are heated and mixed. The amount of metal catalyst added is 3000 ppm or more in terms of the metal element content relative to the total amount of the composition (i.e., the total amount of cellulose ester, aliphatic polyester, and metal catalyst). In this mixing step, the cellulose ester and the aliphatic polyester are heated and melt-mixed in the presence of a predetermined amount of metal catalyst, thereby obtaining a composition of the present disclosure in which the cellulose ester and the aliphatic polyester are compatible with each other. While melt-mixing generally refers to the mixing of multiple polymers in a molten state, in the present disclosure, the term "melt-mixing" also applies when the aliphatic polyester is molten and the cellulose ester is not molten. However, this does not exclude the case in which the aliphatic polyester and the cellulose ester are mixed in a molten state.

[0058] In the manufacturing method of the present disclosure, a transesterification reaction between the cellulose ester and the aliphatic polyester occurs in the mixing step, which is believed to contribute to the compatibilization of the two. Furthermore, in this mixing step, a modified cellulose ester is generated by the transesterification reaction, and this modified cellulose ester (i.e., the transesterification reaction product) is believed to act as a compatibilizer between the cellulose ester and the aliphatic polyester. In other words, the manufacturing method of the present disclosure is a method for producing a suitable compatibilizer between the cellulose ester and the aliphatic polyester in the mixing step.

[0059] The amount of metal catalyst added in the manufacturing method of the present disclosure is 3000 ppm or more in terms of the amount of metal element in this metal catalyst relative to the total amount of the composition (i.e., the total amount of cellulose ester, aliphatic polyester, and metal catalyst).From the viewpoint of easily compatibilizing the cellulose ester and the aliphatic polyester, it is preferably 5000 ppm or more, more preferably 8000 ppm or more, and even more preferably 10000 ppm or more.From the viewpoint of suppressing thermal degradation due to the metal catalyst remaining in the composition, the amount of metal catalyst is preferably 1,000,000 ppm or less, more preferably 500,000 ppm or less, even more preferably 100,000 ppm or less, and particularly preferably 50,000 ppm or less.When two or more metal catalysts are used in combination, the total amount is adjusted to be within the above-mentioned range.

[0060] Preferably, this mixing process comprises a first step of heating and mixing the cellulose ester and the aliphatic polyester to obtain a substrate, and a second step of adding the metal catalyst to the substrate and further heating and mixing. By melt-mixing the cellulose ester and the aliphatic polyester before adding the metal catalyst, the metal catalyst can act more effectively in the second step, and a completely compatibilized composition can be obtained.

[0061] From the viewpoint of easy mixing of the cellulose ester and the aliphatic polyester, it is preferable to add the cellulose ester to a melt of the aliphatic polyester and mix them in the first step. The heating temperature in the first step is not particularly limited and may be set to a temperature equal to or higher than the melting point of the aliphatic polyester used. From the viewpoint of uniformity of the obtained substrate, the heating temperature in the first step is preferably 50°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 160°C or higher. From the viewpoint of suppressing thermal degradation, the heating temperature is preferably 190°C or lower, more preferably 180°C or lower.

[0062] From the viewpoint of facilitating compatibility between the cellulose ester and the aliphatic polyester, the heating temperature in the second step is preferably 70° C. or higher, more preferably 90° C. or higher, even more preferably 120° C. or higher, and particularly preferably 160° C. or higher. From the viewpoint of suppressing thermal degradation, the heating temperature is preferably 200° C. or lower, more preferably 190° C. or lower.

[0063] In a more preferred embodiment, the mixing process includes a third step after the second step, in which a cellulose ester and / or an aliphatic polyester is further added to the composition obtained in the second step and mixed under heating. In this embodiment, the composition obtained in the second step can be used as a so-called masterbatch. This improves the flexibility of blending the cellulose ester and the aliphatic polyester. The cellulose ester used in the first step and the cellulose ester used in the third step may be the same or different. The aliphatic polyester used in the first step and the aliphatic polyester used in the third step may be the same or different.

[0064] In the third step, the blending ratio between the composition obtained in the second step and the cellulose ester and / or aliphatic polyester added is not particularly limited. From the viewpoint of easy compatibility between the cellulose ester and the aliphatic polyester, the blending ratio between the composition obtained in the second step and the cellulose ester and / or aliphatic polyester added in the third step is preferably 1 / 99 or more by weight, more preferably 2 / 98 or more, even more preferably 5 / 95 or more, and particularly preferably 10 / 90 or more. From the viewpoint of the degree of freedom in blend design, the blending ratio between the composition obtained in the second step and the cellulose ester and / or aliphatic polyester added in the third step is preferably 99 / 1 or less by weight, more preferably 95 / 5 or less, and even more preferably 90 / 10 or less.

[0065] An extruder such as a twin-screw extruder can be used for melt mixing in the mixing step. When melt mixing is performed using a twin-screw extruder, the kneading temperature (also referred to as the cylinder temperature) may be 200°C. The kneaded material may be extruded in the form of a strand from a die attached to the tip of the twin-screw extruder, and then hot-cut into pellets. In this case, the die temperature may be about 220°C.

[0066] In the mixing step, known additives such as colorants, ultraviolet absorbers, light stabilizers, antioxidants, heat stabilizers, optical property adjusters, fluorescent brighteners, flame retardants, lubricants, hydrolysis inhibitors, water repellents, etc. may be added within the range that does not impair the effects of the present invention. In this case, it is preferable to add them so that the total content of the cellulose ester, aliphatic polyester, and metal catalyst in the composition is 90% by weight or more.

[0067] [Application] The cellulose ester composition of the present disclosure is compatibilized by the transesterification reaction between cellulose ester and aliphatic polyester in the above-mentioned mixing step.It is considered that this transesterification reaction produces a suitable compatibilizer between cellulose ester and aliphatic polyester.Therefore, the cellulose ester composition of the present disclosure can be suitably used as a compatibilizer between cellulose ester and aliphatic polyester.

[0068] Furthermore, the cellulose ester composition of the present disclosure can be melt-molded at a temperature lower than the thermal decomposition temperature of the cellulose ester. Since the composition of the present disclosure has appropriate fluidity when melted, it can also be suitably applied to injection molding.

[0069] Molded articles obtained by melt molding or injection molding of the cellulose ester composition of the present disclosure have excellent biodegradability and good mechanical properties.Preferred molded articles include the film or sheet obtained by injection molding and melt film formation.According to the composition of the present disclosure, by stretching or inflation molding after melt extrusion, thinner films can be obtained.

[0070] The cellulose ester composition according to the present disclosure can be suitably used as a material for, for example, tableware, packaging containers, trays, agricultural materials, fishing materials, office automation parts, construction materials, medical parts, home appliance parts, automotive components, daily necessities, stationery, eyeglass frames, and the like. [Example]

[0071] The effects of the present disclosure will be clarified by the following examples, but the present disclosure should not be construed as being limited by these examples. Note that all of the following tensile property evaluation tests were performed indoors (temperature 25°C ± 5°C, humidity 50% RH).

[0072] [Example 1] According to the formulation shown in Table 1, polylactic acid (Toyota Ecoplastics Corporation, trade name "U'z S-09", weight average molecular weight 106,000), cellulose acetate (Daicel Corporation, trade name "L-30", acetyl substitution degree = 2.44, weight average molecular weight 175,000), and tin octoate (Fujifilm Wako Pure Chemical Industries, Ltd.) were charged in this order into a twin-screw extruder (Imoto Machinery Works, trade name "IMC-1979", cylinder temperature: 180°C), melt-kneaded, and then extruded to obtain the cellulose ester composition of Example 1. The amount of tin octoate added was 100,000 ppm based on the total amount of polylactic acid and cellulose acetate.

[0073] [Example 2] A cellulose acetate composition of Example 2 was obtained in the same manner as in Example 1, except that cellulose acetate, polylactic acid, and tin octoate were charged into the twin-screw extruder in this order.

[0074] [Comparative Example 1] A cellulose acetate composition of Comparative Example 1 was obtained in the same manner as in Example 1, except that tin octoate, a metal catalyst, was not added.

[0075] [Example 3] Cellulose ester compositions of Examples 3-5 were obtained in the same manner as in Example 1, except that polycaprolactone was used instead of polylactic acid.

[0076] [Example 4] Five parts by weight of the cellulose ester composition of Example 1 and 95 parts by weight of polylactic acid (manufactured by Toyota Ecoplastics Corporation under the trade name "U'z S-09", weight average molecular weight 106,000) were sequentially added to a melt-kneading machine (manufactured by Imoto Machinery Works under the trade name "IMC-1979", cylinder temperature: 190°C), melt-kneaded, and then extruded to obtain the cellulose ester composition of Example 4.

[0077] [Example 5] The cellulose ester composition of Example 5 was obtained in the same manner as in Example 6, except that the polylactic acid and the cellulose ester composition were charged into the twin-screw extruder in this order.

[0078] [Example 6] The cellulose ester composition of Example 6 was obtained in the same manner as in Example 6, except that stannous octoate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added following the addition of the cellulose ester composition and polylactic acid. The amount of stannous octoate added was 100,000 ppm of the total amount of polylactic acid and cellulose ester.

[0079] [Metal content] The tin content of the cellulose ester composition of Example 1 was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) according to the method described above, and the result was that the tin content of Example 1 was 3000 ppm.

[0080] [Glass transition temperature] The glass transition temperatures of the cellulose ester compositions of the examples and comparative examples were measured using a differential scanning calorimeter (DSC) manufactured by SII Corporation under conditions of a temperature rise rate of 20°C / min and a temperature range of 30°C to 250°C. It was confirmed that the glass transition temperatures of Examples 1 to 6 were in the range of 170°C to 200°C.

[0081] [Tensile property evaluation] The cellulose ester compositions of the Examples and Comparative Examples were each hot-pressed at 220°C to obtain a sheet having a thickness of 1.7 mm. The obtained sheets were then punched out to prepare dumbbell-shaped test pieces. A photograph of the test piece obtained in Example 1 is shown in Figure 1. The composition of Comparative Example 1 did not melt uniformly during hot-pressing and could not be punched out into the desired shape, so the following tensile test was not performed. A photograph of the sheet obtained by hot-pressing Comparative Example 1 is shown in Figure 2.

[0082] A tensile test (tensile speed 10 mm / min, grip distance 115 mm) was conducted in accordance with the provisions of ISO 527-1 using a tensile tester (manufactured by Minebea, product name "LTS-1kNB-S100") to measure the breaking strength (MPa) of Examples 1-6. The average of five measurements was calculated, and it was confirmed that Examples 1-6 had excellent mechanical strength.

[0083] [Injection molding] The cellulose ester composition of Example 1 was injection molded using an injection molding machine (trade name "MiniJET PRO" manufactured by Thermo Scientific). The molding conditions were a cylinder temperature of 190°C, a mold temperature of 75°C, an injection pressure of 900 bar, an injection time of 10 seconds, a holding pressure of 600 bar, and a holding time of 5 seconds. The obtained test piece is shown in Figure 3.

[0084] [Table 1]

[0085] [Table 2]

[0086] As explained above, it is confirmed that the cellulose ester compositions of Examples can be melt-molded and injection-molded.It is also confirmed that the cellulose ester compositions of Examples have good mechanical properties.From these evaluation results, the advantages of the present disclosure are clear. [Industrial Applicability]

[0087] The cellulose ester composition described above can be applied to various fields using melt molding, injection molding, and melt film formation.

Claims

1. A cellulose ester composition comprising a cellulose ester, an aliphatic polyester, and a metal catalyst, the metal catalyst is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table; the content of the metal catalyst is 3,000 ppm or more in terms of the amount of metal element in the metal catalyst relative to the total amount of the cellulose ester, the aliphatic polyester, and the metal catalyst; The cellulose ester composition comprises a transesterification reaction product of the cellulose ester and the aliphatic polyester.

2. A cellulose ester composition as described in claim 1, wherein the metal catalyst is a salt and / or complex of a metal selected from Group 14 of the periodic table.

3. A cellulose ester composition described in claim 1 or 2, wherein the complex is selected from the group consisting of acetylacetone metal complexes, salicylic acid-based metal complexes, metal phthalocyanine-based complexes and β-diketone complexes.

4. 4. The cellulose ester composition according to claim 1, which has a glass transition temperature measured in accordance with JIS K7121 in the range of 170°C or higher and 200°C or lower.

5. 5. The cellulose ester composition according to claim 1, wherein the cellulose ester is cellulose acetate.

6. 6. The cellulose ester composition according to claim 1, wherein the aliphatic polyester is one or more selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycolic acid, polyethylene adipate, and polybutylene succinate.

7. 7. The cellulose ester composition of claim 1, wherein the metal catalyst is a salt of a metal selected from Group 14 of the periodic table.

8. 8. The cellulose ester composition according to claim 7, wherein the metal salt is a salt of a carboxylic acid having 1 to 10 carbon atoms.

9. the metal catalyst is tin octoate, 9. The cellulose ester composition according to claim 1, wherein the tin content is 3,000 ppm or more and 50,000 ppm or less.

10. A compatibilizer for cellulose ester and aliphatic polyester, comprising the cellulose ester composition according to claim 1 .

11. A molded article obtained by melt molding or injection molding the cellulose ester composition according to any one of claims 1 to 9.

12. The method includes a mixing step of heating and mixing an aliphatic polyester together with a cellulose ester and a metal catalyst, the metal catalyst is a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table; The method for producing a cellulose ester composition, wherein the amount of the metal catalyst added is 3,000 ppm or more in terms of the amount of metal element in the metal catalyst relative to the total amount of the cellulose ester, the aliphatic polyester and the metal catalyst.

13. The mixing step a first step of heat-mixing the aliphatic polyester with the cellulose ester to obtain a substrate; a second step of adding the metal catalyst to the base material and further heating and mixing; The method for producing the cellulose ester composition of claim 12, comprising:

14. 14. The method for producing a cellulose ester composition according to claim 13, wherein in the first step, the cellulose ester is added to a melt of the aliphatic polyester and mixed.

15. The method for producing a cellulose ester composition according to claim 13 or 14, wherein the heating temperature in the first step is 50°C or higher and 190°C or lower.

16. The method for producing a cellulose ester composition according to any one of claims 13 to 15, wherein the heating temperature in the second step is 70°C or higher and 200°C or lower.

17. 17. The method for producing a cellulose ester composition according to claim 13, further comprising a third step, after the second step, of adding a cellulose ester and / or an aliphatic polyester to the composition obtained in the second step, and heating and mixing the mixture.

18. A method for producing a cellulose ester composition according to any one of claims 12 to 17, wherein in the mixing step, the aliphatic polyester and the cellulose ester are melt-mixed in the presence of a metal catalyst.

19. 19. The method for producing a cellulose ester composition according to claim 12, wherein the metal catalyst is a salt and / or complex of a metal selected from Group 14 of the periodic table.

20. A method for producing a cellulose ester composition described in any of claims 12 to 19, wherein the complex is selected from the group consisting of an acetylacetone metal complex, a salicylic acid metal complex, a metal phthalocyanine complex, and a β-diketone complex.

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