Cellulose acetate polymer composition

Abstract

To provide a cellulose acetate polymer composition having excellent fluidity during melt kneading. A cellulose acetate polymer composition containing: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc compound.

Description

CELLULOSE ACETATE POLYMER COMPOSITION

[0001] The present disclosure relates to a polymer composition. In particular, the present disclosure relates to a cellulose acetate polymer composition with high fluidity during melting even without substantially containing a plasticizer.

[0002] In recent years, there has been a demand for biodegradable plastic products due to the growing interest in the global environment. Furthermore, also for these plastic products, from the viewpoints of carbon-neutral, zero emission, and the like, there has been a demand that plastic products are derived from biomass resources, which replace materials derived from petroleum resources, or that plastic products have a high degree of biomass. While various types of materials derived from biomass resources are available, in recent years, interest has focused on a cellulose acetate, which has excellent properties, such as flame retardancy, insulating properties, solvent resistance, and chemical resistance. A cellulose acetate is a biomass resource-derived material produced by acetylation of cellulose, which is a main component of wood, cotton, and the like, and are known to be decomposed by activated sludge.

[0003] A cellulose acetate is a thermoplastic polymer. However, the fluidity during melting of the cellulose acetate is not sufficient, and the cellulose acetate is used with being mixed with a plasticizer. Cellulose acetates can be plasticized using an external plasticizer with a low molecular weight, such as a phthalate ester or triacetin, but this has a problem in that the melt fluidity of the cellulose acetate is still insufficient even though the cellulose acetate is mixed with such a plasticizer, and furthermore, the mist of the added plasticizer is generated during hot-press molding. In addition, mixing another polymer in a cellulose acetate to improve the physical properties of the cellulose acetate has also been proposed. Examples of such a composition include a combination of a polyester and a cellulose acetate. For example, PTL 1 discloses a composition containing a combination of a cellulose ester and an aliphatic polyester. However, compatibility between a cellulose acetate and a polyester is poor, and thus a molded article with high strength cannot be produced. In addition, a technique of adding an external plasticizer with a high molecular weight, such as polycaprolactone, in a cellulose acetate has also been proposed. In this case, the polymers are poorly compatible with each other, and this results in insufficient physical properties and thus is not effective. Techniques for improving the compatibility of these have also been proposed. For example, PTL 2 discloses a thermoplastic cellulose acetate composition in which an external plasticizer having a cyclic ester structure is further added to a modified cellulose acetate to further reduce the melting point. The modified cellulose acetate has a grafted oligomer obtained by graft polymerization of a cyclic ester, in particular ε-caprolactone. In this technique, a cellulose acetate as a raw material is dissolved in a solvent and reacted with ε-caprolactone using a tin catalyst in a nitrogen atmosphere. Then, the resulting crude product is heated to evaporate the solvent, and then the solid is milled with a hammer mill to produce a composition. On the other hand, PTL 3 discloses a method for producing lactic acid copolymers by ring-opening copolymerization of lactide, a dimer of lactic acid, with cellulose esters or cellulose ethers in the presence of a polymerization catalyst and a plasticizer For the external plasticizer in PTL 3, a low-molecular-weight compound, such as a phthalate ester, an adipate ester, or a glycolic acid derivative, is used, and this has a problem in that, when the resulting polymer is hot-press molded, the mist of the added plasticizer is generated or the added plasticizer is bled out. PTL 4 discloses that blending a cellulose ester including a cellulose acetate, an aliphatic polyester, and a specific metal catalyst enables melt molding and injection molding, and enables production of a cellulose ester composition with good mechanical properties. This document discloses that a dumbbell-shaped injection-molded article can be produced using tin octylate in a very large amount of 100000 ppm (2.9 wt.% as the amount of metal element) of the total amount of polylactic acid and the cellulose ester. In addition, PTL 5 discloses that generation of a foreign odor can be prevented and a cellulose ester composition with excellent moldability can be produced by blending a cellulose ester including a cellulose acetate, a thermoplastic other than a cellulose ester, a plasticizer, and a bleed-out inhibitor.

[0004] PTL 1: JP H02-057817 B PTL 2: JP H07-179662 A PTL 3: JP H11-240942 A PTL 4: JP 2023-012765 A PTL 5: JP 2007-161943 A

[0005] If a cellulose acetate and a polyester had good compatibility to each other in a composition containing the cellulose acetate and the polyester, a composition with excellent mechanical properties would be expected to be produced. However, it cannot be said that a composition with satisfactory mechanical properties has been produced. A technique for producing a cellulose acetate graft polymer (CAGP) has been disclosed, in which at least a portion of a polyester is graft-polymerized to a cellulose acetate through a process of subjecting a composition composed of a cellulose acetate and a polyester to a transesterification reaction in another reactor. However, the process is complicated, consumes a lot of energy. And thus the process imposes a heavy burden on the environment. PTL 4 discloses that when an aliphatic polyester is melt-kneaded with a cellulose ester, a transesterification reaction occurs therebetween by the action of a metal catalyst of a salt and / or complex of a metal selected from Groups 4 and 14 of the periodic table. The document discloses that this composition can be extrusion-molded and injection-molded, and also describes that a dumbbell-shaped test piece can be injection-molded. However, actual injection molding is required to produce a molded article with a complicated shape, such as a shape with a rib to maintain strength and rigidity of the molded article. Such a practical injection molding requires high melt fluidity, and further improvement of high melt fluidity is expected. In addition, tin octylate used in Examples of PTL 4 is a highly safe compound. On the other hand, among organotin compounds in the same category as tin octylate, some compounds, such as triphenyltin (TPT) and tricyclohexyltin compounds, are known to be biotoxic. In PTL 5, the bleed-out inhibitor of the plasticizer can be prevented by adding a bleed-out inhibition, but the compatibility between the cellulose ester and the thermoplastic other than a cellulose ester is not sufficient, and this may have failed to obtain sufficient performance. Thus, the present disclosure provides a cellulose acetate polymer composition having excellent fluidity during melt kneading.

[0006] As a result of diligent research, the inventors of the present disclosure have found that the above problems can be solved by preparing a composition containing a polymer with a specific structure and a compound containing a specific metal element, and have achieved the present disclosure.

[0007] That is, the gist of the present disclosure is as follows. [1] A cellulose acetate polymer composition containing: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc compound. [2] The cellulose acetate polymer composition according to [1], further containing an alkaline earth metal carboxylate. [3] The cellulose acetate polymer composition according to [1] or [2], in which the zinc compound includes a fatty acid zinc salt. [4] The cellulose acetate polymer composition according to [2] or [3], in which the alkaline earth metal carboxylate includes a fatty acid alkaline earth metal salt. [5] The cellulose acetate polymer composition according to any of [1] to [4], in which the polyester includes an aliphatic polyester. [6] The cellulose acetate polymer composition according to [5], in which the aliphatic polyester includes at least one selected from the group consisting of polylactic acid, poly(butylene succinate), and polycaprolactone. [7] The cellulose acetate polymer composition according to any of [1] to [6], in which the cellulose acetate polymer composition contains zinc element at an amount from 0.1 mass% to 10 mass%. [8] The cellulose acetate polymer composition according to any of [1] to [7], in which the polymer includes a cellulose acetate graft polymer in which at least a portion of the polyester is graft-polymerized to at least a portion of the cellulose acetate. [9] The cellulose acetate polymer composition according to any of [1] to [8], wherein the cellulose acetate polymer composition has a glass transition temperature in a range from at least 110°C to 190°C.

[0010] The cellulose acetate polymer composition according to any of [1] to [9], in which the cellulose acetate polymer composition contains an external plasticizer at an amount of 5 mass% or less, and the cellulose acetate polymer composition has an a melt flow rate (MFR) of 1 g / 10 min or greater at 220°C under a 10-kg load.

[0011] The cellulose acetate polymer composition according to any of [1] to

[0010] , in which the cellulose acetate polymer composition has a light transmittance from 30% to 80%, the light transmittance being measured according to JIS K7136: 2000 in the thickness direction when the composition is molded into a plate shape with a thickness of 0.2 mm.

[0012] A molded article produced by injection-molding or extrusion-molding the cellulose acetate polymer composition described in any of [1] to

[0011] .

[0013] The molded article according to

[0012] , further containing a coloring material of at least one of a blue dye or a purple dye, in which the molded article contains the blue dye or the purple dye at an amount from 0.0001 mass% to 0.1 mass%.

[0014] A plastic pellet containing: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc-containing compound, in which the plastic pellet contains an external plasticizer at an amount of 5 mass% or less, and the plastic pellet has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load.

[0015] A compatibilizer for a cellulose acetate and a polyester, the compatibilizer containing: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc-containing compound in which the compatibilizer contains an external plasticizer at an amount of 5 mass% or less, and the compatibilizer has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load.

[0016] A cellulose acetate polymer composition containing a melt-kneaded product of a mixture containing a cellulose acetate, a polyester, and a zinc compound, in which the melt-kneaded product contains a polymer in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other.

[0017] A method for producing a cellulose acetate polymer composition, the method including: melt-kneading a cellulose acetate, a polyester, and a zinc compound to produce a polymer in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other.

[0008] According to the present disclosure, there can be provided a cellulose acetate polymer composition with excellent fluidity during melt kneading.

[0009] Figs. 1, (a) and (b) are charts showing1H-NMR measurement results obtained by using solutions 1 and 2 in Examples, respectively.Figs. 2, (a)-(d) are charts showing DSC measurement results obtained by using compositions 1-4 in Examples, respectively.Fig. 3 is a chart showing DSC measurement results in Examples.Fig. 4 is a chart showing DSC measurement results in Examples.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail, but each configuration, a combination of configurations, and the like in each embodiment are an example, and an addition, an omission, a substitution, and another change can appropriately be made without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments and is limited only by the claims. In addition, in the present disclosure, “X to Y” indicating a range means a range including the numerical values described before and after “to” as the lower limit value and the upper limit value and means “A or more and B or less” or “A or greater and B or less”. Furthermore, in the case where a numerical range represented by “X to Y”, or “X or greater and Y or less” or “X or greater and Y or less” is described stepwise (e.g., in the order of preference), the upper limit and the lower limit of each numerical range can be freely combined. Moreover, although a plurality of embodiments will be described in the present disclosure, various conditions in each embodiment can be applied to each other within an applicable range. Still more, the expression “A or B” in the present disclosure can be read as “at least one selected from the group consisting of A and B”. Yet more, in the present disclosure, “a plurality of” means “two or more”. A dimension, a material, a shape, a relative arrangement, or the like of a constituent element described in the present disclosure is an example. In the present disclosure, mass percent (mass%) is a description of a mass fraction in percentage and does not mean mass concentration. In the present disclosure, weight percent (wt.%) and mass percent are synonymous.

[0011] Configuration of Cellulose Acetate Polymer Composition A cellulose acetate polymer composition according to an embodiment of the present disclosure (hereinafter also referred to simply as the “cellulose acetate polymer composition” or the “composition”) is a cellulose acetate polymer composition containing: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other (hereinafter also referred to as a “CA-PE polymer”); and a zinc compound. The composition of the polymer in the composition according to the present disclosure is not particularly limited as long as the composition contains a CA-PE polymer; the composition may be composed only of a CA-PE polymer or may be composed by containing a CA-PE polymer and at least one polymer of a cellulose acetate or a polyester. Furthermore, the composition may contain a polymer other than these polymers in a range in which the effects of the present disclosure are provided. In the present disclosure, a composition containing a CA-PE polymer is referred to as a cellulose acetate polymer composition.

[0012] The inventors of the present disclosure have conducted studies and experiments on melt kneading of a mixture containing a cellulose acetate and a polyester and have found that a composition with excellent melt fluidity during melt kneading can be produced by adding a zinc-containing compound to a cellulose acetate and a polyester and melt-kneading the mixture. Furthermore, a DSC chart of a composition produced by melt kneading has shown that there is a glass transition point other than those of a cellulose acetate and a polyester. This indicates the occurrence of compatibilization of a cellulose acetate and a polyester. From these studies and experiments, the inventors presume that a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other (hereinafter also referred to as a “CA-PE polymer”) is produced by melt-kneading a mixture containing a cellulose acetate, a polyester, and a zinc compound, using zinc contained in the zinc-containing compound as a catalyst. At least a portion of the cellulose acetate contains at least a part of the main chain of the cellulose acetate, and at least a portion of the polyester contains at least a part of the main chain of the polyester.

[0013] The effect of the CA-PE polymer will be described below. First, a cellulose derivative, such as a cellulose acetate, has a rigid main chain. Thus, the molecular chain has low bendability during melting, and a cellulose derivative has poor thermal fluidity. However, when the CA-PE polymer is produced, that is, a bulky substituent (at least a portion of the polyester) is bound to a cellulose acetate, a spatial distance is provided between the molecular chains, thus even the rigid main chain can exhibit bendability. This improves fluidity during melt kneading. Second, although a cellulose acetate and a polyester are not compatible with each other, the CA-PE polymer can be present between the cellulose acetate molecular chain and the polyester molecular chain. Specifically, a part of the main chain of the cellulose acetate is present in the CA-PE polymer, and thus the CA-PE polymer has excellent compatibility with the cellulose acetate. Owing to compatibilization, when the composition containing a CA-PE polymer, a cellulose acetate, and a polyester is cooled, a compatibilized product can be crystalized, resulting in the formation of a different crystal from the crystal of the cellulose acetate and the crystal the polyester. The crystal of the compatibilized product is not a single crystal part of either the cellulose acetate or the polyester, and thus no interface between the cellulose acetate and the polyester is present in a system in which these components coexist. Brittle fracture (fracture not accompanied by plastic deformation) in a polymer alloy occurs at the interface between the polymers of the respective components. Thus, in the compatibilized product in which the interface is not present, brittle fracture at the interface does not occur. Furthermore, the composition containing a CA-PE polymer or a molded article produced using the composition can prevent brittle fracture at the interface and thus tends to have excellent mechanical strength. The CA PE polymer produces an interaction with both polymers of a cellulose acetate and a polyester as described above and thus also functions as a compatibilizer. Thus, also in the case of melt molding using a blend pellet prepared by adding and mixing a CA-PE polymer to a cellulose acetate and a polyester, excellent fluidity and compatibility are exhibited.

[0014] The composition according to the present disclosure is not particularly limited as long as the composition contains a CA-PE polymer and a zinc compound. For example, the composition may be a melt-kneaded product produced by melt-kneading a cellulose acetate, a polyester, and a zinc compound to produce a CA-PE polymer, or may be a polymer alloy containing a cellulose acetate, a polyester, a CA-PE polymer, and a zinc compound. In any embodiment, the composition exhibits excellent fluidity during melt kneading.

[0015] In addition, the composition according to the present disclosure can be subjected to melt molding after further adding a pellet containing a cellulose acetate and / or a polyester.

[0016] Polymer in Which at Least Portion of Cellulose Acetate and at Least Portion of Polyester Are Bound to Each Other (CA-PE Polymer) The CA-PE polymer is not particularly limited as long as at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other, and examples thereof include a transesterification reaction product produced by a transesterification reaction between an unsubstituted hydroxyl group of the cellulose acetate (which may be at least a portion of the cellulose acetate) and an ester group of the polyester (which may be at least a portion of the polyester) or a transesterification reaction between an acetyl group of the cellulose acetate (which may be at least a portion of the cellulose acetate) and a hydroxyl group of the polyester (which may be at least a portion of the polyester). More specifically, examples of these transesterification products include a cellulose acetate graft polymer (hereinafter also referred to as a “CAGP”) produced by the occurrence of the transesterification reaction, in which at least a portion of a polyester is graft-polymerized to at least a portion of a cellulose acetate. In comparison of the above two transesterification reactions, the present inventors presume that the former reaction is more dominant. The CAGP can be produced by blending at least a cellulose acetate, a polyester, and a zinc compound, and melt-kneading these. The cellulose acetate and the polyester may be a cellulose acetate and a polyester that can be contained in the composition described below. Hereinafter, a preferred embodiment in the case where the CA-PE polymer is a CAGP will be described. Thus, the wording “CAGP” is used in the following descriptions, but “CAGP” may be appropriately replaced by “CA-PE polymer” within an applicable range.

[0017] When a cellulose acetate and a polyester are melt-kneaded in the presence of a zinc compound, a transesterification reaction occurs between an unsubstituted hydroxyl group of the cellulose acetate and an ester group of the polyester or between an acetyl group of the cellulose acetate and a hydroxyl group of the main chain of the polyester, resulting in the formation of a transesterified product. This reaction graft-polymerizes at least a portion of the polyester to a hydroxyl group of a glucose ring contained in the cellulose acetate. As described above, in the present disclosure, the polymer produced by this graft polymerization is referred to as a cellulose acetate graft polymer (CAGP). In this reaction, the zinc compound acts as a catalyst. In addition, the polyester and the cellulose acetate need to be melted in advance. Although the cellulose acetate and the polyester are immiscible, the cellulose acetate and the polyester react at the melt interface to produce a graft polymer. This graft polymer functions as a kind of compatibilizer for the mixed system of the cellulose acetate / the polyester. Such melt kneading accompanied by interfacial reaction is called reactive processing. In the present disclosure, an ester bond of the main chain of the polyester is cleaved by using a zinc compound, and a transesterification reaction occurs with an acetyl group of the cellulose acetate. This leads to a mode in which a bulky polyester is bound to a glucose ring of the main chain of the cellulose acetate. This enables the CAGP to have a sufficient space due to the polyester bound to the periphery of the main chain, significantly increasing the melt fluidity. In the case of producing the CAGP by melt-kneading a cellulose acetate, a polyester, and a zinc compound, depending on the quantitative proportion of these materials, all polymer phases may become a CAGP phase, or a plurality of phases of a CAGP phase and a phase of at least one of a cellulose acetate phase or a polyester phase may be present. Even in a structure having at least one phase of a cellulose acetate phase or a polyester phase in addition to a CAGP phase, the presence of the CAGP increases the thickness of the interface between the cellulose acetate and the polyester, which are originally incompatible, and increases the adhesive strength between the two phases. This increases the impact resistance of a molded article by molding the composition and makes it easier to avoid brittle fracture. As described above, the CAGP is easily compatible with both a cellulose acetate and a polyester. And thus, the CAGP can be preferably used not only for the application as a material constituting a molded article but also as an application for a compatibilizer for a cellulose acetate and a polyester.

[0018] Hereinafter, properties of the CAGP contained in the composition according to the present disclosure will be described. In the case where the entire amount of the composition is a CAGP, the glass transition temperature shows a single peak. Otherwise, when exhibiting a single glass transition temperature, cellulose acetate and polyester are miscible and form a single phase. The composition described above has a two-phase structure, and the glass transition temperature of the composition shows peaks each assigned to the CAGP, the polyester, and the cellulose acetate.

[0019] Glass Transition Temperature of CAGP Hereinafter, the glass transition temperature (Tg) of a CAGP will be described. Tg is determined by the primary structure of a polymer. Thus, a difference in Tg indicates that the primary structure of each CAGP is different. In polymer compounds, the glass transition depends on freezing and releasing of micro-Brownian motion of the molecules. In that sense, differences in the length of the CAGP lead to variations in Tg. The physical properties of a molded article vary greatly around the Tg. Thus, a molded article with a Tg higher than the use temperature range has stable physical properties. However, a lower Tg may be preferred for some applications. In the present disclosure, the Tg of the CAGP can be changed by adjusting conditions of raw materials, specifically, such as the zinc compound, the weight-average molecular weight of the polyester, the average degree of substitution of the cellulose acetate, and the blending amount of a fatty acid alkaline earth metal salt that can be optionally contained. The Tg of the CAGP can be a Tg of the composition. In this case, a CAGP with a low Tg can be produced by using a polyester with a small number of carbons between ester bonds, using a polyester with a small weight-average molecular weight, or increasing the blending amount of a zinc compound and an alkaline earth metal carboxylate that can be optionally contained. The Tg may be 110°C or higher, 120°C or higher, or 130°C or higher, and is preferably 140°C or higher, more preferably 150°C or higher, and from the viewpoint of melt fluidity, it is preferably 190°C or lower, more preferably 180°C or lower, and particularly preferably 175°C or lower. Specifically, the composition may have a glass transition temperature, for example, in a range from 110 to 190°C, from 120 to 190°C, from 130 to 190°C, from 140 to 190°C, from 140 to 180°C, or from 50 to 175°C. The glass transition temperature also depends on the average molecular weight (such as weight-average molecular weight) of the polyester. Thus, the glass transition point can be lowered by selecting a polyester with a small average molecular weight. In addition, when a plasticizer with affinity for a polyester, particularly an aliphatic polyester, is mixed with the cellulose acetate, the glass transition temperature of the polyester is lowered.

[0020] In addition, along with the production of a CAGP, the glass transition temperature (Tg) based on the cellulose acetate can decrease. When the amount of decrease in the glass transition temperature (Tg) based on the cellulose acetate is represented by ΔTg, from the viewpoint of ensuring good fluidity during melt kneading, the ΔTg is preferably 8°C or greater, may be 10°C or greater, or may be 20°C or greater, and the upper limit is not particularly limited and may be 100°C or less.

[0021] The glass transition temperature (Tg) is measured according to JIS K0129: 2005 (using a differential scanning calorimeter (DSC) under conditions of a temperature increase rate of 20°C / min in a temperature range of 30°C to 240°C in a nitrogen gas atmosphere). An object to be measured with a low Tg may be measured from -50°C. The composition according to the present disclosure is easily affected by moisture. Thus, it is necessary to ensure that the moisture content of the sample is reduced by vacuum drying or the like before the measurement with a DSC. In the measurement, the temperature is once increased to 240°C at a temperature increase rate of 20°C / min, then reduced to 30 or -50°C at a rate of 20°C / min, and then increased again at a temperature increase rate of 20°C / min under the above conditions. Tg is measured in the DSC curve observed in the second temperature raising process.

[0022] Primary Structure of CAGP A method for confirming the primary structure of a CAGP will be described below. A CAGP is graft-polymerized by a transesterification reaction as described above. And thus, the primary structure of a CAGP cannot be identified by an ester group with the NMR measurement. However, for a substance with a single peak at the above Tg, the presence of an acetyl group, a glucose ring, a polyester group, an aliphatic chain, and / or the like can be confirmed by dissolving the substance in an appropriate solvent and measuring1H-NMR or13C-NMR. For the composition showing a plurality of Tg's, the object to be measured is frozen and milled, and then an unreacted cellulose acetate is dissolved with an excess amount of acetic acid and removed. Thereafter, the polyester is eluted with a good solvent for the polyester whose structure is estimated by NMR measurement or the like of the composition, and the remaining residue is analyzed by NMR.

[0023] Cellulose Acetate The composition according to the present disclosure may contain a cellulose acetate. The cellulose acetate is not particularly limited, and a known one can be used. One type of cellulose acetate may be used alone, or two or more types in combination. The cellulose acetate needs to have an unsubstituted hydroxyl group.

[0024] The blending proportion of a cellulose acetate in the composition according to the present disclosure is not particularly limited. By way of an example, the blending proportion in the composition as a dry-blended product will be described below. The dry-blended product is a mixture of each pellet of a CAGP and at least one of a cellulose acetate or a polyester. For the dry blend containing a cellulose acetate, the blending proportion can be considered as the proportion of dilution of the CAGP with the cellulose acetate. Specifically, the effects of the present disclosure are exhibited even when the CAGP is diluted with the cellulose acetate in an amount four times the amount of the CAGP. In this mode, the blending proportion of the cellulose acetate is 80 mass%. As described above, the CAGP is produced when a cellulose acetate, a polyester, and a zinc compound are melt-kneaded. At this time, with thermal history, the blending proportion of the cellulose acetate decreases. That is, in the case of injection-molding a dry-blended product of a CAGP, a cellulose acetate, and a polyester into a molded article, the content of the cellulose acetate is lower in the injection-molded article than in the dry-blended product.

[0025] Polyester The composition according to the present disclosure may contain a polyester, and the is not particularly limited but is preferably an aliphatic polyester from the viewpoint of biodegradability. In the present disclosure, the aliphatic polyester is a polyester produced using only those having an aliphatic constituent unit as constituent units of the polyester. That is, the aliphatic polyester is a polyester produced by dehydration condensation of an aliphatic polycarboxylic acid and an aliphatic polyol, or a polyester produced by polycondensation of an aliphatic hydroxydicarboxylic acid.

[0026] Examples of the dicarboxylic acid include terephthalic acid (TPA), 2,6-naphthalenedicarboxylic acid (NDC), succinic acid, glutaric acid, or adipic acid. Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, or 1,4-butanediol. The polycarboxylic acid and the polyol can be freely combined, but in particular, the combination of the polycarboxylic acid and the polyol may be a combination of succinic acid and 1,4-butanediol or a combination of succinic acid and dipropylene glycol. Examples of the polyester having, as a repeating unit, a constituent unit with a dicarboxylic acid and a diol being dehydrated and condensed include poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate), or poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH).

[0027] Examples of the polyester having, as a repeating unit, a constituent unit derived from a hydroxycarboxylic acid 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), or poly(ε-caprolactone).

[0028] Among the polyesters described above, from the viewpoints of availability and imparting good tensile properties to the resulting molded article, the polyester is preferably at least one aliphatic polyester selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycolic acid, polyethylene adipate, and poly(butylene succinate), more preferably at least one selected from the group consisting of polylactic acid, poly(butylene succinate), and polycaprolactone, and from the viewpoint of compatibilization with the cellulose acetate, the polyester is particularly preferably polylactic acid. One type of polyester may be used alone, or two or more types in combination. In addition, the composition may further contain another polyester in a range in which the effects of the present disclosure are not inhibited.

[0029] Among the polyesters described above, examples of the polyester with a high degree of biomass include polylactic acid (PLA), poly(butylene succinate) (PBS), or poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH).

[0030] In the present disclosure, the CAGP is considered to be graft-polymerized by a transesterification reaction of an ester group and / or a terminal hydroxyl group of a molecular chain of the melt-kneaded polyester and a hydroxyl group and / or an acetyl group of the cellulose acetate. Thus, in the present disclosure, the melt-kneaded polyester is graft-polymerized while being partially decomposed, thus the side chain to be graft-polymerized may have a molecular weight less than that of the added polyester. The CAGP in the present disclosure also includes a CAGP produced by a transesterification reaction of a hydroxyl group generated by cleavage from an ester bond part of a molecular chain of a polyester and an acetyl group of a cellulose acetate. In particular, aliphatic polyesters are susceptible to cleavage of the main chain due to heat. In addition, these cleavages are more likely to occur in the presence of moisture. Cellulose acetates have bound water. Thus, melt-kneading a cellulose acetate and an (aliphatic) polyester makes the polyester main chain more susceptible to cleavage. Thus, it is conceivable that, when a cellulose acetate, an (aliphatic) polyester, and a zinc compound are melt-kneaded, the main chain of at least a portion of the polyester cleaves, facilitating production of a CAGP resulting from a transesterification reaction of a hydroxyl group in the molecular chain of the cleaved polyester and an acetyl group of the cellulose acetate. As described above, from the viewpoint of producing a CAGP, examples of the polyester suitable for the present disclosure include an aliphatic polyester, and in particular, an aliphatic polyester with a small number of carbons between ester bonds is preferred. Specific examples include a poly(α-hydroxy acid), such as polyglycolic acid; polylactic acid; and a poly(β-hydroxyalkanoate), such as poly(β-hydroxybutyrate).

[0031] When the composition according to the present disclosure contains a polyester, the blending proportion of the polyester in the composition is not particularly limited. However, there is a concern that the polyester contained in 50 mass% or greater would form a continuous phase. In the case where the polyester is aliphatic, the polyester in the continuous phase would significantly reduce the heat resistance. Thus, the blending amount of the polyester may be 40 mass% or less and desirably 30 mass% or less. In addition, the lower limit of the blending proportion may be 5 mass% or greater or 10 mass% or greater. Specific examples of the blending proportion include from 5 to 50 mass%, from 5 to 40 mass%, from 5 to 30 mass%, and from 10 to 30 mass%.

[0032] Zinc Compound The zinc compound is not particularly limited as long as it is a compound containing zinc, and a known one can be used. The zinc compound may be obtained by synthesis or may be obtained from commercially available products. In addition, one type of zinc compound may be used alone, or two or more types in combination. Zinc compounds are highly safe substances. For example, zinc sulfate may be mixed with agricultural chemicals or fertilizers to prevent phytotoxicity to crops and / or alkalization of soil, or may be added to livestock feed for the purpose of enhancing mineral content. For a similar purpose, there are also products containing a water-soluble compound of zinc in milk powders for babies or pets. In addition, a zinc compound is used for plating, sewage treatment, and as an additive for eye drops for reducing eye inflammation, such as conjunctivitis. Furthermore, zinc oxide is often used in cosmetics.

[0033] Specific examples of the zinc compound include zinc oxide and zinc carboxylate. Examples of the zinc carboxylate include a fatty acid zinc salt, such as a saturated fatty acid zinc salt and an unsaturated fatty acid zinc salt. Examples of saturated fatty acid zinc include zinc acetate, zinc acetate (II), zinc pentadecanoate, zinc palmitate, zinc margarate, zinc stearate, zinc oleate, zinc linoleate, and zinc salicylate. Among these, from the viewpoint of ensuring excellent fluidity during melt kneading, a fatty acid zinc salt is preferred, and zinc stearate is particularly preferred. When a highly basic zinc compound is used, the composition can be colored. Thus, the composition does not have to use such a compound. Examples of the highly basic zinc compound include zinc chloride. In addition, the zinc compound may be a water-insoluble zinc compound or may be hydrophobic.

[0034] Amount of Zinc The upper limit of the blending amount of the zinc-containing compound in the composition according to the present disclosure is not particularly limited, but in the present disclosure, the composition with a small quantitative proportion of the zinc-containing compound also has sufficient effects. In addition, the catalytic function of the zinc-containing compound is presumably due to the zinc element contained in the zinc-containing compound. Thus, from the viewpoint of the effect, the amount of the zinc element is preferably adjusted although the blending amount of the zinc compound depends on the molecular formula of the compound. The concentration of the zinc element in the composition is not particularly limited but is usually 100 mass ppm or greater, preferably 500 mass ppm or greater, more preferably 1,000 mass ppm or greater (0.1 mass % or greater), and preferably 1, 300 mass ppm or greater. Furthermore, the upper limit may be 30, 000 mass ppm or less. Specific examples of the concentration include from 100 to 100, 000 mass ppm, from 500 to 100, 000 mass ppm, from 1, 000 to 100, 000 mass ppm(0.1 mass % to 10.0 mass % or less), and from 1, 300 to 100, 000 mass ppm, from 100 to 30, 000 mass ppm, from 500 to 30, 000 mass ppm, from 1, 000 to 30, 000 mass ppm, and from 1, 300 to 30, 000 mass ppm. The concentration of the zinc element in the composition is particularly preferably 3000 mass ppm or greater. For example, zinc stearate with a formula weight of 632.35 g / mol is blended in an amount of about 4 mass% or greater as a raw material. For zinc oxide, the blending amount is about 0.4 mass% or greater. Zinc stearate is also inexpensive and thus may be blended in a certain amount. The blending amount of the zinc compound as a raw material can be analyzed, for example, by atomic absorption spectrometry. In this method, the blending amount can be measured by dissolving the composition in an appropriate solvent and then supplying the solution to an atomic absorption spectrometer. Zinc oxide, zinc stearate, and the like are highly safe substances. Thus, from the viewpoint of safety, the blending amount may be increased. In addition, in the case of using two or more types of zinc compounds in combination, their total amount is preferably adjusted to the numerical range described above.

[0035] The concentration of zinc in the composition according to the present disclosure can be measured, for example, by inductively coupled plasma atomic emission spectrometry (ICP-AES) using an ICP emission spectrometer (e.g., Agilent 5110 available from Agilent Technologies Japan, Ltd.). Specific measurement conditions for performing ICP-AES will be described below. In a magnetic crucible, 0.1 g of a sample (composition) to be measured is precisely weighed. Then, operation A below is performed. Operation A: The sample is then heated on a sand bath to evaporate a solvent. To this, 0.3 mL of concentrated sulfuric acid (for atomic absorption spectrometry, available from Kanto Chemical Co., Inc.) is added, and the mixture is pre-incinerated to ash on a hot plate. Then, this is transferred in a state of emitting no gas to a muffle furnace and heated at 450°C, 500°C, and 550°C in this order to incinerate to ash. After allowing to cool, 1 mL of concentrated nitric acid (for atomic absorption spectrometry, available from Kanto Chemical Co., Inc.) is added to decompose the sample on a sand bath. Then, a small amount of water and 0.12 mL of concentrated nitric acid are added and refluxed on a sand bath. A value determined by similarly performing the above operation A with an empty magnetic crucible is used as a blank test value, and a value determined by subtracting the blank test value from the measurement result is calculated as the metal concentration in the sample. For the calibration curve, a standard solution prepared by appropriately diluting a Zn 1000 standard solution to give the same concentration as that of the sample is used.

[0036] Alkaline Earth Metal Salt The composition according to the present disclosure may further contain an alkaline earth metal salt. The melt viscosity of the composition during molding can be reduced by blending an alkaline earth metal salt into the composition. In the present disclosure, it is presumed that only in the presence of the zinc compound, the alkaline earth metal salt functions as a catalytic promoter for the zinc compound during melt kneading and can increase the CAGP in the composition. Depending on the quantitative proportion of the zinc compound, a sufficient amount of CAGP is produced even when the composition does not contain an alkaline earth metal salt. Thus, the alkaline earth metal salt is not an essential component in the composition according to the present disclosure. However, from the viewpoint of reducing the melt viscosity during molding, the composition preferably contains an alkaline earth metal salt. In addition, among alkaline earth metal salts, a compound containing a zinc element, such as zinc potassium chromate, is treated as a zinc compound.

[0037] Examples of the alkaline earth metal salt include calcium carbonate, magnesium carbonate, magnesium acetate, or an alkaline earth metal carboxylate. Among these, from the viewpoint of improving fluidity during melt kneading, the alkaline earth metal salt is preferably calcium carbonate, magnesium carbonate, or an alkaline earth metal carboxylate, more preferably an alkaline earth metal carboxylate, and particularly preferably a fatty acid alkaline earth metal salt. One type of alkaline earth metal salt may be used alone, or two or more types in combination.

[0038] Examples of the fatty acid constituting the fatty acid alkaline earth metal salt include lauric acid, tridecanoic acid, myristic acid, myristoleic acid, pentadecanoic acid, pentadecenoic acid, palmitic acid, palmitoleic acid, margaric acid, heptadecenoic acid, stearic acid, oleic acid, linoleic acid, or salicylic acid. Among these, an alkaline earth metal stearate is preferably used. Examples of the alkaline earth metal contained in the fatty acid alkaline earth metal salt include calcium or magnesium. One type of fatty acid alkaline earth metal salt may be used alone, or two or more types in combination. The composition can be colored with a fatty acid alkali metal salt, and thus a fatty acid alkaline earth metal salt is preferably used.

[0039] Amount of Alkaline Earth Metal Salt The content of the alkaline earth metal salt in the composition according to the present disclosure is not particularly limited. It may be adjusted by the quantitative proportion of a CAGP and a zinc compound in the composition. A specific addition amount may be, in terms of the content in the composition, 1 mass% or greater, 2 mass% or greater, or 3 mass% or greater, and may be 6 mass% or less or 5 mass% or less. In the case where two or more types of alkaline earth metal salts are contained in the composition, the above content is the total content of the two or more types of alkaline earth metal salts. In the present disclosure, “content” may be replaced with “concentration”. In addition, from the viewpoint of the effect of improving fluidity during melt kneading, the amount of the alkaline earth metal element is preferably adjusted although the blending amount of the alkaline earth metal salt depends on the molecular formula of the compound similarly to the zinc compound described above. The concentration of the alkaline earth metal element in the composition is not particularly limited and may be 1 mass% or greater, 2 mass% or greater, or 3 mass% or greater, and may be 6 mass% or less or 5 mass% or less. A flake of the cellulose acetate can contain an alkali metal and / or an alkaline earth metal as a heat-resistant stabilizer. The above concentration is a concentration as the total amount of these. The alkaline earth metal salt and the alkaline earth metal element include not only those contained by addition as the alkaline earth metal salt but also those contained in a material used as a raw material and in turn contained in the composition. In the case where two or more types of alkaline earth metal elements are contained in the composition, the above content is the total content of the two or more types of alkaline earth metal elements. The content of the alkaline earth metal element in the composition can be measured by the same method as the method for measuring the content of the zinc element described above.

[0040] A composition according to another embodiment of the present disclosure is a cellulose acetate polymer composition containing a melt-kneaded product of a mixture containing a cellulose acetate, a polyester, and a zinc compound, in which the melt-kneaded product contains a polymer (CA-PE polymer) in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other. For the conditions of the CA-PE polymer, the cellulose acetate, the polyester, and the zinc compound, the conditions of each component described above can be similarly applied. In addition, for the conditions for melt-kneading for producing the melt-kneaded product, conditions for melt-kneading in a section of a method for producing the composition described below can be similarly applied.

[0041] Method for Producing Composition A method for producing the composition according to the present disclosure is exemplified below.

[0042] For the method for producing the composition according to the present disclosure, a method including melt-kneading components to be contained in the composition while mixing the components (mixing step) can be employed. Specifically, in the method, a cellulose acetate, a polyester, and a zinc compound are melt-kneaded to produce a polymer in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other. The mixing step may specifically include: mixing a polyester, a zinc compound, and an optional component to produce a mixture A-1 (step A-1); and further mixing the mixture A-1 with a cellulose acetate and melt-kneading the mixture to produce a composition (step A-2). In the case where the polyester is an aliphatic polyester, in step A-1, the aliphatic polyester and a zinc compound may be mixed in a heated mixer to attach the zinc compound and / or an alkaline earth metal salt as an optional component to an aliphatic polyester pellet surface. A fatty acid alkaline earth metal salt may be further added to the mixture A-1 later. Alternatively, a fatty acid alkaline earth metal salt may be added at the stage of melt-kneading in step A-2. In addition, the cellulose acetate can be used in the form of a cellulose acetate flake, and the mixing step may include mixing an alkaline earth metal salt as an optional component in the cellulose acetate flake to produce a pellet. The cellulose acetate pellet produced in this step does not contain a CAGP. The cellulose acetate pellet may be mixed with an aliphatic polyester pellet with a surface to which a zinc compound and / or an alkaline earth metal salt as an optional component is attached.

[0043] In addition, for the method for producing the composition according to the present disclosure, a method of preparing a mixture containing components to be contained in the composition and then melt-kneading the mixture may be employed. Specifically, the mixture can be obtained by mixing a cellulose acetate flake, a polyester, a zinc compound, and as necessary an alkaline earth metal salt. The method for mixing is not particularly limited, and the components can be mixed by a known dry blend method. More specifically, pellets, flakes, and / or powders of these may be mixed in a tumbler mixer. These (tumbler) mixers may be heatable devices.

[0044] As described above, regardless of whether the mixture is prepared in advance, in the production of the composition according to the present disclosure, melt-kneading a cellulose acetate, a polyester, a zinc-containing compound, and as necessary an alkaline earth metal salt is necessary. A CAGP is produced by melt kneading.

[0045] The various materials used for the production of the composition of the present disclosure can be used in various ways. Hereinafter, conditions of each component that can be used for the production of the composition according to the present disclosure will be described.

[0046] Cellulose Acetate The total degree of acetyl substitution of the cellulose acetate is not particularly limited as long as a CAGP can be produced. The degree of substitution of the cellulose acetate is preferably 2.6 or less, more preferably 2.5 or less, even more preferably 2.4 or less, particularly preferably 2.3 or less, and especially preferably 2.2 or less. The degree of substitution of the cellulose acetate is preferably 1.8 or greater. The cellulose acetate with a degree of substitution of less than 1.8 has water solubility and thus can have lower water resistance. In addition, the degree of substitution of the cellulose acetate is more preferably 1.9 or greater and even more preferably 2.0 or greater. In addition, in the case of a polymer blend, a cellulose acetate with a degree of substitution of 2.5 or less improves biodegradability of a cellulose acetate phase and thus is preferred.

[0047] The above total degree of acetyl substitution can be measured by the following method. For example, the total degree of acetyl substitution can be measured by NMR according to the method of Tezuka (Tezuka, Carbonydr. Res. 273, 83 (1995)). That is, a free hydroxyl group of the cellulose acetate is acylated with a carboxylic anhydride in pyridine. The type of the carboxylic anhydride used here should be selected according to the purpose of the analysis; for example, for analyzing the total degree of substitution of the cellulose acetate, butyric anhydride is suitably used. The resulting sample is dissolved in deuterated chloroform, and the13C-NMR spectrum is measured. In the case where the substituent is an acetyl group, carbon signals of the acetyl group appear in the order of the 2-position, the 3-position, and the 6-position from a high magnetic field in a region of 169 ppm to 171 ppm. The total degree of substitution (total degree of esterification) of the cellulose acetate treated with the carboxylic anhydride by the method of Tezuka or a similar method is 3.0. Thus, when the sum of areas of the carbonyl carbon signals of the acyl group originally contained in the cellulose acetate and the carbonyl signals of the acyl group introduced by the treatment with the carboxylic anhydride is normalized to 3.0, and the presence proportion of each acyl group at the corresponding position (in other words, area proportion of each signal) is determined, the presence proportion can be applied as each degree of acetyl substitution at the 2-, 3-, and 6-positions each of a glucose ring in the cellulose acetate. For a material mixed in pellet state, several pellets are selected and determined whether each pellet is of a cellulose acetate or of a polyester, and a13C-NMR spectrum may be measured for a pellet determined to be of a cellulose acetate. This technique can also be applied to a pellet in a dry blend.

[0048] The weight-average molecular weight of the cellulose acetate is not particularly limited but is preferably 10000 or greater, more preferably 90000 or greater, even more preferably 130000 or greater, particularly preferably 170000 or greater, and especially preferably 300000 or greater. In addition, the weight-average molecular weight of the cellulose acetate is preferably 500000 or less, more preferably 400000 or less. With the weight-average molecular weight not less than the lower limit of the above range, a molded article with excellent tensile properties is produced. Furthermore, with the weight-average molecular weight not greater than the upper limit of the above range, appropriate fluidity is achieved when the composition is produced. Moreover, for a dry-blended product of the composition, the weight-average molecular weight of the cellulose acetate is preferably 250000 or less, more preferably 200000 or less, and even more preferably 150000 or less. The reason for that is as follows. A CAGP has a low viscosity when melted. If the cellulose acetate to be kneaded with this CAGP has a high viscosity, kneading properties of the cellulose acetate with the CAGP decreases. This would not form a polymer alloy but produce a two-phase polymer blend in which partial phase separation occurs. In a dry-blended product of the composition, a cellulose acetate is the main component. Thus, the weight-average molecular weight of the cellulose acetate affects the mechanical strength of the resulting molded article. Thus, the weight-average molecular weight is preferably higher within the range of the quantitative proportion of the cellulose acetate and the CAGP in which phase separation does not occur. This can be achieved by controlling the quantitative proportions of the CAGP, the cellulose acetate, and the polyester. In the ideal dry-blended product of the composition, both the quantitative proportion of the CAGP and the weight-average molecular weight of the cellulose acetate are large. In such case, the lower limit of the weight-average molecular weight of the cellulose acetate is still more preferably 130000 or greater and particularly preferably 170000 or greater.

[0049] The weight-average molecular weight can be determined by a known method. For example, the weight-average molecular weight of the cellulose acetate is determined by performing size exclusion chromatography (e.g., gel permeation chromatography (GPC)) measurement with the following apparatus under the following conditions (e.g., GPC-light scattering method). Apparatus: GPC “SYSTEM-21H” available from Shodex Solvent: acetone Column: two GMHxls (available from Tosoh Corporation) and a guard column (TSK gel guardcolumn HXL-H available from Tosoh Corporation) Flow rate: 0.8 mL / min Temperature: 29°C Sample concentration: 0.25% (wt / vol) Injection volume: 100 micro L Detection: MALLS (multi-angle light scattering detector) (“DAWN-EOS” available from Wyatt) Reference material for MALLS calibration: PMMA (molecular weight 27600) A pellet in a dry blend can be measured in the same manner as the degree of substitution of the cellulose acetate.

[0050] The blending proportion of the cellulose acetate with respect to the entire materials used for the production of the composition according to the present disclosure is not particularly limited but is preferably 50 mass% or greater, more preferably 75 mass% or greater, and even more preferably 80 mass% or greater, and is preferably 95 mass% or less, more preferably 90 mass% or less, and even more preferably 85 mass% or less. Specific examples of the blending proportion include from 50 to 95 mass%, from 75 to 90 mass%, and from 80 to 85 mass%. With the blending proportion not less than the lower limit of the above range, the cellulose acetate can be a continuous phase even if a polymer blend is produced. On the contrary, with the blending proportion less than the lower limit of the above range, the polyester would be a continuous phase. Depending on the type of polyester, the crystallization acceleration can be slow, and in this case, the heat resistance of the continuous phase would decrease. In addition, with the blending proportion over the upper limit of the above range, the quantitative proportion of the polyester to the cellulose acetate would be insufficient, and this would limit the production of the CAGP. Ideally, a sufficient amount of the polyester necessary for producing the CAGP needs to be present. In the case of using two or more types of cellulose acetates, the total amount is preferably adjusted to the above numerical range.

[0051] Polyester The weight-average molecular weight of the polyester is not particularly limited but is preferably 1000 or greater, 3000 or greater, 5000 or greater, 9000 or greater, 15000 or greater, 50000 or greater, 100000 or greater, 200000 or greater, 300000 or greater, 500000 or greater, or 600000 or greater in this order, and is preferably 3000000 or less, 2500000 or less, 2000000 or less, 1000000 or less, 900000 or less, or 800000 or less in this order. Among these, a polyester with a weight-average molecular weight from 50000 to 100000 is easily available and preferred.

[0052] In the composition according to the present disclosure, the blending proportion of the polyester is appropriately selected according to the type thereof. The blending proportion of the polyester needs to exceed 0 mass%. In addition, the blending proportion of the polyester is preferably at least 5 mass% or greater. This blending proportion means the blending proportion of the polyester to the total amount of the polyester and the cellulose acetate. This is because the effects of the present disclosure are exhibited through a transesterification reaction of the polyester and an acetyl group of the cellulose acetate. In addition, with too large a content of the polyester, the entire amount of the polyester cannot be transesterified with acetyl groups of the cellulose acetate. In this case, a polymer blend in which a polyester phase remains is formed. In such a mode, peaks of glass transition temperature and a melting point assigned to the polyester are observed by thermal analysis. In general, aliphatic polyesters have a low melting point and low crystallization. Thus, a final molded article containing a large amount of the polyester phase may have lower heat resistance. In addition, when the polyester phase increases, the transparency decreases. However, in applications not requiring heat resistance or transparency, a polymer blend may be produced by a method in which the polyester content in the raw material mixture is increased and then a polyester phase is formed into a polymer blend..

[0053] In addition, from the viewpoint of facilitating thermoforming, the amount of the polyester is preferably 20 parts by weight or greater, more preferably 25 parts by weight or greater, and particularly preferably 30 parts by weight or greater per 100 parts by weight of the cellulose ester. From the viewpoint of improving compatibility with the cellulose ester, the amount of the 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. In the case of using two or more polyesters, the total amount is preferably adjusted to the above range. The above range is particularly suitable in the case where the polyester is an aliphatic polyester.

[0054] In addition, in the polyester composed of an aromatic dicarboxylic acid, main-chain cleavage is less likely to occur. Thus, the blending proportion of the polyester is preferably increased. Furthermore, in the case where the degree of acetyl substitution of the cellulose acetate to be used is high, the blending proportion may be increased.

[0055] In the case where the polymer component in the composition is only a CAGP, the composition can be produced by adjusting the blending proportion of the polyester to about 10 mass% or greater and 25 mass% or less.

[0056] Zinc Compound The zinc compound can be added in the above amount or preferably according to the above concentration of the zinc element. In the production of the composition according to the present disclosure, the zinc compound may be used in such a manner that the zinc compound is added to at least one of the cellulose acetate or the polyester, and this can be performed using, for example, a tumbler mixer. Specifically, a pellet of at least one of the polyester or the cellulose acetate and the zinc compound may be stirred and mixed using a tumbler mixer. Alternatively, a ribbon mixer may be used. For the addition of the zinc compound to at least one of the cellulose acetate or the polyester, a device of various types capable of attaching a pigment to the pellet can be used. For the addition, a dry color technique is preferably used. The tumbler mixer may be a heatable mixer. In that case, the temperature must be lower than the melting point of the pellet being added. For example, the zinc compound may be attached to the polyester using a heated tumbler mixer to a temperature not lower than the glass transition temperature and lower than the melting point.

[0057] Alkaline Earth Metal Salt As described above, the composition according to the present disclosure may contain an alkaline earth metal salt, and the alkaline earth metal salt can be blended according to the blending amount described above.

[0058] Odor Masking Agent The composition according to the present disclosure may contain an odor masking agent. Addition of an odor masking agent can suppress an acetic acid odor produced by thermal decomposition of the cellulose acetate. Examples of the odor masking agent include vanillin, a vanillin derivative, or ethyl vanillin.

[0059] Plasticizer The composition according to the present disclosure may or may not contain an external plasticizer. However, even when a composition containing no external plasticizer is intended to be produced, an external plasticizer can be unintentionally contained because an external plasticizer may be generally used in molding a cellulose acetate. In addition, in the composition according to the present disclosure, the amount of an external plasticizer that has been used in the art can be greatly reduced. For example, even in the case in which an external plasticizer has been contained in an amount of 30 mass% with respect to the entire composition from the viewpoint of ensuring sufficient melt fluidity in the art, the content of the external plasticizer can be reduced to a low range, such as 5 mass% or less, in the composition according to the present disclosure.

[0060] As described above, an external plasticizer bleeds out on the surface of a composition or the like and causes a problem of peeling off ink and / or the like applied or printed on the surface. Thus, not to cause these problems of the external plasticizer, the content of the external plasticizer in the composition is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, particularly preferably 0,5 mass% or less, and preferably the external plasticizer is not substantially contained. In the present disclosure, “not substantially contained” means not being contained to the extent of not being intentionally contained in the production process. The quantification of the external plasticizer in the composition (composition including a molded article) according to the present disclosure can be determined by freezing and milling a sample, dissolving the milled sample in a solvent capable of dissolving the sample, such as, for example, acetone, diluting the solution to an appropriate amount, and then quantifying by gas chromatography. For the cellulose acetate composition according to the present embodiment, even with a content of the external plasticizer of 5 mass% or less, in particular, even substantially not containing the external plasticizer, the a melt flow rate (MFR) at 220°C under a 10-kg load can be within the numerical range shown in the section of the melt fluidity described below. In the present disclosure, the external plasticizer is a component other than the above components, such as the CA-PE polymer and the alkaline earth metal salt among components capable of plasticizing (externally plasticizing) the cellulose acetate composition according to the exemplary embodiment. Specific examples include a plasticizer disclosed in JP 2017-052961 A and a plasticizer disclosed in JP 2023-506478 A.

[0061] Melt Kneading Hereinafter, melt kneading in the present disclosure will be described. Melt kneading in the dictionary meaning includes the case in which polymers are mixed in a molten state, and ultimately a composition can be formed into a shape, such as a pellet. Melt kneading in the present disclosure means a process of producing a CAGP. Thus, in such a case where a cellulose acetate is melted with a polyester and another component not containing a zinc compound to form a pellet shape as described above, these components are melt-kneaded in the dictionary meaning, but this is distinguished from the melt kneading in the present disclosure. In the melt kneading of the present disclosure, a cellulose acetate, a polyester, and a zinc compound are kneaded while at least the polyester is in a molten state. In graft polymerization of a polymer, an interface of the polymer to be grafted is formed. The polymer to be grafted is a cellulose acetate in the case of the present disclosure. Thus, when there is a sufficient amount of solid surface of the cellulose acetate, the cellulose acetate does not necessarily need to be melted. However, in view of ease and uniformity of the reaction, cellulose acetates are preferably mixed in a molten state.

[0062] For the production of the composition according to the present disclosure, there is also a method including melt-kneading a cellulose acetate, a polyester, and a zinc-containing compound at one time to produce a pellet of the composition described above (step B). In addition, the method may include further mixing the composition thus produced with a polyester and / or a cellulose acetate to produce a mixture (step C). In this case, the mixture contains a CAGP but composed of a plurality of polymers. Furthermore, as described above, depending on the composition of a polyester, a cellulose acetate, a zinc compound, and an alkaline earth metal salt as an optional component, not the entire amount can become a CAGP even though these components are melt-kneaded. In this case, measuring the glass transition temperature and / or the melting point by thermal analysis observes peaks attributed to a polyester and / or a cellulose acetate. Even in such a case, melt fluidity sufficient for injection molding is achieved because a CAGP is highly effective in contributing to the melt fluidity in the present disclosure. In addition, a method may include: mixing a polyester and a zinc-containing compound to produce a mixture (step D-1); and further melt-kneading the mixture with a cellulose acetate to produce a composition (step D-2). In this case, step D-1 may be a process of producing a pellet by melt kneading in the dictionary meaning. A method may include further mixing a zinc-containing compound and, as necessary, an alkaline earth metal salt in a cellulose acetate flake, melting the mixture, and pelletizing the mixture to obtain a mixture (step E-1). In this case, the composition can be produced by further melt-kneading the mixture with a polyester (step E-2) after step E-1.

[0063] The temperature in step D-1 is not particularly limited. The polyester and the zinc-containing compound may be melted at a temperature not lower than the melting point of the polyester and pelletized. Alternatively, the mixture may be in a state where a powder of a zinc compound is attached to the surface of a polyester pellet softened in a tumbler mixer heated to a temperature lower than the melting point of the polyester. Alternatively, the mixture may be produced by uniformly dry-blending a polyester pellet and a zinc compound powder.

[0064] The temperature in step E-1 is not particularly limited, but the components may be mixed approximately at a temperature at which the cellulose acetate can be pelletized.

[0065] A melt-kneading apparatus is not limited, and an extruder, such as a single-screw extruder or a twin-screw extruder can be used. A twin-screw extruder is preferred in terms of good kneadability. For a single-screw extruder, an extruder excellent in kneadability, equipped with a Maddock or a pin is suitable. In the case of melt kneading using a twin-screw extruder, the kneading temperature (also referred to as cylinder temperature) may be about 220°C. In this case, melt temperature is about 235°C. The die temperature may be 250°C. The kneaded product may be extruded into a strand shape from a die attached to the tip of the twin-screw extruder and underwater-cut or hot-cut into a pellet.

[0066] Properties of Cellulose Acetate Polymer Composition Light Transmittance Light transmittance (total light transmittance) in the thickness direction when the cellulose acetate polymer composition is molded into a plate shape with a thickness of 0.2 mm is not particularly limited. However, from the viewpoint of ensuring sufficient light transmittance, the light transmittance is preferably 30% or greater and more preferably 40% or greater. In addition, the upper limit is not particularly required but may be 80% or less or 70% or less. Specific examples of the light transmittance include from 30 to 90%, from 40 to 90%, from 30 to 80%, and from 40 to 80%. The light transmittance can be measured according to JIS K7136: 2000. The plate-shaped sample is produced by extrusion-molding a polymer composition melt-kneaded using a small twin-screw extruder or the like.

[0067] Melt Fluidity In general, melt viscosity is high in the molding a cellulose acetate. Thus, when a cellulose acetate is molded without a plasticizer, it is molded at a melt temperature of 280°C or higher. Such a temperature is close to the decomposition temperature of a cellulose acetate, and thus the cellulose acetate turns brown. Thus, in a widely used technique, about 20 to 30 wt.% of a plasticizer is added to a cellulose acetate. This widens the space between the polymer chains during melting by the plasticizer and improves the thermal fluidity. However, there is a problem due to containing the plasticizer. Furthermore, even when a plasticizer is contained, melt fluidity close to 100 g / 10 min in terms of an MFR cannot be achieved in a molding temperature range in which browning does not occur. For the composition according to the present disclosure, a mixture containing a cellulose acetate, a polyester, and a zinc compound is melt-kneaded to produce a CAGP. The CAGP has a bulky side chain and thus has a large distance between molecules during melting and high melt fluidity even if the cellulose skeleton is difficult to bend. The melt fluidity of the composition is affected by the proportion of the CAGP; for example, the composition in which all the polymer components are composed of the CAGP exhibits the best melt fluidity. In such a case, the melt fluidity in terms of an MFR measured at 250°C under a 5-kg load is 100 g / 10 min or greater. The MFR at 250°C does not need to be 100 g / 10 min or greater and is specifically preferably 34 g / 10 min or greater, more preferably 40 g / 10 min or greater, even more preferably 50 g / 10 min or greater, and particularly preferably 70 g / 10 min or greater. Furthermore, the composition exhibits a numerical value of about 1 to 10 g / 10 min in terms of a melt flow rate (MFR) at 220°C, a temperature at which a cellulose acetate does not melt, under a 10-kg load. In addition, the composition according to the present disclosure has excellent melt fluidity and thus has capillary flow properties capable of producing a molded article with a complicated shape with a rib. Specifically, the MFR of the composition at 220°C is preferably 1 g / 10 min or greater from the viewpoint of producing a molded article with a complicated shape with a rib. In the case of a film or sheet, a melt fluidity of 10 g / 10 min or less in terms of an MFR at 220°C is sufficient. In such a case, the melt temperature during molding can be reduced, and this can further reduce a trouble, such as coloration. The MFR can be measured by JIS K7210-1: 2014.

[0068] Molded Article The composition according to the present disclosure can be formed into a molded article. This is preferably a molded article produced by injection molding or extrusion molding. The extruder for injection molding is not limited and may be a single-screw extruder. There is also a method in which the composition is melt-kneaded using a twin-screw extruder and then injected to mold. The molded article may be produced by melt-kneading a raw material mixture with a single-screw injection molding machine. In addition, an injection molding machine having a heating cylinder for preplasticizing and an injection plunger may be used.

[0069] Coloring Material The molded article is preferably colored in a desired color according to its use. From this viewpoint, the composition according to the present disclosure may further contain a coloring material. The composition can have a high Y value depending on the blending proportion. Thus, the coloring material is effective for the molded article to have a desired color. In the present disclosure, the types of coloring materials are described based on the Colour Index defined by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colourists.

[0070] A blue dye is preferably one or two or more selected from the group consisting of C. I. Disperse Blue 60, C. I. Solvent Blue 35, C. I. Solvent Blue 36, C. I. Solvent Blue 45, C. I. Solvent Blue 59, C. I. Solvent Blue 63, C. I. Solvent Blue 67, C. I. Solvent Blue 83, C. I. Solvent Blue 94, C. I. Solvent Blue 97, C. I. Solvent Blue 104, C. I. Solvent Blue 105, C. I. Solvent Blue 122, and C. I. Solvent Violet 33. Among these, C. I. Solvent Blue 94 and C. I. Solvent Blue 97 are more preferred from the viewpoint of reducing a yellow tinge.

[0071] A purple dye is preferably one or two or more selected from the group consisting of C. I. Solvent Violet 13, C. I. Disperse Violet 26, C. I. Disperse Violet 28, C. I. Disperse Violet 31, C. I. Solvent Violet 31, C. I. Solvent Violet 36, and C. I. Solvent Violet 49. Among these, C. I. Solvent Violet 13 is more preferred from the viewpoint of reducing a yellow tinge.

[0072] The composition preferably contains at least one of a blue dye or a purple dye as a coloring material but may contain a dye other than a blue dye and a purple dye in a range in which the effects of the present disclosure are achieved. Examples of a red dye include C. I. Disperse Red 22, C. I. Disperse Red 50, C. I. Disperse Red 60, C. I. Disperse Red 191, C. I. Solvent Red 27, C. I. Solvent Red 52, C. I. Solvent Red 111, C. I. Solvent Red 135, C. I. Solvent Red 145, C. I. Solvent Red 146, C. I. Solvent Red 149, C. I. Solvent Red 150, C. I. Solvent Red 151, C. I. Solvent Red 155, C. I. Solvent Red 168, C. I. Solvent Red 179, C. I. Solvent Red 180, C. I. Solvent Red 195, C. I. Solvent Red 197, or C. I. Solvent Red 207. Examples of a green dye include C. I. Solvent Green 3, C. I. Solvent Green 5, C. I. Solvent Green 20, or C. I. Solvent Green 28. Examples of an orange dye include C. I. Solvent Orange 60 or C. I. Disperse Orange 47. Examples of a yellow dye include C. I. Solvent Yellow 33, C. I. Solvent Yellow 93, C. I. Solvent Yellow 114, C. I. Disperse Yellow 54, or C. I. Disperse Yellow 160. Examples of a brown dye include C. I. Solvent Brown 53. Examples of a black dye include C. I. Solvent Black 5 or C. I. Solvent Black 7. A content of the coloring material in the composition (the molded article) is not particularly limited. However, when the composition (the molded article) contains the coloring material of at least one of the blue dye or the purple dye, the content of the coloring material is preferably from 0.0001 mass% to 0.1 mass%.

[0073] The composition according to the present disclosure can also further contain an organic pigment as a coloring material. Examples of the organic pigment include C. I. Pigment Blue 15:1 or C. I. Pigment Green 7.

[0074] The composition according to the present disclosure can also further contain a white pigment as a coloring material. Examples of the white pigment include C. I. Pigment White 6 (titanium oxide) or C. I. Pigment White 21 (barium sulfate).

[0075] The composition may contain a black pigment (carbon black), such as C. I. Pigment Black 6 or C. I. Pigment Black 7, in a range in which the effects of the present disclosure are achieved.

[0076] The composition according to the present disclosure can also further contain an ultraviolet absorber. Examples of the ultraviolet absorber include a triazine ultraviolet absorber, such as 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)phenol, or a benzotriazole ultraviolet absorber, such as 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol.

[0077] Applications Applications of the composition according to the present disclosure and the molded article thereof are not particularly limited. However, the composition and the molded article thereof can be suitably used particularly in applications requiring properties, such as flame retardancy, insulating properties, solvent resistance, and chemical resistance. Specifically, the composition and the molded article thereof can be suitably used as a material, for example, for tableware, packaging containers, trays, materials for agriculture, materials for fishery, parts for OA, materials for building, parts for medical use, home electrical appliance parts, members for automobiles, daily goods, stationery, or eyeglass frames.

[0078] In addition, the composition according to the present disclosure with high content of a CAGP can be suitably used as a compatibilizer for a cellulose acetate and a polyester.

[0079] Plastic Pellet Another embodiment of the present disclosure provides a plastic pellet (hereinafter also referred to simply as the “pellet”). The pellet contains a zinc element (a zinc-containing compound) and a CA-PE polymer as essential components. In addition, the plastic pellet preferably contains an external plasticizer at an amount of 5 mass% or less and has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load. The pellet may be a molded article in pellet form produced using a composition that has already been melt-kneaded, and in this case, the conditions of the composition described above and the conditions described below can be appropriately applied to the conditions of the plastic pellet.

[0080] The melt flow rate (MFR) of the plastic pellet at 220°C under a 10-kg load is not particularly limited but is, from the viewpoint of handling properties, preferably 1 g / 10 min or greater, more preferably 5 g / 10 min or greater, even more preferably 8 g / 10 min or greater, and particularly preferably 10 g / 10 min or greater. In addition, the upper limit is not particularly limited and may be about 100 g / 10 min or less, which is the measurement limit of the MFR. For an injection-molded article, the MFR is preferably 30 g / 10 min or greater.

[0081] The content of a cellulose acetate in the plastic pellet is not particularly limited. That is, the entire amount of the polymer component may be the CAGP, a cellulose acetate phase and a polyester phase may be each present, or only one of them may be present. The plastic pellet may be a mixture containing and using a composition described below as a compatibilizer.

[0082] The plastic pellet itself can be mixed to produce a molded article or can be used as a masterbatch containing a cellulose acetate and a polyester as base materials by blending an additional component. In the case where the plastic pellet is used as a masterbatch and the plastic pellet contains, for example, a colorant as an additional component, the plastic pellet can be suitably used in applications as a colorant. Not only the plastic pellet is used as a masterbatch, but also a molded article can be produced using only a plastic pellet containing a colorant.

[0083] A formulation example in the case of diluting as a masterbatch is shown in Table 1-1. This formulation can be used as the composition described above without a problem. The formulation example shown in Table 1-1 is a masterbatch of a compatibilizer with one-fold dilution. The amounts of a cellulose acetate effectively added to the masterbatch are shown in Table 1-2. As shown in Table 1-2, the masterbatch with the composition shown in Table 1-1 can be effectively used up to five-fold dilution.

[0084]

[0085]

[0086] Compatibilizer Another embodiment of the present disclosure is a compatibilizer for a cellulose acetate and a polyester (hereinafter also referred to simply as the “compatibilizer”). The compatibilizer contains a zinc element and a CA-PE polymer as essential components. The compatibilizer preferably contains a plasticizer at an amount of 5 mass% or less and has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load. The compatibilizer may be a compatibilizer produced using a composition that has already been melt-kneaded, and in this case, the conditions of the composition described above and the conditions described below can be appropriately applied to the conditions of the compatibilizer. As described above, the composition contains the CAGP. The CAGP is easily compatible with both a cellulose acetate and a polyester and thus can be used as an application for the compatibilizer for a cellulose acetate and a polyester. In addition, the compatibilizer is substantially the same as the above plastic pellet except that it is essential that the plastic pellet be in pellet form. Thus, the conditions of the plastic pellet can be applied in the same manner except for the condition that the plastic pellet is in pellet form. However, the shape of the compatibilizer may be in pellet form, and in this case, the conditions of the compatibilizer are the same as the conditions of the plastic pellet. The method for producing the compatibilizer is not particularly limited, and the method for producing the composition or the method for producing the plastic pellet described above can be similarly employed.

[0087] The melt flow rate (MFR) of the compatibilizer at 220°C under a 10-kg load is not particularly limited but is, from the viewpoint of handling properties, preferably 1 g / 10 min or greater, more preferably 5 g / 10 min or greater, and even more preferably 8 g / 10 min or greater. In addition, the upper limit is not particularly limited and may be 100 g / 10 min or less.

[0088] The content of a cellulose acetate in the compatibilizer is not particularly limited.

[0089] In addition, the content of a polyester in the compatibilizer is not particularly limited. In a preferred form, the entire amount is the CAGP (with particularly excellent compatibility) but can be appropriately set according to the mode of the molded article to be used and the desired melt fluidity. Furthermore, for the application of the compatibilizer, there are differences in fluidity and / or heat resistance according to the required physical properties of the molded article to be used. The compatibilizer can be prepared by using a compatibilizer with known physical properties and pellets of a polyester and / or a cellulose acetate.

[0090] The compatibilizer may contain a component besides a cellulose acetate, a polyester, and a zinc-containing compound. For example, the compatibilizer containing a colorant as an additional component can be suitably used in applications as a colorant.

[0091] Hereinafter, the present disclosure will be further specifically described by showing examples. However, the present disclosure is not to be interpreted as being limited to the examples below.

[0092] Materials Used The following materials were used in the present examples. Cellulose Acetate ・ Acetate flake: L-50 (available from Daicel Corporation; glass transition temperature measured by the measurement method described below is 196°C) Polyester ・ Polylactic acid (PLA): FY601 (available from Anhui Fengyuan Group Co., Ltd., weight-average molecular weight of 140700) ・ Poly(butylene succinate) (PBS): BioPBS (available from Mitsubishi Chemical Group Corporation) ・ Poly-ε-caprolactone (PCL): PCL of a molecular weight grade of about 10000 available from FUJIFILM Wako Pure Chemical Corporation Zinc Compound ・ Zinc oxide: available from Sakai Chemical Industry Co., Ltd. ・ Zinc acetate: available from FUJIFILM Wako Pure Chemical Corporation ・ Zinc stearate: available from FUJIFILM Wako Pure Chemical Corporation Alkaline Earth Metal Salt ・ Calcium carbonate: available from Shiraishi Kogyo Kaisha, Ltd. ・ Calcium Stearate: available from Tokyo Chemical Industry Co., Ltd. ・ Magnesium stearate: Tokyo Chemical Industry Co., Ltd. ・ Stearic acid: available from FUJIFILM Wako Pure Chemical Corporation Coloring Material ・ Purple dye: 1-hydroxy-4-(p-toluidino)anthraquinone, “Diaresin Blue G” available from Arimoto Chemical Co., Ltd. ・ Blue dye: “MACROLEX BLUE RR Gran” available from LANXESS AG Additional Materials ・ For materials other than those shown in Tables 2-1, 2-2 and described above, a reagent available from FUJIFILM Wako Pure Chemical Corporation were used.

[0093] Production Production of Cellulose Acetate Polymer Composition According to the formulations shown in Tables 2-1 and 2-2, the polyester, the zinc-containing compound, and the optional material were placed in this order in a twin-screw extruder (Labo Plastomill available from Toyo Seiki Seisaku-sho, Ltd., rotational speed of 30 to 50rpm, cylinder temperature of 250°C (melt temperature of 235 to 255°C)) and mixed. Then, the cellulose acetate was placed, the mixture was melt-kneaded and then extruded in a strand form, and a cellulose acetate polymer composition was produced.

[0094] Injection Molding The composition was injection-molded using an injection molding machine (trade name “MiniJET PRO” available from Thermo Scientific Inc.). The molding conditions were a cylinder temperature of 255°C, a mold temperature of 50°C, an injection pressure of 800 bar, an injection time of 5 seconds, a holding pressure of 800 bar, and a holding time of 5 seconds.

[0095] Evaluation of Properties Glass Transition Temperature The glass transition temperature Tg of the composition was determined in a DSC curve observed in a second temperature raising process using a differential scanning calorimeter (DSC, “DSC Q2000” available from TA Instruments.

[0096] Melt Fluidity The melt flow rate (MFR) at 250°C under a 5-kg load and the melt flow rate (MFR) at 220°C under a 10-kg load of the composition were measured based on the method described above.

[0097] Zinc Content The content of zinc (element) in the composition was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using an Agilent 5110 (available from Agilent Technologies Japan, Ltd.) as an ICP emission spectrometer according to the method described above.

[0098] Light Transmittance To check the light transmittance, the composition was molded into a plate shape with a thickness of 0.2 mm at a melt temperature of 226°C with a small twin-screw extruder and a sheet die (available from Thermo Fisher Scientific Inc.). The total light transmittance in the thickness direction of the resulting molded article was measured according to JIS K7136: 2000.

[0099] b*Value L*a*b*was measured according to JIS Z8781-4: 2013 using the molded article produced in the above section of the light transmittance.

[0100] The evaluation results of properties described above are shown in Tables 2-1 and 2-2.

[0101] In Comparative Example 6, the glass transition temperature, the total light transmittance, and the b*value were not evaluated.

[0102]

[0103]

[0104] From Tables 2-1 and 2-2, it was found that while the MFRs at 220°C of the compositions according to the comparative examples were all 0 g / min, those of the compositions according to the examples were all 1 g / min or greater, and that the compositions according to the examples had excellent fluidity during melt kneading. The improvement of the fluidity of the compositions according to the examples during melt kneading is presumed to be due to promotion of the production of the CAGP by the zinc compound and improvement of the compatibility between the cellulose acetate and the polyester by the increase of the CAGP. In addition, it was found that using the PLA as the cellulose acetate provided a particularly high MFR when a zinc compound was combined with an alkaline earth metal carboxylate, such as Ca stearate, or when a zinc stearate was used as the zinc compound. Specifically, in these cases, the MFR at 220°C was 8 g / min or greater, and the MFR at 250°C was 100 g / min or greater.

[0105] Confirmation of CAGP Production A composition was produced in the same manner as described above with a formulation of 79 mass% of the cellulose acetate, 20 mass% of the PLA, 0.4 mass% of zinc oxide, 1 mass% of calcium stearate, 0.012 mass% of the purple dye, and 0.006 mass% of the blue dye. After the composition was frozen and milled, the cellulose acetate contained in the milled product was dissolved and removed with an excess amount of acetic acid, and the polyester was dissolved and removed with an excess amount of acetone. The solution (solution 1) produced by this treatment was used to measure H1-NMR. This measurement result is shown in Fig. 1, (a). In addition, a solution (solution 2) produced by dissolving the cellulose acetate in acetone was used to measure H1-NMR. This measurement result is shown in Fig. 1, (b). Figs. 1, (a) and 1, (b) showed that peaks based on the PLA, which were not detected in the solution 2, were detected in the solution 1. That is, the results confirmed that the composition contained the CAGP. The results of the confirmation above confirmed that the CAGP was produced by melt-kneading the cellulose acetate and the polyester in the presence of a zinc compound. Thus, it can be presumed that the CAGP was also produced in each composition in Examples 1 to 11.

[0106] DSC Charts DSC measurement was performed using the following samples by the method described in the measurement of the glass transition temperature described above. DSC charts observed in the DSC measurement are shown in Figs. 2 and 3. Figs. 2-4 all show similar results, although the figures are shown in different ways. Specifically, Fig. 2 shows charts prepared for each line (Fig. 2, (a): CA, Fig. 2, (b): PLA, Fig. 2, (c): CA / PLA, Fig. 2, (d): CA / PLA / ZnO / Ca Stearate), and Figs. 3 and 4 show charts prepared to include all lines within one chart. Further, the chart in Fig. 3 is prepared not to overlap each line, while the chart in Fig. 4 is prepared to overlap each line. ・ Composition 1 (CA): a composition composed only of the cellulose acetate. ・ Composition 2 (PLA): a composition composed only of the PLA. ・ Composition 3 (CA / PLA): a composition produced in the same manner as in Example 1 except that no zinc compound and no calcium stearate were used. ・ Composition 4 (CA / PLA / ZnO / Ca stearate): a composition produced in the same manner as in Example 1.

[0107] The comparison between the CA / PLA and the CA / PLA / ZnO / Ca stearate in Figs. 2-4 revealed that blending ZnO and Ca stearate reduced the Tg and further that the endothermic peak observed near 170°C disappeared. The present inventors presume that the disappearance of the endothermic peak is due to the following reasons. First, Ca contained in Ca stearate is presumed to promote decomposition of the PLA in the presence of a zinc compound and reduce the crystallinity of the PLA. Second, Ca stearate is presumed to promote dispersion of the polyester and a zinc compound, thus promoting reaction of producing the CAGP from the cellulose acetate and the polyester and increasing the amount of the CAGP, and relatively reducing the amount of the PLA. The third reason is that, first, the crystal that melts around 170°C is presumed to be caused by cold crystallization in an amorphous portion that cannot be crystallized when the temperature is reduced at a constant rate in DSC. In addition, a highly dispersible solid, such as Ca stearate, usually acts as a crystal nucleating agent. Thus, blending Ca stearate is presumed to reduce the amorphous portion and the degree of cold crystallization, thus leading to the apparent disappearance of the peak.

[0108] From the above, it was found that blending the cellulose acetate, the polyester, and the zinc-containing compound can provide the novel cellulose acetate polymer composition having excellent fluidity during melt kneading.

Claims

1. A cellulose acetate polymer composition comprising: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc compound.

2. The cellulose acetate polymer composition according to claim 1, further comprising an alkaline earth metal carboxylate.

3. The cellulose acetate polymer composition according to claim 1, wherein the zinc compound comprises a fatty acid zinc salt.

4. The cellulose acetate polymer composition according to claim 2, wherein the alkaline earth metal carboxylate comprises a fatty acid alkaline earth metal salt.

5. The cellulose acetate polymer composition according to claim 1, wherein the polyester comprises an aliphatic polyester.

6. The cellulose acetate polymer composition according to claim 5, wherein the aliphatic polyester comprises at least one selected from the group consisting of polylactic acid, poly(butylene succinate), and polycaprolactone.

7. The cellulose acetate polymer composition according to claim 1, wherein the cellulose acetate polymer composition contains zinc element at an amount from 0.1 mass% to 10 mass%.

8. The cellulose acetate polymer composition according to claim 1, wherein the polymer comprises a cellulose acetate graft polymer in which at least a portion of the polyester is graft-polymerized to at least a portion of the cellulose acetate.

9. The cellulose acetate polymer composition according to claim 1, wherein the cellulose acetate polymer composition has a glass transition temperature in a range from at least 110°C to 190°C.

10. The cellulose acetate polymer composition according to claim 1, wherein the cellulose acetate polymer composition contains an external plasticizer at an amount of 5 mass% or less, and the cellulose acetate polymer composition has a melt flow rate (MFR) of 1 g / 10 min or greater at 220°C under a 10-kg load.

11. The cellulose acetate polymer composition according to claim 1, wherein the cellulose acetate polymer composition has a light transmittance from 30% to 80%, the light transmittance being measured according to JIS K7136: 2000 in the thickness direction when the cellulose acetate polymer composition is molded into a plate shape with a thickness of 0.2 mm.

12. A molded article produced by injection-molding or extrusion-molding the cellulose acetate polymer composition described in any one of claims 1 to 11.

13. The molded article according to claim 12, further comprising a coloring material of at least one of a blue dye or a purple dye, wherein the molded article contains the blue dye or the purple dye at an amount from 0.0001 mass% to 0.1 mass%.

14. A plastic pellet comprising: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc-containing compound, wherein the plastic pellet contains an external plasticizer at an amount of 5 mass% or less, and the plastic pellet has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load.

15. A compatibilizer for a cellulose acetate and a polyester, the compatibilizer comprising: a polymer in which at least a portion of a cellulose acetate and at least a portion of a polyester are bound to each other; and a zinc-containing compound wherein the compatibilizer contains an external plasticizer at an amount of 5 mass% or less, and the compatibilizer has an MFR of 1 g / 10 min or greater at 220°C under a 10-kg load.

16. A cellulose acetate polymer composition comprising a melt-kneaded product of a mixture comprising a cellulose acetate, a polyester, and a zinc compound, wherein the melt-kneaded product comprises a polymer in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other.

17. A method for producing a cellulose acetate polymer composition, the method comprising: melt-kneading a cellulose acetate, a polyester, and a zinc compound to produce a polymer in which at least a portion of the cellulose acetate and at least a portion of the polyester are bound to each other.

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