Cellulose acetate-caprolactone polymer composition and method for producing the same, sheet

Abstract

This invention provides a cellulose acetate-caprolactone polymer composition that can produce sheets with few impurities and high transparency. [Solution] It comprises a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst. A cellulose acetate-caprolactone polymer composition in which the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less.

Description

[Technical Field]

[0001] This disclosure relates to a cellulose acetate-caprolactone polymer composition, a method for producing the same, and a sheet utilizing the cellulose acetate-caprolactone polymer composition. [Background technology]

[0002] In recent years, there has been a growing demand to replace petroleum-derived plastics, which are a contributing factor to environmental problems such as global warming and ocean pollution, with biomass-derived alternatives.

[0003] Cellulose materials are attracting attention as biomass-derived materials. For example, cellulose acetate is the most inexpensive and has the largest industrial production volume among cellulose derivatives. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Yoshioka, M.; Hagiwara, N.; Shiraishi, N. Thermoplasticization of cellulose acetates by grafting of cyclic esters.Cellulose1999,6(3), 193-212. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] For example, Non-Patent Document 1 discloses a plastic in which the thermoplasticity of cellulose diacetate (CDA) is improved without impairing the biodegradability of CDA by graft polymerization of polycaprolactone (PCL) onto CDA using tin-II ethylhexanoate (SnEht2) as a catalyst.

[0006] However, the inventors of this disclosure have found that when attempting to increase the thermoplasticity of a graft polymer by graft polymerizing polycaprolactone (PCL) onto cellulose acetate, a problem arises in that by-products such as caprolactone homopolymers gradually bleed out from the resulting graft polymer composition.

[0007] The primary objective of this disclosure is to provide a cellulose acetate-caprolactone polymer composition that can be used to produce sheets with low impurities and high transparency. It also aims to provide a cellulose acetate-caprolactone polymer composition that, when formed into a sheet, exhibits high transparency, low impurity elution, and high mechanical strength. Furthermore, it aims to provide a method for producing these cellulose acetate-caprolactone polymer compositions. Finally, it aims to provide a sheet containing a highly transparent cellulose acetate-caprolactone polymer composition. [Means for solving the problem]

[0008] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that by employing a polymerization process in which cellulose acetate and caprolactone monomer are polymerized in a twin-screw extruder in the presence of a catalyst, and by keeping the mass ratio of caprolactone monomer and catalyst to the mass of cellulose acetate within a predetermined range, a cellulose acetate-caprolactone polymer composition can be obtained that produces a sheet with few impurities and high transparency. Furthermore, they have found that by employing this method, a cellulose acetate-caprolactone polymer composition with high transparency, low impurity elution, and high mechanical strength when made into a sheet can be obtained.

[0009] This disclosure is the result of further consideration based on these findings. Specifically, this disclosure provides inventions in the following embodiments.

[0010] Item 1. comprising a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst, A cellulose acetate-caprolactone polymer composition in which the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less. Item 2. The cellulose acetate-caprolactone polymer composition according to Item 1, wherein the cellulose acetate-caprolactone polymer has a proportion of 70% by mass or more and 95% by mass or less of the portion derived from cellulose acetate, and a proportion of 5% by mass or more and 30% by mass or less of the portion derived from caprolactone. Item 3. A cellulose acetate-caprolactone polymer composition comprising a cellulose acetate-caprolactone polymer, The cellulose acetate-caprolactone polymer has a proportion of 70% to 95% by mass derived from cellulose acetate and a proportion of 5% to 30% by mass derived from caprolactone. A cellulose acetate-caprolactone polymer composition that is substantially free of impurities. Item 4. The cellulose acetate-caprolactone polymer composition according to item 1 or 2, wherein the total molar ratio of caprolactone units to the total cellulose acetate units is 1.6 or less. Item 5. The cellulose acetate-caprolactone polymer composition according to Item 3, wherein the average number of moles (MS) of caprolactone in the cellulose acetate-caprolactone polymer is 1.0 or less. Item 6. The cellulose acetate-caprolactone polymer composition according to Item 3, wherein the glass transition temperature Tg is 70°C or higher and 170°C or lower. Item 7. A cellulose acetate-caprolactone polymer composition according to item 1 or 2, wherein the melt mass flow rate (MFR, 190°C, 2.16 kg) is 0 g / 10 min or more and 30 g / 10 min or less. Item 8. The cellulose acetate-caprolactone polymer composition according to Item 3, wherein the melt mass flow rate (MFR, 190°C, 2.16 kg) is 0 g / 10 min or more and 20 g / 10 min or less. Item 9. The cellulose acetate-caprolactone polymer composition according to item 1 or 2, wherein the catalyst is a phosphoric acid-based catalyst. Item 10. The cellulose acetate-caprolactone polymer composition according to item 1 or 2, wherein when the tensile breaking strength of a sheet obtained by hot pressing the cellulose acetate-caprolactone polymer composition at a temperature of 165°C, a pressure of 15 MPa, and a time of 180 seconds is measured in accordance with the tensile test specified in JIS K6251, the tensile modulus of elasticity is 400 MPa or more and 2000 MPa or less. Item 11. The cellulose acetate-caprolactone polymer composition according to Item 3, wherein when the tensile breaking strength of a sheet obtained by hot pressing the cellulose acetate-caprolactone polymer composition at a temperature of 210°C, a pressure of 15 MPa, and a time of 180 seconds is measured in accordance with the tensile test specified in JIS K6251, the tensile modulus of elasticity is 700 MPa or more and 2000 MPa or less. Item 12. A sheet comprising the cellulose acetate-caprolactone polymer composition described in Item 1 or 2, wherein the haze value after standing for 12 hours at a temperature of 23°C and a relative humidity of 50% RH is 25% or less. Item 13. A sheet comprising the cellulose acetate-caprolactone polymer composition described in Item 3, wherein the haze value after standing for one month at a temperature of 23°C and a relative humidity of 50% RH is 25% or less. Item 14. The sheet has a thickness of 1 mm and a surface area of ​​1 cm². 2 The sheet according to item 12 or 13, wherein the amount of elution when the sheet is immersed in 2 mL of water per cubic meter for 30 minutes while maintaining the water temperature at 95°C is 10 μg / mL or less. Item 15. For one side of the sheet, the surface area is 1 dm². 2 The amount of extract obtained when immersed in 50 ml of 20% ethanol aqueous solution under reflux conditions for 1 hour is 50 mg / dm 2The sheet according to item 12 or 13, as described below. Item 16. A polymerization step of polymerizing cellulose acetate and a caprolactone monomer in a twin-screw extruder in the presence of a catalyst, The ratio of the caprolactone monomer to 1 part by mass of the cellulose acetate is 0.2 parts by mass or more and 0.8 parts by mass or less, A method for producing a cellulose acetate-caprolactone polymer composition, wherein the ratio of the catalyst to 1 part by mass of the cellulose acetate is 0.001 parts by mass or more and 0.10 parts by mass or less. Item 17. A method for producing a cellulose acetate-caprolactone polymer composition according to item 16, including a step of washing the pellets obtained by pelletizing the cellulose acetate-caprolactone polymer composition obtained in the polymerization step, and a step of drying the washed pellets. Item 18. The method for producing a cellulose acetate-caprolactone polymer composition according to item 17, wherein the step of washing the pellets is either a method of washing the pellets with water and / or alcohol, or a method of redissolving the pellets in an organic solvent and reprecipitating them in a poor solvent. Item 19. The method for producing a cellulose acetate-caprolactone polymer composition according to item 16 or 17, wherein the catalyst is a phosphoric acid-based catalyst.

Advantages of the Invention

[0011] According to the present disclosure, a cellulose acetate-caprolactone polymer composition capable of producing a sheet with few impurities and high transparency can be provided. Further, according to the present disclosure, a cellulose acetate-caprolactone polymer composition with high transparency when formed into a sheet, little elution of impurities, and high mechanical strength can be provided. According to the present disclosure, a method for producing these cellulose acetate-caprolactone polymer compositions can be provided. Furthermore, according to the present disclosure, a sheet containing a cellulose acetate-caprolactone polymer composition with high transparency can be provided.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic diagram of the structure of the twin-screw extruder used in the examples or comparative examples. [Figure 2] It is a schematic diagram of the structure of the twin-screw extruder used in the comparative example.

Mode for Carrying Out the Invention

[0013] Each configuration and their combinations, etc. in each embodiment are examples, and within the scope not departing from the gist of the present disclosure, additions, omissions, substitutions, and other changes of the configuration can be made as appropriate. The present disclosure is not limited by the embodiments.

[0014] In the numerical ranges described stepwise in the present disclosure, the upper limit value or lower limit value described in a certain numerical range may be replaced with the upper limit value or lower limit value of the numerical range described in other stepwise descriptions. Also, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value described separately may be combined to form numerical ranges, respectively. Further, in the numerical ranges described in the present disclosure, the upper limit value or lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0015] [Cellulose Acetate-Caprolactone Polymer Composition] As the cellulose acetate-caprolactone polymer composition of the present disclosure (hereinafter sometimes referred to as the polymer composition of the present disclosure), there are a composition according to the first aspect and a composition according to the second aspect.

[0016] In the following description, regarding matters specific to the first aspect or the second aspect, it is explicitly stated that they are explanations regarding each aspect, and regarding matters common to the first aspect and the second aspect, they are described as explanations regarding the present disclosure.

[0017] In the polymer composition of the present disclosure, the cellulose acetate-caprolactone polymer is a polymer of cellulose acetate and a caprolactone monomer (that is, ε-caprolactone), and more specifically, these are graft polymers.

[0018] From the viewpoint of suitably exhibiting the effects of the invention of this disclosure, the degree of acetyl substitution (DS) of cellulose acetate (the degree of acetyl substitution (DS) of the raw material cellulose acetate used in the polymerization of the polymer composition of this disclosure) is preferably 1.0 or more, more preferably 1.4 or more, even more preferably 1.8 or more, even more preferably 1.9 or more, and also preferably 2.9 or less, more preferably 2.8 or less, even more preferably 2.7 or less, and even more preferably 2.6 or less. Preferred ranges include 1.0 to 2.9, 1.0 to 2.8, 1.0 to 2.7, 1.0 to 2.6, 1.4 to 2.9, 1.4 to 2.8, 1.4 to 2.7, 1.4 to 2.6, 1.8 to 2.9, 1.8 to 2.8, 1.8 to 2.7, 1.8 to 2.6, 1.9 to 2.9, 1.9 to 2.8, 1.9 to 2.7, and 1.9 to 2.6. The degree of acetyl substitution (DS) is a value measured by NMR. The cellulose acetate is preferably cellulose diacetate (for example, with a degree of acetyl substitution (DS) of 1.8 to 2.6).

[0019] In this disclosure, homocaprolactone polymer is a homopolymer of caprolactone monomer produced as a by-product in the polymerization process of cellulose acetate and caprolactone monomer, and is one of the impurities in a cellulose acetate-caprolactone polymer composition.

[0020] Furthermore, in this disclosure, caprolactone monomer is an unreacted product in the polymerization process between cellulose acetate and caprolactone monomer, and is a type of impurity in the cellulose acetate-caprolactone polymer composition.

[0021] Furthermore, in this disclosure, the catalyst is a substance that promotes the polymerization reaction (polymerization reaction between cellulose acetate and caprolactone monomer) in the polymerization process between cellulose acetate and caprolactone monomer, and is a type of impurity in the cellulose acetate-caprolactone polymer composition.

[0022] In the polymer composition of this disclosure, the cellulose acetate-caprolactone polymer has an average molar ratio of caprolactone in cellulose acetate of preferably about 1.6 or less, more preferably about 1.3 or less, and even more preferably about 1.0 or less. The lower limit is, for example, about 0.2 or more, preferably about 0.3 or more, and preferred ranges include about 0.2 to 1.6, about 0.2 to 1.3, about 0.2 to 1.0, about 0.3 to 1.6, about 0.3 to 1.3, and about 0.3 to 1.0.

[0023] In the polymer composition of this disclosure, the average number of moles (MS) of caprolactone in the cellulose acetate-caprolactone polymer is preferably about 1.0 or less, more preferably about 0.95 or less, and even more preferably about 0.9 or less. The lower limit is, for example, about 0.1 or more, preferably about 0.2 or more. Preferred ranges include about 0.1 to 1.0, about 0.1 to 0.95, about 0.1 to 0.9, about 0.2 to 1.0, about 0.2 to 0.95, and about 0.2 to 0.9.

[0024] In the polymer compositions of this disclosure, the average graft substitution degree (DS) of caprolactone in the cellulose acetate-caprolactone polymer is preferably about 0.5 or less, more preferably about 0.3 or less, even more preferably about 0.2 or less, and also preferably about 0.01 or more, more preferably about 0.04 or more, even more preferably about 0.06 or more. Preferred ranges include about 0.01 to 0.5, about 0.01 to 0.3, about 0.01 to 0.2, about 0.04 to 0.5, about 0.04 to 0.3, about 0.04 to 0.2, about 0.06 to 0.5, about 0.06 to 0.3, and about 0.06 to 0.2.

[0025] In the polymer compositions of this disclosure, the graft-average degree of polymerization (DPn) of caprolactone in the cellulose acetate-caprolactone polymer is preferably about 15.0 or less, more preferably about 10.0 or less, even more preferably about 8.0 or less, and also preferably about 1.0 or more, more preferably about 2.0 or more. Preferred ranges include about 1.0 to 15.0, about 1.0 to 10.0, about 1.0 to 8.0, about 2.0 to 15.0, about 2.0 to 10.0, and about 2.0 to 8.0.

[0026] The polymer compositions of this disclosure preferably exhibit a biodegradability in a biodegradability test under composting, measured in accordance with the provisions of JIS K6953-1:2011, where the decomposition rate is 1 / 10 to 2 / 3, more preferably 1 / 9 to 1 / 2, and even more preferably 1 / 8 to 2 / 5 of that of cellulose.

[0027] Furthermore, the polymer composition of this disclosure preferably exhibits a degradability in marine biodegradability tests specified in ISO 22404 that is 1 / 10 to 2 / 3, more preferably 1 / 9 to 1 / 2, and even more preferably 1 / 8 to 2 / 5 of the degradation rate of cellulose.

[0028] The cellulose acetate-caprolactone polymer composition of this disclosure is thermoplastic and can be molded into various forms (e.g., pellets, sheets, etc.). That is, the shape of the polymer composition of this disclosure is not particularly limited and can be shaped according to the application. The shape of the polymer composition of this disclosure can be, for example, pellets, sheets, etc.

[0029] When the polymer composition of this disclosure is in the form of a sheet, for example, the thickness of the sheet may be 2.0 mm or less, 1.5 mm or less, 1.0 mm or less, or 0.3 mm or more, 0.5 mm or more, 1.0 mm or more, and preferred ranges include approximately 0.3 to 2.0 mm, approximately 0.3 to 1.5 mm, approximately 0.3 to 1.0 mm, approximately 0.5 to 2.0 mm, approximately 0.5 to 1.5 mm, approximately 0.5 to 1.0 mm, approximately 1.0 to 2.0 mm, approximately 1.0 to 1.5 mm, and approximately 1.0 mm.

[0030] (First aspect) A cellulose acetate-caprolactone polymer composition according to a first aspect of this disclosure (hereinafter sometimes referred to as the polymer composition of the first aspect) comprises a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst, characterized in that the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less. In the cellulose acetate-caprolactone polymer composition according to a first aspect of this disclosure, the total content of the homocaprolactone polymer and the caprolactone monomer is controlled to be 18% by mass or less. Therefore, the polymer composition of the first aspect can produce a sheet with few impurities and high transparency. Furthermore, the polymer composition of the first aspect can exhibit high transparency, low elution of impurities, and high mechanical strength when used as a sheet.

[0031] The cellulose acetate-caprolactone polymer composition according to the first aspect of this disclosure can be produced, for example, as an unpurified product before purification to remove catalysts, etc., in the method for producing the cellulose acetate-caprolactone polymer composition of this disclosure described later.

[0032] The polymer composition of the first embodiment includes, in addition to the cellulose acetate-caprolactone polymer, at least a homocaprolactone polymer, a caprolactone monomer, and a catalyst.

[0033] In the polymer composition of the first embodiment, the cellulose acetate-caprolactone polymer has a portion derived from cellulose acetate that is preferably about 70% by mass or more, more preferably about 72% by mass or more, even more preferably about 73% by mass or more, and also preferably about 95% by mass or less, more preferably about 92% by mass or less, and even more preferably about 90% by mass or less. Preferred ranges include about 70-95% by mass, about 70-92% by mass, about 70-90% by mass, about 72-95% by mass, about 72-92% by mass, about 72-90% by mass, about 73-95% by mass, about 73-92% by mass, and about 73-90% by mass.

[0034] Furthermore, in the polymer composition of the first embodiment, the cellulose acetate-caprolactone polymer preferably has a caprolactone-derived portion of about 5% by mass or more, more preferably about 8% by mass or more, even more preferably about 10% by mass or more, and also preferably about 30% by mass or less, more preferably about 28% by mass or less, even more preferably about 27% by mass or less. Preferred ranges include about 5-30% by mass, about 5-28% by mass, about 5-27% by mass, about 8-30% by mass, about 8-28% by mass, about 8-27% by mass, about 10-30% by mass, about 10-28% by mass, and about 10-27% by mass.

[0035] In the polymer composition of the first embodiment, the total molar ratio of caprolactone units to the total cellulose acetate units is preferably about 1.6 or less, more preferably about 1.3 or less, and even more preferably about 1.0 or less. The lower limit is, for example, about 0.2 or more, preferably about 0.3 or more. Preferred ranges include about 0.2 to 1.6, about 0.2 to 1.3, about 0.2 to 1.0, about 0.3 to 1.6, about 0.3 to 1.3, and about 0.3 to 1.0. In the polymer composition of the first embodiment, cellulose acetate units refer to cellulose acetate structures contained in the polymer composition. The cellulose acetate-caprolactone polymer contains cellulose acetate units, and if the polymer composition contains raw material cellulose acetate, the raw material cellulose acetate also contains cellulose acetate units. Furthermore, a caprolactone unit is a caprolactone structure contained in a polymer composition. Cellulose acetate-caprolactone polymers contain caprolactone units, and if the polymer composition contains raw material caprolactone, homocaprolactone polymer, etc., these also contain caprolactone units.

[0036] The polymer composition of the first embodiment has a melt mass flow rate (MFR, 190°C, 2.16 kg) of, for example, 0 g / 10 min or more, preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, preferably 0.5 g / 10 min or more, and also preferably 30 g / 10 min or less, more preferably 25 g / 10 min or less, and even more preferably 20 g / 10 min or less, with a preferred range being 0 to Examples include approximately 30g / 10min, 0-25g / 10min, 0-20g / 10min, 0.1-30g / 10min, 0.1-25g / 10min, 0.1-20g / 10min, 0.3-30g / 10min, 0.3-25g / 10min, 0.3-20g / 10min, 0.5-30g / 10min, 0.5-25g / 10min, and 0.5-20g / 10min.

[0037] The polymer composition of the first embodiment is obtained by hot-pressing a cellulose acetate-caprolactone polymer composition at a temperature of 165°C, a pressure of 15 MPa, and a time of 180 seconds. When the tensile modulus of elasticity is measured in accordance with the tensile test specified in JIS K6251, the tensile breaking strength is preferably 400 MPa or more, more preferably 500 MPa or more, even more preferably 700 MPa or more, particularly preferably 800 MPa or more, and also preferably 2000 MPa or less, more preferably 1200 MPa or less, even more preferably 1100 MPa or less, particularly preferably 1000 MPa or less, with a preferred range of approximately 400 to 2000 MPa and 400 to 1 Examples include approximately 200 MPa, 400-1100 MPa, 400-1000 MPa, 500-2000 MPa, 500-1200 MPa, 500-1100 MPa, 500-1000 MPa, 700-2000 MPa, 700-1200 MPa, 700-1100 MPa, 700-1000 MPa, 800-2000 MPa, 800-1200 MPa, 800-1100 MPa, and 800-1000 MPa.

[0038] The catalyst included in the polymer composition of the first embodiment is not particularly limited as long as it is a compound that exhibits the function of promoting the graft polymerization reaction between cellulose acetate and lactones, and may be, for example, a known catalyst. The catalyst included in the polymer composition of the first embodiment is preferably a phosphoric acid-based catalyst. Examples of phosphoric acid-based catalysts include phosphorus compounds that are weak acids, such as dibutyl phosphoric acid, diphenyl phosphoric acid, and bis(4-nitrophenyl) phosphate. The polymer composition of the first embodiment may contain only one type of catalyst or two or more types.

[0039] As described above, the shape of the polymer composition of the present disclosure can be, for example, a sheet, and when the polymer composition of the present disclosure is a polymer composition of the first embodiment, the sheet of the present disclosure (sheet according to the first embodiment) is formed from a cellulose acetate-caprolactone polymer composition comprising a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst, wherein the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less.

[0040] (Second aspect) Furthermore, the cellulose acetate-caprolactone polymer composition according to the second aspect of this disclosure (hereinafter sometimes referred to as the polymer composition of the second aspect) is a cellulose acetate-caprolactone polymer composition containing a cellulose acetate-caprolactone polymer, wherein the cellulose acetate-caprolactone polymer has a proportion of 70% by mass or more and 95% by mass or less of the portion derived from cellulose acetate, a proportion of 5% by mass or more and 30% by mass or less of the portion derived from caprolactone, and is substantially free of impurities. In the cellulose acetate-caprolactone polymer composition according to the second aspect of this disclosure, the proportions of the portion derived from cellulose acetate and the portion derived from caprolactone in the cellulose acetate-caprolactone polymer are controlled to be within predetermined ranges, and it is substantially free of impurities. Therefore, the polymer composition of the second aspect can produce a sheet with few impurities and high transparency. In addition, the polymer composition of the second aspect can exhibit high transparency, low elution of impurities, and high mechanical strength when made into a sheet.

[0041] The cellulose acetate-caprolactone polymer composition according to the second aspect of this disclosure can be produced, for example, as a purified product after purification (such as washing) to remove catalysts, etc., in the method for producing the cellulose acetate-caprolactone polymer composition of this disclosure described later.

[0042] In the polymer composition of the second embodiment, "substantially free of impurities" means that the total content of homopolycaprolactone, caprolactone monomer, and catalyst in the polymer composition is 1000 ppm or less.

[0043] In the polymer composition of the second embodiment, the cellulose acetate-caprolactone polymer has a cellulose acetate-derived portion of 70% by mass or more, preferably about 71% by mass or more, and more preferably about 72% by mass or more. Furthermore, this portion is 95% by mass or less, preferably about 92% by mass or less, and more preferably about 90% by mass or less. The range of this portion is 70 to 95% by mass, and preferred ranges include about 70 to 93% by mass, about 70 to 90% by mass, about 71 to 95% by mass, about 71 to 92% by mass, about 71 to 90% by mass, about 72 to 95% by mass, about 72 to 92% by mass, and about 72 to 90% by mass.

[0044] In the polymer composition of the second embodiment, the cellulose acetate-caprolactone polymer has a caprolactone-derived portion of 5% by mass or more, preferably about 8% by mass or more, and more preferably about 10% by mass or more. Furthermore, this percentage is 30% by mass or less, preferably about 28% by mass or less, and more preferably about 27% by mass or less. The range of this percentage is 5 to 30% by mass, and preferred ranges include about 5 to 28% by mass, about 5 to 27% by mass, about 8 to 30% by mass, about 8 to 28% by mass, about 8 to 27% by mass, about 10 to 30% by mass, about 10 to 28% by mass, and about 10 to 27% by mass.

[0045] In the polymer composition of the second embodiment, the average number of moles (MS) of caprolactone in the cellulose acetate-caprolactone polymer is preferably about 1.0 or less, more preferably about 0.95 or less, and even more preferably about 0.9 or less. The lower limit is, for example, about 0.1 or more, preferably about 0.2 or more. Preferred ranges include about 0.1 to 1.0, about 0.1 to 0.95, about 0.1 to 0.9, about 0.2 to 1.0, about 0.2 to 0.95, and about 0.2 to 0.9.

[0046] The polymer composition of the second embodiment has a melt mass flow rate (MFR, 190°C, 2.16 kg) of preferably 25 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 15 g / 10 min or less, with a lower limit of, for example, 0 g / 10 min.

[0047] Furthermore, the glass transition temperature Tg of the polymer composition of the second embodiment is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and also preferably 170°C or lower, more preferably 160°C or lower, even more preferably 150°C or lower. Preferred ranges include approximately 70-170°C, approximately 70-160°C, approximately 70-150°C, approximately 90-170°C, approximately 90-160°C, approximately 90-150°C, approximately 100-170°C, approximately 100-160°C, and approximately 100-150°C.

[0048] The polymer composition of the second embodiment is obtained by hot-pressing a cellulose acetate-caprolactone polymer composition at a temperature of 210°C, a pressure of 15 MPa, and a time of 180 seconds. When the tensile modulus of elasticity is measured in accordance with the tensile test specified in JIS K6251, the tensile breaking strength is preferably 700 MPa or more, more preferably 900 MPa or more, even more preferably 1000 MPa or more, particularly preferably 1200 MPa or more, and also preferably 2000 MPa or less, more preferably 1800 MPa or less, even more preferably 1600 MPa or less, particularly preferably 1500 MPa or less, with a preferred range being approximately 700 to 2000 MPa and 700 to 1800 MPa. Examples include approximately MPa, 700-1600 MPa, 700-1500 MPa, 900-2000 MPa, 900-1800 MPa, 900-1600 MPa, 900-1500 MPa, 1000-2000 MPa, 1000-1800 MPa, 1000-1600 MPa, 1000-1500 MPa, 1200-2000 MPa, 1200-1800 MPa, 1200-1600 MPa, and 1200-1500 MPa.

[0049] The polymer composition of the second embodiment is substantially free of impurities, but may contain trace amounts of catalyst or not. If the polymer composition of the second embodiment contains a catalyst, the catalyst is not particularly limited as long as it is a compound that promotes the graft polymerization reaction between cellulose acetate and lactones, and may be, for example, a known catalyst. The catalyst included in the polymer composition of the second embodiment is preferably a phosphoric acid-based catalyst. Examples of phosphoric acid-based catalysts include phosphorus compounds that are weak acids, such as dibutyl phosphoric acid, diphenyl phosphoric acid, and bis(4-nitrophenyl) phosphate. If the polymer composition of the second embodiment contains a catalyst, there may be only one type of catalyst or two or more types.

[0050] As described above, the shape of the polymer composition of the present disclosure can be, for example, a sheet, and when the polymer composition of the present disclosure is a polymer composition of the second embodiment, the sheet of the present disclosure (sheet according to the second embodiment) is formed of a cellulose acetate-caprolactone polymer composition in which the proportion of the portion derived from cellulose acetate is 70% by mass or more and 95% by mass or less, the proportion of the portion derived from caprolactone is 5% by mass or more and 30% by mass or less, and which is substantially free of impurities.

[0051] The method for producing the polymer composition of the present disclosure, including the first and second embodiments, is not particularly limited, but it is preferable to employ the method for producing the cellulose acetate-caprolactone polymer composition of the present disclosure as described in the [Method for Producing Cellulose Acetate-Caprolactone Polymer Composition] below.

[0052] The cellulose acetate-caprolactone polymer composition of this disclosure can be suitably used in a variety of applications where thermoplastic resins are applied, such as sheets, films, plates, cutlery, containers, bottles, fibers, filters, absorbents, and foams.

[0053] [Method for producing a cellulose acetate-caprolactone polymer composition] The present disclosure provides a method for producing a cellulose acetate-caprolactone polymer composition, comprising a polymerization step of polymerizing cellulose acetate and caprolactone monomer in a twin-screw extruder in the presence of a catalyst, characterized in that the ratio of caprolactone monomer to 1 part by mass of cellulose acetate is 0.3 parts by mass or more and 0.5 parts by mass or less, and the ratio of catalyst to 1 part by mass of cellulose acetate is 0.005 parts by mass or more and 0.05 parts by mass or less.

[0054] According to the method for producing the polymer composition of this disclosure, it is possible to produce a cellulose acetate-caprolactone polymer composition that has few impurities and can produce a highly transparent sheet, such as the polymer composition of the first embodiment or the polymer composition of the second embodiment described above. Furthermore, according to the method for producing the polymer composition of this disclosure, it is possible to produce a cellulose acetate-caprolactone polymer composition that has high transparency when made into a sheet, has little impurity elution, and has high mechanical strength.

[0055] In the method for producing the polymer composition of the present disclosure, the polymerization step of polymerizing cellulose acetate and caprolactone monomer is characterized by carrying out the polymerization in a twin-screw extruder. By setting the ratios of caprolactone monomer and catalyst to cellulose acetate within predetermined ranges and carrying out the polymerization in a twin-screw extruder, the formation of homocaprolactone polymer is suppressed, and the residue of caprolactone monomer is also reduced.

[0056] The twin-screw extruder is not particularly limited as long as it can polymerize cellulose acetate and caprolactone monomer while mixing and heating them; known extruders can be used, and commercially available ones can also be used.

[0057] In the polymerization process, the ratio of caprolactone monomer to 1 part by mass of cellulose acetate may be within the range of 0.2 parts by mass or more and 0.8 parts by mass or less, preferably 0.25 parts by mass or more, more preferably 0.3 parts by mass or more, and from the viewpoint of more favorably exhibiting the effects of the present invention, preferably 0.6 parts by mass or less, more preferably 0.5 parts by mass or less, and preferred ranges include about 0.2 to 0.6 parts by mass, about 0.2 to 0.5 parts by mass, about 0.25 to 0.8 parts by mass, about 0.25 to 0.6 parts by mass, about 0.25 to 0.5 parts by mass, about 0.3 to 0.8 parts by mass, about 0.3 to 0.6 parts by mass, and about 0.3 to 0.5 parts by mass.

[0058] Furthermore, in the polymerization process, the ratio of catalyst to 1 part by mass of cellulose acetate may be within the range of 0.001 parts by mass or more and 0.10 parts by mass or less, preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and from the viewpoint of more favorably exhibiting the effects of the present invention, preferably 0.07 parts by mass or less, more preferably 0.05 parts by mass or less, and preferred ranges include approximately 0.001 to 0.07 parts by mass, approximately 0.001 to 0.05 parts by mass, approximately 0.005 to 0.10 parts by mass, approximately 0.005 to 0.07 parts by mass, approximately 0.005 to 0.05 parts by mass, approximately 0.01 to 0.10 parts by mass, approximately 0.01 to 0.07 parts by mass, and approximately 0.01 to 0.05 parts by mass.

[0059] In the polymerization process, the types of raw materials used, such as cellulose acetate, caprolactone, and catalyst, are as described in the section above, "[Method for Producing Cellulose Acetate-Caprolactone Polymer Composition]".

[0060] Furthermore, the reaction temperature in the polymerization process is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, and also preferably 150°C or lower, more preferably 140°C or lower, even more preferably 130°C or lower. Preferred ranges include 80°C to 150°C, a more preferred range is 100°C to 140°C, and an even more preferred range is 120°C to 130°C.

[0061] Furthermore, the reaction time in the polymerization step is preferably 3 minutes or more, more preferably 4 minutes or more, even more preferably 5 minutes or more, and also preferably 15 minutes or less, more preferably 12 minutes or less, even more preferably 10 minutes or less. Preferred ranges include approximately 3 to 15 minutes, approximately 3 to 12 minutes, approximately 3 to 10 minutes, approximately 4 to 15 minutes, approximately 4 to 12 minutes, approximately 4 to 10 minutes, approximately 5 to 15 minutes, approximately 5 to 12 minutes, and approximately 5 to 10 minutes.

[0062] In the polymerization process, it is desirable to thoroughly dry the cellulose acetate and lactones used as raw materials. Furthermore, the polymerization process is preferably carried out in an inert gas environment such as nitrogen gas or argon gas. In addition, it is preferable to stir the cellulose acetate and lactones used as raw materials, as well as the catalyst and solvent, during the polymerization process. Stirring can be carried out using a kneader such as a laboplast mill or a twin-screw extruder.

[0063] Furthermore, a solvent may be used in the polymerization step. The solvent is not particularly limited as long as it does not inhibit the polymerization reaction between cellulose acetate and caprolactone; for example, organic solvents such as toluene and cyclohexanone can be used. Only one type of solvent may be used in the polymerization step, or two or more types may be used. It is preferable to remove the solvent from the product after the polymerization step.

[0064] The polymer compositions produced by the method of this disclosure include, for example, the polymer composition of the first embodiment described above, the polymer composition of the second embodiment, and the like.

[0065] In particular, in the method for producing the polymer composition of the present disclosure, if a purification step (such as a washing step) is not provided after the polymerization step to remove homocaprolactone polymer, caprolactone monomer, catalyst, etc., the polymer composition produced by the method for producing the polymer composition of the present disclosure may satisfy the composition of the polymer composition of the first embodiment. That is, the polymer composition produced comprises a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst, and the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less.

[0066] Furthermore, in the method for producing the polymer composition of this disclosure, if a purification step (such as a washing step) is provided after the polymerization step to remove homocaprolactone polymer, caprolactone monomer, catalyst, etc., the polymer composition produced by the method for producing the polymer composition of this disclosure may satisfy the composition of the polymer composition of the second embodiment. That is, the produced polymer composition contains a cellulose acetate-caprolactone polymer, in which the proportion of the portion derived from cellulose acetate is 70% by mass or more and 95% by mass or less, and the proportion of the portion derived from caprolactone is 5% by mass or more and 30% by mass or less, and it is substantially free of impurities. The term "substantially free of impurities" is as described above.

[0067] In the method for producing the polymer composition of this disclosure, the cellulose acetate-caprolactone polymer composition obtained in the polymerization step can be pelletized. Alternatively, the cellulose acetate-caprolactone polymer composition can be pelletized and then further formed into a sheet.

[0068] As described above, in order to produce the polymer composition of the second embodiment, it is desirable to include a purification step after the polymerization step. The purification step can be carried out by washing the polymer composition obtained in the polymerization step and drying it as necessary. For example, the purification step includes a step of washing pellets obtained by pelletizing the polymer composition obtained in the polymerization step, and a step of drying the washed pellets. As for the washing method, a known method for washing cellulose acetate-caprolactone polymer compositions can be used.

[0069] In this disclosure, from the viewpoint of suitably removing impurities in the polymer composition, the step of washing the pellets is preferably either a method of washing the pellets with water and / or alcohol, or a method of redissolving the pellets in an organic solvent and reprecipitation in a poor solvent. In the method of washing the pellets with water and / or alcohol, it is preferable to remove impurities by immersing the pellets in water and / or alcohol at a temperature that does not cause the pellets to lose their shape. In the method of redissolving the pellets in an organic solvent and reprecipitation in a poor solvent, it is preferable to dissolve the impurities in acetone or the like beforehand, and then add alcohol or the like to precipitate only the resin. Examples of alcohols include methanol, ethanol, and isopropanol.

[0070] [Sheet] The sheet of this disclosure is a sheet comprising a cellulose acetate-caprolactone polymer composition, characterized in that the haze value after standing for 12 hours at a temperature of 23°C and a relative humidity of 50%RH is 25% or less.

[0071] A sheet of the present disclosure having such properties can be formed, for example, by a polymer composition of the first embodiment. When the sheet of the present disclosure is formed by a polymer composition of the first embodiment, the sheet of the present disclosure is formed by a cellulose acetate-caprolactone polymer composition comprising a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst, wherein the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less, and furthermore, the haze value after standing for 12 hours in a measurement environment of 23°C and 50% RH is 25% or less.

[0072] Furthermore, the sheet of the present disclosure having the above characteristics can be formed, for example, from the polymer composition of the second aspect. When the sheet of the present disclosure is formed from the polymer composition of the second aspect, the sheet contains a cellulose acetate-caprolactone polymer in which the proportion of the portion derived from cellulose acetate is 70% by mass or more and 95% by mass or less, and the proportion of the portion derived from caprolactone is 5% by mass or more and 30% by mass or less, and is formed from a cellulose acetate-caprolactone polymer composition substantially free of impurities. Further, the haze value after standing for 1 month at a measurement environment of 23°C and 50% RH is 25% or less.

[0073] The types of cellulose acetate, caprolactone, catalyst, etc. are as described in the above item of [Method for Producing Cellulose Acetate-Caprolactone Polymer Composition].

[0074] The sheet of the present disclosure has a sheet thickness of 1 mm, and for a surface area of 1 cm 2 when water at a rate of 2 mL per surface area is heated to 95°C and used, and the elution amount when immersed for 30 minutes while maintaining at 95°C is preferably 10 μg / mL or less, more preferably 9 μg / mL or less, still more preferably 8 μg / mL or less. For the lower limit, for example, 0 μg / mL or more can be mentioned, and preferable ranges include 0 to 10 μg / mL, 0 to 9 μg / mL, 0 to 8 μg / mL, etc.

[0075] Furthermore, the sheet of the present disclosure has a sheet thickness of 1 mm, and for one side of the sheet, when immersed in 50 ml of a 20% ethanol aqueous solution per surface area of 1 dm 2 for 1 hour under reflux temperature conditions, the extract amount is preferably 50 mg / dm 2 , more preferably 30 mg / dm 2 or less, still more preferably 20 mg / dm 2 or less, particularly preferably 10 mg / dm 2 or less. For the lower limit, for example, 0 mg / dm 2 or more can be mentioned, and preferable ranges include about 0 to 50 mg / dm 2 degree, 0 to 30 mg / dm2 Degree, 0~20mg / dm 2 Degree, 0~10mg / dm 2 The degree can be described as follows.

[0076] The sheet of this disclosure can be suitably used in a variety of applications, such as sheets, films, plates, cutlery, containers, bottles, fibers, filters, absorbents, and foams. [Examples]

[0077] The present disclosure will be explained in more detail below with reference to examples.

[0078] [Production of Cellulose Acetate-Caprolactone Polymer Composition] (Example 1) A cellulose acetate-caprolactone polymer composition was produced by polymerizing cellulose acetate and caprolactone monomer within a twin-screw extruder in the presence of a catalyst (DBP: dibutyl phosphate). Specifically, the cellulose acetate-caprolactone polymer composition was produced according to the following procedure. The production conditions are as shown in Table 1.

[0079] Dried cellulose acetate (10 kg, manufactured by Daicel Corporation, VFS, average degree of substitution 2.4), ε-caprolactone (18 kg, manufactured by Daicel Corporation), and dibutyl phosphate (500 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared. Prior to the experiment, the heating temperature of a twin-screw compounding extruder (product name: TEM-26DSS-16 / 2V, ultra-high torque, manufactured by Shibaura Machinery Co., Ltd.) having the structure shown in the schematic diagram of Figure 1 was set to 125°C. The three types of samples prepared—cellulose acetate, ε-caprolactone, and dibutyl phosphate—were supplied by the following method.

[0080] <Sample supply> Cellulose acetate was supplied at a rate of 3.33 kg / hr from inlet F1 using a gravity-type twin-screw feeder mounted on a twin-screw kneading extruder. ε-caprolactone and dibutyl phosphate were supplied using separate metering pumps; ε-caprolactone was supplied at a rate of 1.67 kg / hr from inlet F2, and dibutyl phosphate was supplied at a rate of 2.02 mL / min from section F3.

[0081] A cellulose acetate-caprolactone polymer composition (unrefined) was obtained from the outlet of the twin-screw extruder shown in Figure 1. The mixture obtained from the outlet of the twin-screw extruder was molded into pellets. The composition of the cellulose acetate-caprolactone polymer composition (unrefined) is as shown in Table 2.

[0082] <Purification> 100g was measured from the obtained pellet, and the recovered material was dissolved in 1L of acetone heated to 40°C. The solid was precipitated using 3.5L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the 1H NMR measurement results confirmed that the recovered material was the target cellulose acetate-caprolactone polymer (purified product). The composition of the cellulose acetate-caprolactone polymer composition (purified product) is as shown in Table 3.

[0083] (Example 2) Cellulose acetate-caprolactone polymer composition (unpurified) and cellulose acetate-caprolactone polymer composition (purified) were obtained in the same manner as in Example 1, except that the supply of the three types of samples prepared—cellulose acetate, ε-caprolactone, and dibutyl phosphate—was changed as follows under the manufacturing conditions of Example 1. The composition of the cellulose acetate-caprolactone polymer composition (unpurified) is as shown in Table 2. The composition of the cellulose acetate-caprolactone polymer composition (purified) is as shown in Table 3.

[0084] <Sample supply> Cellulose acetate was supplied at a rate of 3.57 kg / hr from inlet F1 using a gravity-type twin-screw feeder mounted on a twin-screw compounding extruder. ε-caprolactone and dibutyl phosphate were supplied using separate metering pumps; ε-caprolactone was supplied at a rate of 1.43 kg / hr from inlet F2, and dibutyl phosphate was supplied at a rate of 2.16 mL / min from section F3.

[0085] (Example 3) Cellulose acetate-caprolactone polymer composition (unpurified) and cellulose acetate-caprolactone polymer composition (purified) were obtained in the same manner as in Example 1, except that the supply of the three types of samples prepared—cellulose acetate, ε-caprolactone, and dibutyl phosphate—was changed as follows under the manufacturing conditions of Example 1. The composition of the cellulose acetate-caprolactone polymer composition (unpurified) is as shown in Table 2. The composition of the cellulose acetate-caprolactone polymer composition (purified) is as shown in Table 3.

[0086] <Sample supply> Cellulose acetate was supplied at a rate of 3.85 kg / hr from inlet F1 using a gravity-type twin-screw feeder mounted on a twin-screw kneading extruder. ε-caprolactone and dibutyl phosphate were supplied using separate metering pumps; ε-caprolactone was supplied at a rate of 1.15 kg / hr from inlet F2, and dibutyl phosphate was supplied at a rate of 2.33 mL / min from section F3.

[0087] (Example 4) Cellulose acetate-caprolactone polymer composition (unpurified) and cellulose acetate-caprolactone polymer composition (purified) were obtained in the same manner as in Example 1, except that the supply of the three types of samples prepared—cellulose acetate, ε-caprolactone, and dibutyl phosphate—was changed as follows under the manufacturing conditions of Example 1. The composition of the cellulose acetate-caprolactone polymer composition (unpurified) is as shown in Table 2. The composition of the cellulose acetate-caprolactone polymer composition (purified) is as shown in Table 3.

[0088] <Sample supply> 9.9 kg of cellulose acetate and 0.1 kg of dibutyl phosphate were pre-dried and blended in a poly bag. These were then supplied at a rate of 2.86 kg / hr from inlet F1 using the gravimetric twin-screw feeder mounted on the twin-screw kneading extruder shown in Figure 1. ε-caprolactone and dibutyl phosphate were supplied using separate quantitative pumps. ε-caprolactone was supplied at a rate of 1.15 kg / hr from inlet F2, and dibutyl phosphate was supplied at a rate of 0.60 mL / min from section F3.

[0089] (Example 5) A cellulose acetate-caprolactone polymer composition was produced by polymerizing cellulose acetate and caprolactone monomer within a twin-screw extruder in the presence of a catalyst (DPP: diphenyl phosphate) using a twin-screw extruder as the polymerization apparatus. Specifically, the cellulose acetate-caprolactone polymer composition was produced according to the following procedure. The production conditions are as shown in Table 1.

[0090] Dried cellulose acetate (10 kg, manufactured by Daicel Corporation, VFS, average degree of substitution 2.4), ε-caprolactone (18 kg, manufactured by Daicel Corporation), and diphenyl phosphate (101 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared. The dried cellulose acetate and diphenyl phosphate (101 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were transferred to a plastic bag and mixed uniformly. Prior to the experiment, the heating temperature of a twin-screw compounding extruder (product name: TEM-26DSS-16 / 2V, ultra-high torque, manufactured by Shibaura Machinery Co., Ltd.) having the structure shown in the schematic diagram of Figure 1 was set to 125°C. The two samples prepared—a mixture of diphenyl phosphate and cellulose acetate, and ε-caprolactone—were supplied using the following method.

[0091] <Sample supply> The mixture of diphenyl phosphate and cellulose acetate was supplied at a rate of 3.33 kg / hr from inlet F1 using a gravimetric twin-screw feeder mounted on the twin-screw kneading extruder shown in Figure 1. ε-caprolactone was supplied at a rate of 1.67 kg / hr from inlet F2 using a metering pump.

[0092] A cellulose acetate-caprolactone polymer composition (unrefined) was obtained from the outlet of the twin-screw extruder shown in Figure 1. The mixture obtained from the outlet of the twin-screw extruder was molded into pellets. The composition of the cellulose acetate-caprolactone polymer composition (unrefined) is as shown in Table 2.

[0093] <Purification> 100g was measured from the obtained pellet, and the recovered material was dissolved in 1L of acetone heated to 40°C. The solid was precipitated using 3.5L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the 1H NMR measurement results confirmed that the recovered material was the target cellulose acetate-caprolactone polymer (purified product). The composition of the cellulose acetate-caprolactone polymer composition (purified product) is as shown in Table 3.

[0094] (Comparative Example 1) Dried cellulose acetate (Daicel Corporation, CA, average degree of substitution 2.1), ε-caprolactone (Daicel Corporation), and diphenyl phosphate (Tokyo Chemical Industries, Ltd.) were prepared. Using an absolute mill ABS-W (Osaka Chemical Co., Ltd.), 45 g of cellulose diacetate was pulverized at 16,800 rpm for 2 minutes and 30 seconds. Next, the pulverized cellulose diacetate was thoroughly dried. Then, 5 g of cellulose diacetate and 20 g of ε-caprolactone, totaling 25 g, were placed in a beaker and mixed. This mixture was then placed in a batch-type kneader (Laboplast Mill (C model) 4C150, Toyo Seiki Seisakusho Co., Ltd.) and stirred for 10 minutes. Next, 0.63 mL of a toluene solution of diphenyl phosphate as a catalyst (0.2 g / mL) was added (the amount of catalyst was 2.5% by mass relative to the total amount of cellulose diacetate), and graft polymerization was carried out at 80°C for 20 minutes to obtain a bulk polymer composition (unpurified).

[0095] <Purification> 20 g of the obtained resin was dissolved in 200 mL of acetone heated to 40°C, and a solid was precipitated using 1 L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the results by 1H NMR confirmed that the recovered material was the target cellulose acetate-caprolactone polymer (purified product).

[0096] (Comparative Example 2) Dried cellulose acetate (Daicel Corporation, CA, average degree of substitution 2.1), ε-caprolactone (Daicel Corporation), and diphenyl phosphate (Tokyo Chemical Industries, Ltd.) were prepared. Using an absolute mill ABS-W (Osaka Chemical Co., Ltd.), 45 g of cellulose diacetate was pulverized at 16,800 rpm for 2 minutes and 30 seconds. Next, the pulverized cellulose diacetate was thoroughly dried. Then, 5 g of cellulose diacetate and 20 g of ε-caprolactone, totaling 25 g, were placed in a beaker and mixed. This mixture was then placed in a batch-type kneader (Laboplast Mill (C model) 4C150, Toyo Seiki Seisakusho Co., Ltd.) and stirred for 10 minutes. Next, 2.5 mL of a toluene solution of diphenyl phosphate as a catalyst (0.2 g / mL) was added (the amount of catalyst was 10.0% by mass relative to the total amount of cellulose diacetate), and graft polymerization was carried out at 80°C for 20 minutes to obtain a bulk polymer composition (unpurified).

[0097] <Purification> 20 g of the obtained resin was dissolved in 200 mL of acetone heated to 40°C, and a solid was precipitated using 1 L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the results by 1H NMR confirmed that the recovered material was the target cellulose acetate-caprolactone polymer (purified product).

[0098] (Comparative Example 3) Dried cellulose acetate (9.6 kg, manufactured by Daicel Corporation, CA, average degree of substitution 2.1), ε-caprolactone (18 kg, manufactured by Daicel Corporation), and diphenyl phosphate (400 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared. The dried cellulose acetate and diphenyl phosphate were transferred to a plastic bag and mixed uniformly by dry blending.

[0099] Prior to the experiment, the heating temperature of a twin-screw compounding extruder (screw size: φ=25mm, L / D=45, screw rotation direction: same direction) having the structure shown in the schematic diagram of Figure 2 was set to 160°C. The two samples prepared, a mixture of diphenyl phosphate and cellulose acetate, and ε-caprolactone, were supplied using the following method.

[0100] <Sample supply> The mixture of diphenyl phosphate and cellulose acetate was supplied at a rate of 0.5 kg / hr from inlet F1 using a gravimetric twin-screw feeder mounted on the twin-screw kneading extruder shown in Figure 2. ε-caprolactone was supplied at a rate of 0.5 kg / hr from inlet F1 using a metering pump.

[0101] <Purification> A cellulose acetate-caprolactone polymer composition (unpurified) was obtained from the outlet of the twin-screw extruder shown in Figure 2. The mixture obtained from the outlet of the twin-screw extruder was molded into pellets. 100 g was weighed from the pellets, and the recovered material was dissolved using 1 L of acetone heated to 40°C. A solid was precipitated using 3.5 L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the results by 1H NMR measurement confirmed that the recovered material was the target cellulose acetate-caprolactone polymer.

[0102] (Comparative Example 4) Dried cellulose acetate (9.9 kg, manufactured by Daicel Corporation, CA, average degree of substitution 2.2), ε-caprolactone (18 kg, manufactured by Daicel Corporation), and diphenyl phosphate (100 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared. The dried cellulose acetate and diphenyl phosphate were transferred to a plastic bag and mixed uniformly by dry blending. The heating temperature of the twin-screw kneading extruder shown in Figure 1 was set to 140°C in advance. The two samples of the prepared cellulose acetate and diphenyl phosphate mixture and ε-caprolactone were supplied by the following method.

[0103] <Sample supply> The mixture of cellulose acetate and diphenyl phosphate was supplied at a rate of 2.86 kg / hr from inlet F1 using a gravimetric twin-screw feeder mounted on the twin-screw kneading extruder shown in Figure 1. ε-caprolactone was supplied at a rate of 2.14 kg / hr from inlet F2 using a metering pump.

[0104] A cellulose acetate-caprolactone polymer composition (unrefined) was obtained from the outlet of the twin-screw extruder shown in Figure 1. The mixture obtained from the outlet of the twin-screw extruder was molded into pellets. The composition of the cellulose acetate-caprolactone polymer composition (unrefined) is as shown in Table 2.

[0105] <Purification> 100g was measured from the obtained pellet, and the recovered material was dissolved in 1L of acetone heated to 40°C. The solid was precipitated using 3.5L of methanol. The precipitated solid was washed three times with methanol, and the recovered material was dried under reduced pressure overnight to obtain a solid. Analysis of the 1H NMR measurement results confirmed that the recovered material was the target cellulose acetate-caprolactone polymer (purified product). The composition of the cellulose acetate-caprolactone polymer composition (purified product) is as shown in Table 3.

[0106] (Degree of molar substitution of εCL (MS)) For the polymer compositions (unpurified) and polymer compositions (purified) obtained in the examples and comparative examples, the molar ratio of the lactones per glucose unit of cellulose acetate and the average molar substitution degree (MS) were measured by the following method. The results are shown in Table 2. The polymer compositions were dissolved in deuterated chloroform and subjected to 1H NMR measurement. If the polymer is insoluble in deuterated chloroform, trifluoroacetic acid may be used in combination. The sample concentration was 10 mg / mL, and the measurement was performed under the following conditions: observation time 0.15 seconds, relaxation time 1.0 seconds, observation frequency 300.1 MHz, and number of integrations 16 times. The chemical shift values ​​of the obtained spectra were expressed in ppm, with the peak of the methyl group of the internal standard trimethylsilane (TMS) as the reference (0 ppm). All measurements were performed using a 300-MHz NMR spectrometer (Varian INOVA300). The molar ratio was calculated from the 1H NMR measurement results of the polymer composition (unpurified) using the following formula. Here, the H2" and H4" peaks contain g-PCL and h-PCL, respectively, indicating the molar ratio of caprolactone units to cellulose acetate units. The degree of molar substitution (MS) was calculated from the 1H NMR measurement results of the polymer composition (purified product) using the following formula. Here, MS is defined as the number of moles of caprolactone introduced per mole of AGU.

[0107] [ka]

[0108] Chemical shift of acetyl group peak area: 1,800–2.20 ppm Chemical shift of H2 peak area: 2.25–2.45 ppm Chemical shift of peak area for H4'': 1.3~1.5 ppm

[0109] (Average degree of substitution (DS) and average degree of polymerization (DPn) of g-PCL) Analysis of the average degree of substitution (DS) of caprolactone in the cellulose acetate-caprolactone graft polymer (g-PCL) of the polymer composition (purified product), and the average degree of polymerization (DPn) of caprolactone in g-PCL, is performed by propionylating the cellulose acetate-caprolactone graft polymer to be analyzed and determining the distribution of the substituted propionyl groups. 1 The measurement was performed by 1H NMR. Specifically, the procedure is as follows:

[0110] <Instructions> The resulting cellulose acetate-caprolactone graft polymer, propionylated, was dissolved in deuterated chloroform. 1 The samples were subjected to 1H NMR measurements. The sample concentration was 10 mg / mL, and measurements were performed using a JNM-ECZL600R FT NMR spectrometer (JEOL) with 32 integration cycles at a temperature of 40°C. The chemical shift values ​​of the obtained spectra were expressed in ppm, with the peak of the methyl group of the internal standard trimethylsilane (TMS) as the reference (0 ppm). The average degree of substitution of g-PCL was calculated from the 0.80-1.00 ppm peaks corresponding to the terminal methyl group of the propionyl group that reacted with the terminal hydroxyl group of g-PCL. Furthermore, the average degree of polymerization of g-PCL was estimated from the ratio of the integral values ​​of the above peaks and the 1.30-1.50 ppm peaks corresponding to the methylene group of the caprolactone unit of g-PCL.

[0111] (Analysis of composition) The polymer compositions (unpurified) obtained in the examples and comparative examples were analyzed for composition using the following procedure. The proportion of cellulose diacetate (CDA) (mass%), the total proportion of cellulose acetate-caprolactone graft polymer (g-PCL) and homopolycaprolactone (h-PCL) (mass%), the proportion of caprolactone (εCl) (mass%), and the proportion of catalyst (mass%) are shown in Table 2.

[0112] <Instructions> The obtained polymer composition (unrefined and refined) was dissolved in deuterated chloroform. 1The sample was subjected to 1H NMR measurement. The sample concentration was 10 mg / mL, and measurements were performed using a JNM-ECZL600R FT NMR spectrometer (JEOL) with 32 integration cycles at a temperature of 40°C. The chemical shift values ​​of the obtained spectra were expressed in ppm, with the methyl group peak of the internal standard trimethylsilane (TMS) as the reference (0 ppm). The proportion of cellulose diacetate (CDA) (mass%) was calculated from the peak at 1.80–2.20 ppm corresponding to the acetyl group; the total proportion of grafted PCL (g-PCL) and homopolycaprolactone (h-PCL) (mass%) was calculated from the peak at 1.30–1.50 ppm corresponding to the methylene group of the caprolactone unit; the proportion of caprolactone (εCl) (mass%) was calculated from the peak at 2.60–2.70 ppm corresponding to the methylene group of the caprolactone monomer; and the proportion of the catalyst (mass%) was calculated from the peak at 0.85–1.00 ppm corresponding to the methyl group of dibutyl phosphate. Since the purified product does not contain h-PCL, the proportions of g-PCL and h-PCL were calculated from the change in the peak integral value of the methylene group of the caprolactone unit before and after purification.

[0113] Chemical shift of acetyl group peak area: 1.80–2.20 ppm Chemical shift of peak area of ​​methylene group in caprolactone polymer: 1.30–1.50 ppm Chemical shift of peak area of ​​the methylene group of caprolactone monomer: 2.60–2.70 ppm Chemical shift of peak area of ​​methyl group of dibutyl phosphate: 0.85~1.00 ppm

[0114] [Production of sheets containing cellulose acetate-caprolactone polymer composition] Sheets were manufactured using the polymer compositions (purified products) obtained in the examples and comparative examples, following the procedure below. A metal plate (180 mm, 2 mm thick) was placed at the bottom, and a plate with an opening in the center (180 mm, arbitrary thickness) was placed on top of it. 12-15 g of cellulose acetate-caprolactone polymer composition was placed in the opening, and a metal plate (180 mm, 2 mm thick) was placed on top of it. The three metal plates were pressurized to 1 MPa in 3 minutes at a temperature between 165°C and 210°C using a mini test press machine (MP-SNL, manufactured by Toyo Seiki Seisakusho) at a temperature between 165°C and 210°C. Then, the pressure was increased to 15 MPa in 3 minutes. After heating was complete, the pressure was released and the three metal plates were removed simultaneously. Again, the plates were pressurized to 1 MPa in 3 minutes at a temperature between 25-40°C using another mini test press machine (MP-SNL, manufactured by Toyo Seiki Seisakusho) at a temperature between 25-40°C. Then, the pressure was increased to 15 MPa in 3 minutes. After cooling is complete, the pressure is released and the three metal plates are removed. The sheet formed in the opening is then removed and various evaluations are performed.

[0115] Furthermore, the molecular weight (number-average molecular weight (Mn) and weight-average molecular weight (Mw)), glass transition temperature (Tg), MFR (190°C / 2.16 kg or 220°C / 10.0 kg), tensile breaking strength (MPa), tensile breaking elongation (%), elastic modulus (MPa), elution amount in 95°C water, extract amount in 20% ethanol aqueous solution, transparency, and degradability (biodegradability test under composting conditions, marine biodegradability test) of the polymer constituting the obtained sheet were evaluated using the following methods. The results are shown in Tables 4 and 5.

[0116] (molecular weight) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the graft polymer are styrene-equivalent values ​​measured by liquid chromatography, under the following conditions. Measuring device: (Manufactured by Shimadzu Corporation) Column: Shodex LF-804 (used by connecting two columns together) Flow rate: 0.4mL / min Mobile phase and sample solvent: Tetrahydrofuran (stabilizer-free) Sample concentration: 0.05% Column temperature: 40°C Detector: Differential refractometer (RI) Standard sample: Polystyrene

[0117] (Glass transition temperature Tg) The polymer compositions (purified products) obtained in the examples and comparative examples were subjected to DSC measurements using the following temperature profile, and the temperature at the intersection of the baseline and the tangent at the inflection point of the chart obtained during the second heating process was defined as the glass transition temperature. Temperature profile: The temperature is increased from -60°C to 240°C at a rate of 20°C / min (first heating), then cooled from 240°C to -60°C at a cooling rate of 20°C / min, and then heated again from -60°C to 240°C at a heating rate of 20°C / min (second heating).

[0118] (MFR(190℃ / 2.16kg, 220℃ / 10.0kg)) Except for the fact that the opening area of ​​the flat plate with an opening is 10 cm x 10 cm and the thickness is 1 mm, the sheet is manufactured in the same manner as in [manufacturing of a sheet containing a cellulose acetate-caprolactone polymer composition], and then pulverized to a particle size of approximately 1 mm using a mixer or the like. The pulverized material is then set in the raw material input port of a melt flow rate tester (melt flow index tester 120-FWP, manufactured by Yasuda Seiki Seisakusho Co., Ltd.) heated to 190°C or 220°C, and measured in accordance with the provisions of JIS K7210-1 (ISO 1133-1) A, and the average of N=2 is calculated.

[0119] (Tensile breaking strength (MPa), tensile breaking elongation (%), and modulus of elasticity (MPa)) Except for the fact that the opening area of ​​the flat plate with an opening is 5 cm x 5 cm and the thickness is 0.5 mm, the sheet is manufactured in the same manner as in [Production of a sheet containing a cellulose acetate-caprolactone polymer composition], and dumbbell pieces (JIS K6251, dumbbell-shaped No. 7) are made using a sample cutter (SDMP-1000-D, manufactured by Dumbbell Co., Ltd.). Then, a test is performed using a small benchtop tester (EZ-SX, manufactured by Shimadzu Corporation) at a tensile speed of 5 mm / min, and the average of N=5 is calculated.

[0120] (transparency) Except for the fact that the flat plate with an opening had an opening area of ​​5 cm × 5 cm and a thickness of 0.5 mm, a sheet was manufactured in the same manner as in [Production of a sheet containing a cellulose acetate-caprolactone polymer composition] and used as a sample for transparency evaluation. Haze (HZ) (%) and total light transmittance (TT) (%) were measured using a haze meter (Nippon Denshoku Industries Co., Ltd. haze meter NDH4000). The measured values ​​were the average of three measurements with different measurement values.

[0121] (Amount of elution in water at 95°C) Except for the fact that the flat plate with an opening had an opening area of ​​10 cm × 10 cm and a thickness of 1 mm, the sheet was manufactured in the same manner as in [Production of a sheet containing a cellulose acetate-caprolactone polymer composition], and this was used as a sample for the elution test. The amount eluted in water at 95°C was measured based on the elution conditions for synthetic resin utensils or containers / packaging other than those specified in the individual standards of the Food Sanitation Law, Standards and Specifications for Foods, Additives, etc. (Ministry of Health and Welfare Notification No. 370 of 1959) (Last revised: Ministry of Health, Labour and Welfare Notification No. 380 of 2020), which specify usage temperature of 100°C or less. Sheet surface area 1 cm 2 Using 2 mL of water per sample, measure the amount of potassium permanganate consumed in the solution after immersing the sample in 200 mL of 95°C water for 30 minutes. The unit is expressed as μg / mL.

[0122] (Amount of extract in a 20% ethanol aqueous solution) Except for the fact that the opening area of ​​the flat plate with an opening was 5 cm × 5 cm and the thickness was 0.5 mm, the sheet was manufactured in the same manner as in [Preparation of a sheet containing a cellulose acetate-caprolactone polymer composition], and this was used as a sample for the elution test. The test was conducted in accordance with European Standards Committee Regulation (Eu) No. 10 / 2011 and European Standard EN1186. Surface area of ​​one side of the sample: 1 dm² 2 Measurements were taken by immersing each sample in a 50 mL 20% ethanol aqueous solution at reflux temperature for 1 hour.

[0123] (Degradability in biodegradation tests under compost) Degradability evaluation was conducted under the conditions specified in JIS K 6953 (58°C environment required for OK compost INDUSTRIAL certification).

[0124] (Degradability in marine biodegradation tests) A degradability assessment was conducted under the conditions specified in ISO 22404 (Marine Sediments).

[0125] [Table 1]

[0126] In Table 1, "CA DS" refers to the degree of acetyl substitution (DS) of the dried cellulose diacetate used as a raw material, and "CLM / CA mass ratio" is the ratio (mass ratio) of the mass of caprolactone monomer to the mass of cellulose acetate subjected to the polymerization process.

[0127] [Table 2]

[0128] In Table 2, "Molar Ratio" indicates the molar ratio of caprolactone units to cellulose acetate units in the cellulose acetate-caprolactone polymer composition. "CA" is the mass %) content of cellulose acetate in the cellulose acetate-caprolactone polymer composition. "g-PCL" is the mass %) content of cellulose acetate-caprolactone polymer (graft polymer) in the cellulose acetate-caprolactone polymer composition. "PCL" is the mass %) content of homocaprolactone polymer in the cellulose acetate-caprolactone polymer composition. "CLM" is the mass %) content of caprolactone monomer in the cellulose acetate-caprolactone polymer composition.

[0129] [Table 3]

[0130] In Table 3, "PCL degree of polymerization" is the graft-average degree of polymerization (DPn) of caprolactone in the cellulose acetate-caprolactone polymer. "PCL DS" is the graft-average degree of substitution (DS) of caprolactone. "Ac group DS" is the average degree of substitution (DS) of acetyl groups. "DS (total)" is the sum of the average degree of substitution of acetyl groups and the graft-average degree of substitution of caprolactone. In the composition, "CA" is the proportion (mass%) of cellulose acetate in the cellulose acetate-caprolactone polymer, and "g-PCL" is the proportion (mass%) of polycaprolactone.

[0131] [Table 4]

[0132] [Table 5]

[0133] Table 5 shows the MFR (g / 10min) for Examples 3 and 4 measured under conditions of 220°C / 10.0kg, but the MFR value under conditions of 190°C / 2.16kg was 0g / 10min for all of them.

Claims

1. It comprises a cellulose acetate-caprolactone polymer, a homocaprolactone polymer, a caprolactone monomer, and a catalyst. A cellulose acetate-caprolactone polymer composition in which the total content of the homocaprolactone polymer and the caprolactone monomer is 18% by mass or less.

2. The cellulose acetate-caprolactone polymer composition according to claim 1, wherein the cellulose acetate-caprolactone polymer has a proportion of 70% by mass or more and 95% by mass or less of the portion derived from cellulose acetate, and a proportion of 5% by mass or more and 30% by mass or less of the portion derived from caprolactone.

3. A cellulose acetate-caprolactone polymer composition comprising a cellulose acetate-caprolactone polymer, The cellulose acetate-caprolactone polymer has a proportion of 70% by mass or more and 95% by mass or less of the portion derived from cellulose acetate, and a proportion of 5% by mass or more and 30% by mass or less of the portion derived from caprolactone. A cellulose acetate-caprolactone polymer composition that is substantially free of impurities.

4. The cellulose acetate-caprolactone polymer composition according to claim 1 or 2, wherein the total molar ratio of caprolactone units to the total cellulose acetate units is 1.6 or less.

5. The cellulose acetate-caprolactone polymer composition according to claim 3, wherein the average number of moles (MS) of caprolactone in the cellulose acetate-caprolactone polymer is 1.0 or less.

6. The cellulose acetate-caprolactone polymer composition according to claim 3, wherein the glass transition temperature Tg is 70°C or higher and 170°C or lower.

7. The cellulose acetate-caprolactone polymer composition according to claim 1 or 2, wherein the melt mass flow rate (MFR, 190°C, 2.16 kg) is 0 g / 10 min or more and 30 g / 10 min or less.

8. The cellulose acetate-caprolactone polymer composition according to claim 3, wherein the melt mass flow rate (MFR, 190°C, 2.16 kg) is 0 g / 10 min or more and 20 g / 10 min or less.

9. The cellulose acetate-caprolactone polymer composition according to claim 1 or 2, wherein the catalyst is a phosphoric acid-based catalyst.

10. The cellulose acetate-caprolactone polymer composition according to claim 1 or 2, wherein when the tensile breaking strength of a sheet obtained by hot pressing the cellulose acetate-caprolactone polymer composition at a temperature of 165°C, a pressure of 15 MPa, and a time of 180 seconds is measured in accordance with the tensile test specified in JIS K6251, the tensile breaking strength is 400 MPa or more and 2000 MPa or less.

11. The cellulose acetate-caprolactone polymer composition according to claim 3, wherein when a sheet obtained by hot pressing the cellulose acetate-caprolactone polymer composition at a temperature of 210°C, a pressure of 15 MPa, and a time of 180 seconds is measured for tensile strength in accordance with the tensile test specified in JIS K6251, the tensile strength is 700 MPa or more and 2000 MPa or less.

12. A sheet comprising the cellulose acetate-caprolactone polymer composition according to claim 1 or 2, wherein the haze value after standing for 12 hours at a temperature of 23°C and a relative humidity of 50% RH is 25% or less.

13. A sheet comprising the cellulose acetate-caprolactone polymer composition described in claim 3, wherein the haze value after standing for one month at a temperature of 23°C and a relative humidity of 50% RH is 25% or less.

14. The aforementioned sheet has a thickness of 1 mm and a surface area of ​​1 cm². 2 The sheet according to claim 12, wherein the amount of elution when the sheet is immersed in 2 mL of water per unit and the water temperature is maintained at 95°C for 30 minutes is 10 μg / mL or less.

15. For one side of the aforementioned sheet, the surface area is 1 dm². 2 The amount of extract obtained when immersed in 50 ml of 20% ethanol aqueous solution under reflux temperature conditions for 1 hour was 50 mg / dm 2 The sheet according to claim 12, which is as follows:

16. The process includes a polymerization step in which cellulose acetate and caprolactone monomer are polymerized in a twin-screw extruder in the presence of a catalyst. The ratio of the caprolactone monomer to 1 part by mass of the cellulose acetate is 0.2 parts by mass or more and 0.8 parts by mass or less. A method for producing a cellulose acetate-caprolactone polymer composition, wherein the ratio of the catalyst to 1 part by mass of the cellulose acetate is 0.001 parts by mass or more and 0.10 parts by mass or less.

17. A method for producing a cellulose acetate-caprolactone polymer composition according to claim 16, comprising the steps of: pelletizing the cellulose acetate-caprolactone polymer composition obtained in the polymerization step and washing the pellets obtained; and drying the washed pellets.

18. A method for producing a cellulose acetate-caprolactone polymer composition according to claim 17, wherein the step of washing the pellets is either a method of washing the pellets with water and / or alcohol, or a method of redissolving the pellets in an organic solvent and reprecipitation in a poor solvent.

19. A method for producing a cellulose acetate-caprolactone polymer composition according to claim 16 or 17, wherein the catalyst is a phosphoric acid-based catalyst.

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