JP2019044102A - Cellulose acetate composition for thermoforming and molded product - Google Patents

Abstract

To provide a cellulose acetate composition for thermoforming that has excellent biodegradability and excellent thermoformability.SOLUTION: The cellulose acetate composition for thermoforming contains cellulose acetate having an acetyl substitution degree of 1.4 to 1.8 and a glycerol ester-based plasticizer.SELECTED DRAWING: None

Description

  The present invention relates to a cellulose acetate composition for thermoforming and a molded article.

  The demand for electronic cigarettes that do not use fire has increased in recent years for conventional cigarettes. The types of electronic cigarettes are roughly divided into two types: a solution in which nicotine is dissolved in an organic solvent is heated and the resulting aerosol or gas is drawn, and tobacco leaves (where tobacco leaves are processed tobacco leaves) There is a type which aspirates an aerosol containing nicotine that is heated (not burned) and contains an artificial tobacco leaf such as a substrate impregnated with tobacco components or a tobacco component. However, in Japan, nicotine itself is designated as a pharmaceutical product, and in principle the sale is prohibited, and the handling of nicotine is regulated. In such a case, it is impossible to sell electronic cigarettes of a type in which a solution of nicotine dissolved in an organic solvent is heated to suck up the resulting aerosol or gas. In addition, many countries other than Japan are pharmaceutical products. Note that Philip Morris' iQOS (registered trademark) is a type that uses a dedicated cigarette and sucks an aerosol containing nicotine scattered after heating tobacco leaves.

  As a cigarette used for electronic cigarettes, for example, Patent Document 1 has a structure in which a mouthpiece, an aerosol cooling element, a support element, and an aerosol forming substrate are sequentially arranged from the side close to the mouth, mouse The piece is described to include a cellulose acetate tow filter, a polylactic acid sheet as an aerosol cooling element, a hollow cellulose acetate tube as a support element, and tobacco as an aerosol forming substrate.

  In the type of electronic tobacco that heats tobacco leaves, after smoking is finished, members other than the tobacco leaves of the dedicated cigarette will remain. Therefore, environmental problems may occur due to throwing away the remaining members. In order to cope with this environmental problem, as described above, biodegradable polylactic acid is used as a material in the cooling portion of the cigarette used for the electronic cigarette.

  From the viewpoint of excellent biodegradability, the degree of acetyl substitution of cellulose acetate used in cellulose acetate tow filters and cellulose acetate tubes is generally preferably lower, but processing by thermoforming is easy, and The degree of acetyl substitution is required to a certain extent because the effect on taste is small. And in order to acquire more superior thermoforming processability and physical properties, additives, such as a plasticizer, may be added to cellulose acetate (patent documents 2-5).

Japanese Patent Application Publication No. 2015-503335 Japanese Patent Application Laid-Open No. 7-076632 JP 2002-030182 A International Publication No. 2015/194186 JP, 2015-140432, A

  As described in Patent Document 2, phthalic acid ester is conventionally used as a plasticizer added to cellulose acetate, but phthalic acid ester has a strong irritant odor at the time of heat processing such as thermoforming. In addition, they are suspected of being endocrine disrupters (in other words, environmental hormones), may be harmful to the human body, and may have a large environmental impact. In particular, conventional tobacco filters, electronic cigarette members (members used for the mouth of a cellulose acetate tow filter, etc., members as a cooling element of aerosol, and members as a support element such as a hollow cellulose acetate tube When adding the phthalate ester at the time of processing of the member concerned with smoking including (1), the harmfulness to the human body and the influence on the taste may be concerned.

  Cellulose acetate having an acetyl substitution degree of 1.9 to 2.6 as described in Patent Document 3 and cellulose acetate having a substitution degree of 2.5 as described in Patent Document 4 have excellent biodegradability Do not have

  As described in Patent Document 5, polyethylene glycol may be used as a plasticizer added to cellulose acetate having a degree of acetyl substitution of 0.5 to 1.0. However, in particular, as components of conventional tobacco filters, components of electronic cigarettes (components used for the mouth of cellulose acetate tow filters, etc., components as a cooling element of aerosol, and supporting components such as hollow cellulose acetate tubes) When adding a phthalate ester at the time of processing of the member which concerns on smoking including the member of (1), the influence with respect to a taste is concerned about. When polyethylene glycol is used as a plasticizer added to cellulose acetate having a degree of acetyl substitution of 1.4 to 1.8, the thermoforming property that polyethylene glycol imparts to cellulose acetate is not sufficient. Furthermore, polyethylene glycol has a liquid state at room temperature and low polymerization degree and a solid state at high polymerization degree depending on the difference in polymerization degree, while liquid polyethylene glycol is uniform in cellulose acetate. Although it is preferable in that it is easily dispersed in water, there is a concern that it is easy to bleed out from cellulose acetate and solid polyethylene glycol is difficult to disperse uniformly in cellulose acetate. Thus, polyethylene glycol is not substantially easy to handle cellulose acetate as a plasticizer.

  Although the thermoformability of cellulose acetate could be enhanced by the conventional method of adding a plasticizer, the biodegradability and thermoformability of the obtained cellulose acetate composition were not compatible. An object of the present invention is to provide a thermoforming cellulose acetate composition having excellent biodegradability and excellent thermoformability.

  The first of the present invention relates to a thermoforming cellulose acetate composition containing a cellulose acetate having a degree of acetyl substitution of 1.4 or more and 1.8 or less and a glycerin ester plasticizer.

  In the thermoforming cellulose acetate composition, the glycerin ester plasticizer may be 5 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the total amount of the cellulose acetate and the glycerin ester plasticizer.

  In the thermoforming cellulose acetate composition, the glycerin ester plasticizer may be triacetin.

  The cellulose acetate composition for thermoforming may have an acetyl substitution degree of the cellulose acetate of 1.5 or more and 1.8 or less.

  The second of the present invention relates to a molded article obtained by molding the thermoforming cellulose acetate composition.

  The shaped body may be a film.

  The shaped body may have a hollow cylindrical shape.

  The molded body may be a member for electronic cigarette cigarettes.

  According to the present invention, a thermoforming cellulose acetate composition having excellent biodegradability and excellent thermoformability can be provided.

[Cellulose acetate composition for thermoforming]
The cellulose acetate composition for thermoforming of the present disclosure contains a cellulose acetate having a degree of acetyl substitution of 1.4 or more and 1.8 or less, and a glycerin ester plasticizer.

[Cellulose acetate]
(Acetyl substitution degree)
The cellulose acetate contained in the cellulose acetate composition for thermoforming of the present disclosure has a degree of acetyl substitution of 1.4 or more and 1.8 or less, preferably 1.5 or more and 1.8 or less. .6 or more and 1.8 or less are more preferable. When the degree of acetyl substitution is in this range, not only excellent biodegradability but also excellent thermoforming properties are obtained. Specifically, “excellent thermoforming” means, for example, that the molten state can be adjusted to a range suitable for thermoforming, that is, the viscosity at melting is made a range suitable for thermoforming, and is uniform without any unmelted portion It is possible to melt it. In addition, the thermoforming cellulose acetate composition of the present disclosure also has water resistance necessary when it is used as a member used for a tobacco member, particularly, a mouthpiece of a cellulose acetate tow filter or the like. Here, in the present disclosure, thermoforming refers to exhibiting plasticity that can be deformed by heating and creating a predetermined shape by cooling, and as a method of thermoforming, for example, heat compression molding, melt extrusion molding or the like Injection molding etc. are mentioned.

  On the other hand, the cellulose acetate composition obtained when the degree of acetyl substitution is less than 1.4 is poor in thermoforming property, and also tends to be strong in water solubility and water adsorptivity, and is inferior in durability as a molded product. When used as a tobacco member, particularly as a member used for a mouthpiece of a cellulose acetate tow filter or the like, if the water solubility or the water adsorption property is strong, the taste tends to be adversely affected. In addition, when the degree of acetyl substitution exceeds 1.8, there is a tendency that excellent biodegradability can not be realized.

  The degree of acetyl substitution of cellulose acetate can be measured by a known titration method in which cellulose acetate is dissolved in an appropriate solvent according to the degree of substitution, and the degree of substitution of cellulose acetate is determined. According to the method of Tezuka (Tezuka, Carbonydr. Res. 273, 83 (1995)), the degree of acetyl substitution is converted from hydroxyl groups of cellulose acetate to fully derivatized cellulose acetate propionate (CAP) and then dissolved in heavy chloroform, It can also be measured by NMR.

Furthermore, the degree of acetyl substitution can be determined by converting the degree of acetylation obtained according to the method for measuring the degree of acetylation in ASTM: D-817-91 (test method such as cellulose acetate) according to the following equation. This is the most common way of determining the degree of substitution of cellulose acetate.
DS = 162.14 × AV × 0.01 / (60.052−42.037 × AV × 0.01)
DS: degree of acetyl substitution AV: degree of acetylation (%)

First, 500 mg of dried cellulose acetate (sample) is precisely weighed, dissolved in 50 ml of a mixed solvent of ultrapure water and acetone (volume ratio 4: 1), and 50 ml of 0.2 N aqueous sodium hydroxide solution is added. Saponify at 25 ° C. for 2 hours. Next, 50 ml of 0.2 N hydrochloric acid is added, and the amount of acetic acid released is titrated with 0.2 N aqueous sodium hydroxide solution (0.2 N aqueous sodium hydroxide solution) using phenolphthalein as an indicator. In addition, a blank test (a test without using a sample) is performed by the same method. Then, AV (degree of acetylation) (%) is calculated according to the following equation.
AV (%) = (A-B) x F x 1.201 / sample weight (g)
A: Titrate of 0.2 N sodium hydroxide solution (ml)
B: Titration of 0.2 N sodium hydroxide solution in blank test (ml)
F: Factor of 0.2 N sodium hydroxide solution

  In the present disclosure, the degree of acetyl substitution can be rephrased as the total degree of acetyl substitution, that is, the sum of the average degree of substitution at each of the 2, 3, and 6 positions of the glucose ring of cellulose acetate.

(Composition distribution index (CDI))
The cellulose acetate contained in the cellulose acetate composition for thermoforming of the present disclosure preferably has a composition distribution index (CDI) of 3.0 or less (e.g., 1.0 to 3.0). The composition distribution index (CDI) is preferably smaller in the order of 2.8 or less, 2.0 or less, 1.8 or less, 1.6 or less, and further 1.3 or less. The lower limit value is not particularly limited, but may be 1.0 or more.

  Although the lower limit of the composition distribution index (CDI) is calculated to be 0, this is a special synthesis such as acetylating only the 6th position of the glucose residue with 100% selectivity and not acetylating the other positions, for example. It is realized by technology, and such a synthesis technology is not known. In the situation where all of the hydroxyl groups of glucose residues are acetylated and deacetylated with the same probability, the CDI will be 1.0, but in actual cellulose reactions it will be considerable to approach such an ideal state. It requires a device. In the prior art, much attention has not been paid to control of such compositional distribution.

  Since the cellulose acetate has a small composition distribution index (CDI) and a uniform composition distribution (intermolecular substitution degree distribution), the thermoforming cellulose acetate composition of the present disclosure is more excellent in thermoforming property.

  Here, the composition distribution index (Compositional Distribution Index, CDI) is the ratio of the actually measured value to the theoretical value of the composition distribution half width [(measured value of composition distribution half width) / (theoretical value of composition distribution half width)]. It is defined. The composition distribution half value width is also referred to as “intermolecular substitution degree distribution half value width” or simply “substitution degree distribution half value width”.

  In order to evaluate the uniformity of the degree of acetyl substitution of cellulose acetate, the size of the half width (also referred to as the “half width”) of the maximum peak of the intermolecular substitution degree distribution curve of cellulose acetate can be used as an index. When the degree of acetyl substitution is on the horizontal axis (x axis) and the abundance at this degree of substitution is on the vertical axis (y axis), the half width is the width of the chart at half the peak height of the chart. And is an index that represents a measure of distribution variation. The composition distribution half value width (substitution degree distribution half value width) can be determined by high performance liquid chromatography (HPLC) analysis. In addition, about the method of converting the horizontal axis (elution time) of the elution curve of the cellulose ester in HPLC into substitution degree (0-3), it is demonstrated by Unexamined-Japanese-Patent No. 2003-201301 (Paragraphs 0037-0040).

ｍ：セルロースアセテート１分子中の水酸基とアセチル基の全数
ｐ：セルロースアセテート１分子中の水酸基がアセチル置換されている確率
ｑ＝１−ｐ
ＤＰｗ：重量平均重合度（セルロースアセテートの残存水酸基をすべてプロピオニル化して得られるセルロースアセテートプロピオネートを用いてＧＰＣ−光散乱法により求めた値） (Theoretical value of composition distribution half width)
The composition distribution half-value width (substitution degree distribution half-value width) can be calculated theoretically theoretically. That is, the theoretical value of the composition distribution half value width is determined by the following equation (1).

m: total number of hydroxyl groups and acetyl groups in one cellulose acetate molecule p: probability that hydroxyl groups in one cellulose acetate molecule are acetyl-substituted q = 1-p
DPw: Weight average degree of polymerization (value determined by GPC-light scattering method using cellulose acetate propionate obtained by propionylation of all remaining hydroxyl groups of cellulose acetate)

ＤＳ：アセチル置換度
ＤＰｗ：重量平均重合度（セルロースアセテートの残存水酸基をすべてプロピオニル化して得られるセルロースアセテートプロピオネートを用いてＧＰＣ−光散乱法により求めた値） Furthermore, the theoretical value of the composition distribution half value width is represented by the degree of substitution and the degree of polymerization as follows. The following equation (2) is a definition equation for finding the theoretical value of the composition distribution half width.

DS: degree of acetyl substitution DPw: weight average degree of polymerization (value determined by GPC-light scattering method using cellulose acetate propionate obtained by propionylation of all remaining hydroxyl groups of cellulose acetate)

  By the way, in Formula (1) and Formula (2), the degree of polymerization distribution should be taken into account more strictly, and in this case, “DPw” of Formula (1) and Formula (2) is the degree of polymerization It should be replaced by the distribution function and the whole equation should be integrated from 0 degree of polymerization to infinity. However, as long as DPw is used, equations (1) and (2) give theoretical values of approximately sufficient accuracy. If DPn (number average degree of polymerization) is used, DPw should be used because the effect of the degree of polymerization distribution can not be ignored.

(Measured value of composition distribution half width)
In the present disclosure, the actual value of the composition distribution half width is the composition distribution half value width obtained by HPLC analysis of cellulose acetate propionate obtained by propionylation of all remaining hydroxyl groups (unsubstituted hydroxyl groups) of cellulose acetate (sample). It is.

  In general, high performance liquid chromatography (HPLC) analysis can be performed on cellulose acetate having an acetyl substitution degree of 2 to 3 without pretreatment, whereby the composition distribution half value width can be determined. For example, Japanese Patent Application Laid-Open No. 2011-158664 describes a composition distribution analysis method for cellulose acetate having a substitution degree of 2.27 to 2.56.

  On the other hand, the actual measurement value of the composition distribution half value width (substitution degree distribution half value width) is determined by conducting derivatization of the residual hydroxyl group in the cellulose acetate as pretreatment before HPLC analysis and thereafter performing HPLC analysis. The purpose of this pretreatment is to convert cellulose acetate having a low degree of substitution into a derivative that is easily soluble in organic solvents so that it can be analyzed by HPLC. That is, the residual hydroxyl group in the molecule is completely propionylated, and the fully derivatized cellulose acetate propionate (CAP) is subjected to HPLC analysis to determine the composition distribution half value width (measured value). Here, the derivatization is completely carried out, there are no residual hydroxyl groups in the molecule, and only acetyl and propionyl groups must be present. That is, the sum of the degree of acetyl substitution (DSac) and the degree of propionyl substitution (DSpr) is 3. This is because the relationship: DSac + DSpr = 3 is used to generate a calibration curve for converting the horizontal axis (elution time) of the HPLC elution curve of CAP to the degree of acetyl substitution (0 to 3).

  Fully derivatization of cellulose acetate can be carried out by reacting N, N-dimethylaminopyridine as a catalyst with propionic anhydride in pyridine / N, N-dimethylacetamide mixed solvent. More specifically, 20 parts by weight of a mixed solvent [pyridine / N, N-dimethylacetamide = 1/1 (v / v)] as a solvent to cellulose acetate (sample) and propionic anhydride as a propionylating agent 6.0 to 7.5 equivalents to the hydroxyl group of the cellulose acetate, and 6.5 to 8.0 mol% of N, N-dimethylaminopyridine as a catalyst to the hydroxyl group of the cellulose acetate, at a temperature of 100 ° C. Propionylation is carried out under the conditions of a reaction time of 1.5 to 3.0 hours. Then, after the reaction, precipitation is performed using methanol as a precipitation solvent to obtain a fully derivatized cellulose acetate propionate. More specifically, for example, 1 part by weight of the reaction mixture is precipitated in 10 parts by weight of methanol at room temperature, and the resulting precipitate is washed 5 times with methanol and vacuum dried at 60 ° C. for 3 hours. Thus, fully derivatized cellulose acetate propionate (CAP) can be obtained. The weight average degree of polymerization (DPw) is also measured by using cellulose acetate (sample) as fully derivatized cellulose acetate propionate (CAP) by this method.

  In the above-mentioned HPLC analysis, using a plurality of cellulose acetate propionates having different degrees of acetyl substitution as standard samples, HPLC analysis is performed under a predetermined measuring device and measurement conditions, and calibration is performed using the analytical values of these standard samples Determine the composition distribution half width (measured value) of cellulose acetate (sample) from the curve [curve showing relationship between elution time of cellulose acetate propionate and degree of acetyl substitution (0 to 3), usually cubic curve] Can. What is determined by HPLC analysis is the relationship between the elution time and the acetyl substitution degree distribution of cellulose acetate propionate. This is the relationship between the elution time of the substance in which all of the remaining hydroxy groups in the sample molecule have been converted to propionyloxy groups and the acetyl substitution degree distribution, so that the acetyl substitution degree distribution of the cellulose acetate of the present disclosure is determined It is essentially the same.

The conditions for the above HPLC analysis are as follows.
Equipment: Agilent 1100 Series
Column: Waters Nova-Pak phenyl 60 Å 4 μm (150 mm × 3.9 mm +) + guard column Column temperature: 30 ° C
Detection: Varian 380-LC
Injection volume: 5.0 μL (sample concentration: 0.1% (wt / vol))
Eluent: Liquid A: MeOH / H ₂ O = 8/1 (v / v), Liquid B: CHCl ₃ ^/ MeOH = 8/1 (v / v)
Gradient: A / B = 80/20 → 0/100 (28 min); Flow rate: 0.7 mL / min

  Degree of substitution distribution curve [a degree of substitution of cellulose acetate propionate, with the amount of cellulose acetate propionate as the ordinate and the degree of acetyl substitution as the abscissa, obtained from the calibration curve] In addition, regarding the maximum peak (E) corresponding to the average degree of substitution, the substitution degree distribution half value width is determined as follows. Draw a baseline (A-B) in contact with the base (A) on the low substitution degree side of peak (E) and the base (B) on the high substitution degree side, and from this maximum line (E) Draw a vertical line on the horizontal axis. The point of intersection (C) between the perpendicular and the baseline (A-B) is determined, and the midpoint (D) between the maximum peak (E) and the point of intersection (C) is determined. A straight line parallel to the baseline (A-B) is drawn through the middle point (D) to determine two intersection points (A ', B') with the intermolecular substitution degree distribution curve. A vertical line is drawn from the two intersection points (A ', B') to the horizontal axis, and the width between the two intersection points on the horizontal axis is taken as the half width of the maximum peak (i.e., the substitution degree distribution half width).

The half-value width of such substitution degree distribution is a retention time depending on the degree to which the hydroxyl group of one glucose ring of the polymer chain constituting the molecular chain of cellulose acetate propionate in the sample is acetylated. It reflects that the (retention time) is different. Therefore, ideally, the width of the retention time indicates the width of the composition distribution (in degree of substitution). However, in HPLC, there are tubes that do not contribute to the distribution (such as a guide column for protecting the column). Therefore, due to the configuration of the measuring apparatus, the width of the holding time not attributed to the width of the composition distribution is often included as an error. As described above, this error is influenced by the length and inner diameter of the column, the length from the column to the detector, and the like, and varies depending on the apparatus configuration. Therefore, the half value width of the degree of substitution distribution of cellulose acetate propionate can be usually determined as the correction value Z based on the correction equation represented by the following equation. By using such a correction formula, it is possible to obtain a more accurate substitution degree distribution half value width (actually measured value) as the same (approximately the same) value even if the measuring apparatus (and the measuring conditions) are different.
^{Z = (X 2 -Y 2)} 1/2
[Wherein, X is a substitution degree distribution half value width (uncorrected value) determined on a predetermined measuring device and measuring conditions. Y = (a−b) x / 3 + b (0 ≦ x ≦ 3). Here, a is an apparent substitution degree distribution half value width of cellulose acetate having a substitution degree of 3 determined under the same measurement apparatus and measurement conditions as the X (in fact, there is no substitution degree distribution because the substitution degree is 3), b is the X The apparent substitution degree distribution half value width of cellulose propionate having a substitution degree of 3 determined under the same measurement device and measurement conditions as in 1. above. x is the degree of acetyl substitution (0 ≦ x ≦ 3) of the measurement sample

  The cellulose acetate (or cellulose propionate) having a degree of substitution of 3 means a cellulose ester in which all of the hydroxyl groups of the cellulose are esterified, and in fact (ideally) the half value width of the degree of substitution distribution It is a cellulose ester which does not have (ie, it has a substitution degree distribution half width of 0).

  The theoretical distribution of degree of substitution described above is a probabilistic calculation value assuming that all acetylation and deacetylation proceed independently and equally. That is, it is a calculated value according to the binomial distribution. Such an ideal situation is practically impossible. The distribution of degree of substitution of cellulose ester is a probability unless the hydrolysis reaction of cellulose acetate approaches an ideal random reaction and / or special arrangements are made such that a fraction of the composition is generated for post treatment after reaction It is much wider than what is theoretically determined by the binomial distribution.

  One of the special ideas of the reaction is, for example, to maintain the system under conditions in which deacetylation and acetylation are in equilibrium. However, in this case, it is not preferable because decomposition of cellulose proceeds by the acid catalyst. Another special idea of the reaction is to adopt reaction conditions in which the deacetylation rate is low for low-substituted products. However, conventionally, such a specific method is not known. That is, no special device for the reaction is known which controls the substitution degree distribution of the cellulose ester according to the binomial distribution according to the reaction probability theory. Furthermore, various circumstances such as generation of partial and temporary precipitation with water added stepwise in the aging process (hydrolysis process of cellulose acetate) and the heterogeneity of the acetylation process (acetylation process of cellulose) Acts to make the substitution degree distribution wider than the binomial distribution, and it is practically impossible to avoid these all and to realize the ideal condition. This is similar to the fact that the ideal gas is the product of the ideal, and the behavior of the existing gas is more or less different from that.

  In the conventional synthesis and post-treatment of cellulose acetate with a low degree of substitution, little attention has been paid to the problem of such a degree of substitution, and the measurement, verification and consideration of the degree of substitution have not been made. For example, according to the literature (Fiberl Society Journal, 42, p 25 (1986)), it is argued that the solubility of cellulose acetate with a low degree of substitution is determined by the distribution of acetyl groups to glucose residues 2, 3 and 6 Composition distribution is not considered at all.

  According to the present disclosure, as described later, the substitution degree distribution of cellulose acetate can be surprisingly controlled by devising post-treatment conditions after the cellulose acetate hydrolysis step. Literature (CiBment, L., and Rivibre, C., Bull. SOC. Chim., (5) 1, 1075 (1934), Sookne, AM, Rutherford, HA, Mark, H., and Harris, M. J. According to Research Natl. Bur. Standards, 29, 123 (1942), AJ Rosenthal, BB White Ind. Eng. Chem., 1952, 44 (11), pp 2693-2696.), Cellulose having a degree of substitution of 2.3 In the precipitation fractionation of acetate, it is believed that molecular weight-dependent fractionation and slight fractionation associated with the degree of substitution (chemical composition) occur, and significant fractionation can be obtained with the degree of substitution (chemical composition) as described in the present disclosure. There is no report with. Furthermore, for cellulose acetate having a low degree of substitution as disclosed in the present disclosure, it has not been verified that the distribution of substitution degree (chemical composition) can be controlled by dissolution fractionation or precipitation fractionation.

  Another device for narrowing the degree of substitution distribution found by the present inventors is a hydrolysis reaction (aging reaction) of cellulose acetate at a temperature of 90 ° C. or higher (or higher than 90 ° C.). Although decomposition and analysis of the degree of polymerization of the product obtained by the high temperature reaction have not been made in the past, decomposition of cellulose has been given priority in high temperature reactions of 90 ° C. or higher. This idea can be said to be a stereotype based solely on viscosity considerations. When hydrolyzing cellulose acetate to obtain cellulose acetate having a low degree of substitution, the inventors of the present invention obtain a large amount of acetic acid under high temperature of 90 ° C. or higher (or over 90 ° C.), preferably in the presence of a strong acid such as sulfuric acid. It was found that when the reaction is carried out in the medium, the decrease in the degree of polymerization is not observed, while the viscosity decreases with the decrease in CDI. That is, it was clarified that the viscosity decrease due to the high temperature reaction was not due to the decrease of the degree of polymerization but the decrease of the structural viscosity due to the narrowing of the degree of substitution distribution. When hydrolysis of cellulose acetate is performed under the above conditions, not only forward reaction but also reverse reaction occurs, the CDI of the product (cellulose acetate having a low degree of substitution) becomes an extremely small value, and the cellulose acetate for thermal forming of the present disclosure When the composition is formed, the molten state is stable (in other words, the viscosity at the time of melting can be made into a range suitable for thermoforming and can be uniformly melted without unmelted portions), and the particularly excellent thermoformability is realizable. On the other hand, when cellulose acetate is hydrolyzed under conditions where reverse reaction does not easily occur, the degree of substitution distribution becomes wide due to various factors, and when the composition for thermal molding cellulose acetate of the present disclosure is formed, the molten state is It is difficult to be stable, that is, portions that do not melt may remain, and good thermoformability may not be obtained.

(Weight average degree of polymerization (DPw))
The weight average degree of polymerization (DPw) is a value determined by GPC-light scattering method using cellulose acetate propionate obtained by propionylation of all remaining hydroxyl groups of cellulose acetate (sample).

  It is preferable that the weight average polymerization degree (DPw) of the cellulose acetate of this indication is the range of 100-1000. If the weight average degree of polymerization (DPw) is too low, the thermoformability tends to be inferior. When the weight average degree of polymerization (DPw) is too high, the biodegradability tends to be poor. The weight average polymerization degree (DPw) is preferably 100 to 800, more preferably 200 to 700.

  The above weight average degree of polymerization (DPw) is the same as in the case of obtaining the actual measurement value of the composition distribution half width, and after making cellulose acetate (sample) into fully derivatized cellulose acetate propionate (CAP), size exclusion It is determined by performing chromatographic analysis (GPC-light scattering method).

  As described above, the polymerization degree (molecular weight) of cellulose acetate is measured by GPC-light scattering method (GPC-MALLS, GPC-LALLS, etc.). Since cellulose acetate changes its solubility in solvents according to the degree of substitution, when measuring the degree of polymerization of a wide range of degrees of substitution, it may have to be measured and compared in different solvent systems. One of the effective methods to avoid is to derivatize the cellulose acetate so that it dissolves in the same organic solvent and perform GPC-light scattering measurements with the same organic solvent. Propionylation is effective as a derivatization of cellulose acetate for this purpose, and specific reaction conditions and post treatments are as described in the explanation of the measured values of the composition distribution half value width.

(Molecular weight distribution Mw / Mn)
The molecular weight distribution (molecular weight distribution Mw / Mn obtained by dividing the weight average molecular weight Mw by the number average molecular weight Mn) of the cellulose acetate of the present disclosure is preferably 3.0 or less 2.0 or more, and 2.5 or less 2.0 or more Is more preferably 2.4 or less and 2.0 or more. When it is set as a molded object as it is more than 3.0 or less than 2.0, the stability of the molding process (for example, the dimensional stability of the molded product and the physical stability such as strength etc.) Specifically, for example, unnecessary unevenness is not easily generated on the surface of the molded product; holes are not easily generated inside the molded product; variation in mechanical strength of the entire molded product is small; deformation in a short time immediately after molding It is difficult to cause problems). When the molecular weight distribution of cellulose acetate is 3.0 or less and 2.0 or more, good thermoforming processability can be realized.

The number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of cellulose acetate can be determined by a known method using HPLC. In the present disclosure, in order to make the measurement sample soluble in an organic solvent, the molecular weight distribution (Mw / Mn) of cellulose acetate is cellulose acetate (sample) in the same manner as in the case of obtaining the measured value of the composition distribution half width. Is a fully derivatized cellulose acetate propionate (CAP), and then determined by performing size exclusion chromatography analysis under the following conditions (GPC-light scattering method).
Device: GPC "SYSTEM-21H" manufactured by Shodex
Solvent: acetone Column: GMHxl (Tosoh) 2 pieces, same guard column Flow rate: 0.8 ml / min
Temperature: 29 ° C
Sample concentration: 0.25% (wt / vol)
Injection volume: 100 μl
Detection: MALLS (multi-angle light scattering detector) (Wyatt, "DAWN-EOS")
Reference material for MALLS correction: PMMA (molecular weight 27600)

From the weight average molecular weight and the number average molecular weight obtained by the measurement results, the molecular weight distribution can be calculated according to the following formula.
Molecular weight distribution = Mw / Mn
Mw: weight average molecular weight, Mn: number average molecular weight

[Glycerin ester plasticizer]
As a glycerol ester plasticizer which the cellulose acetate composition for thermoforming of this indication contains, the lower fatty acid ester of glycerol, in other words, the ester compound of glycerol and a C2-C4 fatty acid can be used. The C2 fatty acid is acetic acid, the C3 fatty acid is propionic acid, and the C4 fatty acid is butyric acid. The glycerin ester plasticizer of the present disclosure may be one in which all three hydroxyl groups of glycerin are esterified with the same fatty acid, or two hydroxyl groups may be esterified with the same fatty acid, glycerin All three hydroxyl groups of may be esterified with different fatty acids.

  The glycerin ester plasticizer of the present disclosure has a low environmental impact because it is easily biodegradable. Further, by adding to the cellulose acetate of the present disclosure, the glass transition temperature of the obtained thermoforming cellulose triacetate composition can be lowered, so that it can be easily melted uniformly without heating without heating. It is also possible to impart excellent thermoformability to cellulose acetate.

  Among the above-mentioned glycerol ester plasticizers, triacetin (glycerol tris acetate) in which all three hydroxyl groups of glycerol are acetylated by acetic acid is particularly preferable. Triacetin is a component regarded as safe for human consumption, and has a low environmental impact because it is easily biodegradable. Moreover, the cellulose acetate composition for thermoforming obtained by adding triacetin to the cellulose acetate of this indication improves biodegradability more than the case of cellulose acetate single-piece | unit. Furthermore, by adding triacetin to the cellulose acetate of the present disclosure, the glass transition temperature of cellulose acetate can be efficiently reduced, and excellent thermoforming can be imparted.

  And, as described above, triacetin is safe for human consumption and can impart excellent thermoformability to cellulose acetate, so it can be used as a capsule material for drug delivery used in so-called drug delivery systems. It can be used. Furthermore, by adding triacetin to cellulose acetate, there is no risk of impairing the taste of tobacco even when the resulting thermoforming cellulose acetate composition is used as a tobacco member.

  In addition to triacetin, which is composed only of triacetin which is chemically structurally pure, triacetin purity is preferably high, but may be, for example, 80% by weight or more and 90% by weight or more. The remainder may contain monoacetin and / or diacetin.

  The glycerin ester plasticizer contained in the cellulose acetate composition for thermoforming of the present disclosure is preferably 2 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight in total of the cellulose acetate and the glycerol ester plasticizer. More preferably, it is in the range of 10 to 30 parts by weight, and most preferably in the range of 10 to 25 parts by weight. If the amount is less than 2 parts by weight, thermoformability can not be sufficiently imparted to the cellulose acetate, and if it exceeds 40 parts by weight, the possibility of bleeding out of the glycerin ester plasticizer is increased.

[Production of cellulose acetate composition for thermoforming]
The cellulose acetate composition for thermoforming of the present disclosure can be produced by adding a glycerin ester plasticizer to a cellulose acetate having an acetyl substitution degree of 1.4 or more and 1.8 or less. And, cellulose acetate is produced, for example, by hydrolysis process (aging process) of (A) medium to high degree of substitution cellulose acetate, (B) precipitation process, and (C) washing and neutralization process which are performed if necessary. it can.

((A) Hydrolysis process (aging process))
In this step, medium to high substitution degree cellulose acetate (hereinafter sometimes referred to as "raw material cellulose acetate") is hydrolyzed. The degree of acetyl substitution of the medium to high degree of substitution cellulose acetate used as a raw material is, for example, 1.5 to 3, preferably 2 to 3. As raw material cellulose acetate, commercially available cellulose diacetate (acetyl substitution degree 2.27 to 2.56) and cellulose triacetate (acetyl substitution degree more than 2.56 to 3) can be used.

  The hydrolysis reaction can be carried out by reacting the raw material cellulose acetate with water in the presence of a catalyst (aging catalyst) in an organic solvent. As an organic solvent, an acetic acid, acetone, alcohol (methanol etc.), these mixed solvents etc. are mentioned, for example. Among these, a solvent containing at least acetic acid is preferable. As a catalyst, a catalyst generally used as a deacetylation catalyst can be used. As a catalyst, sulfuric acid is particularly preferred.

  The amount of the organic solvent (for example, acetic acid) used is, for example, 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, and more preferably 3 to 10 parts by weight with respect to 1 part by weight of the raw material cellulose acetate. .

  The amount of the catalyst (for example, sulfuric acid) used is, for example, 0.005 to 1 part by weight, preferably 0.01 to 0.5 parts by weight, and more preferably 0.02 to 1 part by weight with respect to 1 part by weight of the raw material cellulose acetate. It is 0.3 parts by weight. If the amount of catalyst is too low, the hydrolysis time may be too long, which may cause a decrease in the degree of polymerization (molecular weight) of cellulose acetate. On the other hand, when the amount of the catalyst is too large, the degree of change in depolymerization rate with respect to the hydrolysis temperature becomes large, and the depolymerization rate becomes large even if the hydrolysis temperature is low to some extent, and cellulose acetate having a large degree of polymerization (molecular weight) Is difficult to obtain.

  The amount of water in the hydrolysis step is, for example, 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, and more preferably 2 to 7 parts by weight with respect to 1 part by weight of the raw material cellulose acetate. The amount of water is, for example, 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, and more preferably 0.5 to 1 parts by weight with respect to 1 part by weight of the organic solvent (for example, acetic acid). .5 parts by weight. Although water may be present in the system in all amounts at the start of the reaction, part of the water used is allowed to be present in the system at the start of the reaction to prevent the precipitation of cellulose acetate, and the remaining water is You may divide into 1 or several times and may add in the system.

  The reaction temperature in the hydrolysis step is, for example, 40 to 130 ° C, preferably 50 to 120 ° C, and more preferably 60 to 110 ° C. In particular, when the reaction temperature is 90 ° C. or higher (or a temperature higher than 90 ° C.), the reaction equilibrium tends to be inclined to increase the rate of the reverse reaction (acetylation reaction) to the forward reaction (hydrolysis reaction) As a result, the degree of substitution distribution becomes narrow, and it is possible to obtain a cellulose acetate having a very low degree of substitution and a low degree of substitution, even if the post-treatment conditions are not particularly devised. In this case, it is preferable to use a strong acid such as sulfuric acid as a catalyst, and it is preferable to use an excess of acetic acid as a reaction solvent. Even when the reaction temperature is 90 ° C. or less, as described later, in the precipitation step, precipitation may be performed using a mixed solvent containing two or more solvents as a precipitation solvent, or precipitation fractionation and / or dissolution By performing fractionation, cellulose acetate with a low degree of substitution and very low composition distribution index CDI can be obtained.

((B) Precipitation process)
In this step, after completion of the hydrolysis reaction, the temperature of the reaction system is cooled to room temperature, and a precipitation solvent is added to precipitate cellulose acetate having a low degree of substitution. As a precipitation solvent, an organic solvent miscible with water or an organic solvent having high solubility in water can be used. For example, ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol and isopropyl alcohol; esters such as ethyl acetate; nitrogen-containing compounds such as acetonitrile; ethers such as tetrahydrofuran; and mixed solvents thereof.

  When a mixed solvent containing two or more solvents is used as a precipitation solvent, the same effect as precipitation fractionation described later is obtained, the composition distribution (intermolecular substitution degree distribution) is narrow, and the composition distribution index (CDI) is small, substitution Cellulose acetate of low degree can be obtained. As a preferable mixed solvent, for example, a mixed solvent of acetone and methanol, a mixed solvent of isopropyl alcohol and methanol, and the like can be mentioned.

  In addition, the cellulose acetate having a low degree of substitution obtained by precipitation is further subjected to precipitation fractionation (fractional precipitation) and / or dissolution fractionation (fractional dissolution) to narrow the composition distribution (intermolecular substitution degree distribution). It is possible to obtain a cellulose acetate having a low degree of substitution, which has a very low composition distribution index CDI.

  In precipitation fractionation, for example, cellulose acetate (solid matter) having a low degree of substitution obtained by precipitation is dissolved in water or a mixed solvent of water and a hydrophilic solvent (for example, acetone), and the appropriate concentration (for example, 2 to 10) (3% to 8% by weight) is added to the aqueous solution, a poor solvent is added to the aqueous solution (or the aqueous solution is added to the poor solvent), and a suitable temperature (eg, 30 ° C. or less, preferably 20) The reaction can be carried out by precipitating cellulose acetate having a low degree of substitution while maintaining the temperature below .degree. C. and recovering the precipitate. Examples of the poor solvent include alcohols such as methanol, and ketones such as acetone. The amount of the poor solvent used is, for example, 1 to 10 parts by weight, preferably 2 to 7 parts by weight, per 1 part by weight of the aqueous solution.

  The dissolution fractionation may be carried out, for example, by using a cellulose acetate (solid) having a low degree of substitution obtained by the precipitation or a cellulose acetate (solid) having a low degree of substitution obtained by the precipitation fractionation, water and an organic solvent (eg, A mixed solvent of ketones such as acetone, alcohols such as ethanol, etc.) is added, stirred at an appropriate temperature (eg, 20 to 80 ° C., preferably 25 to 60 ° C.) and centrifuged to separate into a thick phase and a thin phase It is possible to add a precipitation solvent (for example, a ketone such as acetone, an alcohol such as methanol, etc.) to the dilute phase and recover the precipitate (solid). The concentration of the organic solvent in the mixed solvent of water and the organic solvent is, for example, 5 to 50% by weight, preferably 10 to 40% by weight.

((C) Washing, neutralization process)
The precipitate (solid) obtained in the precipitation step (B) is preferably washed with an organic solvent (poor solvent) such as an alcohol such as methanol or a ketone such as acetone. It is also preferable to wash and neutralize with an organic solvent containing a basic substance (for example, an alcohol such as methanol, a ketone such as acetone, etc.). Impurities such as a catalyst (such as sulfuric acid) used in the hydrolysis step can be efficiently removed by washing and neutralization.

  Examples of the basic substance include alkali metal compounds (for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal carbonates such as sodium hydrogencarbonate) Hydrogen salts; alkali metal carboxylates such as sodium acetate and potassium acetate; sodium alkoxides such as sodium methoxide and sodium ethoxide; alkaline earth metal compounds (for example, alkaline earths such as magnesium hydroxide and calcium hydroxide) Alkaline earth metal carbonates such as metal hydroxides, magnesium carbonate and calcium carbonate; alkaline earth metal carboxylates such as magnesium acetate and calcium acetate; alkaline earth metal alkoxides such as magnesium ethoxide etc. . Among these, alkali metal compounds such as potassium acetate are particularly preferable.

(Addition of glycerin ester plasticizer)
When a glycerol ester plasticizer is added to the obtained cellulose acetate, it is preferable to mix the cellulose acetate and the glycerol ester plasticizer, and the mixing may be carried out using a mixer such as a planetary mill, Henschel mixer, vibration mill, ball mill, etc. It can be carried out. It is preferable to use a Henschel mixer because homogeneous mixing and dispersion can be performed in a short time. Further, the degree of mixing is not particularly limited, but, for example, in the case of a Henschel mixer, mixing is preferably performed for 10 minutes to 1 hour.

  Furthermore, drying can be carried out after mixing of the cellulose acetate and the glycerin ester plasticizer. As a drying method, the method of leaving still for 1 to 48 hours and drying under 50-105 degreeC is mentioned, for example.

  In addition, as a method of adding a glycerol ester plasticizer to the obtained cellulose acetate, a method of dissolving the cellulose acetate and the glycerol ester plasticizer in a common good solvent, uniformly mixing and then evaporating the solvent may be used. Examples of common good solvents include mixed solvents of methylene chloride / methanol (weight ratio 9: 1).

  At the time of mixing the cellulose acetate and the glycerol ester plasticizer, a coloring agent, a heat-resistant stabilizer, an antioxidant, an ultraviolet light absorber and the like can be added according to the use and specification of the molded article.

[Molded body]
The molded article of the present disclosure is formed by molding the above-mentioned cellulose acetate composition for thermoforming. The shape of the molded product is not particularly limited, and examples thereof include one-dimensional molded products such as fibers; two-dimensional molded products such as films; and three-dimensional molded products such as pellets, tubes and hollow cylinders. Be

  When producing a one-dimensional shaped article such as a fiber, it can be obtained by spinning the thermoforming cellulose acetate composition of the present disclosure, and examples of the spinning method include melt spinning (including melt blow spinning method). Be

  For example, the thermoforming cellulose acetate composition (pellets etc.) is heated and melted in a known melt extrusion spinning machine, and then spun from a spinneret, and the spun continuous long fiber filament group is subjected to high-speed high-pressure air by an ejector. A fibrous cellulose acetate composite molded article can be obtained by stretching and winding, or by opening it and collecting it on the surface of a support for collection to form a web. In addition, the thermoforming cellulose acetate composition melted by an extruder is blown out in a filamentous manner by a high-temperature, high-speed air stream, for example, from a die having several hundreds to several thousands of nozzles per 1 m in the width direction. A nonwoven fabric can be manufactured by accumulating the collected resin on a conveyor and causing entanglement and fusion of fibers between them (melt blow spinning method). The spinning temperature during melt spinning is, for example, 130 to 240 ° C., preferably 140 to 200 ° C., and more preferably 150 to 188 ° C. When the spinning temperature is too high, the coloration of the molded article becomes remarkable. On the other hand, if the spinning temperature is too low, the viscosity of the composition becomes low, making it difficult to increase the spinning draft ratio, and the productivity tends to be reduced. The spinning draft ratio is, for example, about 200 to 600.

  The fineness of the yarn obtained by the melt spinning method is, for example, 1 to 9 denier (d), preferably 1.3 to 5 denier (d). The strength of the yarn is, for example, about 0.3 to 1.5 g / d.

  In particular, when used as a cellulose acetate tow filter for cigarettes used in electronic cigarettes, the fineness is 1 to 40 denier (d), 3 to 30 denier (d), 5 to 30 denier (d), 8 to 25 denier (d) ), 10 to 20 denier (d). Unlike conventional cigarettes, electronic cigarettes do not burn, so there is no need to remove by-products resulting from combustion, and the filtration performance (properties) of the cellulose acetate tow filter of cigarettes used for electronic cigarettes is the same as conventional cigarettes. This is because the filter may be much lower than the filter used for tobacco. The production of a hollow cellulose acetate tube of a cigarette used for an electronic cigarette from a tow takes time in the production process including forming into a hollow shape, and is also involved in an increase in production cost. There is also a method of increasing the denier of the tow fiber (making the fiber thicker) in order to realize the low filterability of the filter, but there are industrial limits on the production of thick denier tow fibers. As it is difficult for a tow to meet the demand for further low filterability filters for electronic cigarettes in the future, it may be formed as a three-dimensional molded body as described later.

  Next, when manufacturing a two-dimensional molded article such as a film, a melt film forming method can be adopted. Examples of the melt film-forming method include extrusion molding and blow molding. With regard to extrusion molding, specifically, for example, the thermoforming cellulose acetate composition of the present disclosure is melt-kneaded by an extruder such as a single- or twin-screw extruder, and extruded from a slit of a die into a film and cooled By doing this, a film or sheet can be produced.

  The thickness of the film obtained by the melt film-forming method is, for example, 1 μm to 1000 μm, preferably 5 μm to 500 μm, and more preferably 10 μm to 250 μm. In particular, when used as a cooling element of a cigarette used for electronic cigarette, the thickness of the film may be 15 μm to 200 μm, 20 to 150, 25 to 100, 35 to 70 μm. Electronic cigarettes deliver less to the smoker (people who smoke electronic cigarettes) without loss as much as possible because the amount of nicotine scattered by heating tobacco leaves is small compared to conventional cigarettes There is a need to. Moreover, in the type which heats a tobacco leaf, although nicotine is contained in the droplet in an aerosol, since this droplet is high temperature to aspirate, it is necessary to cool it beforehand. In order to satisfy these requirements, the thickness of the film may be in the above range.

  Furthermore, when manufacturing a three-dimensional molded object, such as a hollow cylindrical shape, it can manufacture by thermoforming. Specifically, for example, a desired three-dimensional molded article including a hollow cylindrical shape is obtained by subjecting the thermoformable cellulose acetate composition of the present disclosure in pellet form to heat compression molding, melt extrusion molding, and injection molding. It can be manufactured. As an apparatus, for example, an injection molding machine Micro-1 manufactured by Meiho Co., Ltd., a heating and compression molding machine ML-48 for molding FRP test pieces of Maruto Seisakusho, and the like can be used. The heating temperature at the time of molding may be between 240 and 180 ° C., and the amount of the additive containing a glycerin ester plasticizer may be appropriately adjusted.

  The method of pelletizing the thermoforming cellulose acetate composition of the present disclosure is not particularly limited. For example, first, the cellulose acetate and glycerin ester plasticizer of the present disclosure may be used as a tumbler mixer, Henschel mixer, ribbon mixer, kneader And the like, and then prepared by preparing them in the form of pellets by melt-kneading with an extruder such as a single- or twin-screw extruder.

  A specific method for forming a three-dimensional molded body by melt extrusion from the pellet-like thermoformable cellulose acetate composition of the present disclosure is not particularly limited. For example, injection molding, extrusion molding, vacuum molding, profile molding Foam molding, injection press, press molding, blow molding, gas injection molding, etc. can be used.

  As described above, in addition to the method of obtaining pellets by melt-kneading the cellulose acetate and glycerin ester plasticizer of the present disclosure with an extruder to obtain pellets, the glycerin ester plasticizer is applied to the surface of cellulose acetate flakes. The deposited material can be heated and compression molded to produce a desired three-dimensional molded article including a hollow cylindrical shape. Compression molding is performed using a commercially available compression molding machine at a temperature of 150 ° C. to 240 ° C., preferably 230 ° C., a pressure of 0.01 MPa or more, preferably 0.5 MPa, preferably for 30 seconds or more, preferably about 2 minutes. Just do it. The cellulose ester flakes refer to flaky cellulose esters obtained by acetylating cellulose and then performing a hydrolysis reaction to adjust the average degree of substitution, and purifying and drying.

  The hollow cylindrical three-dimensional molded body may be used as it is as a hollow cellulose acetate tube of a cigarette used for an electronic cigarette, or it may be cut out perpendicularly to the axial direction, It may be a long member before cutting from which a hollow cellulose acetate tube of a cigarette used for electronic cigarette can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the scope of the present invention is not limited by these examples.

  Each physical property as described in the Example and comparative example which are mentioned later was evaluated by the following methods.

<Acetyl substitution degree, weight average molecular weight (Mw), number average molecular weight (Mn), and composition distribution index CDI>
The degree of acetyl substitution, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the composition distribution index CDI were determined by the methods described above.

<Thermal formability evaluation>
Thermoforming evaluation was performed by measuring the glass transition temperature. Nitrogen atmosphere, 1st heat: 30 ° C to 200 ° C, 2nd heat: 30 ° C to 250 ° C using a differential scanning calorimeter (DSC) (differential scanning calorimeter DSC Q2000 manufactured by TA Instruments Co., Ltd.) A DSC curve was drawn under the conditions of a temperature range and a temperature rising rate of 20 ° C./min. The temperature (mid-point glass transition temperature) at the point where the straight line equidistant from the extended straight line of the baseline before and after the glass transition of this DSC curve and the curve of the step change portion of the glass transition intersects the glass The transition temperature was Tg (° C.).

<Biodegradability evaluation>
The biodegradability was evaluated by a method of measuring the degree of biodegradation using activated sludge according to JIS K 6950. Activated sludge was obtained from Fukuoka Tatara River Purification Center. The supernatant obtained by leaving the activated sludge to stand for about 1 hour (activated sludge concentration: about 360 ppm) was used in an amount of about 300 mL per culture bottle. The measurement was started when 30 mg of the sample was stirred in the supernatant, and every 24 hours thereafter, measurements were made a total of 31 times after 720 hours, that is, after 30 days. The details of the measurement are as follows. Biochemical oxygen demand (BOD) in each culture bottle was measured using Okura Electric Co., Ltd. Coulometer OM3001. The percentage of biochemical oxygen demand (BOD) relative to theoretical biochemical oxygen demand (BOD) in complete degradation based on the chemical composition of each sample was defined as the degree of biodegradation (% by weight).

<Water resistance evaluation>
The mixture is dissolved in a mixed solvent of methylene chloride / methanol (weight ratio 9: 1) at a ratio of 5 parts by weight of the mixed solvent to 1 part by weight of each sample (cellulose acetate or cellulose acetate composition), and a solution using a glass substrate Film samples were prepared by solution casting. The size of the film sample is 2 cm × 2 cm and about 120 μm thick. The film sample was placed in a 100 ml size bottle containing 80 ml pure water, and rotation was started at a rotation speed of 14 rpm by a rotating machine, and the change with time of the shape and weight of the film sample was confirmed. The shape was observed with the naked eye. For weight, take out a film sample from pure water, wipe it with water droplets, dry it in a dryer at 105 ° C for 1 h, measure the weight with a precision electronic balance for analysis, and measure the weight change (%) from the start of rotation I asked. The details of the evaluation shown in Table 1 are as follows.
Good: One hour after the start of rotation, the film sample has no breakage or deformation, and the weight change of the film sample is a reduction of less than 10%.
Δ: 1 hour after the start of rotation, the weight change of the film sample decreases by less than 10%, but there is breakage or deformation; or the film sample does not have breakage or deformation, but the weight change of the film sample Is a reduction of 10% or more.
X: All film samples dissolved within 1 hour from the start of rotation.

Example 1
5.1 parts by weight of acetic acid and 2.0 parts by weight to 1 part by weight of raw material cellulose acetate (made by Daicel, trade name “L-50”, acetyl total substitution degree 2.43, 6% viscosity: 110 mPa · s) Parts by weight of water were added and the mixture was stirred for 3 hours to dissolve the cellulose acetate. To this solution was added 0.13 parts by weight of sulfuric acid, and the obtained solution was kept at 95 ° C. to conduct hydrolysis. The addition of water to the system was done in two portions to prevent the precipitation of cellulose acetate during hydrolysis. That is, after 0.3 hours from the start of the reaction, 0.67 parts by weight of water was added to the system over 5 minutes. After another 0.7 hours, 1.33 parts by weight of water was added to the system over 10 minutes and allowed to react for another 1.5 hours. The total hydrolysis time is 2.5 hours. The first hydrolysis step (first ripening step) from the start of the reaction to the first addition of water, and the second hydrolysis step (second ripening from the first addition of water to the second addition of water) Step), from the second addition of water to the end of the reaction, is referred to as a third hydrolysis step (third ripening step).

  After hydrolysis was carried out, the temperature of the system was cooled to room temperature (about 25 ° C.), and 15 parts by weight of a precipitation solvent (methanol) was added to the reaction mixture to form a precipitate.

  The precipitate was recovered as a wet cake with a solids content of 15% by weight and washed by adding 8 parts by weight of methanol and dewatering to a solids content of 15% by weight. This was repeated three times. The washed precipitate was neutralized by further washing twice with 8 parts by weight of methanol containing 0.004% by weight of potassium acetate, and dried to obtain cellulose acetate having a degree of acetyl substitution of 1.7.

  98 parts by weight of the obtained cellulose acetate having a degree of acetyl substitution of 1.7 and 2 parts by weight of triacetin as a glycerol ester plasticizer are dissolved in a mixed solvent of methylene chloride / methanol (weight ratio 9: 1) and uniformly mixed I did. Thereafter, the conditions were changed in order of 3 minutes at room temperature, 30 minutes with a 45 ° C. drier, and 30 minutes with a 150 ° C. drier, and the solvent was evaporated to obtain a cellulose acetate composition for thermoforming.

  The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. Thermoforming evaluation was performed. The results are shown in Table 1.

Example 2-5
A cellulose acetate composition for thermoforming was obtained in the same manner as in Example 1 except that cellulose acetate having a degree of acetyl substitution of 1.7 and triacetin were changed to the amounts shown in Table 1.

  The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. Thermoforming evaluation was performed. About Example 4, thermoforming evaluation, biodegradability evaluation, and water resistance evaluation were performed by said method. The results are shown in Tables 1 and 2. In the water resistance evaluation of Example 4, the container filled with water was subjected to continuous rotation treatment, and after 1 hour, the weight decreased by about 6%, but the sample itself was not damaged or deformed.

Example 6
A cellulose acetate composition for thermoforming was obtained in the same manner as in Example 1 except that 75 parts by weight of cellulose acetate having an acetyl substitution degree of 1.7 was used and 5 parts by weight of diacetin was used as a glycerine ester plasticizer.

  The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. Thermoforming evaluation was performed. The results are shown in Table 1.

Example 7-8
A cellulose acetate composition for thermoforming was obtained in the same manner as in Example 1 except that cellulose acetate having a degree of acetyl substitution of 1.7 and diacetin were changed to the amounts shown in Table 1.

  The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. , Thermoforming evaluation was performed. The results are shown in Table 1.

Comparative Example 1
A cellulose acetate having a degree of acetyl substitution of 1.7 was obtained by the method of Example 1, and the degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index of the obtained cellulose acetate The CDI) was measured, and the thermoforming cellulose acetate composition was evaluated for thermoformability, biodegradability and water resistance according to the method described above. The results are shown in Tables 1 and 2. In addition, regarding water resistance evaluation, continuous rotation processing was carried out in a container containing water, and no weight loss was observed after 1 hour. The sample itself was not damaged or deformed.

Comparative Example 2
5.1 parts by weight of acetic acid and 2.0 parts by weight to 1 part by weight of raw material cellulose acetate (made by Daicel, trade name “L-50”, acetyl total substitution degree 2.43, 6% viscosity: 110 mPa · s) Parts by weight of water were added and the mixture was stirred for 3 hours to dissolve the cellulose acetate. To this solution was added 0.13 parts by weight of sulfuric acid, and the obtained solution was kept at 100 ° C. to conduct hydrolysis. The addition of water to the system was done in two portions to prevent the precipitation of cellulose acetate during hydrolysis. That is, 0.25 hours after the start of the reaction, 0.67 parts by weight of water was added to the system over 5 minutes. After another 0.5 hours, 1.33 parts by weight of water was added to the system over 10 minutes and allowed to react for an additional 1.25 hours. The total hydrolysis time is 2 hours. The first hydrolysis step (first ripening step) from the start of the reaction to the first addition of water, and the second hydrolysis step (second ripening from the first addition of water to the second addition of water) Step), from the second addition of water to the end of the reaction, is referred to as a third hydrolysis step (third ripening step).

  After the hydrolysis was carried out, the temperature of the system was cooled to room temperature (about 25 ° C.), and 15 parts by weight of a precipitation solvent (methanol) was added to the reaction mixture to form a precipitate.

  The precipitate was recovered as a wet cake with a solid content of 15% by weight, washed by adding 8 parts by weight of methanol and draining to a solid content of 15% by weight. This was repeated three times. The washed precipitate was further washed twice with 8 parts by weight of methanol containing 0.004% by weight of potassium acetate, neutralized, and dried to obtain a cellulose acetate having a degree of acetyl substitution of 0.87.

  The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. , Biodegradability evaluation and water resistance evaluation were performed. The results are shown in Tables 1 and 2. In addition, continuous rotation processing was carried out in a container containing water, and after 1 hour, the sample itself was completely dissolved, and the weight measurement became impossible.

  As shown in Table 1, the cellulose acetate compositions for thermoforming of the examples contained a glycerol ester plasticizer, whereby the degree of biodegradation after 10 days was enhanced and the biodegradability was improved. In addition, it was confirmed that the glass transition temperature was lowered, and it was possible to easily melt uniformly by heating without any unmelted portion, and to have excellent thermoforming properties. Furthermore, as shown in Tables 1 and 2, it was also confirmed that the thermoforming cellulose acetate compositions of the examples had water resistance equivalent to that of cellulose acetate.

Example 6
A thermoforming cellulose acetate composition was obtained in the same manner as in Example 1 except that 95 parts by weight of cellulose acetate having an acetyl substitution degree of 1.7 was used and 5 parts by weight of diacetin was used as a glycerine ester plasticizer.

Example 7-8
A cellulose acetate composition for thermoforming was obtained in the same manner as in Example 6 except that cellulose acetate having a degree of acetyl substitution of 1.7 and diacetin were changed to the amounts shown in Table 1.

The degree of acetyl substitution, weight average molecular weight (Mw), number average molecular weight (Mn) and composition distribution index (CDI) of the obtained cellulose acetate were measured, and the cellulose acetate composition for thermoforming was measured by the above method. Evaluation of biodegradability and evaluation of water resistance were conducted (in the case of water resistance evaluation, however, the solvent was pure water) . The results are shown in Tables 1 and 2. In addition, continuous rotation processing was carried out in a container containing water, and after 1 hour, the sample itself was completely dissolved, and the weight measurement became impossible.

Claims (8)

A cellulose acetate composition for thermoforming, comprising a cellulose acetate having a degree of acetyl substitution of 1.4 or more and 1.8 or less, and a glycerin ester plasticizer.   The cellulose acetate composition for thermoforming according to claim 1, wherein the glycerin ester plasticizer is 5 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the total amount of the cellulose acetate and the glycerin ester plasticizer. .   The thermoforming cellulose acetate composition according to claim 1, wherein the glycerin ester plasticizer is triacetin.   The cellulose acetate composition for thermoforming according to any one of claims 1 to 3, wherein the degree of acetyl substitution of the cellulose acetate is 1.5 or more and 1.8 or less.   The molded object formed by shape | molding the cellulose acetate composition for thermoforming of any one of Claims 1-4.   The molded object of Claim 5 whose said molded object is a film.   The shaped body according to claim 5, wherein the shaped body is in the shape of a hollow cylinder. The shaped body according to claim 5, wherein the shaped body is a member for cigarette of electronic cigarette.