JPH0978339A - Biodegradable cellulose acetate fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose acetate fiber having excellent biodegradability, and to provide a method for producing the same. SOLUTION: A biodegradable cellulose acetate fiber is produced by melt- spinning a biodegradable composition containing a cellulose acetate and a plasticizer as main components. The biodegradable composition comprises 55-70wt.% of a cellulose acetate having a degree of acetylation of <=56% and an average degree of polymerization of >=150 and 30-45wt.% of a bioclegradable polyesterpolyol having an average mol.wt. of 400-2000 or the mixture of the polyesterpolyol with a biodegradable polyetherpolyol having an average mol.wt. of 400-1000 as plasticizers. The biodegradable composition is melt-spun at a spinning temperature of 190-230 deg.C in a spinning draft of >=200.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable cellulose acetate fiber and a method for producing the same. More specifically, the present invention relates to a biodegradable cellulose acetate fiber obtained by melt spinning a biodegradable cellulose acetate composition containing cellulose acetate and a plasticizer as main components, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, as the recognition for environmental protection has deepened, the problem of processing plastic waste has been emphasized, and regarding the non-woven fabrics made of synthetic resin as a raw material and made by the melt-spinning method for disposable use, There is a growing desire to use biodegradable resins that can be composted as raw materials. Under these circumstances, various biodegradable polyester resins have been developed for use in melt spinning, but they have not come into widespread use because of their high price. On the other hand, polysaccharides derived from natural products are expected to be biodegradable, safe, inexpensive, and have a stable supply of raw materials. The composition is unknown.

Cellulose acetate, which is widely used as a general-purpose resin from cellulose as a raw material in the polysaccharide system, is produced by completely acetylating cellulose and then partially saponifying it, and in recent years, the degree of acetylation is 56%. The following have become known to have intrinsic biodegradability. However, since the cellulose acetate has a melting point and a thermal decomposition temperature that are close to each other, it is difficult to perform thermoforming, and is usually used as a composition to which a plasticizer is added. For the above reason, cellulose acetate is generally made into fibers by the dry spinning method in which it is dissolved in a solvent for the above reason, and is widely used as acetate fibers. As a special example not using the dry spinning method, it is known that a fiber for hollow fiber is produced by blending a water-soluble plasticizer such as polyethylene glycol and performing melt spinning.
No. 1564 discloses an average molecular weight of 200 to 1
Even if 000 polyethylene glycol is used alone, a spinning draft of 200 is judged from the viewpoint of the breakage rate during spinning.
As described above, it is difficult to increase the spinning speed and perform melt spinning. In addition, the use of a highly hygroscopic plasticizer such as polyethylene glycol alone is very limited in terms of application.

On the other hand, a plasticizer such as triacetin or triethyl citrate, which has a high plasticity and is used for extrusion injection molding or is known for biodegradability, has a thermoforming temperature higher than that of extrusion injection molding. When it is applied to high melt spinning, the amount of volatile components is large, and unless the spinning draft is considerably low, melt spinnability is not exhibited and productivity is poor. On the other hand, in order to solve these drawbacks of cellulose acetate and enable melt spinning that does not require solvent recovery equipment and can be spun at high speed, cellulose is acetylated and simultaneously propionylated to form cellulose acetate propionate or butyryl. Attempts have been made to impart melt spinnability to some extent by lowering the melting point by using cellulose acetate butyrate, but in this case, the hydrophobicity of the fiber becomes strong and the biodegradability decreases or disappears. Therefore, the production of biodegradable fibers by the melt spinning method using a cellulosic resin has not been realized yet.

[0005]

DISCLOSURE OF THE INVENTION In view of the present situation, the present inventors have firstly prepared cellulose acetate with the purpose of obtaining biodegradable cellulose fibers by a melt spinning method.
The possibility of melt spinning at a spinning draft of 200 or more under various conditions was investigated from the viewpoint of the yarn breakage rate during spinning, using various compositions that are usually used and made of plasticizers having good compatibility.
As a result, it was found that the volatility of the plasticizer and the strength of the composition during melt spinning are important factors for performing stable melt spinning at a spinning draft of 200 or more. That is, when a plasticizer is added, the melt viscosity of the composition is lowered, and the spinning temperature can be lowered, so that spinning can be performed without decomposing the cellulose acetate, but the plasticizer usually used has a small molecular weight from the viewpoint of the plasticizing effect, Since it does not have a polar group such as a hydroxyl group in the molecule, there is vapor pressure even in the spinning temperature range,
Therefore, when such a composition is melt-spun, the volatility becomes high, bubbles are likely to be generated in the fiber during spinning, and the strength of the fiber during melt-spinning is further reduced by adding a plasticizer. It was found that the yarn breakage rate during spinning is higher than that of a resin such as or polyethylene terephthalate in which a plasticizer is not added.

Regarding the blending amount of the plasticizer, when the blending amount of the plasticizer is increased, the spinning temperature is lowered and the volatilization amount is reduced, but the strength of the fiber at the time of melt spinning is lowered and the fiber is broken during spinning. When the blending amount of the plasticizer is increased, the fiber strength during melt spinning can be maintained at a certain level, but the plasticizing effect decreases, so the spinning temperature must be increased,
As a result, it was found that the volatilization amount of the volatile components contained in the plasticizer was increased, the thermal stability of the plasticizer and cellulose acetate was also decreased, and the yarn breakage rate during spinning was increased. The inventors of the present invention, as a result of further intensive studies to solve these problems, the average molecular weight as a plasticizer has a hydroxyl group at the terminal in a specific range, there is almost no vapor pressure near the spinning temperature, Alternatively, a biodegradable polyester polyol having a low vapor pressure, or a mixture of the polyester polyol and a polyether polyol having an average molecular weight in a specific range in a specific ratio is blended in a specific amount to lower the spinning temperature, and melt spinning is performed. By compensating the decrease in the strength of the fiber at the time of making the average degree of polymerization of cellulose acetate within a specific range, cellulose acetate can exhibit excellent melt spinnability at a spinning temperature of 190 to 230 ° C. and a spinning draft of 200 or more, And it was found that the obtained cellulose acetate fiber has excellent biodegradability and strength. This has led to the formation.

The object of the present invention is to perform melt spinning using a biodegradable cellulose acetate composition containing cellulose acetate and a polyester polyol as a plasticizer or a mixture of said polyester polyol and polyether polyol, It is an object of the present invention to provide a biodegradable cellulose acetate-based fiber and a method for producing the same, which solves the above problems when producing fibers by melt spinning using a conventional composition containing a cellulosic resin and a plasticizer.

[0008]

Means for Solving the Problems The first aspect of the present invention is a biodegradable cellulose acetate fiber obtained by melt spinning a biodegradable composition containing cellulose acetate and a plasticizer as main components. The composition has an acetylation degree of 56% or less,
Cellulose acetate having an average degree of polymerization of 150 or more 55 to 7
0% by weight and an average molecular weight of 400 to 2000 as a plasticizer
30 to 45% by weight of a biodegradable polyester polyol, or a mixture of the polyester polyol and a biodegradable polyether polyol having an average molecular weight of 400 to 1000
It is a biodegradable cellulose acetate fiber characterized by containing. A second aspect of the present invention is a method for producing a biodegradable cellulose acetate fiber, which comprises melt-spinning the biodegradable composition according to the first aspect of the present invention in a spinning draft of 200 or more at a spinning temperature of 190 to 230 ° C. Is.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable resin composition used in the present invention has a spinning draft of 200 or more, which is represented by a ratio of a spinning speed and a spinneret hole discharge speed (spinning speed / spinneret hole discharge speed). This is a method for producing a biodegradable cellulose acetate fiber by melt spinning, and this composition is composed mainly of cellulose acetate and a plasticizer.
Cellulose acetate used in the present invention, after pretreatment of cellulose pulp or linter such as softwood bleached kraft pulp or dissolving pulp with acetic acid or sulfuric acid,
It is obtained by a known method in which acetic anhydride is used for acetylation, followed by neutralization and aging, and the acetylation degree is 56% or less and the average degree of polymerization is 150 or more, which has essentially sufficient biodegradability. If the degree of acetylation of cellulose acetate is less than 51%, it becomes easily degradable and biodegradable further easily, but as long as a compound such as a biodegradable polyester polyol having an average molecular weight of 400 to 2000 is used as a plasticizer. In the above, biodegradation easily occurs even when cellulose acetate having an acetylation degree of 51 to 56% is used. However, the degree of acetylation is 3
If the cellulose acetate content is less than 0%, the water resistance is lowered,
Since it is not suitable for practical use, the degree of acetylation is 30 to 56% in the present invention.
Used in the range. Further, for the purpose of adjusting the biodegradability, two or more kinds of cellulose acetates having different degrees of acetylation may be mixed and used within the above range. The average degree of acetylation is measured from the amount of NaOH according to a known neutralization titration method.

When a plasticizer is added to cellulose acetate, the composition is accompanied by a decrease in strength during melt spinning,
The higher the average degree of polymerization of cellulose acetate is, the more preferable it is within the range where kneading with a plasticizer and melt spinning are possible in order to compensate for the decrease in strength due to the blending of the plasticizer, but if it is 150 or more, the desired melt spinnability is obtained. . However, the average degree of polymerization is 25
When it exceeds 0, the kneading property is deteriorated, which is not preferable. The average degree of polymerization (DP) of the present invention is obtained by dissolving cellulose acetate in an acetone solvent according to a known measurement method, and using an intrinsic viscosity [η] obtained from a relative viscosity obtained by an Ostwald viscometer, [η] = 0. It is obtained by the formula of 009 × DP.

The blending amount of cellulose acetate is in the range of 55 to 70% by weight based on the total weight of cellulose acetate and plasticizer. If the blending amount is less than 55% by weight, the strength of the biodegradable resin composition to be melt-spun decreases, and
If the amount exceeds 0% by weight, the spinning temperature will have to be raised, which will increase the volatilization amount of the plasticizer and also reduce the thermal stability of the plasticizer and cellulose acetate, increasing the yarn breakage rate during spinning. Not preferable. Further, in order to adjust the physical properties of the biodegradable composition, other high molecular weight compounds may be partially replaced with cellulose acetate and blended.
Examples of the high molecular weight compound used for this purpose include modified poval, modified starch, cellulose propionate, hydroxyethyl cellulose, hydroxypropyl cellulose and the like, which are essentially known to be biodegradable.

The plasticizer used in the present invention has a molecular weight of 4
A polyester polyol having a hydroxyl group at the terminal in the range of 00 to 2000 and having almost no vapor pressure in the spinning temperature range of 190 to 230 ° C., or having extremely low biodegradability even if there is vapor pressure, or the above polyester polyol And a polyether polyol having a molecular weight in the range of 400 to 1000, and the compounding amount of the plasticizer is in the range of 30 to 45% by weight based on the total weight of the cellulose acetate and the plasticizer. When the content is 45% by weight or more, the strength of the biodegradable composition to be melt-spun decreases, and when the content is less than 30% by weight, the spinning temperature must be increased. The thermal stability of the agent and cellulose acetate decreases, the yarn breakage rate during spinning increases, and melt spinnability deteriorates.

The polyester polyol is not particularly limited in terms of its chemical structure as long as it has biodegradability and good compatibility with cellulose acetate, but has an average molecular weight of 400-400.
2000 polyethylene succinate, polycaprolactone, polyethylene adipate, etc. can be mentioned,
These can be used alone or in combination of two or more selected. When the average molecular weight is less than 400, the plasticizing effect is good, but the spinning temperature is 190 to 2
At 30 ° C., the volatility of low molecular weight components in the polyester polyol is high, and the thermal stability is low, and bubbles are easily generated in the fiber during spinning, and in addition, melt-spinning biodegradable resin composition The strength of the product is greatly reduced. On the other hand, when the average molecular weight exceeds 2000, the plasticizing effect is small and the kneading property is deteriorated. In addition, the temperature range in which melt spinning is possible becomes higher than 230 ° C, and the thermal stability of the plasticizer and cellulose acetate is decreased. To do.

In combination with the above polyester polyol, it has biodegradability for the purpose of preparing melt viscosity, physical properties and the like,
In addition, a polyether polyol such as polyethylene glycol having an average molecular weight of 400 to 1000, which shows good compatibility with cellulose acetate, can be used within a range that does not impair the desired melt spinnability. The acceptable weight ratio of polyester polyol to polyether polyol in this case is less than 1: 1. This ratio is 1: 1
If the amount of the polyether polyol exceeds the above range, the low-molecular-weight component having a high volatility contained in the polyether polyol is volatilized during spinning to form bubbles, which is not suitable because the number of yarn breakage increases.

The main component of the biodegradable resin composition of the present invention is
Cellulose acetate and a plasticizer, but other weak organic acids, epoxy compounds, metal soaps, phosphates as stabilizers for preventing thermal deterioration and thermal discoloration within the range that does not impair the required performance as required. , Thiophosphate, etc. may be added alone or in admixture of two or more. Further, other additives such as organic acid-based biodegradation accelerators, lubricants, antistatic agents, dyes, pigments and lubricants may be blended. The biodegradability used in the present invention is the weight loss after being buried in the soil for a certain period of time or JIS.
It can be evaluated from the weight reduction according to K 6950. Also, the essential biodegradability is ASTM-D-5.
Biodegradability can be assessed using soil or activated sludge-controlled environments containing 338 or microorganisms acclimatized to cellulose acetate or plasticizers.

When the cellulose acetate, the plasticizer and the auxiliary agent used in the present invention are mixed, a known kneader, roll mill, Banbury mixer or the like is used.
In addition, in order to facilitate mixing, it is preferable that the particles of cellulose acetate be finely pulverized to 50 mesh or more in advance by a pulverizer. In addition, it is desirable that the mixture be pelletized by using an extruder before being supplied to the melt spinning machine in order to reduce inclusion of air bubbles as much as possible. Further, the pelletized biodegradable resin composition is preferably dried by heating to prevent hydrolysis or thermal deterioration at the time of melting prior to melt spinning to have a water content of 0.1% or less.

In the melt spinning method used in the present invention, the above-mentioned biodegradable resin composition is heated and melted in a known extrusion spinning machine, then extruded from a spinneret and spun, and a continuous continuous fiber filament group spun at high speed by an ejector. It is a method of forming a web by drawing while drawing with high-pressure air and winding, or by drawing and opening, and forming a web on the surface of a support for collection. The spinning temperature during melt spinning is 190 to 230. ℃
Is the internal temperature of the spinneret. If the spinning temperature exceeds 230 ° C., the volatilization amount of the plasticizer increases, and the thermal stability of the plasticizer and cellulose acetate decreases, resulting in significant thermal decomposition or hydrolysis, which is not preferable. On the contrary, when the spinning temperature is lower than 190 ° C., the melt viscosity of the biodegradable resin composition becomes high and it becomes difficult to raise the spinning draft. The spinning draft as referred to in the present invention refers to the ratio of the spinning speed to the spinneret hole discharge speed (spinning speed / spinneret hole discharge speed).

In the melt spinning method, a resin composition such as polyethylene, polypropylene or polyethylene terephthalate is currently used in more than 200 spinning drafts, and the productivity is extremely higher than that of the dry or wet spinning method which requires a solvent. It's an expensive method. In the present invention, the spinning draft is melt-spun at 200 or more, and the higher the spinning draft is, the higher the production efficiency is, but it is limited in terms of strength, and the upper limit is about 400. Further, as in the case of the spinning draft, the higher the spinning speed is, the higher the production efficiency is. However, the spinning speed is 1000 to 40 including the limitation in terms of strength.
00 m / min is a practical range. In the present invention, biodegradable cellulose acetate long fibers can be obtained with a very low yarn breakage rate during spinning, and the obtained long fibers are spun into a woven fabric or a nonwoven fabric is obtained by a spunbond method. It can be used for various purposes.

[0019]

[Examples] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the following examples, all percentages are by weight.

Example 1 13% dissolved pulp from softwood wood per absolute dry weight, sulfuric acid 2
%, Acetic anhydride 35% and glacial acetic acid 50% were acetylated at 36 ° C. for 3 hours, the reaction product was neutralized with potassium acetate after the reaction, and then hydrolyzed at 60 ° C. for 3 hours to purify, After drying, cellulose acetate flakes having an acetylation degree of 54% and an average polymerization degree of 180 were obtained. Next, the cellulose acetate flakes were made into a fine powder by a pulverizer, and 60% of the total weight of cellulose acetate and the plasticizer of cellulose acetate (hereinafter simply referred to as the total weight) and 60% of caprolactone triol having an average molecular weight of 550 as a plasticizer ( Daicel Chemical Co., Ltd., Trademark: Praxel 305) 30% based on the total weight, and polyethylene adipate having an average molecular weight of 1000 (Nippon Polyurethane, Trademark: Nipporan 40)
10% based on the total weight of 02) was mixed with a Henschel mixer, and then kneaded with a kneader at 160 ° C. for 30 minutes at 30 revolutions. The kneaded material is then fed to the extruder 1
It was melted at 80 ° C to 210 ° C, extruded, cooled as a strand, and then cut into 3 mm to obtain pellets. The pellets were dried in a hot air dryer heated to 80 ° C for 17 hours, then fed to an extruder-type melt spinning machine, melt-spun at a spinning temperature of 210 ° C, discharged through a spinneret with a hole diameter of 0.3 mm, and spun at a spinning speed. Melt spinning was performed with a spinning draft 350 at 1850 m / min, and a spun long fiber filament group was drawn by an ejector and wound. The fineness of the long fibers was 2.2 denier.

The yarn breakage ratio during spinning, the yarn strength and biodegradability of the obtained long fibers were evaluated by the following methods. Evaluation method (1) Spinning breakage rate When the biodegradable resin composition was melt-spun by a spinning machine, the number of breakages per hour was measured, and if the number of breaks was 10 or less, the spinnability was good. It was evaluated. (2) Yarn strength It was carried out according to the method described in JIS L 1013. (3) The long fibers obtained by biodegradable melt spinning were partially thermocompressed with an embossing roll so that the shape could be maintained, and then 20 cm.
Cut to a size of 20 cm and buried in the open soil in Koto-ku, Tokyo (1-10-6 Shinonome, Koto-ku, Tokyo, Shin-Oji Paper Co., Ltd., Central Research Institute) at a depth of 25 cm. ,
After 6 months, it was taken out and evaluated based on the following three grades from the change in shape and the change in weight. ◯: Both morphological change and weight reduction are remarkable. Δ: Change in morphology and change in weight are observed. X: No morphological change and weight change are observed.

Example 2 Cellulose acetate having an acetylation degree of 45% and an average degree of polymerization of 160 was prepared in the same manner as in Example 1 except that the hydrolysis time was changed, and 60% of the total weight of the cellulose acetate was used. And, as a plasticizer, polyethylene adipate having an average molecular weight of 1000 (product name: Nippon Polyurethane 4002) having an average molecular weight of 25% based on the total weight of 25% and an average molecular weight of 60.
Polyethylene glycol of 0 (manufactured by Sanyo Kasei, trademark: PE
G600) mixed with 15% based on the total weight of 21
Long fibers were produced and wound in the same manner as in Example 1 except that melt spinning was performed at 5 ° C., and the obtained long fibers were tested.
The fineness of the long fibers was 2.0 denier.

Comparative Example 1 65% by weight based on the total weight of cellulose acetate having an acetylation degree of 54% and an average degree of polymerization of 180 obtained in Example 1, and triacetin (molecular weight 218, boiling point 260 ° C., Wako Pure Chemical Industries, Ltd.) as a plasticizer. A long fiber was produced in the same manner as in Example 1 except that it was melt-spun at 215 ° C. using 35% by weight of the total weight of the reagent (special grade) manufactured by mixing, and a biodegradability test was conducted.

Comparative Example 2 70% based on the total weight of cellulose acetate having an acetylation degree of 45% and an average degree of polymerization of 160 obtained in Example 2, and polyethylene glycol having an average molecular weight of 400 as a plasticizer (manufactured by Sanyo Kasei, trademark: Except that it was melt-spun at 210 ° C. using a mixture of PEG 400) and 30% based on the total weight.
Long fibers were produced in the same manner as in Example 1, and a biodegradability test was conducted.

Comparative Example 3 Cellulose acetate having a degree of acetylation of 54% and an average degree of polymerization of 80 was prepared in the same manner as in Example 1 except that the type of dissolving pulp was changed. , A caprolactone triol having an average molecular weight of 550 as a plasticizer (trade name: Praxel 3 manufactured by Daicel Chemical)
30% by total weight of 05) and polyethylene adipate having an average molecular weight of 1000 (manufactured by Nippon Polyurethane, trademark: Nipporan 4002) mixed with 10% by total weight, and melt-spun at 205 ° C. Example 1
Long fibers were prepared and tested in the same manner as in. The fineness of the long fibers was 2.4 denier.

Comparative Example 4 60% based on the total weight of cellulose acetate having an acetylation degree of 54% and an average degree of polymerization of 180 obtained in Example 1 and caprolactone triol having an average molecular weight of 300 as a plasticizer (trade name: manufactured by Daicel Chemical Co., Ltd .: trade name: 30% of the total weight of Praxel 303) and polyethylene adipate having an average molecular weight of 1000 (trademark: Nippon Polyurethane 4002)
A long fiber was produced and tested in the same manner as in Example 1 except that the melt spinning was performed at 205 ° C. using 10% of the above. The fineness of the long fibers was 2.1 denier.

Comparative Example 5 50% based on the total weight of cellulose acetate having an acetylation degree of 54% and an average degree of polymerization of 180 obtained in Example 1, and caprolactone triol having an average molecular weight of 550 as a plasticizer (trade name: manufactured by Daicel Chemical Co., Ltd .: trademark). 40% based on the total weight of Praxel 305) and polyethylene adipate having an average molecular weight of 1000 (trademark: Nippon Polyurethane 4002)
A long fiber was produced in the same manner as in Example 1 except that melt-spinning was performed at 200 ° C. by using 10% by weight based on the total weight of, and a biodegradability test was performed.

Comparative Example 6 75% based on the total weight of cellulose acetate having an acetylation degree of 54% and an average polymerization degree of 180 obtained in Example 1 and a caprolactone triol having an average molecular weight of 550 as a plasticizer (trade name: manufactured by DAICEL CHEMICAL CO., LTD. 20% of the total weight of Praxel 305) and polyethylene adipate having an average molecular weight of 1000 (trademark: Nippon Polyurethane 4002, manufactured by Nippon Polyurethane Industry Co., Ltd.)
5% based on the total weight of the above was mixed and used, and long fibers were produced in the same manner as in Example 1 except that melt spinning was performed at 230 ° C., and a biodegradability test was performed.

Comparative Example 7 Long fibers were produced in the same manner as in Example 1 except that melt spinning was performed at 185 ° C., and a biodegradability test was conducted.

Comparative Example 8 A long fiber was produced in the same manner as in Example 1 except that melt spinning was performed at 235 ° C., and a biodegradability test was conducted.

Table 1 shows the acetylation degree, average degree of polymerization (DP), blending amount, type of plasticizer, average molecular weight and blending amount of the cellulose acetate used in Examples and Comparative Examples.

[0032]

[Table 1]

Table 2 also shows the spinning conditions used in Examples and Comparative Examples and the results obtained.

[0034]

[Table 2]

As can be seen from Tables 1 and 2, the present invention is
Even when the spinning draft is as high as 350 or more, there is almost no yarn breakage during spinning, the cellulose acetate fiber can be efficiently produced, and the obtained fiber has high yarn strength and excellent biodegradability (Examples). 1-2). On the other hand, a plasticizer of a low molecular weight compound having a low average molecular weight (218) such as triacetin which is usually used and having a boiling point near the spinning temperature (Comparative Example 1), or similarly, an average molecular weight such as polyethylene glycol When a plasticizer such as a polyether polyol (Comparative Example 2) having a low molecular weight (400) and a low molecular weight component having high volatility is used alone, bubbles are easily generated in the fiber during spinning, resulting in a spinning draft. In the low area (230 to 250), yarn breakage occurs frequently, resulting in extremely poor productivity and fiber quality.

When the average degree of polymerization of cellulose acetate is low (Comparative Example 3), or when the plasticizer used has a low average molecular weight of polyester polyol (Comparative Example 4), the strength of the fiber during melt spinning is increased. As a result, the number of yarn breaks increases and stable melt spinning cannot be performed. When the compounding amount of the plasticizer is increased (50% by weight) (Comparative Example 5), the fiber strength during melt spinning is decreased and the number of yarn breakages is increased, while the compounding amount of the plasticizer is decreased (30% by weight). %) (Comparative Example 6), the melt viscosity becomes low, so that the spinning temperature must be increased, which increases the volatilization amount of the plasticizer and also reduces the thermal stability of the plasticizer and cellulose acetate. The number of times increases, and melt spinning deteriorates. When the spinning temperature during melt spinning is low (Comparative Example 7), the melt viscosity is high, and when the spinning temperature is high (Comparative Example 8), the thermal stability of the cellulose acetate and the plasticizer is low, and both are broken. It is not suitable because the number of times increases.

[0037]

EFFECTS OF THE INVENTION The present invention provides a cellulose acetate fiber having excellent biodegradability and fiber strength, and a spinning temperature of 19
The effect of providing a method for producing a cellulose acetate fiber having an extremely excellent melt spinnability at 0 to 230 ° C. and a spinning draft of 200 or more is exhibited.

Claims (2)

[Claims] 1. A biodegradable cellulose acetate fiber obtained by melt-spinning a biodegradable composition containing cellulose acetate and a plasticizer as main components, wherein the biodegradable composition has an acetylation degree of 56% or less and an average value. 55 to 70% by weight of cellulose acetate having a degree of polymerization of 150 or more and a biodegradable polyester polyol having an average molecular weight of 400 to 2000 as a plasticizer, or the polyester polyol and an average molecular weight of 40.
A biodegradable cellulose acetate fiber, comprising 30 to 45% by weight of a mixture with 0 to 1000 biodegradable polyether polyol. 2. A method for producing a biodegradable cellulose acetate fiber, which comprises melt-spinning the biodegradable composition according to claim 1 in a spinning draft of 200 or more at a spinning temperature of 190 to 230 ° C.