JP3265184B2 - Biodegradable films or sheets and processed products of these films or sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable film or sheet which can be widely used in the field of packaging materials and the like.
The present invention relates to a biodegradable multilayer film or sheet using such a film or sheet, and a thermoformed product comprising such a film or sheet.

[0002]

2. Description of the Related Art Plastic films or sheets made of polyethylene, polypropylene, polystyrene, polyvinyl chloride and the like, and thermoformed products thereof (collectively,
(Sometimes referred to simply as film or film product.)
Means that millions of tons are produced every year in Japan,
It is used in all industrial fields including food packaging. And the convenience and economics they bring are indispensable to our daily lives and to economic activities in a broader sense. On the other hand, although these plastic film products are partially recovered and reused, many cases immediately become waste after fulfilling the mission of packaging, which is the original purpose. Film products are often landfilled as waste.However, their stability and bulkiness shorten the life of landfills. It has caused problems such as impairing the living environment of animals and plants.

[0003] Attention is now focused on biodegradable plastic materials. It is known that biodegradable plastics gradually disintegrate and decompose in soil or water due to hydrolysis or biodegradation, and eventually become harmless decomposition products due to the action of microorganisms. Biodegradable plastics that have begun to be put into practical use are roughly classified into aliphatic polyesters, modified PVA, modified starch, and blends thereof. Aliphatic polyesters include poly (hydroxybutyric acid / valeric acid) as a microbial polymer, polycaprolactone and condensates of aliphatic dicarboxylic acids and aliphatic diols as synthetic polymers, and semi-synthetic polymers. Polylactic acid is typically known as a polymer. Each of these biodegradable plastics has a unique characteristic, and application development corresponding to the characteristic is considered.

[0004] On the other hand, cellulose acetate marketed in the UK in about 1922 was used by Reese in Ind. Eng.
It is known to be biodegradable, as disclosed in 9,89 (1957). Cellulose acetate is widely used today in tobacco filters, photographic base films and the like, but its development history has focused more on how to prevent hydrolysis and biodegradability. Attempts to actively use biodegradability as a function have only recently begun to be studied.

[0005]

Cellulose acetate as a biodegradable material is disclosed in JP-A-4-142344 and JP-A-6-49.
No. 275, these are compared to general-purpose plastic raw materials or their film products, for industrial production, for widespread use as packaging materials, and as a new function called biodegradability. In this respect, there were some problems. These materials have remarkably inferior melt extrusion characteristics compared to general-purpose plastic raw materials, have low elastic modulus due to the effect of humidity in the air after processing into films, are not stable in quality, and have a strong odor of acetic acid. However, the biodegradable raw material or film product could not be said to be practically satisfactory because of the odor transfer and the extremely low biodegradation rate. Further, thermoformed products of cellulose acetate sheet have not been practically used until now.

[0006]

Means for Solving the Problems In view of such a situation, the present inventors have made intensive studies, and as a result, using a specific cellulose acetate and a specific plasticizer, an index indicating the properties of the whole material. The biodegradation is excellent in other properties such as melt extrudability, moisture resistance, low odor, biodegradability and transparency by adjusting Film or sheet, furthermore, biodegradable multilayer film or sheet using these films or sheets
And a thermoformed product were obtained, and the present invention was completed.

The first gist of the present invention is that cellulose acetate having a degree of acetyl group substitution of 2.3 to 2.7 and a biodegradable plasticizer are used as main components at 23.degree. % RH
Tensile modulus of 100 kg / mm ² or more
Tensile modulus at 3 ° C and 60% RH is 23 ° C and 0%
80% or more of the tensile modulus in RH, and
The biodegradable plasticizer is represented by the following general formula (1).
Consisting of compounds described in (2) below
A livestock consisting of one or a combination of two or more selected from
Biodegradable fat with a degradable film or sheet as the inner layer
Characterized by using an aromatic polyester layer as both outer layers
It is in a disintegrable multilayer film or sheet . (1) H ₅ C ₃ (OH) _3-n (OOCCH ₃ ) _n 0 <n ≦ 3 (2) Glycerin alkylate (the alkyl group has carbon atoms
2-20, there may be a hydroxyl residue), ethylene glycol
Alcohol alkylate (the alkyl group has 1 to 20 carbon atoms;
May have a hydroxyl residue), ethylene repeating unit
Having a polyethylene glycol alkylate of 5 or less (Al
The kill group may have 1 to 20 carbon atoms and a hydroxyl residue.
), Aliphatic monocarboxylic acid alkyl esters (alkyl
A C1-20) alkyl group of an aliphatic dicarboxylic acid
Ester (alkyl group has 1 to 20 carbon atoms, carboxyl
There may be a radical residue), an aliphatic tricarboxylic acid
Kill ester (the alkyl group has 1 to 20 carbon atoms,
There may be a residue of a sil group).

Another aspect of the present invention is as follows.
Film or sheet of the invention of the first aspect - consists in preparative or et heat molded article.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Cellulose acetate in the present invention is a purified cotton linter.
Alternatively, high-purity wood pulp is used as a raw material and produced by any of well-known industrial production methods called a mixed acid method, a methylene chloride method, and a benzene method. The mixed acid method is most widely used, in which cellulose acetate is obtained from cellulose as a starting material through the following steps. A drying step to reduce the moisture content to 5% or less, a pretreatment step to wet acetic acid, an acetylation step using acetic acid, acetic anhydride and sulfuric acid, that is, an acetylation step, and an aging step to deacetylate by the action of added water and catalytic sulfuric acid (hydrolysis). , Hydrolysis), precipitation, purification, dehydration and drying for washing and stabilization. In order to obtain cellulose acetate having a desired degree of acetylation, hydrolysis conditions may be adjusted in the aging step of deacetylating cellulose triacetate having all acetylated hydroxyl groups in the acetylation step. .

In the present invention, it is important that the degree of acetyl group substitution of cellulose acetate is in the range of 2.3 to 2.7. If it is lower than the above range, the elasticity is lowered due to the influence of humidity in the air after processing into a film or a sheet, and the quality is not stable. Hardly biodegradable. The degree of polymerization is determined by the degree of polymerization of the starting cellulose and the degree of reduction in the degree of polymerization in the subsequent steps, and the average degree of polymerization of cellulose acetate is preferably in the range of 80 to 400. If the amount is less than the above range, the physical properties are not exhibited. If the amount exceeds the range, the melt moldability is inferior even if a plasticizer described later is added.

Cellulose acetate has a melting point of 280 to 290 ° C., which is higher than the decomposition temperature, and has a high melt viscosity, so that melt extrusion is difficult. Therefore, it is necessary to add a plasticizer in order to lower the melting point and the melt viscosity to enable melt extrusion.
As a plasticizer for cellulose acetate, dimethyl phthalate is used.
Phthalate plasticizers such as phthalate, diethyl phthalate, dibutyl phthalate and dimethoxyethyl phthalate;
Phthalyl glycolate plasticizers such as ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate, tricresyl phosphate, triphenyl phosphate Phosphoric acid ester plasticizers such as (g) and other op-tolueneethylsulfonamides are used because of their good compatibility. However, these are not biodegradable and are the main components of the biodegradable material in the present invention. Is not preferred.

In the present invention, compounds that can be used as suitable biodegradable plasticizers include compounds represented by the following general formula (1) and compounds represented by the following (2). Can be used in combination of two or more.

[0013] _{(1) H 5 C 3 (} OH) 3-n (OOCCH 3) n 0 <n ≦ 3 (2) Glycerin Al chelate - DOO (alkylene Le group having 2 to 20 carbon atoms, residues of hydroxyl Glycerin tripropionate, glycerin tributyrate)
Ethylene glycol alkylate (the alkyl group may have 1 to 20 carbon atoms and may have a hydroxyl group residue), for example, ethylene glycol diacetate; polyethylene glycol alkylate having 5 or less ethylene repeating units ( The alkyl group may have a residue of 1 to 20 carbon atoms and a hydroxyl group.) For example, diethylene glycol monoacetate, diethylene glycol diacetate; an alkyl ester of an aliphatic monocarboxylic acid (the alkyl group has 1 to 20 carbon atoms) Butyl stearate; alkyl ester of an aliphatic dicarboxylic acid (the alkyl group may have 1 to 20 carbon atoms and may have a carboxyl group residue), for example, di (2-ethylhexyl) adipate, di (2-ethylhexyl) azelle −
G; aliphatic tricarboxylic acid alkyl ester (the alkyl group may have 1 to 20 carbon atoms and may have a carboxyl group residue), for example, trimethyl citrate .

The compounds represented by the above formula (1) are glycerin mono-, di- and tri-acetates, which may be a mixture. In the film of the present invention, triacetate called triacetin or a film mainly composed of triacetate is preferable from the viewpoint of compatibility (plasticizing effect) and elastic modulus and humidity dependency.

The above-described plasticizer has biodegradability even when used alone, and does not inhibit the biodegradability of the composition when added to cellulose acetate at an arbitrary ratio. The amount is preferably in the range of 5 to 50% by weight based on the total amount of cellulose acetate and plasticizer. If it is below this range, the melting point or melt viscosity is not sufficiently reduced and the melt extrudability is not developed.If it is higher, the melt viscosity is too low or the plasticizer is separated from the reduced compatibility. This makes it difficult to take out the extruded sheet while maintaining the flatness and appearance of the sheet. However, the extrudability is related not only to the amount of the plasticizer added but also to the degree of polymerization of cellulose acetate. Therefore, the melt viscosity is used as an index as an addition of the actions of both. In the present invention, a shear rate of 100 seconds- ¹ at 220 ° C.
It is important that the melt viscosity as measured by (1) is (1.0 to 100) × 10 ³ poise. Outside of this range, extrusion suitability cannot be obtained even if the extrusion temperature is adjusted for the reasons described above.

With respect to the composition of cellulose acetate and plasticizer,
Furthermore, other polymer materials, particularly biodegradable plastics, may be blended as long as the effects of the present invention are not impaired. Addition of plasticizers, lubricants, inorganic fillers, stabilizers, ultraviolet absorbers, flame retardants, antifogging agents, antifungal agents, pigments, fluorescent agents, etc. for the purpose of adjusting moldability and film properties. It is also possible to add agents and modifiers. In the present invention, such a cellulose acetate composition (hereinafter sometimes simply referred to as cellulose acetate) is melt-extruded to form a sheet.
And film form. Cellulose acetate films are generally made by a solution method (same as the casting method and the wet method). In the solution method, a relatively thick sheet suitable for thermoforming as described later is used. It cannot be made, and a laminate cannot be obtained at the same time as forming a film or sheet. Furthermore, it is disadvantageous in manufacturing cost.

The extruder may be of any type commonly used for extruding plastics. When adding a plasticizer or performing polymer blending, a co-axial twin screw extruder is preferred over a single screw extruder. The set temperature of the extruder is appropriately determined depending on the melt viscosity of cellulose acetate, but is preferably in the range of 180 to 240 ° C. Outside this range, it is not only difficult to obtain the melt viscosity specified in the present invention, but also phase separation and thermal decomposition may occur.
Cellulose acetate melted in an extruder is extruded from a T-die, an I-die, a round die, etc., and is formed into a film or a sheet. When extruded from a round die, inflation is performed subsequently, and one or more locations are slit in the flow direction to obtain a so-called inflation film. In any case, the roll method, tenter method or tuber
Depending on the method, uniaxial or biaxial stretching may be performed as necessary, but the effect of improving mechanical properties and the like by stretching as seen in other materials typified by PET is not so large. When stretching for the purpose of thinning, etc., the film temperature should be 10
Operate at 0 to 150 ° C and within a stretching ratio of 2.5 times. The thickness of the film or sheet ranges from 5 μm to 1 mm and is determined according to the application.

The thus obtained film or sheet is biodegradable, transparent and has a tensile modulus of 10%.
As a polypropylene-like material with a rigidity (lumbar) of 0 kg / mm ² (measured at 23 ° C and 0% RH), it can be used in a wide range of fields, especially for general packaging. The conventional cellulose acetate film has a serious disadvantage in practical use. That is, the water in the atmosphere is adsorbed, and as a result, the water acts as a plasticizer, and the elastic modulus of the film decreases with time or changes in accordance with humidity, so that the quality is not stable. As a result, usable applications are limited. Since the cellulose acetate of the present invention specifies the degree of acetyl group substitution, there is almost no decrease in the elastic modulus due to adsorbed water.
The tensile modulus at% RH can exhibit 80% or more of the tensile modulus at 23 ° C. and 0% RH.

However, the cellulose acetate film of the present invention also has problems. It means that there is an odor of acetic acid remaining in the manufacturing process or produced by hydrolysis after the film is extruded or formed into a film product. In the solution method, not only the heat history during processing is small and the amount of newly generated acetic acid is small, but also the acetic acid derived from the raw material is dissolved in the solution, so that the acetic acid odor of the film product is relatively small. On the contrary, it is remarkable in the melt extrusion method. Since the acetic acid odor is an unpleasant odor, it is not practically preferable that the acetic acid odor is present in the film product even if it is slight. Thus, in the present invention, in order to prevent the acetic acid odor, a multilayer biodegradable film based on two or three layers, in which a cellulose acetate film or sheet is used as an inner layer and an aliphatic polyester is used as an outer layer, is used. It is a sheet. The aliphatic polyester is not particularly limited as long as it has an alkylene bond and an ester bond as a basic skeleton. Urethane bonds, amide bonds, ether bonds, and the like can be introduced as long as the biodegradability is not substantially affected.

Specifically, a polymer obtained by first condensing an aliphatic diol and an aliphatic dicarboxylic acid is exemplified.
Typical examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Representative examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecane diacid. From these,
After the condensation polymerization of one or more types, a polymer having a weight average molecular weight of 50,000 or more by adding a molecular chain extender such as an isocyanate compound, if necessary, usually has a melting temperature of 60 to 110 ° C. Has relatively good basic physical properties similar to polyethylene. Next, there is a series of aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones using an organic metal catalyst. As monomers, ε-caprolactone, δ-
Valerolactone, β-methyl-δ-valerolactone, β
-Propiolactone, pivalolactone, β-butyrolactone, γ-butyrolactone and the like, and in some cases, including lactide and glycolide,
Polymerization is performed by adjusting the conditions so that the weight average molecular weight is selected to be 30,000 or more.

Further, there is a polymer of α-hydroxycarboxylic acid represented by polylactic acid. Lactic acid includes L-lactic acid and D-lactic acid, and other hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, Representatively, 6-hydroxycaproic acid and the like. As these polymerization methods, any known methods such as a condensation polymerization method and a ring-opening polymerization method from a cyclic dimer can be adopted. As the weight average molecular weight of the polymer
A range from 60,000 to 100,000 is preferred. Further, other synthetic aliphatic polyesters include cyclic acid anhydrides and oxiranes, for example, polymers of succinic anhydride and ethylene oxide, propylene oxide or allyl glycidyl ether, and ethylene and cyclic ketene acetal. Two
-Methylene-1,3-dioxolane or 2-methylene-1,3
-A radical polymer with dioxepane.

In cells such as alkaligenes eutrophus, acetyl coenzyme A (acetyl C
Aliphatic polyesters biosynthesized by oA) are known. This aliphatic polyester is mainly poly-β-hydroxybutyric acid (poly 3 HB), but in order to improve the practical properties as a plastic, a fermentation process is devised and a valeric acid unit (HV) is usually copolymerized. And poly (3
It is industrially advantageous to use a copolymer of HB-Co-3 HV). The HV copolymerization ratio is generally 0-40%,
In this range the melting temperature is 130-165 ° C. Investigations have been made to copolymerize 4 HB instead of HV or further copolymerize a long-chain hydroxyalkanoate, but any of them can be used as the aliphatic polyester of the present invention.

As a method for laminating the cellulose acetate film and the aliphatic polyester film, any method for producing a laminated film can be usually employed. For example, a plurality of extruders are connected to one die, so-called co-extrusion, an aliphatic polyester film is coated on an unwound cellulose acetate film, or a plurality of types of films at an appropriate temperature are rolled. Typical examples include a method of thermocompression bonding with a tool or a press machine, or a method of bonding films together using an adhesive. As an adhesive for performing so-called dry lamination or wet lamination, vinyl-based, acrylic-based, polyamide-based, polyester-based, rubber-based, and urethane-based adhesives are generally used, and the adhesive is also biodegradable. In the case of making, starch, amylose, polysaccharides such as amylopectin, proteins and polypeptides such as glue, gelatin, casein, zein, collagen, unvulcanized natural rubber, or low molecular weight aliphatic Polyester and the like are preferably employed.
By forming a laminated film based on two or three layers as described above, the acetic acid odor of the inner cellulose acetate layer is blocked by the aliphatic polyester layer, and the acetic acid odor is not substantially eliminated in the whole film. Further, by laminating, not only does odor of acetic acid disappear, but also processability such as stretchability and inflation suitability, and surface characteristics such as surface lubricity, heat sealability and printability are improved. Therefore, a wider range of applications can be developed.

Next, a thermoformed product from a cellulose acetate film or a sheet (hereinafter simply referred to as a sheet) will be described. Thermoformed articles from cellulose acetate sheets have not been practically used until now. The reason for this is that the rigidity of the product is required in the use of thermoformed products, but cellulose acetate is reduced in elastic modulus due to water absorption and cannot maintain an appropriate rigidity. Further, in a system in which a plasticizer was not added, the glass transition temperature was 150 ° C. or higher, which was significantly higher than that of a general-purpose resin, so that it was not possible to process with a general-purpose vacuum / pressure molding machine. In the cellulose acetate of the present invention, the elastic modulus is hardly reduced by water absorption, and the glass transition temperature is also reduced to 80 to 130 ° C. by the addition of a plasticizer. It is.

The thickness of the sheet suitable for thermoforming is not particularly limited, but is preferably from 50 μm to 1 mm from the application. As the thermoforming method, any known method for thermoforming a sheet, for example, vacuum forming, pressure forming, vacuum and pressure forming, male and female mold forming, plug assist vacuum forming, CD (Cuspation Dilation: tip extension) forming And so on. The sheet temperature during molding is
Depending on the glass transition temperature of the sheet, it is determined in the temperature range of 80-170 ° C, while the mold temperature is preferably 80 ° C or less.
Although deep drawing is somewhat difficult due to the characteristics of the raw material, it can be easily formed if the area forming ratio is 4 times or less.

[0026]

The present invention is not limited by the following examples. The measured values shown in the examples were calculated under the following conditions. (1) Degree of acetyl substitution Based on JIS L1013, acetic acid produced by saponification with an alkali was titrated to determine the degree of acetylation of cellulose acetate, and the degree of acetyl substitution was calculated. The degree of acetyl group substitution is 0 when the hydroxyl group of cellulose is not completely substituted with an acetyl group, and 3.0 (62.5% acetylation degree) when all the hydroxyl groups are substituted. (2) Melt viscosity 1 mmφ x 1 in flow tester CFT-500C manufactured by Shimadzu Corporation
The sample was preheated at 220 ° C. for 5 minutes, extruded at a constant load, and the apparent viscosity (poise) at a shear rate of 100 sec ⁻¹ was defined as the melt viscosity in the present invention.

(3) Tensile Modulus and Humidity Dependence of Tensile Modulus A sample was cut into a strip having a width of 5 mm and left in an atmosphere conditioned at 23 ° C. for 2 days, and then Tensilon manufactured by Toyo Seiki Co., Ltd. Using a type II machine, a tensile test was performed at a chuck distance of 25 mm and a pulling speed of 5 mm / min. From the obtained stress-strain curve, a strong elongation of 1/2 of the yield strength was obtained, and the strength was divided by the elongation. By doing so, the elastic modulus was calculated. The unit is kg / mm ² . The humidity dependence of the elastic modulus is determined by measuring the tensile elastic modulus at 23 ° C and 60% RH at 23.
Percentage (%) divided by the tensile modulus at 0 ° C and 0 ° C
And

(4) Biodegradability A film sample having a thickness of 100 μm is cut into a strip having a width of 25 mm and a length of 130 mm, and the Biodegradable Plastics Society (BPS)
It was buried in the ground in Kawasaki-cho, Nagahama-shi, Shiga Prefecture in accordance with the Soil Field Test Method. After standing for 5 months, the sample was excavated and the weight retention (%) of each sample was measured. Weight retention
(%) Is a percentage (%) obtained by collecting and measuring the weight of visible small pieces in a dug up sample by the weight of the film sample before embedding. Thus, the weight loss portion is the sum of fine powder, decomposition products up to the molecular level, and water and carbon dioxide.

Examples 1-2 and Comparative Examples 1-2 Various cellulose acetates having an average degree of polymerization in the range of 100-300 and an acetyl group substitution degree of 2.1-2.9 were used as plasticizers. Triacetin was added at 30% by weight based on the total weight of cellulose acetate and triacetin, and 40 mm φ
Using a twin screw extruder in the same direction, pelletization was performed at 220 ° C. These pellets were used for 220 mm using a 40 mm φ single screw extruder.
The film was extruded by a T-die at a setting of 100 ° C to obtain a film having a thickness of 100 µm. The lower the degree of acetyl group substitution, the lower the extrudability tended to be, but all were able to be formed into films. Table 1 shows the results of evaluating the tensile modulus and biodegradability of these films.

[0030]

[Table 1]

Examples 3-5 and Comparative Examples 3-4 Various plasticizers were added to cellulose acetate having an average polymerization degree of 180 and an acetyl group substitution degree of 2.4, based on the total weight of cellulose acetate and plasticizer. Example 1
A film was obtained in the same manner as described above. Film formation was possible from any of the raw materials. Table 2 shows the results of evaluating the biodegradability of these films .

[0032]

[Table 2]

Examples 7 to 9 and Comparative Examples 5 to 7 Cellulose acetate having an average degree of polymerization of 180 and an acetyl group substitution degree of 2.6.
Triacetin to the total amount of cellulose acetate and triacetin with respect to the total amount of cellulose acetate and triacetin, and the mixture was stirred with a Henschel mixer and allowed to penetrate into the granules.
Table 3 shows the results of evaluating the extrudability together with the melt viscosity when a film having a thickness of 100 μm was obtained by extruding a T-die with a φ single screw extruder. For extrudability and film formability, see 22
Evaluation was performed at a setting of 0 ° C., and in the case of failure, the temperature setting was changed in a direction to improve the failure.

[0034]

[Table 3]

Examples 10 to 11 and Comparative Example 8 Cellulose acetate having an average degree of polymerization of 180 and an acetyl group substitution degree of 2.6.
Then, triacetin as a plasticizer was added at a ratio of 30% by weight based on the total amount of cellulose acetate and triacetin, and pelletized using a 40 mm φ same-direction twin-screw extruder.
Next, a two-type, three-layer T-die die is used so that the melt from the 50 mm φ single-screw extruder becomes the inner layer and the melt from the 30 mm φ single-screw extruder becomes both outer layers. And co-extrusion. The thickness ratio of the outer layer / inner layer / outer layer was adjusted to 1/8/1 to obtain a film having a total thickness of 100 μm. As the inner layer, the above cellulose acetate was used, and as the outer layer,
Biono, an aliphatic polyester manufactured by Showa Polymer Co., Ltd.
1010 (melting temperature = 114 ° C.) and Biopol D300G manufactured by Zeneca Corporation (melting temperature = 162 ° C.).

The above bionole 1010 is combined with succinic acid.
A compound obtained by chain-extending a copolymer with 1,4-butanediol with hexamethylene diisocyanate.
D300G is a composition obtained by adding a plasticizer and a nucleating agent to a copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid. Further, as Comparative Example 8, a substantially single-layer film in which both the inner and outer layers were the above-mentioned cellulose acetate was obtained using this apparatus. Odor on the surface of these films (acetic acid odor)
Table 4 shows the results of the evaluation of biodegradability.

[0037]

[Table 4]

Example 12 Cellulose acetate having an average degree of polymerization of 180 and a degree of acetyl substitution of 2.6 was added to cellulose acetate as a plasticizer.
And triacetin at a ratio of 30% by weight based on the total amount, and pelletized using a 40 mm φ co-rotating twin screw extruder. Further, a sheet having a thickness of 450 μm was sampled by extruding a T-die with a 40 mmφ single screw extruder, and a sheet cut into 100 mm × 100 mm was set in an aluminum mold and was set by CDK Corporation.
After heating the hot plate to 125 ° C using a pressurized air forming machine FKS-03-410, press forming at 1.5kg / cm ² air pressure and 45 ° C mold temperature.
A good molded product could be obtained. This molded article is a cup-shaped container having an open upper edge of 5 cm on a side, a height of 3 cm, and a cup-like shape narrowing toward the bottom.

[0039]

According to the present invention, by using a specific cellulose acetate and a specific plasticizer, an index indicating the properties of the whole material is adjusted to a specific range, and the melt extrudability, moisture resistance, and low odor property are obtained. A biodegradable film or sheet having good biodegradability and transparency can be obtained.

──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁷ Identification symbol FI C08K 5/11 C08K 5/11 (72) Inventor Hiroya Kobayashi 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (56) References JP-A-8-53575 (JP, A) JP-A-6-289536 (JP, A) JP-A-4-142344 (JP, A) JP-A-8-143710 (JP, A) JP-B-43-16305 (JP, B1) JP-T-Hei 6-501040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 1/00-1/32

Claims (5)

(57) [Claims] 1. Vinegar having an acetyl group substitution degree of 2.3 to 2.7.
Acid cellulose and a biodegradable plasticizer as main components,
Tensile modulus at 3 ° C. and 0% RH is 100 kg / m
m ² or more and tensile elasticity at 23 ° C. and 60% RH
80% of the tensile modulus at 23 ° C and 0% RH
And the biodegradable plasticizer comprises the following (1)
And a compound represented by the following formula (2):
Or a combination of two or more selected from the group consisting of
A biodegradable film or sheet comprising
Use both biodegradable aliphatic polyester layers as the outer layers.
And a biodegradable multilayer film or sheet. (1) H ₅ C ₃ (OH) _3-n (OOCCH ₃ ) _n 0 <n ≦ 3 (2) Glycerin alkylate (the alkyl group has carbon atoms
2-20, there may be a hydroxyl residue), ethylene glycol
Alcohol alkylate (the alkyl group has 1 to 20 carbon atoms;
May have a hydroxyl residue), ethylene repeating unit
Having a polyethylene glycol alkylate of 5 or less (Al
The kill group may have 1 to 20 carbon atoms and a hydroxyl residue.
), Alkyl esters of aliphatic monocarboxylic acids (alkyl
A C1-20) alkyl group of an aliphatic dicarboxylic acid
Ester (alkyl group has 1 to 20 carbon atoms, carboxyl
There may be a radical residue), an aliphatic tricarboxylic acid
Kill ester (alkyl group has 1 to 20 carbon atoms,
There may be a residue of a sil group). 2. The biodegradable plasticizer is mixed with cellulose acetate at a ratio of 5 to 50% by weight based on the total weight of cellulose acetate and biodegradable plasticizer. A biodegradable multilayer film or sheet according to claim 1. 3. A 220 ° C., the biodegradation of claim 1 or 2 melt viscosity measured at a shear rate of 100 sec ^-1 characterized in that it is a (1.0 to 100) × 10 ³ poise Multi-layer film or sheet. 4. The biodegradable multilayer film or sheet according to any one of claims 1 to 3, characterized in that is obtained by melt extrusion - and. 5. A molded article obtained by thermoforming the biodegradable multilayer film or sheet according to any one of claims 1 to 4 .