JP4318495B2 - Resin composition and biodegradable film - Google Patents

Description

【００３０】
得られた各フィルムについてヤング率（ＡＳＴＭ Ｄ−８２２）、引張破断強度（ＪＩＳ Ｚ−１７０２）、引張破断伸度（ＪＩＳ Ｚ−１７０２）、引裂き強度（ＪＩＳ Ｐ−８１１６）、インパクト強度（ＪＩＳ Ｐ−８１３４）および生分解性を評価した。以上の結果を表２に示す。なお、表２において、フィルムの機械（延伸）方向をＭＤ、フィルムの機械方向に対して垂直方向をＴＤとして示す。
実施例１〜３で得られたフィルムは、比較例に比べて高い引裂き強度を示し、特に機械（延伸）方向の引裂き強度（ＭＤ）の改善は著しく高いものであった。
【００３１】
【表２】

【００３２】
【発明の効果】
本発明によれば、引裂き強度、特に機械（延伸）方向の引裂き強度が改善された、樹脂組成物および生分解性フィルムが提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin composition and a biodegradable film, and more particularly to a resin composition and a biodegradable film suitable for biodegradable compost bags, agricultural films, packaging materials, and the like.
[0002]
[Prior art]
Biodegradable resins are known to decompose relatively easily in water and soil. For this reason, it is attracting worldwide attention from the viewpoint of environmental conservation such as the problem of waste disposal. Among these, the aliphatic polyester resin may have physical properties close to that of polyethylene, and the film obtained by molding the resin may be used for films such as agricultural materials, civil engineering materials, vegetation materials, and packaging materials. It is expected (see, for example, Patent Documents 1 and 2).
However, the above films have a problem in practical use because the tear strength, particularly the tear strength in the machine (stretching) direction of the film is not sufficient.
[0003]
[Patent Document 1]
JP-A-5-271377 [Patent Document 2]
Japanese Patent Laid-Open No. 6-170941
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a resin composition and a biodegradable film having improved tear strength, particularly tear strength in the machine (stretching) direction.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, the present invention comprises an aliphatic polyester copolymer (A) obtained by polymerizing a diol component and an aliphatic dibasic acid component, and a polylactic acid resin (B), and the following (1 ) To (3), all of the requirements: (1) containing succinic acid and adipic acid as the aliphatic dibasic acid component; and (2) succinic acid , And a ratio of 55 to 78 mol% of the aliphatic dibasic acid component ; and (3) The component (A) and the component (B) are based on the total amount of the component (A) and the component (B). The resin composition which has the relationship of 93-72 mass% of said (A) component and 7-28 mass% of (B) component is provided.
Further, the present invention, the diol component, there is provided the resin composition is selected from ethylene glycol and 1,4-butanediol.
Moreover, this invention provides the biodegradable film obtained by shape | molding the said resin composition.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The resin composition of the present invention contains (A) an aliphatic polyester copolymer and (B) a polylactic acid resin.
[0007]
(A) Aliphatic polyester copolymer The aliphatic polyester copolymer (A) used in the present invention is obtained by polymerizing a diol component and an aliphatic dibasic acid component, and (1) the aliphatic diester copolymer. It is essential that succinic acid and adipic acid are included as the basic acid component; and (2) succinic acid is in a proportion of 55 to 78 mol% of the aliphatic dibasic acid component .
[0008]
The polymerization method may be a method generally used as a polyester synthesis method. For example, a condensation polymerization method involving dehydration may be employed. In the present invention, for example, it is preferable to employ a polymerization reaction in which an esterification reaction is performed by dehydrating and condensing a diol component and an aliphatic dibasic acid component.
[0009]
The aliphatic polyester copolymer (A) has a melting point of 50 to 190 ° C., preferably 60 to 150 ° C., and a weight average molecular weight of 50,000 or more, preferably 1,000,000 or more. However, it is preferable for obtaining a molded article such as a film having improved tear strength.
[0010]
Examples of the diol component include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, and neopentyl glycol. In particular, ethylene glycol and 1,4-butanediol are preferable.
[0011]
As the aliphatic dibasic acid component, succinic acid and adipic acid are used . Also, the aliphatic dibasic acid component, a polyhydric alcohol having other trifunctional or tetrafunctional above, may be one containing oxy acid or polycarboxylic acid.
[0012]
When the diol component is composed of two or more types, the first component most contained in the diol component needs to be in a proportion of 55 to 78 mol%. If it is less than 55 mol%, the crystallinity of the resin composition cannot be obtained, and if it exceeds 78 mol%, the tear strength of a molded article such as a film is not improved.
Further, the aliphatic dibasic acid component needs to have a ratio of succinic acid of 55 to 78 mol% of the aliphatic dibasic acid component . If it is less than 55 mol%, the crystallinity of the resin composition cannot be obtained, and if it exceeds 78 mol%, the tear strength of a molded article such as a film is not improved.
[0013]
In the present invention, the aliphatic polyester copolymer (A) may be blended with other copolymers having different content ratios of the diol component and the aliphatic dibasic acid component.
[0014]
(B) Polylactic acid-type resin The polylactic acid-type resin (B) used in this invention should just polymerize by using a lactic acid monomer as an essential component. For example, poly L-lactic acid whose structural unit is L-lactic acid, poly D-lactic acid whose structural unit is D-lactic acid, poly DL-lactic acid whose structural units are L-lactic acid and D-lactic acid, and mixtures thereof It can be a polymer containing as a main component.
[0015]
Moreover, as a structure of the above-mentioned polylactic acid, it is preferable that it is D-lactic acid: L-lactic acid = 100: 0-85: 15 or 0: 100-15: 85 as molar ratio. It is also possible to blend other polylactic acids having different constituent ratios of D-lactic acid and L-lactic acid. The polylactic acid resin (B) having only D-lactic acid or L-lactic acid as a structural unit is a crystalline resin, has a high melting point, and tends to be excellent in heat resistance and mechanical properties. However, when used as a heat-shrinkable film-like material, if the crystallinity is very high, stretching and orientation crystallization proceeds at the time of stretching, so that it is difficult to adjust the heat shrinkage rate. On the other hand, in the case of DL-lactic acid, the crystallinity of the polylactic acid resin (B) decreases as the proportion of the optical isomer increases. Therefore, when used as a heat-shrinkable film-like product, it is preferable to increase the proportion of DL-lactic acid as a structural unit to moderately reduce crystallinity.
[0016]
Furthermore, the polylactic acid resin (B) may be a copolymer of the above-mentioned polylactic acid and other hydroxycarboxylic acid units described later, and may contain a small amount of a chain extender residue. As other hydroxycarboxylic acid units, optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid 2-functional aliphatic hydroxycarboxylic acids such as 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, and the like, and Examples include lactones such as caprolactone, butyrolactone, and valerolactone. Such other hydroxycarboxylic acid units are preferably used in an amount of less than 15 mol% in the component (B).
[0017]
As a polymerization method of the polylactic acid resin (B), a known method such as a condensation polymerization method or a ring-opening polymerization method can be employed. For example, in the condensation polymerization method, polylactic acid resin (B) having an arbitrary composition and crystallinity can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid, or a mixture thereof. In the ring-opening polymerization method (lactide method), lactide, which is a cyclic dimer of lactic acid, is prepared by using a suitable catalyst with a polylactic acid resin (B) using a polymerization regulator or the like as necessary. Obtainable. The lactide includes L-lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, DL-lactide which is a dimer of D-lactic acid and L-lactic acid. These are mixed as necessary and polymerized to obtain a polylactic acid resin (B) having an arbitrary composition and crystallinity.
[0018]
The polylactic acid resin (B) used in the present invention preferably has a weight average molecular weight of 60,000 to 700,000, more preferably 80,000 to 400,000, and particularly preferably 100,000 to 300,000. When the molecular weight is less than 60,000, practical physical properties such as mechanical properties and heat resistance are hardly expressed. When the molecular weight is more than 700,000, the melt viscosity is too high and the molding processability is poor.
[0019]
In the resin composition of the present invention, the aliphatic polyester copolymer (A) and the polylactic acid-based resin (B) are the components (A) 93 to 93 with respect to the total amount of the component (A) and the component (B). It has a relationship of 72 mass% and (B) component 7-28 mass%. Even if the component (A) is less than 72% by mass or more than 93% by mass, the tear strength is not improved.
[0020]
As a manufacturing method of the resin composition of this invention, there exists the method of melt-mixing an aliphatic polyester copolymer (A) and a polylactic acid-type resin (B) using an extruder, and setting it as a composition pellet. In addition, when shape | molding to a film etc., each of an aliphatic polyester copolymer (A) and a polylactic acid-type resin (B) may be mixed in a pellet state, and you may shape | mold directly.
[0021]
Another embodiment of the present invention is a biodegradable film obtained by molding the resin composition.
Examples of the method for producing the biodegradable film of the present invention include a method in which the resin composition is melted or each component constituting the resin composition is melt-mixed and formed into a film by a known molding method. . Examples of the film forming method include water cooling or air cooling inflation molding, T-die film extrusion molding, extrusion lamination molding, and the like. In addition, the biodegradable film of the present invention may be obtained by further uniaxially or biaxially stretching the film.
[0022]
In addition, the biodegradable film of the present invention may contain additives that are usually used in the technical field as desired, for example, antioxidants, heat stabilizers, UV inhibitors, antistatic agents, flame retardants, and crystallization accelerators. May be added as long as the characteristics of the present invention are not impaired. Specifically, hindered phenolic antioxidants such as pt-butylhydroxytoluene and pt-butylhydroxyanisole as antioxidants; triphenyl phosphite and trisnorylphenyl phosphite as thermal stabilizers Etc .; Examples of ultraviolet absorbers include pt-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2,4,5-trihydroxybutyrophenone, etc. N, N-bis (hydroxyethyl) alkylamine, alkylamine, alkylallyl sulfonate, alkyl sulfonate, etc. as inhibitors; hexabromocyclododecane, tris- (2,3-dichloropropyl) phosphate, pentabromo as flame retardants Phenyla Examples of crystallization accelerators include talc, holon nitrite, polyethylene terephthalate, and poly-transcyclohexanedimethanol terephthalate.
[0023]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
The measurement method used is shown below.
MFR (melt flow rate) was measured in accordance with JIS K7210 under conditions of a temperature of 190 ° C. and a load of 21.18 MPa.
The weight average molecular weight (hereinafter referred to as “Mw”) was measured using gel chromatography (Showa Denko, Shodex GPC System-11) under the following conditions.
Solvent: Hexafluoroisopropyl alcohol solution containing 15 mmol / l of ammonium acetate Resin concentration: 0.1% by mass Calibration curve: PMMA standard sample (Showa Denko, Shodex Standard M-75)
[0024]
The biodegradability test was conducted by embedding a film cut into a 10 cm square at a depth of about 10 cm from the ground next to the ground in Showa High Polymer Co., Ltd.'s Tatsuno Plant, and embedding it for one month. The amount of mass reduction was measured, and the reduction rate was evaluated in the following four stages.
◎… 80% or more ○… 50 or more and less than 80% △… 10 or more and less than 50% ×… less than 10% [0025]
The materials used are shown below.
<Production Example 1>
(Polyester A)
After replacing the 700 L reactor with nitrogen, 194.3 kg of 1,4-butanediol, 173 kg of succinic acid, and 91.8 kg of adipic acid (molar ratio of adipic acid to succinic acid, 70:30) were charged. Subsequently, 46 g of catalyst tetraisopropoxytitanium was added. The temperature was raised in a nitrogen stream, and the esterification reaction by dehydration condensation was carried out for 3.5 hours at 192 to 220 ° C. for 3.5 hours and further for 3.5 hours under a reduced pressure of 260 to 2600 Pa. The sample collected had an acid value of 25 mg / g and a weight average molecular weight (Mw) of 12670. The temperature was raised, and the deglycolization reaction was performed at a temperature of 215 to 220 ° C. under a reduced pressure of 26 to 1940 MPa for 5.5 hours. After the deglycolization reaction, 190 g of Irganox 1010 (manufactured by Ciba Specialty Chemicals) as an antioxidant and 190 g of calcium stearate as a lubricant were added, and stirring was continued for another 30 minutes. The sample collected had a weight average molecular weight (Mw) of 69600. The yield of this polyester was 380 kg when condensed water was removed. A reactor containing 380 kg of polyester was charged with 57 g of phosphorous acid at 160 ° C., and stirring was continued for another 30 minutes. Next, 4180 g of hexamethylene diisocyanate was added to the reactor under stirring, and a coupling reaction was performed at 160 to 190 ° C. for 1 hour. The viscosity increased rapidly, but no gelation occurred. The reaction product was extruded into water with a gear pump and cut into a pellet by a cutter. The polyester yield after drying in a dehumidifying air circulation dryer at 70 ° C. for 3 hours was 350 kg. The obtained polyester was in the form of white pellets, the melting point was 76 ° C., the weight average molecular weight (Mw) was 210000, and the MFR was 2.3 g / 10 min.
[0026]
<Comparative Production Example 1>
(Polyester B)
After the 700 L reactor was purged with nitrogen, 174 kg of 1,4-butanediol, 173 kg of succinic acid, and 54 kg of adipic acid (molar ratio of adipic acid to succinic acid, 80:20) were charged. Subsequently, 46 g of catalyst tetraisopropoxytitanium was added. The temperature was raised in a nitrogen stream, and the esterification reaction by dehydration condensation was carried out for 3.5 hours at 192 to 220 ° C. for 3.5 hours and further for 3.5 hours under a reduced pressure of 260 to 2600 Pa. The collected sample had an acid value of 9.6 mg / g and a weight average molecular weight (Mw) of 12670. The temperature was raised, and the deglycolization reaction was performed at a temperature of 215 to 220 ° C. under a reduced pressure of 26 to 1940 MPa for 5.5 hours. After the deglycolization reaction, 190 g of Irganox 1010 (manufactured by Ciba Specialty Chemicals) as an antioxidant and 190 g of calcium stearate as a lubricant were added, and stirring was continued for another 30 minutes. The sample collected had a weight average molecular weight (Mw) of 69600. This polyester had a yield of 325 kg excluding condensed water. To a reactor containing 325 kg of polyester, 57 g of phosphorous acid was added as a coloring inhibitor at 160 ° C., and stirring was continued for 30 minutes. Next, 3600 g of hexamethylene diisocyanate was added to the reactor under stirring, and a coupling reaction was performed at 160 to 190 ° C. for 1 hour. The viscosity increased rapidly, but no gelation occurred. The reaction product was extruded into water with a gear pump and cut into a pellet by a cutter. The polyester yield after drying with a dehumidifying air circulation dryer at 70 ° C. for 3 hours was 300 kg. The obtained polyester was in the form of white pellets, the melting point was 92 ° C., the weight average molecular weight (Mw) was 230000, and the MFR was 1.2 g / 10 minutes.
[0027]
(Polylactic acid resin)
Reisia H-400 (MFR; 2.7 g / 10 min) manufactured by Mitsui Chemicals was used.
[0028]
<Examples 1-3 and Comparative Examples 1-6>
Table 1 shows the type and blending amount of the polyester and the blending amount of the polylactic acid resin.
Examples 1 and 3 and Comparative Examples 1, 3 and 4 were prepared by melt-kneading polyester A or B and a polylactic acid resin at 190 ° C. using a same-direction twin screw extruder having a screw diameter of 30 mm. Got. The obtained pellets of each Example were dried at a temperature of 80 ° C. for 3 hours with a dehumidifying air circulation dryer, and then 30 μm thick and 300 mm folded width (blow-up ratio = 3) using an inflation molding machine manufactured by Yoshii Iron Works. Equivalent film).
In Example 2 and Comparative Examples 2, 5, and 6, polyester A or B and polylactic acid resin were mixed in a pellet state, respectively, and then a thickness of 30 microns was folded using an inflation molding machine manufactured by Yoshii Iron Works. A film having a width of 300 mm (equivalent to a blow-up ratio = 3) was formed.
[0029]
[Table 1]

[0030]
About each obtained film Young's modulus (ASTM D-822), tensile breaking strength (JIS Z-1702), tensile breaking elongation (JIS Z-1702), tear strength (JIS P-8116), impact strength (JIS P) -8134) and biodegradability was evaluated. The results are shown in Table 2. In Table 2, the machine (stretching) direction of the film is shown as MD, and the direction perpendicular to the machine direction of the film is shown as TD.
The films obtained in Examples 1 to 3 showed higher tear strength than the comparative examples, and the improvement in tear strength (MD) in the machine (stretching) direction was particularly high.
[0031]
[Table 2]

[0032]
【The invention's effect】
According to the present invention, there are provided a resin composition and a biodegradable film having improved tear strength, particularly tear strength in the machine (stretching) direction.

Claims (3)

It comprises an aliphatic polyester copolymer (A) obtained by polymerizing a diol component and an aliphatic dibasic acid component, and a polylactic acid resin (B), and satisfies all the following requirements: Resin composition:
Requirements for the resin composition:
(1) containing succinic acid and adipic acid as the aliphatic dibasic acid component;
(2) Succinic acid is a proportion of 55 to 78 mol% of the aliphatic dibasic acid component ; and (3) The component (A) and the component (B) are the component (A) and component (B). It has the relationship of 93-72 mass% of said (A) component and 7-28 mass% of (B) component with respect to the total amount of a component. The diol component, Ru is selected from ethylene glycol and 1,4-butanediol, the resin composition of claim 1.   A biodegradable film obtained by molding the resin composition according to claim 1.