JP2003128797A - Biodegradable resin product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable resin product comprising a resin mainly comprising a polylactic acid polymer and excellent in mechanical suitability, heat resistance and heat sealability at high speed and provide a package and a composite material using the same. SOLUTION: In the biodegradable resin product mainly comprising the polylactic acid polymer mainly comprising L-lactic acid and/or D-lactic acid, the biodegradable resin product has >=10 J/g calorie of crystal heat fusion ΔHm and <=15 deg.C phase transition index (Tα-Tg) [wherein Tα denotes the phase transition temperature (unit: deg.C) of loss tangent tanδ in the test (JIS-K7198A) for temperature dependence of dynamic viscoelasticity, Tg denotes the glass transition temperature (unit: deg.C) by differential scanning calorimetry (JIS-K7122) and ΔHm denotes calorie of crystal heat fusion (unit: J/g). Those values are obtained in the temperature range between 0 deg.C and 200 deg.C.].

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin product having biodegradability which is excellent in mechanical suitability, heat resistance and suitability for high speed heat sealing. The biodegradable resin product of the present invention means a film and a sheet (particularly, a stretched film and a sheet), a molded product, a fiber, a nonwoven fabric, a foam, and a package packaged by the product, and It includes a composite material using. More specifically, a biodegradable heat-shrinkable or heat-non-shrinkable stretched film and sheet made of polylactic acid-based resin, specifically, a shrinkable film and sheet for bento or prepared food container overlap, or The present invention relates to a stretched film and sheet useful for a non-shrinkable film for a bag with a zipper, a package using the same, and a composite material.

[0002]

2. Description of the Related Art Polyethylene terephthalate, which is a resin material excellent in mechanical suitability, heat resistance and heat seal suitability,
Materials such as polypropylene, polyethylene and polystyrene are mentioned and widely used. However, from the perspective of protecting the natural environment related to the disposal of this resin material,
It is desired to have low combustion heat, decompose in soil, and be safe. Products using biodegradable resins such as aliphatic polyesters such as polylactic acid resins, specifically films, sheets, bottles, etc. Active research is being conducted on containers, molded articles, fibers, non-woven fabrics, foams, and composite materials using them.

A polylactic acid polymer is a polycondensation product of lactic acid having an optically active center, and is calculated from the composition ratio of L-lactic acid and / or D-lactic acid monomer units constituting the polymer by the following formula. Depending on the purity (OP: unit%), the one having a high optical purity of 80% or more is crystalline, and the optical purity is 80.
Those as low as less than 10% become amorphous. OP = | [L] − [D] |, where [L] + [D] =
100 Here, [L] is the weight ratio of L-lactic acid constituting the polylactic acid polymer (unit%), [D] is the weight ratio of D-lactic acid constituting the polylactic acid polymer (unit%), || Represents the absolute value of the calculated value.

Polylactic acid polymer has a tensile modulus of elasticity (based on ASTM-D882-95a) as compared with other biodegradable resins.
Has a rigidity of about 2 to 5 GPa, and in particular, a product obtained by stretching or heat treating it has a tensile breaking strength (ASTM).
-D882-95a) has a high mechanical strength of about 70 to 300 MPa. For example, in the case of a film or sheet, it has excellent mechanical suitability for continuous cutting of a roll-shaped raw film and is suitable as a film for various packaging. However, a biodegradable resin product mainly composed of a polylactic acid polymer that has both heat resistance and suitability for high-speed heat sealing without impairing these properties has not yet been obtained. In particular, shrinkable films for lunch boxes and side dish containers are heat resistant to the heat shrinkage treatment (shrink process) of the package, and non-shrinkable films used for zipper bags etc. are heat shrinkage suppression treatments after stretching ( Heat resistance against heat setting process) and high-speed heat-sealing suitability that can develop sufficient hot tack strength suitable for heat-sealing packages, bags, etc. from roll-shaped raw film with a packaging machine or bag-making machine. There is still no satisfactory biodegradable resin product.

Regarding the polylactic acid-based resin product having biodegradability, Japanese Patent Laid-Open No. 2001-122989 discloses 120 in a test (JIS-K7198) for temperature dependence of dynamic viscoelasticity composed of crystalline polylactic acid. Storage modulus E at ℃
^* The crystallinity of the polylactic acid resin film of 100～230MPa, the JP 2000-198913, although easy splitting property biaxially oriented film consisting of crystalline polylactic acid and aliphatic polyesters have been disclosed, fast heat It has a problem of lacking in sealability. Further, in JP-A No. 11-222528, the polylactic acid-based polymer conversion heat of fusion ΔHm1 is 3
Although a heat-sealable film composed of an amorphous polylactic acid of 5 J / g or less and an aliphatic polyester is disclosed, it has a problem of poor heat resistance.

In particular, JP-A-11-222528 discloses a test for the temperature dependence of dynamic viscoelasticity (JIS-K.
7198B), a mixed composition of crystalline polylactic acid and amorphous polylactic acid stable at a storage elastic modulus E ^* of 6 MPa or less is disclosed. The composition is a low elastic thermoplastic elastomer and is The average optical purity is less than 80%, and the polylactic acid-based film or sheet made of the composition has good moldability but is easily flow-deformed. Therefore, it is biodegradable by heat treatment in an atmosphere at a temperature exceeding 100 ° C. It has a problem of lacking heat resistance required for resin products.

[0007]

DISCLOSURE OF THE INVENTION The present invention comprises a biodegradable resin product comprising a resin mainly composed of a polylactic acid polymer, and having excellent mechanical suitability, heat resistance and suitability for high speed heat sealing, and a packaged product thereof. The purpose is to provide a composite material.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have surprisingly found that polylactic acid-based resins have a phase transition temperature Tα and a glass transition temperature Tg. The smaller the difference (Tα-Tg), the better the thermoresponsiveness of viscoelasticity, and it can be utilized as an index of the phase transition rate from the glass state to the rubber state and the rubber state to the molten state at the time of temperature increase (in the present application, (Tα- Tg) is called a phase transition index), and further, a specific heat of fusion of crystal ΔHm
It was found that the object of the present invention can be achieved by using a polylactic acid-based resin having a phase transition index (Tα-Tg) and completed the present invention.

That is, the present invention is as follows. L
-In the biodegradable resin product mainly composed of polylactic acid polymer containing lactic acid and / or D-lactic acid as a main component, the heat of crystal fusion ΔH
m is 10 J / g or more, and phase transition index (Tα-Tg)
Is 15 ° C. or lower, a biodegradable resin product. [However, the symbols in the above formula are the phase transition temperature (unit: ° C) of the loss tangent tan δ in the test (JIS-K7198A) for the temperature dependence of dynamic viscoelasticity, Tα, the differential scanning calorimetry (JIS-K7121 and The glass transition temperature (unit: ° C) according to JIS-K7122) was Tg, and the heat of crystal fusion at the melting point Tm (unit: J / g) was ΔHm. These are measured values in the range of 0 ° C to 200 ° C. ]

That is, the present invention relates to L-lactic acid and / or D
A combination of the following two requirements in a biodegradable resin product formed by stretching and / or heat-treating a polylactic acid-based resin containing a polylactic acid polymer containing lactic acid as a main component. The heat of fusion of crystal is within the range of ΔHm ≧ 10 J / g.
This means that the biodegradable resin product has an appropriate amount of crystal components that can withstand the heat treatment at a temperature exceeding 100 ° C., and can exhibit heat resistance. The phase transition index is in the range of (Tα-Tg) ≦ 15 ° C.
This indicates that the amorphous component of the resin component of the biodegradable resin product is effectively present and the mobility of the molecular chain with respect to heat and the thermal response are good (the phase transition rate is fast), and the hot tack strength Can express excellent suitability for high-speed heat sealing.

The present invention will be specifically described below. The biodegradable resin product of the present invention includes a film and a sheet-like product (particularly, a stretched film and a sheet-like product) and a molded product, a fiber, a non-woven fabric, a foam made of a polylactic acid resin,
It includes a package packaged thereby, and a composite material using the package. The polylactic acid resin means L
-Homopolymer of lactic acid unit or D-lactic acid unit, copolymer of L-lactic acid unit and D-lactic acid unit, L-lactic acid and / or D
-Lactic acid, DL-lactic acid unit as a main component (80% by weight or more) and at least one selected from copolymers with other monomers of the group consisting of hydroxycarboxylic acids, lactones, dicarboxylic acids, and polyhydric alcohols Mainly polylactic acid polymer (5
0% by weight or more), preferably a differential scanning calorimetry (JIS-K7121 and JIS-K)
7122) has a crystal melting point Tm of 140 ° C. or higher. If the Tm is less than 140 ° C, the heat resistance may be insufficient during the heat treatment at a temperature exceeding 100 ° C.

Examples of the hydroxycarboxylic acid as the monomer include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid and 6-hydroxycaproic acid; Is glycolide, lactide, β-propiolactone, γ
-Butyrolactone, δ-valerolactone, ε-caprolactone and lactones in which various groups such as a methyl group are substituted, etc .; dicarboxylic acids include succinic acid,
Glutaric acid, adipic acid, azelaic acid, sebacic acid,
Terephthalic acid, isophthalic acid, etc .; Polyhydric alcohols include aromatic polyhydric alcohols such as bisphenol / ethylene oxide addition reaction products, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylol Examples include aliphatic polyhydric alcohols such as propane and neopentyl glycol, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol.

The heat of crystal fusion ΔHm at the crystal melting point Tm of the biodegradable resin product of the present invention is 100 of that of the resin product.
10 J / g from the viewpoint of heat resistance to a temperature exceeding ℃, for example, in the case of shrink film, heat resistance to heat shrink treatment after product production, and in the case of non-shrink film, heat resistance to heat shrink inhibition treatment at product manufacture That is all. If ΔHm is less than 10 J / g, there is a problem that the amount of crystals is small and heat resistance is insufficient. When ΔHm exceeds 30 J / g, the amount of crystals is large and the hot tack strength is low and the heat seal suitability may be lacking. 10 J / g or more and 30 J / g or less are preferable, and 15 J / g or more and 25 J / g or less are more preferable. In addition, the phase transition index (Tα-Tg) of the biodegradable resin product of the present invention is 15 ° C. or less from the viewpoint of the temporal stability of the heat seal strength of the resin product. This is because when the phase transition index exceeds 15 ° C., the phase transition rate becomes slow, the hot tack strength is low, and heat sealability is insufficient. When the phase transition index is less than 10 ° C, the phase transition rate is high, but the heat resistance may be insufficient, and 10 ° C or more and 15 ° C or less is preferable.

By the way, the heat of crystal fusion ΔHm of the biodegradable resin product of the present invention represents the amount of crystal as described above, and the phase transition index (Tα-Tg) is relative to the heat of the polylactic acid resin. It represents the molecular chain mobility (thermoresponsiveness), in other words, the ease of rearrangement of molecular chains with respect to heat of the amorphous component (phase transition rate). Further, further describing this phase transition rate governs the melting / solidifying rate of the polylactic acid-based resin, and if this rate is high, the melting / solidifying rate of the polylactic acid-based resin will be high, and fusion will occur instantaneously. It develops a heat seal strength of a certain level or higher, and conversely, when the speed is slow, the melting / solidifying speed of the polylactic acid resin becomes slow, and it is instantly fused to develop a heat seal strength of a certain level or higher. Becomes difficult. From the above, the phase transition rate, and thus the phase transition index (Tα-Tg), can be used as an index of hot tack strength (peak intensity observed within 1 second after opening the heat seal die). When the index (Tα-Tg) ≦ 15 ° C., the polylactic acid-based resin instantly fuses and exhibits a heat seal strength of a certain level or higher (high hot tack strength), and as a result, high-speed heat seal processing is possible. Becomes

The heat of crystal fusion ΔHm and the phase transition index (T
α-Tg) depends on the amount and orientation degree of the amorphous component of the polylactic acid-based resin and the dispersibility of the crystalline component, that is, a large proportion depends on the resin composition, but by stretching and / or heat treatment Therefore, the usefulness of the biodegradable resin product is great in terms of the performance (machine suitability, heat resistance, high-speed heat seal suitability) of the biodegradable resin product. Then, the biodegradable resin product of the present invention is obtained by a simple screening method using a commercially available device (dynamic viscoelasticity measuring device, differential scanning calorimeter) as described below, and the resin composition (for example, the optical purity OP
_(A) crystalline polylactic acid (A) / optical purity OP _(B) amorphous polylactic acid (B), each crystallinity level and both
(A) / (B) ratio or addition of compatible plasticizer as third component), stretching and / or heat treatment processing conditions are appropriately selected and controlled to obtain the specific heat of fusion of crystal ΔH
m and a phase transition index (Tα-Tg).

The difference between the present invention and the prior art is that a polycrystal having a composition structure of a dense crystalline portion having a high optical purity and a sparse amorphous portion having a low optical purity having a specific heat of fusion of crystal and a specific phase transition index. A biodegradable resin product obtained by stretching and / or heat-treating a polylactic acid-based resin, which is mainly a lactic acid resin, does not impair its good mechanical suitability and may undergo thermal deformation or the like even at temperatures exceeding 100 ° C. It has both heat resistance that does not exist and high-speed heat-sealing suitability with a hot tack strength of 5 N / inchW or more (a level that enables high-speed sealing with packaging machines). Here, the good mechanical suitability is, for example, mechanical suitability such as continuous cutting of a roll-shaped raw film in the case of a film / sheet-like product, and a tensile elastic modulus in a range of about 0.5 to 5 GPa. It has rigidity. If it is out of such a range, it may be too soft or too hard, and wrinkles may be generated during the transport of the film in a packaging machine, a bag-making machine, etc., the film may be stretched or cut, or the film may be curled, resulting in mechanical suitability. There is a lack of problems.

The heat of crystal fusion at the crystal melting point Tm of the present invention
Phase transition index (Tα-Tg) when the amount ΔHm is 10 J / g or more
Of a biodegradable resin product with a high phase transition rate of less than 15 ° C
As a good resin composition, a certain amount of high optical purity and high density
Crystal parts and sparse amorphous parts with low optical purity are sea-island
Composition based on polylactic acid metered polymer having molecular structure
Is mentioned. More preferably, crystalline with high optical purity
A mixed resin of polylactic acid and amorphous polylactic acid with low optical purity
Optical purity OP as the main polylactic acid resin_(A)But
100-90% highly crystalline polylactic acid (A) and optical purity O
P_(B)Of 80-70% low crystalline polylactic acid (B)
And the weight ratio (A) / (B) is 80 / 20-40 /
60, and weighted average optical purity OP_(av)Is 90-80%
Mainly polylactic acid polymer in the range of (50% by weight or more)
There is a crystalline resin composition. Weight ratio (A) / (B)
(A) The ratio is over 90% and the weighted average optical purity OP_(av)
A biodegradable resin due to the large amount of crystal components above 90%
The product may not be suitable for heat sealing.
(A) ratio in (A) / (B) is less than 40% and OP
_(av)If it is less than 80%, the amount of crystal components is small
Degradable resin products may have poor heat resistance during heat treatment.

The weighted average optical purity OP _(av) (unit:%)
Is calculated by the following formula. OP _(av) = ([A] x OP _(A) + [B] x OP _(B) ) /
100, where [A] + [B] = 100, where OP _(A) and [A] are optical purity (unit%) and weight ratio (unit%) of crystalline polylactic acid (A), OP _(B ) ₎
And [B] represent the optical purity (unit%) and the weight ratio (unit%) of the amorphous polylactic acid (B). The mixing method and the mixing device of the polylactic acid polymers having different crystallinity are not particularly limited, and for example, the respective raw materials are supplied to the same single-screw or twin-screw extrusion kneader and melt-mixed. A method of directly extruding and processing products such as films,
Alternatively, there may be mentioned a method of extruding into a strand shape to prepare pellets and then again processing into a product such as a film with an extruder. The melt extrusion temperature is appropriately selected in consideration of the melting point and mixing ratio of the polylactic acid resin, but is usually 100 to 2
A temperature range of 50 ° C is chosen.

The polylactic acid polymer can be polymerized by condensation polymerization method (solution method: the method described in JP-A-7-2987, etc.), ring-opening polymerization method (lactide method: JP-A-9-31).
Publicly known method such as the method described in Japanese Patent No. 171) can be adopted, and the crystallinity and melting point can be changed by changing the monomer ratio (L / D ratio) derived from L-lactic acid and D-lactic acid. It can be adjusted freely. For example, in the polycondensation method (solution method), L-lactic acid or D-lactic acid or a mixture thereof can be directly dehydrated and polycondensed to obtain polylactic acid having an arbitrary composition. In addition, in the ring-opening polymerization method (lactide method), polylactic acid can be obtained by using lactide, which is a cyclic dimer of lactic acid, using a selected catalyst while using a polymerization regulator and the like as necessary. . It is also possible to use a polymerization method of increasing the molecular weight by using a binder such as polyisocyanate, polyepoxy compound, acid anhydride or polyfunctional acid chloride. The weight average molecular weight of the polylactic acid resin is preferably in the range of 50,000 to 1,000,000, and more preferably in the range of 100,000 to 500,000. When the molecular weight is less than 50,000, practical physical properties such as mechanical strength and heat resistance cannot be sufficiently obtained, and when the molecular weight exceeds 1,000,000, there is a problem that moldability is poor.

Next, a method for producing the biodegradable resin product of the present invention will be described. As a method of stretching and / or heat treatment, for example, in the form of a film or sheet, uniaxial stretching by a conventionally known stretching method such as an inflation method or a tenter method, or simultaneous or sequential biaxial stretching is performed. Is obtained by At that time, the extruded tube-shaped or sheet-shaped resin is rapidly cooled from the molten state and solidified in a state close to the amorphous state, and then the tube-shaped or sheet-shaped resin is heated to the glass transition temperature or higher and the melting point or lower. Stretching by the inflation method or the tenter method, or by subsequently performing heat treatment in a state in which the film or sheet-like material is gripped in order to suppress the heat shrinkability of the film or sheet-like material, A non-shrinkable film or sheet can be obtained.

The stretching ratio is preferably 1.5 to 6 times in each of the MD and TD directions, and is preferably in the range of 2 to 5 times from the viewpoint of mechanical suitability due to mechanical strength and rigidity. A larger stretch ratio is preferable from the viewpoint of strength and thickness accuracy of the obtained film or sheet, but if the stretch ratio exceeds 6 times in both the MD and TD directions, the stretching stability is extremely reduced. , Stable film formation may not be possible. When obtaining a non-shrinkable film or sheet, the heat treatment temperature is 100 ° C to the melting point T.
During m, the heat treatment time is at least in the range of 2-10 seconds. If it falls below this range, the heat shrinkage rate of the obtained film is high and it does not become a non-shrink film. If it exceeds this range, the film may melt and break during the heat treatment. The thickness of the stretched film or sheet-like material is preferably 5 to 500 μm, more preferably 7 to 400.
μm, but is not particularly limited in the present invention.

If desired, the biodegradable resin product of the present invention contains additives commonly used in the art, such as plasticizers, fillers, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants and antistatic agents. It is possible to add agents, flame retardants, nucleating agents, cross-linking agents, coloring agents, etc. within a range that does not impair the requirements and characteristics of the present invention. As the plasticizer, one generally used in the art can be selected and used.
Those that do not bleed out even if added in an amount of about 0% by weight are preferred. For example, aliphatic polycarboxylic acid ester, fatty acid polyhydric alcohol ester, oxy acid ester, epoxy plasticizer, etc. are included. Specific examples include triacetin (TA), tributyl acetyl citrate (ATB)
C), dioctyl sebacate (DBS), triethylene glycol diacetate, glycerin esters, butyl oleate (BO), adipic acid ether ester, epoxidized soybean oil (ESO), and the like. The filler is a substance generally added in the field of synthetic resins for the purpose of improving various properties such as strength and durability. There are inorganic type and organic type as the kind of the filler, but they can be appropriately selected and used depending on the intended film. Examples of the inorganic fillers include oxides of metals such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony and titanium, hydrates (hydroxides), sulfates, carbonates and silicates thereof. Compounds, double salts thereof, and mixtures thereof are roughly classified. Specific examples include, for example, aluminum oxide (alumina), its hydrate, calcium hydroxide, magnesium oxide (magnesia), magnesium hydroxide, zinc oxide (zinc white), lead oxides such as red lead and white lead. , Magnesium carbonate, calcium carbonate, basic magnesium carbonate, white carbon, mica, talc, glass fiber, glass powder, glass beads, clay, diatomaceous earth, silica, wollastonite, iron oxide, antimony oxide, titanium oxide (titania), Examples include lithopone, pumice powder, aluminum sulfate (gypsum, etc.), zirconium silicate, barium carbonate, dolomite, molybdenum disulfide, and iron sand. On the other hand, examples of the organic filler include cellulose type and starch type (including plasticized starch). Antioxidants include hindered phenolic antioxidants such as pt-butylhydroxytoluene and pt-butylhydroxyanisole; heat stabilizers include triphenyl phosphite, trilauryl phosphite and trisnolyl phenyl phosphite. Etc .; as the ultraviolet absorber, pt-butylphenyl salicylate, 2-
Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,4,5-trihydroxybutyrophenone, etc .; lubricants such as calcium stearate, zinc stearate, barium stearate, sodium palmitate, etc. Antistatic agents such as N, N-bis (hydroxyethyl) alkylamines, alkylamines, alkylallyl sulfonates, alkyl sulfonates; flame retardants such as hexabromocyclododecane and tris- (2,3-
Dichloropropyl) phosphate, pentabromophenyl allyl ether, etc .; Nucleating agents include polyethylene terephthalate, poly-transcyclohexanedimethanol terephthalate, etc.

The biodegradable resin product of the present invention may be a single material or a composite material of different types or the same type. Furthermore, printing,
For the purpose of coating, laminating, etc., the surface of the biodegradable resin product can be further hydrophilized by corona treatment, although it is more hydrophilic than the polyolefin resin product. The surface tension at that time is 40 dyn /
The range of cm to 60 dyn / cm is preferable.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to Examples and Comparative Examples. The evaluation methods used in the examples and comparative examples will be described below. First, the evaluation method of the constituent composition of the biodegradable resin product is as follows. (1) Optical Purity OP of Polylactic Acid Polymer As described above, the optical purity (OP: unit%) of the polylactic acid polymer which is the main resin constituting the biodegradable resin product constitutes the polylactic acid polymer. It is calculated by the following formula from the constituent ratio of L-lactic acid and / or D-lactic acid monomer units. OP = | [L] − [D] |, where [L] + [D] =
100

L-lactic acid constituting the polylactic acid polymer and /
Alternatively, the composition ratio of the D-lactic acid monomer unit is 1N-H after alkali decomposition of the sample with 1N-NaOH under the following measurement conditions.
A hydrolyzed sample (liquid) neutralized with Cl and adjusted in concentration with distilled water was used for high performance liquid chromatography (HPLC: L) manufactured by Shimadzu Corporation equipped with an optical isomer separation column.
C-10A-VP), UV at UV 254nm L
From the detection peak area ratio of lactic acid and D-lactic acid (area measurement by the perpendicular method), the weight ratio [L] (unit%) of L-lactic acid forming the polylactic acid polymer and D forming the polylactic acid polymer
-The weight ratio [D] (unit%) of lactic acid was determined, and the arithmetic mean (rounding) of 3 points per polymer was used as the measured value. Column: Tosoh TSKgel-Enantio-L1
[4.6 mm length × 25 cm length] Mobile phase: 1 mM-CuSO ₄ aqueous solution sample solution concentration: 25 pg / μL [concentration as polylactic acid polymer] Sample solution injection amount: 10 μL Solvent flow rate: 0.5 to 0.8 ml / Min column temperature: 40 ℃

(2) Weight average molecular weight M of polylactic acid polymer
w Tosoh gel permeation chromatography device (GPC: data processing unit GPC-8020, detector R
I-8020) under the following measurement conditions to obtain polystyrene-converted weight average molecular weight Mw using standard polystyrene, and obtain an arithmetic average of 3 points per polymer (rounded off).
Was used as the measured value. Column: Showa Denko Shodex K-805 and K-801 connection column [7.8 mm length × 60 cm length] Eluent: chloroform Sample solution concentration: 0.2 wt / vol% Sample solution injection amount: 200 μL Solvent flow rate: 1 ml / Minute column / detector temperature: 40 ° C

(3) Melting point Tm, glass transition temperature Tg, heat of crystal fusion ΔHm In accordance with JIS-K7121 and JIS-K7122, melting point Tm of biodegradable resin product, glass transition temperature T
g, heat of fusion of crystal ΔHm were measured. That is, from a biodegradable resin product that has been conditioned under standard conditions (23 ° C 65% RH) (left at 23 ° C for 1 week), 2 points (2 locations) each in the longitudinal direction (MD) and the width direction (TD) as test pieces. After cutting out about 10 mg each, Perkin Elmer (Per
Using a differential scanning calorimeter (heat flow rate type DSC), DSC-7 type manufactured by Kin-Elmer), a nitrogen gas flow rate of 25 m
The temperature was raised from room temperature (23 ° C.) to 200 ° C. at 1 / min (10 ° C./min) (first temperature rise), held at 200 ° C. for 10 minutes to completely melt, and then at 30 ° C./min to 0 ° C. Down to 0 ℃
For 2 minutes, and then under the above temperature rising conditions, the second heating (2
In the DSC curve drawn during the subsequent temperature increase), the melting (endothermic) peak apex during the primary temperature increase is the melting point Tm (° C.), and the endothermic peak area is the crystal fusion heat amount ΔHm (unit J / g), 2
Measured as the intersection (midpoint glass transition temperature) of the stepwise change partial curve at the next temperature rise and the straight line equidistant from the extension line of each base line in the vertical axis direction as Tg (unit: ° C), 4 per product The arithmetic mean (rounding off) of the points was used as the measured value.

(4) Phase transition temperature Tα From a biodegradable resin product which has been conditioned under standard conditions (23 ° C., 65% RH) (left at 23 ° C. for 1 week), 30 μ as a test piece
A strip-shaped film having a thickness of 7 mm, a width of 35 mm, and a length of 35 mm was cut out at two points each in the longitudinal direction (MD) and the width direction (TD), and then a film manufactured by Rheometrics Co., Ltd. according to JIS-K7198A. Viscoelasticity measuring device (Dynamic Mechanical Anal)
of the loss tangent tan δ of the temperature dependence curve of the dynamic viscoelasticity drawn while the temperature was raised from 0 ° C. to 160 ° C. at a measurement frequency of 1 Hz and 2 ° C./min. The temperature at the maximum point is the phase transition temperature Tα (unit: ° C)
As an average of 4 points per product (rounded)
Was used as the measured value. (5) Phase Transition Index The phase transition index (Tg-Tα) in the present invention is the absolute value of the difference between Tg and Tα measured by the methods (1) and (2).

Next, the method for evaluating the performance of the biodegradable resin product is as follows. <Mechanical suitability> 30 μm in the longitudinal direction (MD) and width direction (TD) as a test piece from a biodegradable resin product that has been conditioned under standard conditions (23 ° C 65% RH) (left at 23 ° C for 1 week).
After cutting three strips each having a thickness of 10 mm, a width of 200 mm, and a length of 200 mm, according to ASTM-D882-95a, a Tensilon universal tester manufactured by A & D Co., RTC
-1210 type is used to perform a tensile test under a standard condition with a chuck distance of 100 mm and a pulling speed of 10 mm / min, and a tensile elastic modulus (unit GPa) is calculated with an arithmetic average value (two significant digits) of 6 points per product. did. From the viewpoint of mechanical suitability, as a measure of the waist strength to the extent that wrinkles do not occur when the film is conveyed, those having a tensile modulus of elasticity of 0.5 GPa or more and 5 GPa or less are suitable (evaluation code: ○), Those out of the range were evaluated as not suitable (evaluation symbol: x).

<Heat resistance> Standard state (23 ° C 65% RH)
Approximately 20 mm thickness x 300 m after cutting out 3 points as a test piece into a square film of 30 μm thickness x 300 mm square as a test piece from the biodegradable resin product that has been conditioned (left at 23 ° C for 1 week)
A film (tensile test piece) in which a film was fixed in a tension state with a double-sided tape and a metal clip on a wooden frame having an outer corner (inner corner of 260 mm) was used. The evaluation of the heat resistance of the biodegradable resin product is performed by the heat shrinkage treatment step (for example, 3
Side-sealed pillow or L-type wrapping machine shrinking process), and heat-setting treatment process for suppressing heat shrinkage during production of non-shrinkable film (for example, heat after sequential biaxial stretching in a tenter) This is a device that can set the heat treatment temperature (hot air temperature) and heat treatment time (heating furnace passage time) by moving this tension test piece in the heating furnace with a belt conveyor to assume set processing). Heating tunnel, shrink tunnel manufactured by K & U Systems, MS-
Using a Model 8441, changes in the appearance before and after the heat treatment, in which the tension test piece was passed through a heating tunnel at 120 ° C. for 3 seconds, were observed and evaluated as follows. Evaluation scale: Evaluation symbol Scale ○ The appearance of the film was unchanged and good. × Haze (appearance with thick and thin spots) partially occurred, impairing aesthetics.

<High Speed Heat Seal Suitability> Standard state (23
3 in the longitudinal direction (MD) as a test piece from a biodegradable resin product that has been conditioned (left at 23 ° C for 1 week) at 65 ° C RH)
0 μm thickness x 25.4 mm width (= 1 inch width) x 250
After cutting 3 mm long strips of film, ASTM
-1000 mS after opening the die using a hot tack measuring device manufactured by Theler in accordance with F1921-98.
The hot tack strength (HT strength: unit N / 1 inchW), which is the peak strength observed until (= 1 second), was measured under the following sealing conditions. Upper die shape: 60 degree V-shaped (semicircular shape with tip section R = 1 mm x 5.25 inch length) Metal die Lower die shape: flat type (0.5 inch width x 5.25 inch)
ch length) Rubber lining die seal surface dimension: 1 inch × 1 mm Seal temperature: (upper die temperature) 120 ° C., (lower die temperature) 25 ° C. Sealing time: 1000 mS Sealing pressure: 13 ± 1 MPa

The suitability of a biodegradable resin product for high-speed heat sealing is that the resin product of a film or sheet is continuously wound on a packaging machine or bag-making machine from the state of a roll-shaped raw film in a packaging machine or bag. High-speed heat-sealing strength in packaging machines and bag-making machines from the viewpoint of continuous heat-sealing stability in which the packaged item does not break out of the seal part or the seal part partially peels (or breaks) when heat-sealing The hot tack strength (HT strength: peak strength, unit: N / 1 inchW) corresponding to was evaluated as follows. Evaluation scale: Evaluation symbol HT strength scale ○ 5 or more The strength is in the practical range, and there is no breakage of the packaged object or breakage of the seal line. × Less than 5 The sealed part may peel off (break) and the packaged item may break out.

(8) Comprehensive Evaluation The following is a comprehensive result index of the above-mentioned evaluation of mechanical suitability, heat resistance and suitability for high speed heat sealing. Evaluation scale: Evaluation symbol If there is no evaluation ○ × or △, and there is ○, the task is achieved at a high level. It is hard to say that the task has been achieved when there is no Δ and there is Δ. In the case where XX exists, the problem has not been achieved. In the following examples and comparative examples, a film, which is one form of a biodegradable resin product, was evaluated.
The polylactic acid resin is a known polycondensation method (solution method).
The polylactic acid polymer shown in Table 1 obtained by the ring-opening polymerization method (lactide method) was used. Incidentally, it goes without saying that commercially available polylactic acid polymers can also be obtained by the same method.
Like the plasticizers and aliphatic polyesters shown in Table 1, they are easily commercially available.

The film is stretched by melt-kneading the resin raw materials shown in Table 1 using a co-directional twin-screw extruder so that the resin composition shown in Table 2 is obtained, and extruding the resin having a resin temperature of 200 ° C. from a T-die. A substantially amorphous sheet obtained by rapidly cooling with a casting roll at 35 ° C. is heated to 75 ° C. and then heated in the MD direction to 3
Double roll drawing, then T with a tenter at a drawing temperature of 80 ° C
A stretched film of polylactic acid resin having a thickness of 30 μm was obtained by stretching the film 4 times in the D direction and then cooling the film in the stretched state to around room temperature. In all of the examples and comparative examples, the film obtained by the above stretching process was used. However, the resin composition and form of the biodegradable resin product in the present invention are not limited to this.

[0035]

Examples 1 to 3 and

Comparative Examples 1 and 2 Examples 1 to 3 and Comparative Example 1 shown in Table 2
The resin products of Nos. 2 to 2 are evaluated with respect to a stretched film having a resin composition composed only of a polylactic acid polymer of highly crystalline polylactic acid (A) and low crystalline polylactic acid (B) shown in Table 1. As shown in the evaluation results in Table 2, ΔHm ≧ 10 and phase transition index (Tα-Tg) ≦ 15, or weight ratio (A) /
Examples 1 to 3 in which (B) is in the range of 80/20 to 40/60 and the weighted average optical purity OP _(av) is in the range of 90 to 80
Was excellent in all of mechanical suitability, heat resistance and suitability for high speed heat sealing.

[0036]

Example 4 and

Comparative Example 3 The resin products of Example 4 and Comparative Example 3 shown in Table 2 were compared with the polylactic acid polymer of highly crystalline polylactic acid (A) and / or low crystalline polylactic acid (B) shown in Table 1. Was evaluated for a stretched film having a resin composition containing a plasticizer (the polylactic acid polymer was defined as 100 parts by weight and the plasticizer content was expressed in parts by weight). As shown in the evaluation results in Table 2, in Comparative Example 3, a slight improvement in hot tack strength was observed due to the incorporation of a plasticizer compatible with the polylactic acid polymer, but the phase transition index (Tα-Tg) was Since it is still large, it cannot be said that the hot tack strength is sufficient, resulting in lack of suitability for high-speed heat sealing in a practical range. In Example 4, ΔHm ≧
Since 10 and the phase transition index (Tα-Tg) ≦ 15,
It was excellent in mechanical suitability, heat resistance, and heat seal suitability.

[0037]

Example 5 and

Comparative Examples 4 and 5 Example 5 and Comparative Examples 4 and 5 shown in Table 2
The resin product of is an evaluation of a stretched film having a resin composition in which an aliphatic polyester is blended with a polylactic acid polymer of highly crystalline polylactic acid (A) and / or low crystalline polylactic acid (B) shown in Table 1. (Polylactic acid polymer is 100 parts by weight and the amount of the aliphatic polyester compounded is shown in parts by weight).
As shown in the evaluation results in Table 2, although the composition was an aliphatic polyester having poor compatibility with the polylactic acid polymer, Example 5 was used.
Since ΔHm ≧ 10 and the phase transition index (Tα-Tg) ≦ 15, all of the mechanical suitability, heat resistance, and heat seal suitability were excellent. In Comparative Example 4, the heat of crystal fusion is low and the melting point of the crystal is also low, so that the heat resistance is inferior. In Comparative Example 5, the phase transition index (Tα-Tg) is large, so the hot tack strength cannot be said to be sufficient. It was not suitable for high-speed heat sealing in the area.

As a precaution, regarding the films which are resin products of Examples 1 to 5 and Comparative Examples 1 to 5 shown in Table 2, a horizontal pillow shrink wrapping machine FW3451A manufactured by Fujikikai Co., Ltd.
Using the mold, 100 packs of shrink wrappings were prepared at a speed of 40 packs / minute, and the finished appearance was evaluated. As a packaged item, use a bento container with a lid of expanded polystyrene transparent sheet on a tray made of expanded polystyrene,
The film is sent in a tubular shape around the bento container, and the seam of the film on the bottom of the package is heat-sealed.
Both ends of the tubular film were fused and sealed (the margin ratio was 30% in both the vertical and horizontal directions). The small holes for venting air were created by needle-like protrusions on the bottom of the package. Subsequently, it was conveyed to a heating tunnel of 120 ° C., and the shrinkage was carried out at a tunnel residence time of 3 seconds to obtain a shrink package. Comparative Example 1
Also, the shrink wrapping body made of the film of Comparative Example 4 has a finish aesthetic in that the haze like the thickness unevenness of the film is partially seen on the surface of the film portion covering the polystyrene transparent sheet lid of all the wrapping bodies. It becomes bad, and the shrink wrapping bodies made of the films of Comparative Examples 2, 3, and 5 are
In each case, breakage was observed in the seal portion of 80% of the packages.
The shrink wrapping body made of the film of the present example is excellent in the appearance and finish of the film in all 100 packs without tearing at the seal portion, and satisfies all the mechanical suitability, heat resistance and heat seal suitability. I confirmed that it was a thing.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

The biodegradable resin product of the present invention is a resin product which is biodegradable in a natural environment and is excellent in mechanical suitability, heat resistance and high-speed heat sealing suitability. Further, a package packaged thereby, and a composite material using the same are biodegradable heat-shrinkable or heat-nonshrinkable stretched film or sheet-like materials, specifically, Is
It is very useful as a shrinkable film or sheet material for lunch boxes or prepared food containers, or as a non-shrinkable film or sheet material for zipper bags.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA43 AA83 AF29 AF35                 4F100 AK41A AL05A AS00B BA01                       EJ37 GB15 GB23 JA05A                       JA11A JD04A JJ03 JK01                       YY00A                 4J002 CF18W CF18X GG02 GK01

Claims (5)

[Claims] 1. A biodegradable resin product mainly comprising a polylactic acid polymer containing L-lactic acid and / or D-lactic acid as a main component,
A biodegradable resin product having a heat of crystal fusion ΔHm of 10 J / g or more and a phase transition index (Tα-Tg) of 15 ° C. or less. [However, the symbols in the above formula represent the test for the temperature dependence of dynamic viscoelasticity (JIS-K7198).
The phase transition temperature (unit: ° C) of loss tangent tan δ in A) is T
α, differential scanning calorimetry (JIS-K7121 and JIS
-K7122) glass transition temperature (unit: ° C) Tg,
ΔHm is the heat of fusion of crystal (unit: J / g) at the melting point Tm.
And These are measured values in the range of 0 ° C to 200 ° C. ] 2. 10 ≦ (Tα−Tg) ≦ 15, and 1
The biodegradable resin product according to claim 1, wherein 0 ≦ ΔHm ≦ 30. 3. A biodegradable resin product, which is a composite containing at least one layer comprising the biodegradable resin product according to claim 1 or 2. 4. The raw material according to any one of claims 1 to 3, wherein the peak value of the hot tack strength per 25.4 mm width of the heat-sealed portion according to ASTM-F1921-98 is 5 N or more. Degradable resin product. 5. L-lactic acid and / or D-lactic acid as a main component
In biodegradable resin products mainly composed of polylactic acid polymer,
The polylactic acid polymer satisfies the following formulas (1) to (3)
Optical purity OP_(A)Crystalline polylactic acid (A) and optical purity OP
_(B)The composition should be a mixture of amorphous polylactic acid (B)
Biodegradability according to any one of claims 1 to 5,
Resin products. (1) 90% ≤ OP_(A)≤100%, 70% ≤OP
_(B)≤80% (2) 40% ≦ [A] / ([A] + [B]) ≦ 80% (3) 80% ≤ OP_(av)≤ 90% [However, OP_(av)Is the weighted average optical purity, OP_(av)=
([A] × OP_(A)+ [B] × OP_(B)) / 100,
[A] + [B] = 100. Also OP_(A)as well as
[A] is the optical purity (%) of crystalline polylactic acid (A) and
And weight ratio (unit%), OP _(B)And [B] are amorphous
Optical purity (unit%) and weight ratio (unit) of polylactic acid (B)
%). ]