JP2002249556A - Molded article for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded article prepared from a thermoplastic resin composition mainly composed of a glycolic acid-based copolymer, the article being biodegradable, having excellent gas barrier properties, heat resistance, transparency and mechanical strength, and being suitable for packaging use. SOLUTION: This molded article for packaging is prepared from a thermoplastic resin composition mainly composed of a glycolic acid-based copolymer, wherein the melting point in the first temperature elevating step is >=175 deg.C and <=205 deg.C, the heat of crystallization in the first cooling step is 0 J/g, and the heat of fusion in the second temperature elevating step is >=0 J/g and <20 J/g in the DSC measurement, the relative degree of crystallinity is >=3% and <=50%, and the logarithmic viscosity number is >=0.15 m<3> /kg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article made of a thermoplastic resin composition mainly composed of a glycolic acid copolymer suitable for use as a packaging material. More specifically, it is a thermoplastic resin composition mainly composed of a glycolic acid-based copolymer suitable for packaging materials, having biodegradability, and having excellent gas barrier properties, heat resistance, transparency, and mechanical strength. It relates to a molded article.

[0002]

2. Description of the Related Art Packaging of foods and pharmaceuticals facilitates the work of transporting and distributing their contents,
Maintaining quality is a particularly important role. Therefore, packaging materials are required to have high quality maintenance performance. Specifically, the properties that protect the contents during long-term storage include mechanical strength against external forces such as impact and puncture, gas barrier properties against oxidative deterioration of the contents due to external oxygen and deterioration due to moisture evaporation of the contents, and packaging materials. Stability such as oil resistance and heat resistance, which are not denatured or deformed during storage or use, and hygiene without transfer of harmful substances, off-flavors and off-flavors from the packaging material itself.

Conventionally, plastic products have been used for these packaging materials because of their convenience in processing and use. However, in today's consumer society, the amount of use is increasing year by year, and at the same time, the problem of plastic waste is getting more serious every year. Most of plastic waste is disposed of by incineration or landfill, but in recent years, from the viewpoint of environmental conservation, material recycling that is collected and reused as a raw material for plastic products has been proposed.

However, as described above, the performance requirements of plastic products as packaging materials vary widely, and a single type of plastic alone cannot satisfy all of these requirements. For example, a multilayered gas barrier film or molded container In general, several types of plastics are used in combination. Such packaging materials are very difficult to separate into various resins, and material recycling is impossible in view of cost and the like.

On the other hand, JP-A-10-60137 discloses that the melting point Tm is 150 ° C. or higher and the heat of fusion ΔHm is 20 or more.
J / g or more, density of non-oriented crystallized product is 1.50 g / cm
Disclosed is a polyglycolic acid sheet comprising a thermoplastic resin containing a specific polyglycolic acid of ³ or more, wherein the polyglycolic acid sheet exhibits disintegration in soil, and has excellent toughness and barrier properties. There is also a statement that it can be used as.

However, Japanese Patent Application Laid-Open No.
No. 7 discloses a polyglycolic acid sheet having a melting point Tm.
However, at about 150 ° C., the heat resistance is still insufficient,
When used as a microwave oven container, there has been a problem that the material is greatly deformed due to heat from the heated contents, or melt-punching occurs. As a required characteristic of the packaging material, transparency is also an important factor in order to enhance the product value by making the contents easily recognizable and a display effect that encourages the purchaser's willingness to purchase. However, Japanese Patent Application Laid-Open No. Hei 10-60
The polyglycolic acid sheet described in Japanese Patent No. 137 has a high heat of fusion of 20 J / g or more and a density of non-oriented crystallized material of 1.50 g / cm ³ or more. There has been a problem that it is difficult to obtain a sheet or that the sheet has to be rapidly cooled during molding in order to improve transparency, so that the sheet manufacturing process becomes very complicated.

The relation between the heat of fusion and the density and the crystallinity will be described in detail later. For example, there are a thermal analysis method and a density method as a method for measuring the crystallinity of a resin. It is associated with the density (edited by the Society of Analytical Chemistry, Japan, New Edition, Polymer Analysis Handbook, p. 340, Kinokuniya Shoten (1995)).

[0008]

An object of the present invention is to provide a glycolic acid-based copolymer which has biodegradability and is excellent in gas barrier properties, heat resistance, transparency and mechanical strength, and is suitable for use in packaging materials. It is an object of the present invention to provide a molded article comprising a thermoplastic resin composition mainly composed of:

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the melting point, heat of crystallization, heat of fusion, and relative crystallization of a copolymer whose repeating unit is mainly composed of glycolic acid are obtained. Degree, and by specifying the logarithmic viscosity number, the molded body made of a thermoplastic resin composition mainly comprising the polymer has biodegradability, and gas barrier properties, heat resistance,
The inventors have found that they have excellent transparency and mechanical strength and are suitable for use in packaging materials, and have reached the present invention.

That is, the present invention provides: Amorphous sheet of glycolic acid copolymer is heated to 150 ° C
Scanning calorimetry (JIS K) using a test piece heat-treated for 100 minutes at a heating and cooling rate of 10 ° C./min.
7121 and K7122), the melting point Tm (° C.) in the first heating process, the heat of crystallization ΔHc (J / g) in the first cooling process, and the heat of fusion ΔH in the second heating process.
m (J / g) satisfies the following formulas (1) to (3), the relative crystallinity Xr represented by the following formula (4) is 3% or more and 50% or less, and the logarithmic viscosity number [η] is 0. A molded article for a packaging material comprising a thermoplastic resin composition mainly composed of a glycolic acid-based copolymer of not less than 15 m ³ / kg, Formula (1) 175 ≦ Tm ≦ 205 Formula (2) ΔHc = 0 Equation (3) 0 ≦ ΔHm <20 Equation (4) Xr = [(ρb−ρa) / (ρc−ρa)] ×
(Ρc / ρb) × 100, where ρa: density of amorphous substance (g / cm ³ ) ρb: density of crystallized substance heated at 150 ° C. for 5 minutes (g / cm ³ )
cm ³ ) ρc: density of crystallized material heated at 150 ° C. for 100 minutes (g / cm ³ ) A glycolic acid-based copolymer is a copolymer obtained by ring-opening polymerization using glycolide and a monomer other than glycolide, wherein the proportion of a repeating unit composed of glycolide is 78 to 90 mol%, 2. The molded article for a packaging material according to the above item 1, wherein the component ratio of the repeating unit composed of the monomer is 22 to 10 mol%. 3. The molded article for a packaging material according to the above item 2, wherein the monomer other than glycolide comprises at least one selected from a cyclic dimer of an aliphatic hydroxycarboxylic acid and a lactone.

Hereinafter, the molded article for packaging material of the present invention will be described in detail. The molded product for a packaging material of the present invention uses a glycolic acid-based copolymer having crystallinity such that the heat of crystallization ΔHc, the heat of fusion ΔHm, and the relative crystallinity Xr defined in the present invention are each in a specific range. Thereby, it has been found that transparency can be obtained without going through complicated steps such as rapid cooling at the time of production of a molded article, and that the transparency can be maintained at a high level even when the molded article is stored for a long period of time. It is based on that.

[0012] The crystallinity of a polymer refers to the easiness of crystallization of the polymer, and is expressed using the crystallization speed and the degree of crystallization as indices. The crystallization rate is the rate at which an irreversible transition from a supercooled melt to a crystalline state occurs.As a guide, the crystallization temperature is measured during the uniform cooling process in thermal analysis. It is said that the higher the speed, the higher the crystallization temperature (edited by the Japan Society for Analytical Chemistry, New Edition, Polymer Analysis Handbook, p. 339, Kinokuniya Shoten (1995)).

The glycolic acid-based copolymer used in the present invention has a differential scanning calorimeter (hereinafter referred to as DS according to JIS K7121 and K7122) measured at a cooling rate of 10 ° C./min.
Called C. ) Heat of crystallization during the first cooling process
It is necessary that Hc is 0 J / g. That is, it is necessary to have a crystallization rate at which crystallization does not occur under the DSC measurement conditions (cooling rate 10 ° C./min). When the crystallization peak does not appear in the DSC uniform cooling process (heat of crystallization ΔHc = 0 J / g), the crystallinity of the test piece is amorphous and does not crystallize at all, or the crystallization speed is low. Under DSC measurement conditions (cooling rate: 10 ° C./min), two types of crystallization do not occur. Here, the glycolic acid-based polymer of the present invention has a melting point Tm of 175 ° C. or more and 205 ° C. in the first heating process in DSC as described later.
This is different from the above-described case where the film is amorphous and does not crystallize at all.

The glycolic acid copolymer used in the present invention has a heat of crystallization ΔHc of 0 J in the first cooling step.
/ G other than the above, a molded article for a packaging material composed of a thermoplastic resin composition mainly composed of the polymer requires a special non-crystallization step such as a quenching operation at the time of its production, and the transparency of the molded article is increased. Cannot be maintained at a high level. On the other hand, the crystallinity is defined as a weight fraction of a crystalline region in a polymer solid, and is measured by, for example, a thermal analysis method or a density method.

In the thermal analysis method, the ratio of the measured heat of fusion ΔHm of the test piece to the theoretical heat of fusion ΔHf is generally obtained from the crystallinity Xc (%) = ΔHm / ΔHf × 100 (edited by the Japan Society for Analytical Chemistry, New Edition Molecular analysis handbook,
p. 339, Kinokuniya Bookstore (1995)). In the formula, ΔHm is the value of differential scanning calorimetry (DSC; JIS K7).
ΔHf is, for example, POLYMER HANDBOO in the case of a homopolymer.
K (John Wiley & Sons) and the like are used.

In the density method, the measured density of a test piece is generally d, and the densities of completely amorphous and completely crystalline are respectively da.
And dc, the degree of crystallinity Xc (%) = [(dd−
a) / (dc-da)] × (dc / d) × 100 (edited by the Japan Society for Analytical Chemistry, New Edition, Polymer Analysis Handbook, p.586, Kinokuniya Shoten (1995)).
In the formula, d and da are values obtained by measuring a test piece or an amorphous substance obtained by heating and melting the test piece and then quenching the material by, for example, a float-sink method or a density gradient tube method (based on JIS K7112). In the case of a homopolymer, for example, POLY
MER HANDBOOK (JOHN WILEY &
SONS) and the like are used. However, in the case of a copolymer, ΔHf and dc often have no literature value because the copolymerization components and their component ratios are diversified.

In the thermal analysis method, the above formula for determining the crystallinity Xc means that the larger the measured heat of fusion ΔHm of the test piece, the higher the crystallinity. The crystallinity is determined based on the value of ΔHm.
Heat of fusion ΔHm in the second heating process in DSC measurement
Is less than 0 J / g and less than 20 J / g. Further, in the density method, the crystallinity of the polymer is determined from the value of the relative crystallinity obtained using the density obtained by heating and crystallizing under conditions that the crystallization is considered to proceed sufficiently. In the present invention, the relative crystallinity Xr represented by the following formula (4) needs to be in the range of 3% or more and 50% or less. Formula (4) Xr = [(ρb−ρa) / (ρc−ρa)] ×
(Ρc / ρb) × 100, where ρa: density of amorphous substance (g / cm ³ ) ρb: density of crystallized substance heated at 150 ° C. for 5 minutes (g / cm ³ )
cm ³ ) ρc: density of crystallized material heated at 150 ° C. for 100 minutes (g / cm ³ )

The fact that the value of ΔHm of the glycolic acid-based copolymer used in the present invention is 0 J / g means that the polymer of the present invention has a value of 1 in DSC as described later, as in the case of the heat of crystallization ΔHc described above. Since the melting point Tm in the second heating process is 175 ° C. or more and 205 ° C. or less, unlike the case where it is amorphous and does not crystallize at all, crystallization is not performed under the measurement conditions of DSC (heating rate 10 ° C./min). This means that the crystallization rate does not occur, and a molded article for a packaging material composed of a thermoplastic resin composition mainly composed of the polymer does not require a special non-crystallization step such as a quenching operation during its production. The manufacturing process is simplified, and the molded article has excellent transparency, and the transparency can be maintained at a high level even when stored for a long period of time.

On the other hand, when the value of ΔHm is not less than 20 J / g, since the polymer has very high crystallinity, a molded article for a packaging material composed of a thermoplastic resin composition containing the polymer as a main component is not provided. In order to remarkably deteriorate the transparency or to improve the transparency, a special non-crystallization step such as a quenching operation is required at the time of molding, which complicates the production process. The value of ΔHm is preferably 0 J / g or more and 1 to obtain a molded article for packaging material having higher transparency.
The range of 8.0 J / g or less is preferable.

When the relative crystallinity Xr represented by the above formula (4) is lower than 3%, the crystallinity of the glycolic acid-based copolymer is too low, and the thermoplastic polymer mainly composed of the polymer is used. A molded article for a packaging material made of a resin composition has extremely poor heat resistance. On the other hand, when the value of Xr is higher than 50%, since the polymer has very high crystallinity, the molded article for a packaging material composed of a thermoplastic resin composition mainly composed of the polymer has a high transparency. In order to improve the transparency significantly or to improve the transparency, a special non-crystallization step such as a quenching operation is required at the time of molding, which complicates the production process. The value of Xr should be 10% or more to combine higher heat resistance and higher transparency.
A range of 0% or less is preferable.

In the above formula (4), when the density ρc when heated at 150 ° C. for 100 minutes is equal to the density ρa of the amorphous material before the heating, the relative crystallinity Xr is calculated by the formula. It cannot be calculated. In this case, the sample subjected to the measurement does not crystallize under the heating conditions, meaning that the crystallinity is extremely low or amorphous, and the relative crystallinity Xr is 0%. Deemed departures from the claims of the invention.

The melting point of the glycolic acid copolymer used in the present invention is determined by heating and pressurizing the glycolic acid copolymer with a heating press set at 250 ° C. for 5 minutes and then quenching with a cooling press. Differential scanning calorimetry (according to DSC, JIS K7121) in which a crystallized product obtained by heating a sheet in a hot-air circulating thermostat set at 150 ° C. for 100 minutes was used as a test piece at a heating and cooling rate of 10 ° C./min. Melting point Tm in the first heating process is 175 ° C or higher and 205 ° C
Within the following range. If the value of Tm is lower than 175 ° C., the melting point of the glycolic acid-based copolymer is too low, and the heat resistance of the molded article composed of the thermoplastic resin composition containing the polymer as a main component is extremely poor. It cannot be used in applications that require heat resistance as containers or containers.

On the other hand, when the value of Tm is higher than 205 ° C., the crystallinity of the glycolic acid-based copolymer becomes extremely high, so that a molded article made of a thermoplastic resin composition mainly comprising the polymer is used. Is extremely deteriorated in transparency and cannot be used in applications where transparency is required as a packaging material, or a special amorphization step such as a quenching operation is required during molding to improve transparency. The process becomes complicated. The value of Tm is preferably selected from the range of 185 ° C. or more and 200 ° C. or less in order to combine higher heat resistance and higher transparency. In the above differential scanning calorimetry,
When there are a plurality of endothermic peaks due to melting of the crystal, the highest endothermic peak temperature is defined as the melting point Tm.

The glycolic acid copolymer which is a main material constituting the molded article for packaging material of the present invention is glycolide (1,4) which is a cyclic dimer of glycolic acid as a main monomer.
-Dioxa-2,5-dione), or direct dehydration polycondensation using glycolic acid, for example, polycondensation using a glycolic acid ester such as methyl glycolate while removing alcohol. And copolymers obtained by copolymerizing monomers other than glycolide which can be copolymerized with these main monomers, which satisfy the requirements of the present invention.

Examples of monomers other than glycolide used for copolymerization other than the main monomer include L-lactic acid and D-lactic acid.
-Lactic acid, 2-hydroxy-2,2-dialkylacetic acid including 2-hydroxyisobutyric acid, 3-hydroxybutyric acid,
Hydroxyvaleric acid, 3-hydroxyhexanoic acid, 4-hydroxybutanoic acid, other known aliphatic hydroxycarboxylic acids, ester derivatives of these aliphatic hydroxycarboxylic acids, same or different cyclic dimers of these aliphatic hydroxycarboxylic acids And β-butyrolactone, β-propiolactone, pivalolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-
At least one is selected from lactones such as valerolactone and ε-caprolactone.

In addition to the above, an equimolar amount of a polyhydric alcohol and a polycarboxylic acid may be combined and copolymerized with the above-mentioned main monomer. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 2,2-dimethyl-1. Aliphatic diols such as 1,3-propanediol, 1,6-hexanediol, 1,3-cyclohexanol, 1,4-cyclohexanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or These aliphatic diols include a plurality of bonds, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, and the like. Examples of the polycarboxylic acid include malonic acid, succinic acid, glutaric acid, 2,2-dimethylglutaric acid, and adipine. Acid, pimelic acid, spearic acid, azelaic acid, Bhasin acid, 1,3-cyclopentane dicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as diglycolic acid, terephthalic acid, isophthalic acid, 1,
Aromatic dicarboxylic acids such as 4-naphthalene dicarboxylic acid and 2,6-naphthalene dicarboxylic acid; aliphatic dicarboxylic acids and ester derivatives of aromatic dicarboxylic acids; anhydrides of these aliphatic dicarboxylic acids; and the like. You may combine with an ingredient.

Among the glycolic acid-based copolymers which are the main materials constituting the molded article for packaging material of the present invention exemplified above, preferred copolymers are selected from the viewpoint that it is easy to obtain a copolymer having a higher molecular weight. A copolymer obtained by ring-opening polymerization using glycolide and a monomer other than glycolide, wherein the proportion of the repeating unit composed of glycolide is 78 to 90 m
ol%, and a component ratio of a repeating unit composed of a monomer other than glycolide is 22 to 10 mol%.
More preferably, the proportion of the repeating unit composed of glycolide is 81 to 88 mol%, and the proportion of the repeating unit composed of monomers other than glycolide is 19 to 12 mol%.

Among the monomers constituting the copolymer, the monomer other than glycolide is preferably at least one selected from cyclic dimers of aliphatic hydroxycarboxylic acids and lactones. Lactide (3,6-dimethyl-1,4-dioxa-2,5-dione) which is a dimer is particularly preferred. In addition, lactide is an optically active substance and may be any of L-form and D-form.
It may be an L-isomer mixture or a meso-isomer. Further, a mixture of a glycolide-L-lactide copolymer and glycolide-D-lactide may be used.

The method for producing the glycolic acid copolymer used in the present invention is not particularly limited, and is carried out by a conventionally known general method. For example, in order to obtain a glycolic acid-based copolymer by ring-opening polymerization using glycolide as a main monomer, the method of Gilding et al. (Polymer, vo.
l. 20, December (1979)) and the like, but are not limited thereto.

The molecular weight of the polymer is at least 0 in terms of logarithmic viscosity number so that a molded article composed of a thermoplastic resin composition mainly composed of the polymer has a mechanical strength against an external force required as a packaging material. .15 m ³ / kg or more is required, and preferably 0.18 m ³ / kg or more. The logarithmic viscosity number [η] is generally a value determined by the following equation (5), and can be approximated to the intrinsic viscosity used as an index of the molecular weight of a polymer in a dilute solution having a concentration of 0.2% or less (Comprehensive Dictionary of Chemical Encyclopedia) Edition, p.746, Kyoritsu Shuppan (196
3), and the new edition Polymer Analysis Handbook, p. 12
0, Kinokuniya Bookstore (1995)). Formula (5) [η] = {ln (t / to)} / c, where t: Flowing time of polymer solution measured by capillary viscometer (second) to: Flowing of solvent measured by capillary viscometer Time (sec) c: Concentration of solute polymer (kg / m ³ )

On the other hand, the upper limit of the molecular weight of the polymer is preferably 0.8 to 0.8 in terms of logarithmic viscosity in order to more easily form a molded product.
It is desirable to keep the melt flow rate at 0 m ³ / kg or less, but there is no particular limitation as long as the melt fluidity can be adjusted by adding a plasticizer or the like. The molecular weight of the glycolic acid-based copolymer used in the present invention is 7.0 × 1 when represented by a number average molecular weight.
0 ⁴ or more, preferably 1.0 × 10 ⁵ or more. In addition,
The upper limit of the molecular weight is 7.0 × 10 when represented by the number average molecular weight.
⁵ or less, preferably kept to 6.0 × 10 ⁵ or less. The molded article for a packaging material of the present invention is characterized by being composed of a thermoplastic resin composition mainly containing the above-mentioned specific glycolic acid copolymer, and the thermoplastic resin composition referred to in the present invention below. explain.

In the present invention, the thermoplastic resin composition containing the above-mentioned specific glycolic acid-based copolymer as the main component refers to the glycolic acid-based copolymer alone or the glycolic acid-based copolymer and another polymer. It refers to a composition with a coalescence, a composition of a copolymer alone or a copolymer with another polymer, and a composition with additives such as a plasticizer and an antioxidant. The composition ratio of the thermoplastic resin composition varies depending on the quality retention performance of the content required when used as a packaging material, for example, gas barrier properties and heat resistance, but desirably, the repetition of each polymer of the composition is repeated. This is a case in which a component ratio of 50 mol% or more of the whole unit is mixed so as to be a repeating unit composed of glycolide. In a case of a packaging material application in which a higher quality retention performance of contents is required, the component ratio is more preferably 70 m.
ol% or more.

Specifically, for example, as a glycolic acid copolymer, 80 mol% of glycolide and 20 mol of lactide
% Of a repeating unit and 100 m of lactide
In the case of mixing with polylactic acid consisting of ol% of repeating units, the composition ratio of the glycolic acid-based copolymer is required to be 50 mol% or more of the total repeating units of the composition. It must be at least 66.5% by weight. When a glycolic acid-based copolymer is mixed with a copolymer composed of repeating units of 90 mol% of glycolide and 10 mol% of lactide and a polylactic acid composed of repeating units of 100 mol% of lactide, all the repeating units of the composition are mixed. The proportion of glycolide in the total is 50
In order to make it equal to or more than mol%, the composition ratio of the glycolic acid-based copolymer must be made 60.3% by weight or more.

The proportion of the repeating unit composed of glycolide in the thermoplastic resin composition constituting the molded article can be analyzed by a usual analytical technique. For example, a molded article is made of hexafluoroisopropanol (hereinafter, HFIP).
Abbreviated. ) And remove insolubles by filtration.
Next, the HFIP solution of the obtained thermoplastic resin composition is poured into methanol to reprecipitate the resin composition components.
After sufficiently drying the obtained reprecipitated resin composition component with a vacuum dryer, deuterated trifluoroacetic acid or deuterated HF is used.
By measuring 1H-NMR or 13C-NMR using IP as a solvent, the component ratio of a repeating unit composed of glycolide in the thermoplastic resin composition can be analyzed.

In the thermoplastic resin composition of the present invention, when another polymer is mixed with the glycolic acid-based copolymer specified in the present invention, the other polymer that can be mixed is as described in the above specific examples. At least one is selected from the polylactic acids listed above and the polymers listed below, and among these, those having biodegradability are desirable. For example, in the glycolic acid-based polymer, the component ratio of glycolide may be higher and higher in crystallinity than the glycolic acid-based copolymer specified in the present invention, or the component ratio may be lower and the crystallinity may be lower. It may be something. In the case of polylactic acid in which the monomer is an optically active substance, the L-form or the D-form may be used.
The mixture ratio of the L-form may be any mixed composition, and the copolymerization ratio of the D and L-forms may be any copolymer or meso form.

In addition to these, 2-hydroxy-2,2-dialkylacetic acid containing 2-hydroxyisobutyric acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid, 3-hydroxyhexanoic acid, 4-hydroxybutanoic acid, and others Known aliphatic hydroxycarboxylic acids, ester derivatives of these aliphatic hydroxycarboxylic acids, homopolymers obtained from the same or different cyclic dimers of these aliphatic hydroxycarboxylic acids, or two arbitrarily selected from these Polyhydroxycarboxylic acids, β-butyrolactone, β-propiolactone, which are copolymers obtained from the above,
Pivalolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, homopolymers obtained from lactones such as ε-caprolactone, or copolymers obtained from two or more arbitrarily selected from these A polylactone, a combination of an equimolar amount of a polyhydric alcohol and a polycarboxylic acid, wherein the polyhydric alcohol includes, for example, ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 1,3-cyclohexanol, 1,4-cyclohexanol, 1, Aliphatic dimers such as 3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol All or a plurality of these aliphatic diols are bonded, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, etc., as polycarboxylic acids, such as malonic acid, succinic acid,
Glutaric acid, 2,2-dimethylglutaric acid, adipic acid, pimelic acid, spearic acid, azelaic acid, sebacic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid , Aliphatic dicarboxylic acids such as diglycolic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 1,4-naphthalene dicarboxylic acid, and 2,6-naphthalene dicarboxylic acid; these aliphatic dicarboxylic acids and aromatic dicarboxylic acids Ester derivatives, polyhydric alcohols and polycarboxylic acids obtained from anhydrides of these aliphatic dicarboxylic acids, etc., are each a homopolymer, or one of polyhydric alcohols and polycarboxylic acids is one. The other is a copolymer obtained from two or more arbitrarily selected, or polyvalent Aliphatic polyesters, which are copolymers obtained from two or more arbitrarily selected alcohols and polycarboxylic acids, and other known biodegradable plastics such as polyaspartic acid and the like. Amino acids, cellulose esters such as cellulose acetate, aliphatic polyester carbonates, polyvinyl alcohols, polyethylene oxide, low molecular weight polyethylene and the like may be used.

The copolymer may be a copolymer obtained by copolymerizing two or more of the monomers constituting the various polymers mentioned above at an arbitrary ratio, and the monomer may be an optically active substance. In some cases, either the L-form or the D-form may be used,
The mixing ratio of the D and L-forms may be any mixed composition, the copolymerization ratio of the D and L-forms may be any copolymer or meso form. In addition, as the other polymer that can be mixed, those that do not have biodegradability may be mixed as long as the biodegradability of the thermoplastic resin composition of the present invention is not impaired. For example, polyolefins, aromatic polyesters, polyamides, ethylene-vinyl alcohol-based copolymers, petroleum resins, terpene-based resins, hydrogenated products thereof and the like can be mentioned.

The thermoplastic resin composition of the present invention may contain, if necessary, additives composed of inorganic and / or organic compounds, for example, plasticizers, lubricants, antistatic agents, antifogging agents, antioxidants, heat stabilizers. , A light stabilizer, an ultraviolet absorber, a coloring agent, a flame retardant, a crystal nucleating agent, and the like may be appropriately mixed. Specific examples of the plasticizer used include, for example, phthalic acid esters such as dioctyl phthalate and diethyl phthalate, fatty acid esters such as ethyl laurate and butyl oleate, octyl linoleate, and fats such as dioctyl adipate and dibutyl sebacate. Aliphatic dibasic acid esters, aliphatic tribasic acid esters such as tributyl acetyl citrate and triethyl acetyl citrate, glycerin fatty acid esters such as glycerin diacetate traurate and glycerin triacetate, and phosphoric acid esters such as dioctyl phosphate And modified vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; and polyester plasticizers such as polybutylene sebacate. Glycerin fatty acid esters are particularly desirable from the viewpoint of safety and health. One or more of these are selected, and the amount of addition is about 1 to 30 parts by weight based on 100 parts by weight of the thermoplastic resin composition.

Specific examples of the antioxidant to be used include, for example, phenol type, phenyl acrylate type,
One type or two or more types are selected from phosphorus-based, sulfur-based, and the like, and the amount added is 0.0 to 100 parts by weight of the thermoplastic resin composition.
It is about 1 to 10 parts by weight. Production of the thermoplastic resin composition used in the present invention, the above-mentioned specific glycolic acid-based copolymer of the present invention, other resins that can be mixed therewith and additives used as necessary, all or a part of Is desirably melt-mixed using a single-screw or twin-screw extruder, Banbury mixer, mixing roll, kneader or the like.

Next, the molded article of the present invention will be described.
Examples of the type of the molded article include molded articles for container packaging materials obtained by injection molding, blow molding, and sheet molding. As a method for producing a molded article, for example, in the case of a sheet-shaped molded article, a casting method, a melt extrusion method, a calendar method,
A melt molding method is exemplified. Specifically, a thermoplastic resin composition mainly comprising the glycolic acid copolymer of the present invention is used as a raw material. For example, in a melt extrusion method, the raw material is supplied to an extruder, heated and melted, and the extruder is heated. It can be manufactured by extruding from a die connected to the tip. In the melt molding method, the raw material can be supplied to a mold, heated and melted under normal pressure or reduced pressure atmosphere, and then pressed. In this case, the temperature of the raw material for heating and melting is preferably a temperature appropriately selected from a temperature range of (melting point−5 ° C.) to (melting point + 65 ° C.). In addition, the thickness of the sheet-like molded body obtained by the molding method exemplified here is appropriately selected depending on its use, and is usually 5 µm to 1 mm, but is not particularly limited.

The obtained molded product may be used as it is as a packaging material.
For the purpose of improving gas barrier properties, printability, and the like, lamination processing, coating processing, or vacuum deposition of aluminum or the like may be performed, or formed into a shape suitable for the intended use by subsequent secondary processing. As the secondary processed product, specifically, for example, in the case of a sheet-shaped molded body, a vacuum molding process such as a plug assist molding method or an air cushion molding method, a pressurized molding process, a tray obtained by a male / female molding process, or the like. Containers such as cups, blister packaging sheets and the like can be mentioned. In order to obtain the secondary processed products of these specific examples, it is desirable that the sheet-like molded body be produced by melt extrusion from a T-die by a melt extrusion method.

The obtained molded article is used by heating in a microwave oven or the like, and is used for packaging materials and containers that require heat resistance. For the purpose of preventing deformation due to heat from the heated contents and perforation by melting, Alternatively, it is desirable to perform a heat treatment or an aging treatment for the purpose of improving the stability of physical properties. In this case, it is desirable that the heat treatment is usually performed at a temperature appropriately selected from a temperature range of 60 to 160 ° C. for 1 second to 3 hours. If necessary, various surface treatments such as coating and corona treatment may be performed for the purpose of improving the antistatic agent and the anti-fogging property.

The obtained molded article of the present invention has biodegradability and gas barrier properties by using a glycolic acid copolymer having a specific range of crystallinity as a main material constituting the molded article. Excellent in heat resistance, it is possible to increase the transparency without the need for complicated steps such as rapid cooling during production of the molded body, and the transparency is maintained at a high level even when the molded body is stored for a long time. It can maintain excellent mechanical strength without being embrittled and can be suitably used for packaging materials.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. However, these specific examples do not limit the scope of the present invention. The methods for measuring physical properties, evaluation methods and scales are shown below. Samples were prepared in an atmosphere at a temperature (23 ± 2) ° C. and a relative humidity (50 ± 5)% after preparation of a measurement sample, unless otherwise specified. Those stored for days were subjected to physical property measurement and evaluation. [Physical property measurement method] (1) Differential scanning calorimetry (DSC) Melting point Tm, heat of crystallization ΔHc, heat of fusion ΔHm were measured using a DSC6200 manufactured by Seiko Electronics Industry Co., Ltd.
The measurement was performed according to JIS K7121 and K7122. The sample was pressurized with a glycolic acid-based copolymer at about 12 Pa for 5 minutes by a heating press (compression molding machine SA-301 manufactured by Tester Sangyo Co., Ltd.) set at 250 ° C., and then quenched by a cooling press to obtain a thickness of about 200 μm. To obtain an amorphous sheet
The amorphous sheet was heated and crystallized in a hot-air circulating thermostat set at 150 ° C. for 100 minutes to produce. The sample amount was 7.5 mg, which was first kept at 0 ° C. for 3 minutes, heated to 250 ° C. at a heating rate of 10 ° C./min, and the melting point Tm in the first heating process was measured. After holding at 250 ° C. for 1 minute, the mixture was cooled to 0 ° C. at a cooling rate of 10 ° C./min, and the heat of crystallization ΔHc in the first cooling process was measured.

Next, after holding at 0 ° C. for 1 minute, the sample was heated again to 250 ° C. at a heating rate of 10 ° C./min, and the heat of fusion ΔHm in the second heating process was measured. The calibration of the temperature and the calorific value was performed using indium as a standard substance. In addition,
The amorphous sheet referred to in the present invention refers to a sheet obtained by measuring a diffraction intensity curve by a wide-angle X-ray diffraction method using the sheet prepared in the above procedure as a sample and having no diffraction peak due to the crystal in the diffraction intensity curve. . Further, in the above differential scanning calorimetry, when there are a plurality of endothermic peaks due to melting of the crystal, the highest endothermic peak temperature is defined as the melting point Tm.

(2) Relative Crystallinity In the present invention, the value of the relative crystallinity represented by the formula (4) is adopted. An amorphous sheet of a glycolic acid copolymer was obtained by the procedure described in the above DSC measurement method, and the amorphous sheet was crystallized by heating and crystallizing the amorphous sheet in a hot-air circulating thermostat set at 150 ° C. for 5 minutes and 100 minutes. I got The density of each of the test pieces of the amorphous sheet, the crystallized material heated at 150 ° C. for 5 minutes, and the crystallized material heated at 150 ° C. for 100 minutes was measured in accordance with JIS K7112C. The density was measured at 20 ° C. by observing the floating state by an ethanol / zinc chloride aqueous solution floating method. From the result of the density measurement of the sample, the crystallinity Xr was determined by the equation (4). Formula (4) Xr = [(ρb−ρa) / (ρc−ρa)] ×
(Ρc / ρb) × 100, where ρa: density of amorphous substance (g / cm ³ ) ρb: density of crystallized substance heated at 150 ° C. for 5 minutes (g / cm ³ )
cm ³ ) ρc: density of crystallized material heated at 150 ° C. for 100 minutes (g / cm ³ )

(3) Logarithmic Viscosity A pure solvent HFIP and an HFIP solution in which a glycolic acid-based copolymer was dissolved at a concentration of 1.0 kg / m ³ were used as a sample, and were subjected to 20 ° C. using an Ubbelohde capillary viscometer.
The time required to flow down in the capillary was measured, and the logarithmic viscosity number [η] was determined by equation (5). Formula (5) [η] = {ln (t / to)} / c, where t: Flowing time of polymer solution measured by capillary viscometer (second) to: Flowing of solvent measured by capillary viscometer Time (sec) c: Concentration of solute polymer (kg / m ³ )

[Evaluation Method and Scale] (1) Transparency An amorphous sheet of a glycolic acid copolymer obtained by the procedure described in the above DSC measurement method,
Crystallized material heated and crystallized for 5 minutes in a hot-air circulating thermostat set at 50 ° C., and the amorphous sheet was heated for 50 days in a thermo-hygrostat set at (23 ± 2) ° C. and relative humidity (50 ± 5)%. The haze of the stored long-term storage sheet was measured. The ratio Hc / Ha between the haze Hc of the crystallized material and the haze Ha of the amorphous sheet is used as the change in transparency due to the heat treatment, and the ratio Hk between the haze Hk of the long-term storage and the haze Ha of the amorphous sheet is used as the change in transparency due to long-term storage. / Ha was calculated, and the transparency was evaluated from the results of both determinations. The measurement of haze uses a haze meter HR-100 manufactured by Murakami Color Research Laboratory Co., Ltd.
It was measured according to JIS K7105. The obtained amorphous sheet having a thickness of about 200 μm,
Crystallized product after heating and crystallizing for 5 min.
Each sheet sample of the long-term storage sheet stored for 0 days
A 50 mm square was cut out and set in a holder, and the haze of each sample was measured.

The measurement results were obtained by measuring the number of samples for each five samples to obtain an average value, and calculating the haze ratios Hc / Ha and Hk.
/ Ha was calculated. The obtained values of the haze ratios Hc / Ha and Hk / Ha were used as indices, and the lower one of the two was directly used as the transparency determination result. However, if the haze of the sheet obtained in the above-described procedure for preparing an amorphous sheet is 2.0% or more, it is not easy to produce a molded article having excellent transparency, so that it is excluded from the evaluation and judged. Indicates “×”. <Evaluation scale> Haze ratio Hc / Ha Judgment Remarks Less than 50 ◎ Visibility is excellent with slight whitening 50 or more and less than 70 ○ Whitened but no problem in visibility 70 or more and less than 80 △ Whitened and poor visibility 80 or more x Significant whitening and very poor visibility <Evaluation scale> Haze ratio Hk / Ha Judgment Remarks Less than 2 ◎ Transparency is maintained and visibility is excellent 2 or more and less than 5 ○ No change in visibility is observed 5 or more and less than 10 △ slightly whitened 10 or more × whitened

(2) Mechanical strength The mechanical strength was measured by using a MI device manufactured by Toyo Seiki Seisaku-Sho, Ltd.
Using a T-rubbing fatigue tester, the bending strength of the sheet-shaped molded product was measured and evaluated with reference to JIS P8115. The amorphous sheet of the glycolic acid copolymer obtained by the procedure described in the above DSC measurement method was used as a sample,
mm and a width of 15 mm. Bending angle 135 °, bending speed 175 cpm, load 0.5 kg
The test was performed under the following conditions, and the number of times of bending until breaking was measured. The measurement result of the number of times of bending was measured by the above procedure for each of five samples, and the average value was shown. The number of times of bending was used as an index of mechanical strength. <Evaluation scale> Number of times of bending Judgment Remarks 100 times or more ◎ Very high bending strength and no practical problems 50 to 99 times ○ High bending strength and usable depending on the application 1 to 49 times △ Folding strength Low and not suitable for practical use 0 times × Very brittle and cannot be bent

(3) Gas Barrier Property The gas barrier property was measured according to JIS by using an oxygen permeability measuring device OX-TRAN200H manufactured by mocon as a measuring device.
The oxygen permeability was measured and evaluated according to the K7126B method. An amorphous sheet of the glycolic acid copolymer obtained by the procedure described in the above DSC measurement method was cut into a square having a side of 120 mm as a sample. The test was performed under the conditions of a temperature of 23 ° C. and a relative humidity of 65%, and the oxygen permeability was measured. The measurement results of the oxygen permeability were measured and averaged for each of three samples by the above procedure, and converted to a thickness of 10 μm. This oxygen permeability was used as an index of gas barrier properties. <Evaluation scale> Oxygen permeability Judgment Remarks Less than 100 ◎ Very high gas barrier property 100 or more and less than 500 ○ High gas barrier property 500 or more and less than 1000 △ Low gas barrier property and cannot be used depending on the application 1000 or more × Very high gas barrier property Low and cannot be used depending on the application. Unit of oxygen permeability: cc ・ 10μm / m ²・ day ・ atm

(4) Heat resistance Heat resistance is determined by heating the strip-shaped sample for 1 hour in a hot-air circulating thermostat set at a constant temperature while applying a load of 50 g, and examining whether the sample has been cut. Not rated as the highest temperature. A sample obtained by crystallizing an amorphous sheet of a glycolic acid-based copolymer obtained by the procedure described in the above DSC measurement method in a hot air circulating thermostat set at 150 ° C. for 5 minutes was used as a sample.
m, and cut into strips 10 mm wide. A fixing jig and a load jig are respectively attached to the upper and lower ends of the strip-shaped sample at 25 mm intervals, and each is placed in a hot air circulating thermostat set at a constant temperature.
The sample was heated for a period of time to check whether the sample was cut. If the strip sample did not cut, the above procedure was repeated with a new sample at a set temperature of 5 ° C. The measurement result of the maximum temperature at which the strip-shaped sample was not cut was indicated by a mode value obtained by performing this test five times for each sheet sample. The maximum temperature at which the strip-shaped sample was not cut was used as an index of heat resistance. <Evaluation scale> Maximum temperature at which cutting does not occur Judgment Remarks 180 ° C or higher ◎ Extremely high heat resistance and no practical problem 160 to 175 ° C ○ High heat resistance and usable depending on application 140 to 155 ° C △ Inferior heat resistance 135 ° C or less × Heat resistance is extremely low and not practical

[0053]

Example 1 Purification of Monomer Glycolide (MAYBR)
250 g of 1,4-dioxane-2,5-dione manufactured by IDGE, melting point 81-83 ° C.)
And then left at room temperature for 10 hours to precipitate. The precipitate collected by filtration was washed with about 500 g of dehydrated ethyl acetate at room temperature. After repeating this washing operation again, the washed matter was put into an eggplant-shaped flask, immersed in an oil bath set at 60 ° C., and vacuum-dried for 24 hours. The dried product was immersed in an oil bath set at 170 ° C., and the pressure was reduced to 6 to 7 mmHg under a dry nitrogen atmosphere, and 80 g of distilled and purified glycolide was obtained as a distillate of 133 to 134 ° C. by simple distillation.

L-lactide (first-class reagent manufactured by Wako Pure Chemical Industries) 2
50 g was dissolved in 500 g of dehydrated toluene at 80 ° C., and left standing at room temperature for 10 hours to precipitate. The precipitate collected by filtration was washed with about 500 g of dehydrated toluene at room temperature. After repeating this washing operation again, the washed matter was placed in an eggplant-shaped flask, immersed in an oil bath set at 60 ° C., and vacuum-dried for 24 hours to obtain purified L-lactide 12.
0 g was obtained. [Preparation of polymer] 70 g of glycolide and 32 g of lactide obtained by purification of the above monomer, 0.03 g of tin 2-ethylhexanoate (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.01 g of dehydrated lauryl alcohol were used as a catalyst. The tube was charged and dried at room temperature for about 30 minutes while blowing dry nitrogen. Then
It was immersed in an oil bath set at 130 ° C. while blowing dry nitrogen, and stirred for 20 hours to carry out polymerization. After the completion of the polymerization operation, the mixture was cooled to room temperature, and the bulk polymer taken out of the pressure-resistant tube was pulverized into fine particles of about 3 mm or less. The pulverized product was subjected to Soxhlet extraction for 10 hours using dehydrated ethyl acetate, and then dissolved in 200 g of HFIP at 50 ° C.
Reprecipitated with 000 g of purified methanol. This reprecipitate was vacuum-dried in a vacuum drier set at 110 ° C. for 24 hours to obtain 85 g of a glycolic acid copolymer.

The obtained copolymer is designated as P1. In the copolymer P1, the proportion of the repeating unit composed of glycolide was 86 mol%, and the proportion of the repeating unit composed of lactide was 14 mol%. HFIP
And the remaining monomer was quantified by gas chromatography, and the residual amounts of the monomers glycolide and lactide were 490 ppm in total. Using the copolymer P1 as a sample, the aforementioned DSC, relative crystallinity,
When the logarithmic viscosity number was measured, the melting point Tm in the first heating process in the DSC was 194 ° C., and the heat of crystallization ΔHc in the first cooling process was 0 J / g, and the melting temperature Tm was 0 J / g in the second heating process. The heat of fusion ΔHm is 0 J / g, and the relative crystallinity Xr is 33.
% And logarithmic viscosity number [η] were 0.25 m ³ / kg.

[Preparation and evaluation of sheet-like molded product] Glycolic acid-based copolymer P1 obtained in the preparation of the above polymer
Was dried in a hot air circulating thermostat set at 130 ° C. for about 2 hours until the water content became 200 ppm or less, followed by heating and pressurizing with a heating press set at 250 ° C. for 5 minutes, After that, it is quenched with a cooling press and the thickness is about 200
A μm amorphous sheet was obtained. The transparency, mechanical strength, gas barrier properties, and heat resistance were evaluated using the amorphous sheet as a sample. The haze ratio Hc / Ha was 45, the haze ratio Hk / Ha was 1, the number of times of bending was 140, Oxygen permeability is 10.7cc ・ 10μm / m ²・ day ・ at
m, the maximum temperature at which cutting was not performed was 185 ° C., and the judgment was が for transparency, ◎ for mechanical strength, ガ ス for gas barrier properties, ◎ for heat resistance, and ◎ for overall judgment. From the above evaluation results, the sheet-shaped molded body composed of the thermoplastic resin composition mainly composed of the glycolic acid-based copolymer P1 is composed of the biodegradable resin,
Moreover, it turns out that it is a molded object suitable for the use of packaging materials excellent in gas barrier property, heat resistance, transparency, and mechanical strength.

[0057]

Examples 2 to 7 and Comparative Examples 1 to 4 Next, the same experiment as in Example 1 was repeated except that the glycolide was 65 g, the lactide was 36 g, and the polymerization time was 30 hours. The system copolymer is designated as P2. In the copolymer P2, the component ratio of the repeating unit composed of glycolide was 8%.
The proportion of the repeating unit composed of 3 mol% and lactide was 17 mol%. The copolymer P2 has a melting point Tm of 188 ° C. in the first heating process in DSC and a crystallization heat ΔHc of 0 J / g in the first cooling process, and a heat of fusion ΔHm in the second heating process. Is 0 J / g, relative crystallinity Xr
Was 34% and the logarithmic viscosity number [η] was 0.36 m ³ / kg (Example 2).

The same experiment as in Example 1 was repeated except that the lactide was 29 g and the polymerization time was 25 hours, and the obtained glycolic acid copolymer was designated as P3. In the copolymer P3, the component ratio of the repeating unit composed of glycolide was 8%.
8 mol%, the component ratio of the repeating unit composed of lactide was 12 mol%. The copolymer P3 has a melting point Tm of 199 ° C. in the first heating step in DSC, a crystallization heat ΔHc of 0 J / g in the first cooling step, and a heat of fusion ΔHm in the second heating step. Is 5.8 J / g, relative crystallinity Xr is 33%, and logarithmic viscosity number [η] is 0.29 m ³ / kg.
(Example 3).

60 g of glycolide, 38 g of lactide,
The same experiment as in Example 1 was repeated except that the polymerization time was changed to 40 hours, and the obtained glycolic acid-based copolymer was
4 is assumed. In the copolymer P4, the component ratio of the repeating unit composed of glycolide was 80 mol%, and the component ratio of the repeating unit composed of lactide was 20 mol%. The copolymer P4 has a melting point T in the first heating process in DSC.
m is 182 ° C., the heat of crystallization ΔHc in the first cooling process is 0 J / g, and the heat of fusion ΔHm in the second heating process is 0 J / g.
g, the relative crystallinity Xr was 19%, and the logarithmic viscosity number [η] was 0.40 m ³ / kg (Example 4).

75 g of glycolide, 26 g of lactide,
Same as Example 1 except that the polymerization time was 15 hours.
The same experiment was repeated, and the resulting glycolic acid copolymer was
5 is assumed. The copolymer P5 is composed of a repeating glycol glycolide.
The unit ratio of lactide is 90 mol%
The component ratio of the return unit was 10 mol%. The copolymerization
The body P5 has a melting point T in the first heating process in DSC.
m is 203 ° C., and the heat of crystallization ΔHc in the first cooling process is
0J / g, heat of fusion ΔHm in the second heating process
2J / g, relative crystallinity Xr is 30%, logarithmic viscosity number
[Η] is 0.19 m ^Three/ Kg (Example 5).

The same experiment as in Example 1 was repeated except that the glycolide was changed to 60 g and the lactide was changed to 46 g, and the obtained glycolic acid copolymer was designated as P6. The copolymer P6 has a repeating unit composed of glycolide having a component ratio of 7%.
8 mol%, the component ratio of the repeating unit composed of lactide was 22 mol%. The copolymer P6 has a melting point Tm of 175 ° C. in the first heating step in DSC and a crystallization heat ΔHc of 0 J / g in the first cooling step, and a heat of fusion ΔHm in the second heating step. Is 0 J / g, relative crystallinity Xr
Was 14%, and the logarithmic viscosity number [η] was 0.24 m ³ / kg (Example 6).

55 g of glycolide, 24 g of lactide,
Ε-purified by distillation after dehydration and drying with anhydrous potassium carbonate
2 g of caprolactone (6-hexanolactone), 0.2 g of dibutyltin dimethoxide as a catalyst, and a polymerization time of 30 g
The same experiment as in Example 1 was repeated except that the time was changed, and the obtained glycolic acid-based copolymer was designated as P7. In the copolymer P7, the component ratio of the repeating unit composed of glycolide was 86 mol%, the component ratio of the repeating unit composed of lactide was 10 mol%, and the component ratio of the repeating unit composed of ε-caprolactone was 4 mol%. The copolymer P7 had a melting point Tm in the first heating process in DSC.
Is 185 ° C. and the heat of crystallization ΔHc in the first cooling process is 0.
J / g, heat of fusion ΔHm in the second heating process is 0 J / g.
g, the relative crystallinity Xr was 25%, and the logarithmic viscosity number [η] was 0.22 m ³ / kg (Example 7).

80 g of glycolide, 22 g of lactide,
The same experiment as in Example 1 was repeated except that the polymerization time was changed to 10 hours, and the obtained glycolic acid-based copolymer was
8 is assumed. In the copolymer P8, the component ratio of the repeating unit composed of glycolide was 93 mol%, and the component ratio of the repeating unit composed of lactide was 7 mol%. The copolymer P8 had a melting point Tm in the first heating process in DSC.
Is 206 ° C. and the heat of crystallization ΔHc during the first cooling process is −
36.5 J / g, heat of fusion ΔHm in the second heating process was 51.6 J / g, relative crystallinity Xr was 78%, and logarithmic viscosity number [η] was 0.10 m ³ / kg ( Comparative example 1).

90 g of glycolide, 10 g of lactide,
The same experiment as in Example 1 was repeated except that the polymerization time was changed to 15 hours, and the resulting glycolic acid-based copolymer was
9 is assumed. In the copolymer P9, the component ratio of the repeating unit composed of glycolide was 97 mol%, and the component ratio of the repeating unit composed of lactide was 3 mol%. The copolymer P9 had a melting point Tm in the first heating process in DSC.
Is 218 ° C., and the heat of crystallization ΔHc during the first cooling process is −
58.2 J / g, heat of fusion ΔHm during the second heating process was 55.5 J / g, relative crystallinity Xr was 100%, and logarithmic viscosity number [η] was 0.19 m ³ / kg ( Comparative Example 2).

The same experiment as in Example 1 was repeated except that the polymerization time was 5 hours without using 100 g of glycolide and lactide, and the obtained glycolic acid homopolymer was designated as P10. In the copolymer P10, the proportion of the repeating unit composed of glycolide was 100 mol%. The polymer P10 has a melting point Tm of 222 ° C. in the first heating process in DSC and a crystallization heat Δ in the first cooling process.
Hc is −69.6 J / g, heat of fusion ΔHm in the second heating process is 72.6 J / g, and relative crystallinity Xr is 100.
% And logarithmic viscosity number [η] were 0.08 m ³ / kg (Comparative Example 3). 55 g of glycolide and 46 g of lactide
Other than that, the same experiment as in Example 1 was repeated, and the obtained glycolic acid-based copolymer was designated as P11. In the copolymer P11, the proportion of the repeating unit composed of glycolide was 75 mol%, and the proportion of the repeating unit composed of lactide was 25 mol%. The copolymer P11 has a D
The melting point Tm in the first heating process in SC did not appear,
The heat of crystallization ΔHc in the first cooling process is 0 J / g, the heat of fusion ΔHm in the second heating process is 0 J / g, the relative crystallinity Xr is 0%, and the logarithmic viscosity number [η] is 0. 25m ³ / kg
(Comparative Example 4). Tables 1 and 2 summarize the measurement results of DSC, relative crystallinity, and logarithmic viscosity of the glycolic acid-based copolymer and glycolic acid homopolymers P1 to P11 described above.

[0066]

[Table 1]

[0067]

[Table 2]

For the glycolic acid-based copolymers and glycolic acid homopolymers P2 to P11, an amorphous sheet was prepared in the same manner as in the preparation and evaluation of the sheet-like molded article described above, and the amorphous sheet was used as a sample. An evaluation was performed. Tables 3 and 4 summarize the evaluation results of these polymers P1 to P11.

[0069]

[Table 3]

[0070]

[Table 4]

According to Table 3, the melting point Tm in the first heating process in the DSC was 175 ° C. or more and 205 ° C. or less, and the heat of crystallization ΔHc in the first cooling process was 0 J / g, and the second heating process was performed. A glycolic acid-based copolymer having a heat of fusion ΔHm of from 0 J / g to less than 20 J / g, a relative crystallinity Xr of from 3% to 50%, and a logarithmic viscosity number [η] of 0.15 m ³ / kg. The sheet-shaped molded article composed mainly of the thermoplastic resin composition is a molded article composed of a biodegradable resin and having excellent gas barrier properties, heat resistance, transparency, and mechanical strength, which is suitable for use as a packaging material. (Examples 1 to 7). Above all, the melting point Tm of the glycolic acid-based copolymer in the first heating process in DSC is from 185 ° C to 200 ° C,
The heat of fusion ΔHm in the second heating process is 0 J / g or more and 18
In the case of J / g or less, a sheet-shaped molded article made of a thermoplastic resin composition containing the copolymer as a main component has remarkably excellent properties of both heat resistance and transparency, and is particularly suitable for use as a packaging material. (Examples 1-3).

On the other hand, according to Table 4, the DSC of glycolic acid-based copolymer or glycolic acid homopolymer was determined.
, The melting point Tm in the first heating step is higher than 205 ° C., and the heat of crystallization ΔHc in the first cooling step is 0 J / g.
Instead, the heat of fusion ΔHm in the second heating process is 20 J
/ G or more, and when the relative crystallinity Xr is higher than 50%, the sheet-shaped molded article composed of the thermoplastic resin composition mainly composed of the polymer has excellent gas barrier properties and heat resistance. It was found that the transparency and mechanical strength were remarkably inferior, and were not suitable for use in packaging materials (Comparative Examples 1 to 3). More specifically, the heat of crystallization ΔHc in the first cooling process described above
Is not 0 J / g, even if the logarithmic viscosity number [η] is 0.15 m ³ / kg or more, a sheet having a thickness of about 5 to 500 μm used as a packaging material because of high crystallinity. It can be seen that the molded article or the film-shaped molded article becomes very brittle (Comparative Example 2).

In the case of glycolic acid homopolymer P10 having extremely high crystallinity, it was difficult to obtain an amorphous sheet. The crystallized sheet obtained by using the homopolymer P10 in the same manner as the above method is fragile and easily broken,
The transparency, gas barrier properties, and heat resistance could not be evaluated (Comparative Example 3). On the other hand, DSC of glycolic acid copolymer
In the case where the melting point Tm in the first heating process is lower than 175 ° C., more specifically, in the case of a glycolic acid-based copolymer having a copolymerization component ratio in which the melting point Tm will be lower than 175 ° C., Because of its low property, it does not crystallize even when heated at 150 ° C., and a sheet-shaped molded article made of a thermoplastic resin composition mainly containing the copolymer has excellent transparency, but has remarkable heat resistance. It is inferior and not suitable for use as a packaging material (Comparative Example 4).

[0074]

According to the present invention, by using a glycolic acid-based copolymer having a specific range of crystallinity, it has biodegradability, and has improved gas barrier properties, heat resistance, transparency and mechanical strength. It is possible to provide a molded article suitable for excellent packaging material use.

Continued on the front page F-term (reference) 3E086 BA02 BA15 BB01 BB41 BB85 BB90 CA01 CA28 4F071 AA43 AF07 AF17 AF30 AF45 AH04 BB03 BC01 4J029 AA02 AC01 AC02 AD06 AD08 AD10 AE03 EA02 EA05 EG02 E02 EB03

Claims (3)

[Claims] 1. A differential scanning calorimeter (JIS K7121) in which an amorphous sheet of a glycolic acid copolymer is heat-treated at 150 ° C. for 100 minutes and a heating rate and a cooling rate are measured at 10 ° C./min. K7122), the melting point Tm (° C.) during the first heating process, the crystallization heat ΔHc (J / g) during the first cooling process, and the heat of fusion ΔHm (J / g) during the second heating process. ) Satisfies the following formulas (1) to (3), the relative crystallinity Xr represented by the following formula (4) is 3% or more and 50% or less, and the logarithmic viscosity number [η] is 0.15 m ^3.
A molded article for a packaging material, comprising a thermoplastic resin composition mainly composed of a glycolic acid-based copolymer of not less than / kg. Equation (1) 175 ≦ Tm ≦ 205 Equation (2) ΔHc = 0 Equation (3) 0 ≦ ΔHm <20 Equation (4) Xr = [(ρb−ρa) / (ρc−ρa)] ×
(Ρc / ρb) × 100, where ρa: density of amorphous substance (g / cm ³ ) ρb: density of crystallized substance heated at 150 ° C. for 5 minutes (g / cm ³ )
cm ³ ) ρc: density of crystallized material heated at 150 ° C. for 100 minutes (g / cm ³ ) 2. A copolymer obtained by subjecting a glycolic acid-based copolymer to ring-opening polymerization using glycolide and a monomer other than glycolide, wherein the proportion of a repeating unit composed of glycolide is 78 to 90 mol%. And a component ratio of a repeating unit composed of a monomer other than glycolide is 22 to 10 mo.
The molded product for a packaging material according to claim 1, wherein the content is 1%. 3. The molded article for packaging material according to claim 2, wherein the monomer other than glycolide comprises at least one selected from cyclic dimers of aliphatic hydroxycarboxylic acids and lactones.