JP2024046112A - Polyester resin composition and laminate - Google Patents

Abstract

[Problem] To provide a resin composition having excellent adhesive strength to PVA-based resin. [Solution] The polyester-based resin composition contains a polyester-based resin as a main component and a tackifier, and satisfies formula (I): (Ta/Tb)×(Ma/Mb)<1.00, where Ta is the crystallization temperature of the polyester-based resin composition, Tb is the crystallization temperature of the polyester-based resin, Ma is the crystallization peak area (ΔHc) of the polyester-based resin composition, and Mb is the crystallization peak area (ΔHc) of the polyester-based resin. [Selected Figure] None

Description

The present invention relates to a polyester resin composition, and more particularly to a polyester resin composition preferably used for adhesion to a polyvinyl alcohol resin layer (hereinafter, polyvinyl alcohol is referred to as "PVA"), and the polyester resin composition. The present invention relates to a laminate having a layer containing a substance.

Plastics are widely used as packaging materials because of their excellent moldability, strength, water resistance, transparency, etc. Plastics used in such packaging materials include polyolefin resins such as polyethylene and polypropylene, vinyl resins such as polystyrene and polyvinyl chloride, and aromatic polyester resins such as polyethylene terephthalate. However, these plastics have poor biodegradability, and if they are dumped into nature after use, they may remain for a long time, damaging the landscape or causing environmental destruction.

On the other hand, in recent years, biodegradable resins, which are biodegradable or hydrolyzed in soil or water and are useful for preventing environmental pollution, have attracted attention and are being put into practical use. Known examples of such biodegradable resins include aliphatic polyester resins, cellulose acetate, and modified starch. As packaging materials, polylactic acid, adipic acid/terephthalic acid/1,4-butanediol condensation products, and succinic acid/1,4-butanediol/lactic acid condensation products are used as packaging materials because of their excellent transparency, heat resistance, and strength. Polymers, etc. are used.

However, since aliphatic polyester resins such as polylactic acid have insufficient oxygen gas barrier properties, they cannot be used alone as packaging materials for contents that may be subject to oxidative deterioration, such as foods and medicines. Therefore, an aliphatic polyester resin such as polylactic acid and a PVA resin are laminated to form a laminate.

However, since the polylactic acid resin layer and the PVA resin layer have significantly different surface characteristics, both layers have poor adhesive properties, and it is difficult to obtain practical interlayer adhesive strength by directly laminating the two layers.

Therefore, an adhesive layer using a polyester resin is provided to bond these resin layers. For example, Patent Document 1 proposes a thermoplastic resin composition consisting of a modified polyester elastomer obtained by reacting a polyester elastomer with an unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator, and an ionomer resin.

JP 2003-183484 A

However, conventional polyester adhesive resins have poor adhesion to PVA resins, and further improvements are needed.

Therefore, an object of the present invention is to provide a resin composition that has excellent adhesive strength to PVA-based resins.

As a result of intensive studies, the present inventors have found that a resin composition containing a polyester resin as a main component contains a tackifier as an additive, and the polyester resin as a base resin for the resin composition is crystallized. The inventors have found that the above problem can be solved by setting the product of temperature and crystallization peak area (ΔHc) to less than 1.00, and have completed the present invention.

That is, the present invention comprises the following configuration.
<1> A polyester-based resin composition containing a polyester-based resin as a main component and a tackifier, characterized in that, when the crystallization temperature of the polyester-based resin composition is Ta, the crystallization temperature of the polyester-based resin is Tb, the crystallization peak area (ΔHc) of the polyester-based resin composition is Ma, and the crystallization peak area (ΔHc) of the polyester-based resin is Mb, the polyester-based resin composition satisfies the following formula (I):
(Ta/Tb)×(Ma/Mb)<1.00 (I)
<2> An adhesive comprising the polyester resin composition according to <1>.
<3> A laminate comprising at least one layer containing the polyester resin composition according to <1>.
<4> A laminate having an adhesive layer between a first layer and a second layer, wherein at least one of the first layer and the second layer is a polyvinyl alcohol-based resin layer, and the adhesive layer contains the polyester-based resin composition described in <1>.

The polyester resin composition of the present invention has high adhesive strength and can exhibit excellent adhesion to a PVA resin layer. When the polyester resin is a biodegradable polyester resin, for example, in a laminate containing a PVA resin layer and a biodegradable resin layer, when used as an adhesive layer between both layers, it has excellent adhesive properties and is biodegradable. A transparent laminate is obtained.

The configuration of the present invention is described in detail below, but these are examples of preferred embodiments.

In this specification, "biodegradable" means meeting the conditions specified in JIS K 6953-1:2011 (ISO 14855-1:2005).

The polyester resin composition of the present invention contains a polyester resin as a main component of a resin layer forming component and a tackifier, and the crystallization temperature of the polyester resin composition is Ta, and the crystallization temperature of the polyester resin is When the crystallization temperature is Tb, the crystallization peak area (ΔHc) of the polyester resin composition is Ma, and the crystallization peak area (ΔHc) of the polyester resin is Mb, the following formula (I) is satisfied.
(Ta/Tb)×(Ma/Mb)<1.00...(I)
Here, the main component of the polyester resin composition refers to a component that accounts for 50% by mass or more of the entire composition, preferably 80% by mass or more, and more preferably 90% by mass.

The above formula (I) indicates flexibility and ease of penetration, and when a polyester resin composition satisfies formula (I), the adhesion and anchoring effect become strong, so the adhesive strength between resin materials is can be improved. The value of (Ta/Tb)×(Ma/Mb) is preferably 0.99 or less, more preferably 0.95 or less. The lower limit is not particularly limited, but if the value is too small, crystallization will be difficult to occur during the production of the polyester resin composition, so recrystallization will occur in the extruder when forming a film using the polyester resin composition. It is preferable that it is 0.1 or more, since this may cause deterioration in workability. The lower limit of the value of (Ta/Tb)×(Ma/Mb) is more preferably 0.5 or more, and even more preferably 0.7 or more.

The crystallization temperature Ta of the polyester-based resin composition, the crystallization temperature Tb of the polyester-based resin, and the crystallization peak area (ΔHc)Ma of the polyester-based resin composition, and the crystallization peak area (ΔHc)Mb of the polyester-based resin can be measured by the following 1) to 2) using a differential scanning calorimeter.
1) The sample is heated from -60°C to 220°C at a rate of 10°C/min, and then held at that temperature for 1 minute.
2) When the temperature of the crystallization peak (crystallization temperature) and the area of the crystallization peak (ΔHc) are measured by a differential scanning calorimeter when the temperature is cooled to −60° C. at a cooling rate of 10° C./min.

The crystallization temperature Ta and crystallization peak area (ΔHc) Ma of the polyester resin composition can be adjusted to satisfy formula (I) by adjusting the type and content of the polyester resin and tackifier used. can.

(Polyester resin)
The polyester resin is a component that becomes the base resin of the polyester resin composition of the present invention.
Examples of the polyester resin include polyalkylene arylate resin, polyarylate resin, liquid crystal polyester (LCP), and the like. Examples of polyalkylene arylate resins include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), poly1,4-cyclohexyl dimethylene terephthalate (PCT), and polyethylene naphthalate. It will be done.

The polyester resin is preferably a biodegradable resin from the viewpoint of reducing the impact on the environment. Examples of biodegradable polyester resins include aliphatic-aromatic copolymer polyester resins, aliphatic polyester resins, and aromatic polyester resins, and aliphatic-aromatic copolymer polyester resins and aliphatic polyester resins are preferred from the viewpoint of excellent biodegradability.

The aliphatic-aromatic copolymer polyester resin used in the present invention is an aliphatic-aromatic copolymer polyester resin containing aliphatic diol units, aliphatic dicarboxylic acid units, and aromatic dicarboxylic acid units as main structural units. Specifically, for example, it is preferable that the main structural units are aliphatic diol units represented by the following formula (1), aliphatic dicarboxylic acid units represented by the following formula (2), and aromatic dicarboxylic acid units represented by the following formula (3), and that it is biodegradable.

-O-R ¹ -O- ...(1)
In formula (1), R ¹ represents a divalent aliphatic hydrocarbon group.
-OC-R ² -CO-...(2)
In formula (2), R ² represents a divalent aliphatic hydrocarbon group.
-OC-R ³ -CO- ...(3)
In formula (3), R ³ represents a divalent aromatic hydrocarbon group.

The aliphatic diol that gives the aliphatic diol unit of formula (1) is not particularly limited, but from the perspective of the balance between cost and mechanical strength, one having 2 to 10 carbon atoms is preferred. Examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Among these, aliphatic diols having 2 to 4 carbon atoms are preferred, with ethylene glycol and 1,4-butanediol being more preferred, and 1,4-butanediol being particularly preferred. Note that two or more of the above aliphatic diols can also be used.

The aliphatic dicarboxylic acid component that provides the aliphatic dicarboxylic acid unit of formula (2) is not particularly limited, but is preferably one having 2 or more and 12 or less carbon atoms in view of the balance between cost and biodegradability. Examples include succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid, and derivatives thereof such as alkyl esters. Among these, derivatives such as succinic acid, sebacic acid, adipic acid, azelaic acid, and alkyl esters thereof are preferred. In addition, two or more types of the above aliphatic dicarboxylic acid components can also be used.

Examples of the aromatic dicarboxylic acid component that provides the aromatic dicarboxylic acid unit of formula (3) include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, furandicarboxylic acid, and derivatives thereof such as alkyl esters. Among these, R ³ is preferably a phenylene group from the viewpoint of biodegradability, and examples of the aromatic dicarboxylic acid component that provides the aromatic dicarboxylic acid unit of formula (3) include terephthalic acid, isophthalic acid, and Derivatives such as terephthalic acid and its alkyl esters are preferred, and derivatives such as terephthalic acid and its alkyl esters are particularly preferred. Further, it may be an aromatic dicarboxylic acid in which part of the aromatic ring is substituted with a sulfonate. In addition, two or more types of the above-mentioned aromatic dicarboxylic acid components can also be used.

The content of aromatic dicarboxylic acid units in the aliphatic-aromatic copolymer polyester resin is preferably 5 mol% or more and 95 mol% or less, based on 100 mol% of the total dicarboxylic acid units (the aliphatic dicarboxylic acid units and the aromatic dicarboxylic acid units), from the viewpoint of melting point and biodegradability. Specifically, it is preferably 5 mol% or more, more preferably 35 mol% or more, particularly preferably 40 mol% or more, and preferably 95 mol% or less, more preferably 65 mol% or less, particularly preferably 60 mol% or less.

In addition, when two or more types of aromatic dicarboxylic acids are used, the aliphatic-aromatic copolymer polyester resin preferably has a ratio of terephthalic acid units in all aromatic dicarboxylic acid units of 40 mol% or more and 60 mol% or less. If this ratio is less than 40 mol%, heat resistance is insufficient, and if it exceeds 60 mol%, biodegradability tends to deteriorate. From this perspective, the ratio of terephthalic acid units in all aromatic dicarboxylic acid units in the aliphatic-aromatic copolymer polyester resin is more preferably 42 mol% or more and 58 mol% or less, and even more preferably 45 mol% or more and 55 mol% or less.

The aliphatic-aromatic copolymer polyester resin may have an aliphatic oxycarboxylic acid unit. Specific examples of the aliphatic oxycarboxylic acid component that gives the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, or a mixture thereof. Furthermore, the compound may be a derivative such as a lower alkyl ester or an intramolecular ester of these. When optical isomers exist, they may be in the D-form, L-form, or racemic form, and may be in the form of a solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid or a derivative thereof is preferred. These aliphatic oxycarboxylic acid components may be used alone or as a mixture of two or more types.

When the aliphatic-aromatic copolyester resin contains these aliphatic oxycarboxylic acid units, the content is preferably 100 mol% of the total constitutional units constituting the aliphatic-aromatic copolyester resin. is 20 mol% or less, more preferably 10 mol% or less.

Aliphatic polyester resins are aliphatic polyester resins that contain aliphatic diol units and aliphatic dicarboxylic acid units as the main constituent units. Aliphatic polyester resins are distinguished from the aliphatic-aromatic copolymer polyester resins described above in that they do not contain aromatic dicarboxylic acid units.

More specifically, the aliphatic polyester resin is a polyester resin containing an aliphatic diol unit represented by the following formula (4) and an aliphatic dicarboxylic acid unit represented by the following formula (5).
-O-R ⁴ -O- ... (4)
In formula (4), ^R4 represents a divalent aliphatic hydrocarbon group.
-OC- ^R5 -CO-... (5)
In formula (5), ^R5 represents a divalent aliphatic hydrocarbon group.

The aliphatic diol units and aliphatic dicarboxylic acid units represented by formulas (4) and (5) above may be derived from compounds derived from petroleum or from plant materials. However, it is desirable that the compound be derived from a compound derived from plant materials.

When the aliphatic polyester resin is a copolymer, two or more aliphatic diol units represented by formula (4) may be contained in the aliphatic polyester resin, and the aliphatic polyester resin may contain two or more aliphatic diol units represented by formula (4). The resin may contain two or more types of aliphatic dicarboxylic acid units represented by formula (5).

The aliphatic diol that gives the diol unit represented by formula (4) is not particularly limited, but from the viewpoint of moldability and mechanical strength, an aliphatic diol having 2 to 10 carbon atoms is preferred, and an aliphatic diol having 4 to 6 carbon atoms is particularly preferred. Examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, and of these, 1,4-butanediol is particularly preferred. Note that two or more of the above aliphatic diols can be used.

The aliphatic dicarboxylic acid component that gives the aliphatic dicarboxylic acid unit represented by formula (5) is not particularly limited, but is preferably an aliphatic dicarboxylic acid having 2 to 40 carbon atoms or a derivative such as an alkyl ester thereof, and particularly preferably an aliphatic dicarboxylic acid having 4 to 10 carbon atoms or a derivative such as an alkyl ester thereof. Examples of aliphatic dicarboxylic acids and derivatives such as alkyl esters thereof include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, etc., and derivatives such as alkyl esters thereof. Among these, succinic acid, adipic acid, and sebacic acid are preferred, and succinic acid and adipic acid are particularly preferred. It is also possible to use two or more types of the above aliphatic dicarboxylic acid components.

The aliphatic polyester resin may have a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that gives the aliphatic oxycarboxylic acid unit include, for example, lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, and the like, or derivatives thereof such as lower alkyl esters or intramolecular esters. When optical isomers exist in these, they may be in any of the D-form, L-form, or racemic form, and may be in any of the forms of solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid or derivatives thereof are particularly preferred. These aliphatic oxycarboxylic acids may be used alone or as a mixture of two or more.

When the aliphatic polyester resin contains these aliphatic oxycarboxylic acid units, the content thereof is 20 mol% or less, based on 100 mol% of all constitutional units constituting the aliphatic polyester resin, from the viewpoint of moldability. It is preferably at most 10 mol%, still more preferably at most 5 mol%, and most preferably at most 3 mol%.

The biodegradable polyester resin may be obtained by synthesis, or a commercially available one may be used. In the case of synthesis, known methods for producing polyester can be employed. Furthermore, the biodegradable polyester resin is not limited to one type, and two or more types of biodegradable polyester resins having different types of constituent units, constituent unit ratios, manufacturing methods, physical properties, etc. can be blended and used.

Examples of biodegradable polyester resins include polybutylene succinate terephthalate (hereinafter sometimes referred to as "PBST"), polybutylene adipate terephthalate (hereinafter sometimes referred to as "PBAT"), polybutylene succinate adipate (hereinafter sometimes referred to as "PBSA"), polybutylene succinate (hereinafter sometimes referred to as "PBS"), polybutylene sebacate terephthalate (hereinafter sometimes referred to as "PBSSeT"), polybutylene succinate adipate terephthalate (hereinafter sometimes referred to as "PBSAT"), polycaprolactone (hereinafter sometimes referred to as "PCL"), etc.

Examples of commercially available biodegradable polyester resins include "Ecoflex" manufactured by BASF, whose main component is a condensation product of adipic acid/terephthalic acid/1,4-butanediol, which is polybutylene adipate terephthalate; Examples include "Bio-PBS" manufactured by Mitsubishi Chemical Corporation, which contains a condensation product of succinic acid/1,4-butanediol, which is butylene succinate, as a main component.

The polyester resin may be acid-modified. Including acid-modified polyester resin improves processability and makes handling easier.

Acid-modified polyester resin is produced by adding α,β-unsaturated carboxylic acid or its anhydride (hereinafter referred to as α,β-unsaturated carboxylic acid or its anhydride) to the raw material polyester resin. It is a polyester resin obtained by graft polymerization of carboxylic acids.

Specific examples of the α,β-unsaturated carboxylic acids include α,β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; and α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citrus acid, tetrahydrophthalic acid, crotonic acid, and isocrotonic acid, or anhydrides thereof. Preferably, anhydrides of α,β-unsaturated dicarboxylic acids are used.
These α,β-unsaturated carboxylic acids may be used not only as a single type but also as a combination of two or more types.

Further, when the polyethylene resin is an acid-modified polyester resin, the acid value thereof is preferably 1.0 to 6.5 mg·KOH/g, more preferably 1.1 to 6.0 mg·KOH/g. /g, more preferably 1.2 to 5.0 mg·KOH/g.
If the acid value is too high, the appearance will be poor; if it is too low, the adhesiveness with other resins tends to decrease; if the acid value is too high or too low, the effects of the present invention cannot be obtained.

Note that the acid value is measured as follows.
First, the acid-modified polyester resin to be measured is thoroughly washed with a solvent. The purpose of this washing is to wash away impurities from the acid-modified polyester resin, mainly unreacted α,β-unsaturated carboxylic acids or their anhydrides. As such a solvent, it is necessary to use a solvent in which the acid-modified polyester resin does not dissolve, and examples thereof include water, acetone, methanol, ethanol, and isopropanol.
Next, after drying the washed acid-modified polyester, take 100 ml of tetrahydrofuran as a solvent into a test bottle, and add 5 g of acid-modified polyester resin while stirring with a hot stirrer (set temperature: 75°C, stirrer rotation speed: 750 rpm). do. Stir for 5 to 6 hours until the acid-modified polyester resin is dissolved. After dissolving, 4 ml of ultrapure water is added and stirred for another 10 minutes to prepare a test solution. The test solution is titrated with an aqueous potassium hydroxide solution (N/10) using an automatic titrator to determine the acid value using the following formula.

(formula)
Acid value AV (mg・KOH/g)={(AB)×f×5.61}/S
A = Amount of potassium hydroxide aqueous solution N/10 required for acid-modified polyester resin (ml)
B = Amount of potassium hydroxide aqueous solution N/10 required for blank test (ml)
f=N/10 Potency of potassium hydroxide aqueous solution S=Amount of acid-modified polyester resin collected (g)

As the titration device, for example, the following can be used.
Titration measurement device: Automatic potentiometric titration device AT-610 manufactured by Kyoto Electronics Industry Co., Ltd.
Reference electrode: Composite glass electrode C-171
Titrant: Fuji Film Wako Pure Chemical Industries, Ltd. Potassium hydroxide aqueous solution (N/10)

The weight average molecular weight of the polyester resin is preferably 50,000 to 400,000, more preferably 100,000 to 200,000, particularly preferably 140,000 to 180,000. If the weight average molecular weight is too large, the melt viscosity tends to be high and melt molding becomes difficult, whereas if it is too small, the molded product tends to become brittle.

The melt flow rate (MFR) of polyester resins, measured at 210°C and 2.16 kg, is preferably 1.0 to 20 g/10 min, more preferably 1.5 to 10 g/10 min, and particularly preferably 2.0 to 8.0 g/10 min. The MFR of polyester resins can be adjusted by the molecular weight.

The melting point of the polyester resin is preferably 60 to 260°C, more preferably 70 to 200°C, and even more preferably 75 to 140°C.

In the present invention, the polyester resin is not limited to one type, and two or more types of polyester resins differing in the types of constituent units, the ratio of constituent units, the manufacturing method, the physical properties, etc. can be blended and used.

(tackifier)
The polyester resin composition of the present invention contains a tackifier as an additive. Examples of the tackifier include resins having a melting peak (ΔHm) of 10 J/g or less. By including a resin with a melting peak (ΔHm) of 10 J/g or less, the polyester resin of the present invention can satisfy the above formula (I) because it does not crystallize by itself and is compatible with the polyester resin. The adhesive strength of the resin composition can be improved.

Note that the melting peak (ΔHm) of the tackifier can be measured using a differential scanning calorimeter according to 1) to 3) below.
1) The tackifier is heated from -60°C to 220°C at a heating rate of 10°C/min and held for 1 minute.
2) Cool to -60°C at a cooling rate of 10°C/min.
3) The melting peak (ΔHm) when the temperature is raised again from -60°C to 220°C at a heating rate of 10°C/min is measured using a differential scanning calorimeter.

Resins with a melting peak (ΔHm) of 10 J/g or less preferably have a polar group, and examples of the polar group include an acid anhydride group, a carboxylic acid group, a hydroxyl group, and an ester group, and the same is true for preferred polar groups.

In addition, it is preferable that the resin having a melting peak (ΔHm) of 10 J/g or less has at least one selected from the group consisting of a double bond, an aromatic ring, and a heteroatom. By having at least one selected from the group consisting of a double bond, an aromatic ring, and a heteroatom, it becomes easier to mix with polyester, and the effects of the present invention are more easily obtained. Examples of heteroatoms include a nitrogen (N) atom, an oxygen (O) atom, and a sulfur (S) atom, and among these, it is preferable to have an oxygen (O) atom as the heteroatom.

From the viewpoint of crystallinity, the melting peak (ΔHm) is preferably 10 J/g or less, more preferably 5 J/g or less, and the lower limit is not particularly limited, but it is preferably 0 J/g or more, and 0 .1 J/g or more is more preferable.

Specific examples of resins with a melting peak (ΔHm) of 10 J/g or less include hydrogenated petroleum resins, rosin esters, rosin diols, acid-modified rosins, and terpene phenols.

(Polyester Resin Composition)
As described above, the polyester resin composition of the present invention contains a polyester resin as a base resin and a tackifier.

The polyester resin content in the resin composition is preferably 80 to 99.99% by mass, more preferably 85 to 99.70% by mass, and even more preferably 90 to 99.50% by mass. If the polyester resin content is 80% by mass or more, the strength of the substrate can be ensured, and if it is 99.99% by mass or less, adhesive strength can be exerted.

The tackifier is preferably contained in the polyester resin composition in the range of 0.01 to 20% by mass. If the tackifier is contained in the polyester resin composition in an amount of 0.01% by mass or more, the desired effect of the present invention can be obtained, and if the tackifier content is too high, the pellets may become tacky and difficult to handle, so it is preferable to contain the tackifier in an amount of 20% by mass or less. The tackifier content in the polyester resin composition is more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

Further, the polyester resin composition of the present invention may contain other components within a range that does not impair the effects of the present invention. Other ingredients include, for example, reinforcing agents, fillers, plasticizers, pigments, dyes, lubricants, antioxidants, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, surfactants, antibacterial agents, Examples include antistatic agents, drying agents, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, and the like.

The polyester resin composition of the present invention is usually molded into pellets, powder, etc., for use as a molding material. Among them, pellets are preferred because they are easy to handle when put into a molding machine or during transportation, and because they pose little problem of fine powder generation.
While known methods can be used for forming the material into pellets, it is efficient to extrude the material in the form of a strand from an extruder, cool it, and then cut it to a predetermined length to form cylindrical pellets.
The size of such cylindrical pellets is usually 1 to 4 mm, preferably 2 to 3 mm in length, and usually 1 to 4 mm, preferably 2 to 3 mm in diameter.

Examples of the method for producing the polyester resin composition of the present invention include the following (i) to (iii).
(i) Method of dry blending polyester resin and tackifier, then melting and kneading (ii) Method of dissolving polyester resin and tackifier in a solvent and mixing in solution form (iii) Polyester resin layer and a method of crushing, melting, and kneading the laminate containing the tackifier layer. Note that the method (iii) is mainly used when recycling the ends of the laminate.

As a method for melt-kneading, in the production method (i) above, for example, a method in which the polyester resin, the tackifier and any optional components are mixed using a mixer such as a Henschel mixer or a ribbon blender, and then melted and kneaded using a melt kneader such as a single-screw or twin-screw extruder, a roll, a Banbury mixer, a kneader or a Brabender mixer can be mentioned.
As for the manufacturing method of (iii) above, for example, there can be mentioned a method in which unnecessary parts such as both ends of a multilayer film having layers each containing a polyester-based resin and a tackifier are crushed, and optional components are added as necessary, and the mixture is melted and kneaded in a melt kneader such as a single-screw or twin-screw extruder, a roll, a Banbury mixer, a kneader, or a Brabender mixer.

The temperature during melt kneading can be set appropriately within a temperature range that is equal to or higher than the melting points of the polyester resin and tackifier and does not cause thermal degradation, but is preferably 100 to 300°C, particularly preferably 140 to 250°C, and even more preferably 160 to 230°C.

The resin composition used in the present invention has excellent fluidity and is easy to handle, so it is useful as a molding material. As the melt molding method, known molding methods such as extrusion molding, inflation molding, injection molding, blow molding, vacuum molding, pressure molding, compression molding, and calendar molding can be used.

The molded products of the present invention can have a wide variety of shapes, including films, sheets, pipes, disks, rings, bags, bottles, and fibers.

The polyester resin composition of the present invention can be used as the main component of an adhesive, and an adhesive containing the acid-modified polyester resin composition of the present invention has excellent adhesion to PVA-based resins, so that it can improve the adhesion between two materials containing PVA-based resins.

The content of the polyester resin composition contained in the adhesive of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and the adhesive contains polyester resin It may be made of a composition (100% by mass of polyester resin composition).

The adhesive may contain any component of the polyester resin composition of the present invention, such as a reinforcing agent, a filler, a plasticizer, a pigment, a dye, a lubricant, an antioxidant, an antistatic agent, an ultraviolet absorber, a heat stabilizer, a light stabilizer, a surfactant, an antibacterial agent, an antistatic agent, a drying agent, an antiblocking agent, a flame retardant, a crosslinking agent, a curing agent, a foaming agent, a crystal nucleating agent, etc.

[Laminate]
The polyester resin composition of the present invention is used as an adhesive resin to bond two members together. The laminate of the present invention has at least one layer containing the polyester resin composition of the present invention.
The laminate of the present invention further includes an adhesive layer between a first layer and a second layer, at least one of the first layer and the second layer being a PVA-based resin layer, and the adhesive layer contains the polyester-based resin composition of the present invention.

Among these, the laminate of the present invention is preferably one that uses a PVA-based resin (B) layer as the gas barrier layer and a biodegradable resin (C) layer as the outer layer, and has an adhesive (A) layer containing the polyester-based resin composition of the present invention between the PVA-based resin (B) layer and the biodegradable resin (C) layer.

(PVA resin (B) layer)
The PVA resin (B) layer preferably plays a role in the gas barrier properties of the laminate of the present invention.
The PVA resin (B) layer is laminated to the biodegradable resin (C) layer described below via an adhesive (A) layer containing the polyester resin composition of the present invention on at least one surface thereof. It is preferable that

The PVA-based resin (B) layer used in the present invention is a layer mainly composed of PVA-based resin (B) and usually contains 70% by mass or more of PVA-based resin (B), preferably 80% by mass or more, and more preferably 90% by mass or more. The upper limit is 100% by mass. If the content is too low, the gas barrier properties tend to be insufficient.

The PVA resin (B) used in the present invention is a resin mainly composed of vinyl alcohol structural units, which is obtained by saponifying a polyvinyl ester resin obtained by polymerizing a vinyl ester monomer. It is composed of vinyl alcohol structural units and vinyl ester structural units corresponding to the same degree of alcohol.

The above vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl benzoate. , vinyl versatate, etc., but vinyl acetate is preferably used economically.

The average degree of polymerization of the PVA-based resin (B) used in the present invention (measured according to JIS K6726) is preferably 200 to 1800, more preferably 300 to 1500, and even more preferably 300 to 1000.

If the average degree of polymerization is too low, the mechanical strength of the PVA-based resin (B) layer tends to be insufficient. Conversely, if the average degree of polymerization is too high, the flowability tends to decrease when the PVA-based resin (B) layer is formed by hot melt molding, and moldability tends to decrease. In addition, abnormal shear heat may occur during molding, making the PVA-based resin (B) more susceptible to thermal decomposition.

The PVA-based resin (B) used in the present invention preferably has a saponification degree (measured in accordance with JIS K6726) of 80 to 100 mol %, particularly preferably 90 to 99.9 mol %, and even more preferably 98 to 99.9 mol %.
If the degree of saponification is too low, the gas barrier properties tend to decrease.

In addition, in the present invention, the PVA-based resin (B) may be one obtained by copolymerizing various monomers during the production of a polyvinyl ester-based resin and then saponifying the copolymer, or one of various modified PVA-based resins obtained by introducing various functional groups into unmodified PVA through post-modification.

Examples of monomers used for copolymerization with vinyl ester monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxyl-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, and 3,4-dihydroxy-1-butene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid; salts, monoesters, or dialkyl esters of the same; nitriles such as acrylonitrile and methacrylonitrile; and diacetone acrylate. Examples of suitable vinyl acetates include amides such as arylamide, acrylamide, and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, or their salts; alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, and vinyl compounds such as 3,4-diacetoxy-1-butene; substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate; vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate.

In addition, modified PVA resins into which functional groups have been introduced through post-modification include those that have acetoacetyl groups through reaction with diketene, those that have polyalkylene oxide groups through reaction with ethylene oxide, and those that have polyalkylene oxide groups through reaction with epoxy compounds, etc. Examples include those having a hydroxyalkyl group according to the above, and those obtained by reacting aldehyde compounds having various functional groups with PVA.

The content of modified species in such modified PVA-based resins, i.e., structural units derived from various monomers in the copolymer, or functional groups introduced by post-reaction, cannot be generalized because the characteristics vary greatly depending on the modified species, but it is preferably 1 to 20 mol%, and especially preferably in the range of 2 to 10 mol%.

Among these various modified PVA-based resins, in the present invention, a structural unit having a 1,2-diol structure in the side chain represented by the following general formula (6) (hereinafter referred to as "1,2-diol structural unit") is used. In the method for producing a laminate of the present invention, which will be described later, a PVA-based resin having the following formula is preferably used because it facilitates melt molding.

In the 1,2-diol structural unit represented by the general formula (6), R ¹¹ to R ¹⁴ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.

Examples of the alkyl group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group, and the alkyl group may optionally be a halogen group. , a hydroxyl group, an ester group, a carboxylic acid group, a sulfonic acid group, or other functional groups.

Furthermore, X in the 1,2-diol structural unit represented by general formula (6) represents a single bond or a bonded chain.
Such bonded chains include linear or branched alkylene groups having 1 to 6 carbon atoms, linear or branched alkenylene groups having 1 to 6 carbon atoms, and linear or branched alkylene groups having 1 to 6 carbon atoms. In addition to hydrocarbons such as branched alkynylene groups, phenylene groups, and naphthylene groups (these hydrocarbons may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms), -O- , -(CH ₂ O) _t -, -(OCH ₂ ) _t -, -(CH ₂ O) _t CH ₂ -, -CO-, -COCO-, -CO(CH2) _t CO-, -CO(C ₆ H ₄ ) CO-, -S-, -CS-, -SO-, -SO ₂ -, -NR-, -CONR-, -NRCO-, -CSNR-, -NRCS-, -NRNR-, -HPO ₄ -, -Si(OR) ₂ -, -OSi(OR) ₂ -, -OSi(OR) ₂ O-, -Ti(OR) ₂ -, -OTi(OR) ₂ -, -OTi(OR) ₂ O-, -Al(OR)-, -OAl(OR)-, -OAl(OR)O-, etc. (R is each independently an arbitrary substituent, hydrogen atom, straight chain having 1 to 6 carbon atoms) represents a branched or branched alkyl group, and t represents an integer of 1 to 5).
Among these, the bonding chain is preferably a linear or branched alkylene group having 1 to 6 carbon atoms, particularly a methylene group, or -CH ₂ OCH ₂ - from the viewpoint of stability during production or use.

X is most preferably a single bond in terms of thermal stability and stability under high temperatures and acidic conditions.

Among the 1,2-diol structural units represented by general formula (6), a structural unit represented by the following general formula (6') in which R ¹¹ to R ¹⁴ are all hydrogen atoms and X is a single bond is most preferred.

Examples of the method for producing a PVA-based resin having a 1,2-diol structural unit in the side chain include the method described in paragraphs [0026] to [0034] of JP-A-2015-143356.

The content of 1,2-diol structural units contained in the PVA resin having 1,2-diol structural units in the side chain is preferably 1 to 20 mol%, more preferably 2 to 10 mol%, particularly 3 to 8 mol% is preferably used. If this content is too low, it is difficult to obtain the effect of the side chain 1,2-diol structure, and on the other hand, if this content is too high, gas barrier properties tend to deteriorate significantly at high humidity.

The content of 1,2-diol structural units in a PVA-based resin can be determined from the ^1H -NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane) of a completely saponified PVA-based resin. Specifically, the content can be calculated from the peak areas derived from hydroxyl group protons, methine protons, and methylene protons in the 1,2-diol structural unit, methylene protons in the main chain, and protons of hydroxyl groups linked to the main chain.

Further, the PVA resin (B) used in the present invention may be one type or a mixture of two or more types. When the PVA resin (B) is a mixture of two or more types, the unmodified PVA mentioned above, the unmodified PVA and the PVA resin having the structural unit represented by the general formula (1), the degree of saponification, and the degree of polymerization. , PVA resins having structural units represented by general formula (1) with different degrees of modification, unmodified PVA, or PVA resins having structural units represented by general formula (1) and other modified PVA resins. A combination of the following can be used.

In addition, the PVA-based resin (B) layer used in the present invention may contain, in addition to the PVA-based resin (B), a heat stabilizer, an antioxidant, an ultraviolet absorber, a crystal nucleating agent, an antistatic agent, a flame retardant, a plasticizer, a lubricant, a filler, a lubricant, and a crystal nucleating agent.

(Biodegradable resin (C) layer)
Next, the biodegradable resin (C) layer preferably used as the outer layer of the laminate of the present invention will be explained. This biodegradable resin (C) layer is a layer containing biodegradable resin (C) as a main component, and preferably contains 70% by mass or more of biodegradable resin (C), more preferably 80% by mass. % or more, more preferably 90% by mass or more. The upper limit is 100% by mass.

Examples of the biodegradable resin (C) include polylactic acid, a condensation product of adipic acid/terephthalic acid/1,4-butanediol (polybutylene adipate terephthalate (PBAT)), and succinic acid/1,4-butanediol. Condensation products of polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), polybutylene succinate (PBS), polybutylene sebacate terephthalate (PBSeT), polybutylene succinate adipate terephthalate (PBSAT), Examples include aliphatic polyesters such as polycaprolactone (PCL) and polyglycolic acid; modified starch; casein plastic; and cellulose, and these may be used alone or in combination of two or more.

Among these, polylactic acid and polybutylene adipate terephthalate are preferred in terms of strength. Furthermore, a mixture of polylactic acid and polybutylene adipate terephthalate is preferred in terms of adhesion and strength.

Polylactic acid is an aliphatic polyester resin whose main component is a lactic acid structural unit, and is made from L-lactic acid, D-lactic acid, or their cyclic dimers L-lactide, D-lactide, and DL-lactide. It is a polymer that

The polylactic acid used in the biodegradable resin (C) layer is preferably a homopolymer of these lactic acids, but other than lactic acids may be used in an amount that does not impair the properties, for example, 10 mol% or less. It may also contain a copolymer component.

Such copolymerization components include, for example, aliphatic hydroxycarboxylic acids such as glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, and 6-hydroxycaproic acid; caprolactone, etc. Lactones; Aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, 1,4-butanediol; Aliphatic diols such as succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, etc. Basic acids can be mentioned.

The content ratio of L-lactic acid and D-lactic acid in polylactic acid (mass of L-lactic acid/mass of D-lactic acid) is preferably 95/5 or more, particularly 99/1 or more, and especially 99.8/0.2 or more. The higher this value, the higher the melting point and the better the heat resistance, and conversely, the lower this value, the lower the melting point and the more likely the heat resistance is insufficient.

Specifically, in the case of a homopolymer of polylactic acid, the melting point of a polylactic acid homopolymer having the content ratio of 95/5 is about 152°C, and the melting point of a polylactic acid homopolymer of 99.8/0. 2 has a melting point of 175°C or higher.

The weight-average molecular weight of the polylactic acid used in the present invention is preferably 20,000 to 1,000,000, particularly 30,000 to 300,000, and especially 40,000 to 200,000. If the weight-average molecular weight is too large, the melt viscosity during hot melt molding tends to be too high, making it difficult to form a good film, and conversely, if the weight-average molecular weight is too small, the mechanical strength of the resulting laminate tends to be insufficient.

The weight average molecular weight can be measured by size exclusion chromatography (GPC, gel permeation chromatography) as polystyrene equivalent according to ISO 16014-1 and ISO 16014-3 standards using tetrahydrofuran as the eluent and a column (polystyrene gel) heated to 40°C.

Examples of commercially available polylactic acid include "Ingeo" manufactured by NatureWorks, "Lacea" manufactured by Mitsui Chemicals, Inc., "REVODE" manufactured by Zhejiang Haizheng Biomaterials Co., Ltd., and "Vyloecol" manufactured by Toyobo Co., Ltd.

Polybutylene adipate terephthalate is obtained by polycondensing adipic acid, terephthalic acid, and 1,4-butanediol.

The content of adipic acid in polybutylene adipate terephthalate is preferably 10 to 50 mol %, more preferably 15 to 40 mol %.
The content of terephthalic acid in polybutylene adipate terephthalate is preferably from 5 to 45 mol %, more preferably from 8 to 35 mol %.
The content of 1,4-butanediol in polybutylene adipate terephthalate is preferably 5 to 45 mol %, more preferably 10 to 30 mol %.
If the content of each component is too high or too low, the workability and corrosion resistance tend to decrease.

The weight average molecular weight of polybutylene adipate terephthalate is preferably 3,000 to 1,000,000, more preferably 20,000 to 600,000, and even more preferably 50,000 to 400,000. If the weight average molecular weight is too small, production becomes difficult, and if the weight average molecular weight is too large, the melt viscosity tends to increase and moldability tends to decrease.

Such weight average molecular weight can be measured by the method described above.

Polybutylene adipate terephthalate may contain other copolymer components in addition to adipic acid, terephthalic acid, and 1,4-butanediol.

Other copolymerization components include, for example, dihydroxy compounds such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran (poly-THF); glycolic acid, D-lactic acid, L-lactic acid, D,L-lactic acid, 6-hydroxyhexanoic acid, and cyclic derivatives thereof such as glycolide (1,4-dioxane-2,5-dione), D-dilactide, and L-dilactide (3,6-dimethyl-1,4-dioxane-2,5-dione); and hydroxycarboxylic acids such as p-hydroxybenzoic acid and oligomers and polymers of p-hydroxybenzoic acid.

The content of these other copolymer components is about 0.1 to 30 mol% of the total polybutylene adipate terephthalate (C2).

Further, when using a mixture of polylactic acid and polybutylene adipate terephthalate, the mixing ratio of polylactic acid/polybutylene adipate terephthalate (mass ratio) is preferably 10/90 to 90/10, more preferably It is 20/80 to 60/40.

In addition to the biodegradable resin (C), the biodegradable resin (C) layer used in the present invention also contains heat stabilizers, antioxidants, ultraviolet absorbers, crystal nucleating agents, antistatic agents, and flame retardants. , a plasticizer, a lubricant, a filler, a lubricant, a crystal nucleating agent, etc. may be blended.

The laminate of the present invention preferably has a layer structure of 3 to 15 layers, more preferably 3 to 7 layers, particularly preferably 5 to 7 layers.

The structure of the laminate of the present invention is not particularly limited, but the adhesive (A) layer containing the polyester resin composition of the present invention is a, the PVA resin (B) layer is b, and the biodegradable resin (C) layer is When c is any combination such as c/a/b, c/a/b/a/c, c/b/a/b/a/b/c, etc., is possible. In addition, when a plurality of biodegradable resin (C) layers exist in the laminate, the plurality of biodegradable resin (C) layers may be the same or different. The same applies when a plurality of PVA resin (B) layers are present in the laminate and when a plurality of adhesive (A) layers are present in the laminate.

In order to prevent deterioration of the gas barrier performance due to moisture absorption by the PVA-based resin (B) layer, it is usually preferable to provide a layer configuration in which a biodegradable resin (C) layer is provided in the portion of the PVA-based resin (B) layer that comes into contact with the outside air or the contents containing moisture.

The thickness of the laminate of the present invention is preferably 1 to 30,000 μm, more preferably 3 to 13,000 μm, and even more preferably 10 to 3,000 μm.

Furthermore, regarding the thickness of each layer constituting the laminate, the thickness of the biodegradable resin (C) layer is preferably 0.4 to 14,000 μm, more preferably 1 to 6,000 μm, and particularly preferably is 4 to 1,400 μm. If the thickness of the biodegradable resin (C) layer is too thick, the laminate tends to become too hard; conversely, if the thickness of the biodegradable resin (C) layer is too thin, the laminate becomes brittle. Tend.

Further, the thickness of the PVA resin (B) layer is preferably 0.1 to 1,000 μm, more preferably 0.3 to 500 μm, particularly preferably 1 to 100 μm. If the thickness of the PVA resin (B) layer is too thick, the laminate tends to become hard and brittle, and conversely, if the PVA resin (B) layer is too thin, the gas barrier properties tend to decrease. There is.

The thickness of the adhesive (A) layer containing the polyester resin composition of the present invention is preferably 0.1 to 500 μm, more preferably 0.15 to 250 μm, particularly preferably 0.5 to 50 μm. be. If the thickness of the adhesive (A) layer is too thick, the appearance may become poor, and conversely, if the thickness of the adhesive (A) layer is too thin, the adhesive force tends to be weak.

When there are multiple layers of each, the ratio of the thickness of the biodegradable resin (C) layer to the thickness of the PVA-based resin (B) layer (thickness of the biodegradable resin (C) layer/thickness of the PVA-based resin (B) layer) is preferably 1 to 100, more preferably 2.5 to 50, in terms of the ratio of the total thicknesses. If this ratio is too large, the barrier properties tend to be reduced, and if this ratio is too small, the laminate tends to be hard and brittle.

Further, the ratio of the thickness of the laminate of the present invention and the adhesive (A) layer (adhesive layer) (thickness of the adhesive (A) layer/thickness of the laminate of the present invention) is When there are multiple layers, the ratio of their total thickness is preferably 0.005 to 0.5, more preferably 0.01 to 0.3. If this ratio is too large, the appearance tends to be poor, and if this ratio is too small, the adhesive strength tends to be weak.

The laminate of the present invention can be manufactured by a conventional molding method, specifically, a melt molding method or a molding method from a solution state.

For example, in the melt molding method, adhesive (A) containing the polyester resin composition of the present invention and PVA resin (B) are sequentially or simultaneously melted onto a film or sheet of biodegradable resin (C). A method of extrusion lamination; conversely, a method of melt-extrusion laminating a PVA resin (B) film or sheet with an adhesive (A) and a biodegradable resin (C) sequentially or simultaneously, or a biodegradable resin (C), adhesive (A), and PVA resin (B) are co-extruded.

Among these, the melt molding method is preferred because it can be produced in one step and a laminate with excellent interlayer adhesion can be obtained, and the coextrusion method is particularly preferably used. When such a melt molding method is used, it is preferable to use a PVA-based resin having a 1,2-diol structural unit in its side chain as the PVA-based resin (B).

Examples of the co-extrusion method include an inflation method, a T-die method, a multi-manifold die method, a feed block method, and a multi-slot die method. The shape of the die may be a T-die, a round die, or the like.
The melt molding temperature during melt extrusion is preferably in the range of 140 to 250°C, more preferably 160 to 230°C.

The laminate of the present invention may be further subjected to a heat stretching treatment, which is expected to improve the strength and gas barrier properties.

Note that for the above-mentioned stretching treatment, etc., a known stretching method can be employed.
For example, specifically, uniaxial stretching and biaxial stretching in which a multilayer structure sheet is widened by gripping both edges; deep drawing, vacuum forming, and pressure forming in which a multilayer structure sheet is stretched using a mold. and mold forming methods such as vacuum-pressure forming methods; methods of processing a preformed multilayer structure such as a parison by a tubular drawing method, a stretch-blowing method, and the like.

When the objective is to produce a film or sheet-like molded product, it is preferable to use uniaxial or biaxial stretching as such a stretching method.

In addition, in the case of mold forming methods such as deep drawing, vacuum forming, pressure forming, and vacuum pressure forming, the laminate is uniformly heated in a hot air oven, heater type oven, or a combination of both. It is preferable to stretch the film using a chuck, a plug, a vacuum force, a compressed air force, or the like.

When aiming at molded products such as cups and trays whose drawing ratio (depth of molded product (mm)/maximum diameter of molded product (mm)) is usually 0.1 to 3, deep drawing method, vacuum It is preferable to employ a mold forming method in which stretching is performed using a mold such as a molding method, a pressure forming method, a vacuum pressure forming method, or the like.

The thus obtained laminate of the present invention exhibits strong adhesion between any of the layers, for example, the biodegradable resin (C) layer and the adhesive (A) layer, and the PVA resin (B) layer and the adhesive (A) layer. have power.

In addition, the adhesive (A), the biodegradable resin (C), and the PVA-based resin (B) are all biodegradable, and the laminate of the present invention also has excellent biodegradability.

Since the laminate of the present invention is biodegradable, it is suitable for use in items that can be disposed of directly in compost, such as coffee capsules (coffee bean containers for capsule coffee makers), shrink films, and other containers for food and beverages. used for.

Furthermore, when the laminate of the present invention has a PVA-based resin (B) layer, the PVA-based resin (B) layer can be dissolved in water and removed, and only the remaining water-insoluble resin can be recycled.

As described above, the present specification discloses the following configurations.
[1] A polyester-based resin composition containing a polyester-based resin as a main component and a tackifier, characterized in that, when the crystallization temperature of the polyester-based resin composition is Ta, the crystallization temperature of the polyester-based resin is Tb, the crystallization peak area (ΔHc) of the polyester-based resin composition is Ma, and the crystallization peak area (ΔHc) of the polyester-based resin is Mb, the polyester-based resin composition satisfies the following formula (I):
(Ta/Tb)×(Ma/Mb)<1.00 (I)
[2] The polyester resin composition according to [1] above, wherein the tackifier is a resin having a melting peak (ΔHm) of 10 J/g or less.
[3] The polyester resin composition according to [2] above, wherein the resin having a melting peak (ΔHm) of 10 J/g or less has a polar group.
[4] The polyester resin composition according to [2], characterized in that the resin having a melting peak (ΔHm) of 10 J/g or less has at least one selected from the group consisting of a double bond, an aromatic ring, and a heteroatom.
[5] The polyester resin composition according to any one of [1] to [4], characterized in that the tackifier is contained in an amount of 0.01 to 20% by mass.
[6] The polyester-based resin composition according to any one of [1] to [5] above, wherein the polyester-based resin is biodegradable.
[7] An adhesive comprising the polyester resin composition according to any one of [1] to [6] above.
[8] A laminate comprising at least one layer containing the polyester resin composition according to any one of [1] to [6] above.
[9] A laminate having an adhesive layer between a first layer and a second layer,
At least one of the first layer and the second layer is a polyvinyl alcohol-based resin layer,
A laminate, characterized in that the adhesive layer contains the polyester resin composition according to any one of [1] to [6] above.

The present invention will be described below with reference to examples. However, the present invention is not limited to the description of the examples as long as it does not depart from the gist of the present invention.
In the examples, "parts", "%" and "ppm" are by mass unless otherwise specified.

The raw material resins and additives used in each example are as follows:
<Raw material resin>
(A) Polybutylene succinate terephthalate (PBST): polyester copolymer produced in Production Example 1 below (B) Polybutylene adipate terephthalate (PBAT): "Ecoflex C1200" manufactured by BASF
(C) Polybutylene succinate (PBS): "BioPBS" manufactured by Mitsubishi Chemical Corporation

(Production Example 1: Production of Polybutylene Succinate Terephthalate (PBST))
[Preparation of polycondensation catalyst]
343.5 parts of magnesium acetate tetrahydrate were placed in a reactor equipped with a stirrer, and 1434 parts of anhydrous ethanol (purity 99% or more) were added. 218.3 parts of ethyl acid phosphate (mixture mass ratio of monoester and diester is 45:55) were added and stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved, 410.0 parts of tetra-n-butyl titanate were added. Stirring was continued for another 10 minutes to obtain a homogeneous mixed solution. This mixed solution was concentrated under reduced pressure while controlling the temperature at 60 ° C. or less. Approximately half of the amount of ethanol added was distilled off, leaving a translucent viscous liquid. 1,108 parts of 1,4-butanediol were added thereto, and further concentration was performed under reduced pressure while controlling the temperature at 80 ° C. or less to obtain a catalyst solution with a titanium atom content of 3.5%.

[Polymerization of polybutylene succinate terephthalate (PBST)]
In a reaction vessel equipped with a stirring device, a nitrogen inlet, a heating device, a thermometer, and a pressure reduction port, 33.6 parts of succinic acid, 38.6 parts of terephthalic acid, 69.7 parts of 1,4-butanediol, and tritriol were added as raw materials. 0.138 parts of methylolpropane (0.200 mol% based on the total of 100 mol% of succinic acid and terephthalic acid), 0.10 parts of polyethylene wax (“ACumist B6” manufactured by Honeywell, melting point: 124°C), sodium hydroxide 0.0017 part of (NaOH) was charged, and further added to give 30 ppm of titanium atoms per polyester resin from which tetra-n-butyl titanate was obtained. While the contents of the container were being stirred, nitrogen gas was introduced into the container, and the inside of the system was brought into a nitrogen atmosphere by vacuum displacement. Next, the temperature of the system was raised from 160°C to 230°C over 1 hour while stirring, and the reaction was carried out at this temperature for 3 hours. When the terminal acid value of the obtained ester oligomer was measured, it was 90 eq. /ton.
To this ester oligomer, the above catalyst solution was added in an amount of 70 ppm as titanium atoms per polyester obtained, and the temperature was raised to 250°C over 45 minutes, and at the same time 0.07 x 10 ³ over 1 hour and 20 minutes. The pressure was reduced to below Pa, and polycondensation was continued while maintaining the heating and reduced pressure state, and when the predetermined viscosity was reached, the polymerization was terminated to obtain polybutylene succinate terephthalate (PBST).

<Additive (tackifier)>
(a) Hydrogenated petroleum resin: "M-100" manufactured by Arakawa Chemical Co., Ltd. (melting peak (ΔHm) 1.3 J/g, has a double bond and an aromatic ring in the structure.)
(b) Rosin diol: "D90B" manufactured by Arakawa Chemical Co., Ltd. (melting peak (ΔHm) 2.4 J/g, has a double bond and a hetero atom (O atom) in the structure.)
(c) Acid-modified rosin: "R140B" manufactured by Arakawa Chemical Co., Ltd. (melting peak (ΔHm) 0.9 J/g, has a double bond and a hetero atom (O atom) in the structure.)
(d) Polycaprolactone: "Capa2205" manufactured by Ingevity UK Limited (melting peak (ΔHm) 91.6 J/g, has a double bond and a hetero atom (O atom) in the structure.)
(e) Polycaprolactone: "Capa2100" manufactured by Ingevity UK Limited (melting peak (ΔHm) 57.4 J/g, has a double bond and a hetero atom (O atom) in the structure.)

The melting peak (ΔHm) of the above additive was measured by the following 1) to 3) using a differential scanning calorimeter ("DSC Q2000" manufactured by TA Instruments).
1) The additive was heated from -60°C to 220°C at a heating rate of 10°C/min and held for 1 minute.
2) Cooled to -60°C at a cooling rate of 10°C/min.
3) The melting peak (ΔHm) when the temperature was raised again from -60°C to 220°C at a heating rate of 10°C/min was measured using a differential scanning calorimeter.

(Example 1)
[Preparation of polyester resin composition]
(A) Hydrogenated petroleum resin as a tackifier was added to (A) PBST as a raw material polyester resin so that the content of the hydrogenated petroleum resin was 5% by mass, and the mixture was passed through a twin-screw extruder. The mixture was melt-kneaded under the following conditions, extruded into strands, cooled with water, and then cut with a pelletizer to obtain a polyester resin composition in the form of cylindrical pellets.

Twin screw extruder diameter (D): 15mm
L/D:60
Screw rotation speed: 200rpm
Mesh: 60/90/60mesh
Processing temperature: 160℃

(Examples 2 to 3)
A polyester resin composition was obtained in the same manner as in Example 1, except that the additives were changed to those shown in Table 1.

(Comparative Example 1)
A polyester resin composition was obtained in the same manner as in Example 1, except that no additive was added.

(Comparative Examples 2 to 3)
A polyester resin composition was obtained in the same manner as in Example 1, except that the additives were changed to those shown in Table 1.

(Examples 4 to 6, Comparative Examples 4 to 5)
A polyester resin composition was obtained in the same manner as in Example 1, except that the raw material resins and additives were as shown in Table 2.

(Examples 7 to 9, Comparative Example 6)
A polyester resin composition was obtained in the same manner as in Example 1, except that the raw material resins and additives were as shown in Table 3.

Examples 1 to 9 and Comparative Examples 1 to 6 were evaluated as follows.
The results are shown in Tables 1 to 3.

[Measurement of crystallization temperature and crystallization peak area (ΔHc)]
First, the crystallization temperature and crystallization peak area (ΔHc) of the raw polyester resin, and the crystallization temperature and crystallization peak area (ΔHc) of the polyester resin composition were measured using a differential scanning calorimeter (TA Instruments'"DSCQ2000") according to the following 1) to 2).
1) The sample was heated from -60°C to 220°C at a heating rate of 10°C/min, and then held at that temperature for 1 minute.
2) The crystallization peak temperature (crystallization temperature) and crystallization peak area (ΔHc) when cooled to −60° C. at a cooling rate of 10° C./min were measured using a differential scanning calorimeter.
Next, from the obtained crystallization temperature and crystallization peak area (ΔHc), (Ta/Tb)×(Ma/Mb) was calculated, where Ta is the crystallization temperature of the polyester-based resin composition, Tb is the crystallization temperature of the polyester-based resin, Ma is the crystallization peak area (ΔHc) of the polyester-based resin, and Mb is the crystallization peak area (ΔHc) of the polyester-based resin.

[Evaluation of Adhesion (Hot Press)]
The raw material PVA ("Nichigo G-Polymer BVE8049P" manufactured by Mitsubishi Chemical Corporation) was melt-kneaded under the following conditions in a single screw extruder, extruded into a film shape from a T-die, and taken up and cooled by a roll to obtain a PVA film having a thickness of 30 μm.
Single screw extruder diameter (D): 40 mm
L/D: 28
Screw rotation speed: 20 rpm
Mesh: 60/90/60 mesh
Processing temperature: 210°C
Roll Roll temperature: 80°C

0.01 to 0.03 g of pellets of the polyester resin composition were sandwiched between the PVA films prepared above, and then pressed using a manual hydraulic vacuum heating press (manufactured by Imoto Seisakusho Co., Ltd., model number: IMC-11FD-A). The mixture was heated at 130° C. for 4 minutes and then pressed at 20 kN for 10 seconds at 130° C. to obtain a laminated film.
The peelability of the obtained laminated film was evaluated based on the following criteria.
<Evaluation criteria>
A (Good): Does not peel off even if force is applied B (Poor): Easily peels off when force is applied

Each example in Table 1 uses PBST as the raw resin, and each example in Tables 2 and 3 uses PBAT and PBS as the raw resin. All of Examples 1 to 9, which have a (Ta/Tb) x (Ma/Mb) value of less than 1.00, did not peel off even when force was applied, had strong adhesive strength (A rating), and were found to have excellent adhesiveness.

Claims (9)

A polyester-based resin composition containing a polyester-based resin as a main component and a tackifier,
A polyester-based resin composition characterized by satisfying the following formula (I): Ta is a crystallization temperature of the polyester-based resin, Tb is a crystallization temperature of the polyester-based resin, Ma is a crystallization peak area (ΔHc) of the polyester-based resin, and Mb is a crystallization peak area (ΔHc) of the polyester-based resin.
(Ta/Tb)×(Ma/Mb)<1.00 (I) The polyester resin composition according to claim 1, characterized in that the tackifier is a resin having a melting peak (ΔHm) of 10 J/g or less. The polyester resin composition according to claim 2, wherein the resin having a melting peak (ΔHm) of 10 J/g or less has a polar group. The polyester resin composition according to claim 2, characterized in that the resin having a melting peak (ΔHm) of 10 J/g or less has at least one selected from the group consisting of a double bond, an aromatic ring, and a heteroatom. The polyester resin composition according to claim 1, characterized in that it contains 0.01 to 20% by mass of the tackifier. The polyester resin composition according to claim 1, characterized in that the polyester resin is biodegradable. An adhesive comprising the polyester resin composition according to any one of claims 1 to 6. A laminate having at least one layer containing the polyester resin composition according to any one of claims 1 to 6. A laminate including an adhesive layer between a first layer and a second layer,
At least one layer of the first layer and the second layer is a polyvinyl alcohol resin layer,
A laminate characterized in that the adhesive layer contains the polyester resin composition according to any one of claims 1 to 6.