WO2023112514A1

WO2023112514A1 - Resin composition and molded article

Info

Publication number: WO2023112514A1
Application number: PCT/JP2022/040376
Authority: WO
Inventors: 祐介服部
Original assignee: 株式会社Tbm
Priority date: 2021-12-17
Filing date: 2022-10-28
Publication date: 2023-06-22
Also published as: JP7094590B1; JP2023090470A

Abstract

The present invention addresses the problem of providing a biodegradable-resin-containing composition having excellent molding processability, the biodegradable-resin-containing composition being capable of yielding a molded article that has exceptional mechanical properties, especially elongation at break, and that is unlikely to undergo deterioration of appearance due to bleeding.　The present invention provides a resin composition containing a biodegradable resin, heavy calcium carbonate, and an epoxy compound, the mass ratio of the biodegradable resin and the heavy calcium carbonate ranging from 10:90 to 70:30, the biodegradable resin including at least polybutylene adipate terephthalate or polybutylene succinate adipate, the epoxy compound being one or more compounds selected from the group consisting of epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A epoxy resin, and bisphenol F epoxy resin, and the epoxy compound content being 2-8 mass% inclusive relative to 100 mass% of the resin composition.

Description

Resin composition and molded article

The present invention relates to resin compositions and molded articles.

Biodegradable resins are attracting attention as environmentally friendly resins because they decompose into substances that originally exist in nature through the action of microorganisms and hydrolysis. It has been proposed to add various components to biodegradable resins in order to impart favorable properties without impairing the low environmental load (for example, Patent Documents 1 and 2). Calcium carbonate etc. are mentioned as such a component.

With a biodegradable resin composition containing a high content of calcium carbonate, there is a possibility that the mechanical properties of the molded product obtained by molding the composition, especially the elongation at break, will decrease. Among them, a resin composition in which a large amount of calcium carbonate, for example, about 30% by mass or more, is added to a biodegradable resin such as polybutylene adipate terephthalate, is difficult to mold, and hydrolysis proceeds during molding, resulting in deterioration of mechanical properties and molded products. The surface appearance of the surface is deteriorated, and there are even cases where a molded article that can withstand practical use cannot be obtained. As a technique for improving the mechanical properties of a resin composition, it has been proposed to add a plasticizer such as a citrate ester or glycerol (for example, Patent Documents 3 and 4). Further, Patent Document 5 discloses a resin composition in which polybutylene adipate terephthalate or polybutylene succinate adipate and heavy calcium carbonate are combined.

JP 2017-119850 A Japanese Patent Publication No. 2018-527416 Japanese Patent Publication No. 2020-531678 JP 2020-183496 A Japanese Patent No. 6916571

Although the elongation at break can be improved to some extent by adding a plasticizer, the plasticizer may bleed and deteriorate the surface appearance of the molded product. If the amount of the plasticizer is suppressed to prevent bleeding, the mechanical properties are not significantly improved, and the moldability is also difficult to improve. Also in the resin compositions described in Patent Documents 3 and 4, the content of calcium carbonate is limited to 20% by mass or less, and further to about 10% by mass or less. The resin composition described in Patent Document 5 contains about 30 to 90% by mass of heavy calcium carbonate, which suppresses bleeding, but further improvement in elongation at break is required depending on the application.

The present invention has been made in view of the above circumstances, and it is possible to obtain a molded product that has good moldability, excellent mechanical properties, especially excellent elongation at cutting, and is unlikely to cause deterioration in appearance due to bleeding. An object of the present invention is to provide a resin composition containing a flexible resin.

The present inventors solved the above problems by using a biodegradable resin containing at least polybutylene adipate terephthalate or polybutylene succinate adipate, combining it with ground calcium carbonate, and adding a predetermined amount of a specific epoxy compound. The inventors have found the points that can be achieved, and have completed the present invention. More specifically, the present invention provides:

(1) A resin composition containing a biodegradable resin, ground calcium carbonate, and an epoxy compound,
The biodegradable resin and the heavy calcium carbonate have a mass ratio of 10:90 to 70:30,
The biodegradable resin contains at least polybutylene adipate terephthalate or polybutylene succinate adipate,
The epoxy compound is one or more compounds selected from the group consisting of epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A type epoxy resin, and bisphenol F type epoxy resin. can be,
The content of the epoxy compound is 2.0% by mass or more and 8.0% by mass or less with respect to 100% by mass of the resin composition.
Resin composition.

(2) The resin composition according to (1), wherein the epoxy compound has an epoxy equivalent of 100 g/eq to 200 g/eq.

(3) The resin composition according to (1) or (2), which contains the biodegradable resin and the ground calcium carbonate at a mass ratio of 10:90 to 50:50.

(4) the biodegradable resin comprises polybutylene adipate terephthalate and polylactic acid;
The mass ratio of the polybutylene adipate terephthalate and the polylactic acid is 50:50 to 90:10,
(1) The resin composition according to any one of (3).

(5) the biodegradable resin comprises polybutylene succinate adipate and polylactic acid;
The mass ratio of the polybutylene succinate adipate and the polylactic acid is 50:50 to 90:10,
(1) The resin composition according to any one of (3).

(6) further comprising 5% by mass or more and 30% by mass or less of a natural organic substance with respect to 100% by mass of the resin composition;
The natural organic matter is one or more selected from the group consisting of cellulose powder, wood flour, starch, rice husk, bean curd refuse, and wheat bran.
(1) The resin composition according to any one of (5).

(7) According to any one of (1) to (6), the average particle size of the heavy calcium carbonate measured by an air permeation method according to JIS M-8511 is 0.7 μm or more and 6.0 μm or less. Resin composition.

(8) The resin composition according to any one of (1) to (7), further containing acetyltributyl citrate in an amount of 5% by mass or more and 20% by mass or less with respect to 100% by mass of the resin composition. .

(9) A molded article obtained from the resin composition according to any one of (1) to (8).

(10) The molded product according to (9), wherein the molded product is an inflation film.

(11) The molded article according to (9), wherein the molded article is an extruded sheet.

According to the present invention, there is provided a biodegradable resin-containing composition that is excellent in moldability, excellent in mechanical properties, especially elongation at break, and capable of producing a molded article that is less likely to deteriorate in appearance due to bleeding. be.

Embodiments of the present invention will be described below, but the present invention is not limited thereto.

<Resin composition>
The resin composition of the present invention is a resin composition containing a biodegradable resin, ground calcium carbonate, and an epoxy compound,
The biodegradable resin and the heavy calcium carbonate have a mass ratio of 10:90 to 70:30,
The biodegradable resin contains at least polybutylene adipate terephthalate or polybutylene succinate adipate,
The epoxy compound is one or more compounds selected from the group consisting of epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A type epoxy resin, and bisphenol F type epoxy resin. can be,
The content of the epoxy compound is 2.0% by mass or more and 8.0% by mass or less with respect to 100% by mass of the resin composition.

Polybutylene adipate terephthalate (PBAT) and polybutylene succinate adipate (PBSA) have good biodegradability.
It is known that a biodegradable resin composition containing calcium carbonate together with such a biodegradable resin can impart good properties (tearability, etc.) to molded articles obtained from the composition. .

However, the present inventors have previously found that when the biodegradable resin composition contains a large amount of calcium carbonate, the tensile strength and elongation at break of the molded article obtained from the composition are likely to be impaired, and that calcium carbonate It was found that by selecting heavy calcium carbonate, it is possible to suppress a decrease in tensile strength and elongation at break.

The present inventors conducted further studies and found that by blending a specific epoxy compound in a relatively small amount, the moldability was improved and the deterioration of the mechanical properties of the molded product was suppressed, and in particular, the elongation at break was greatly improved. Furthermore, it was found that deterioration of the appearance due to bleeding hardly occurs.

Some of this type of epoxy compound may be blended as a plasticizer in a resin composition in an amount of about 10 to 30% by mass, as will be described later. In particular, an unexpected finding was obtained that the elongation at break was significantly improved. The reason for this is not clear, and the present invention is not limited by any particular theory, but it is possible that the epoxy compound blended in the present invention reacts with the decomposition product of the biodegradable resin as described later. gender can be considered.

In the present invention, "biodegradability" means the property of being decomposed by the action of microorganisms or hydrolysis, and can be evaluated by the method shown in the Examples.

In the present invention, the term "tensile strength" means the value obtained by dividing the maximum load reached before breaking by the cross-sectional area before applying the tensile load, when the target is broken by applying a tensile load. It can be evaluated by the method shown in Examples.

In the present invention, "elongation at break" means the elongation at break when a tensile load is applied to an object to break it, and can be evaluated by the method shown in the Examples.

In the present invention, phrases such as "improved mechanical properties" and "suppressed reduction in tensile strength and elongation at break" refer to molded articles obtained from resin compositions that satisfy the requirements of the present invention. At least one of mechanical properties such as tensile strength and elongation at break is a characteristic value of a molded article obtained from a resin composition that does not satisfy the requirements of the present invention except that the type and amount of biodegradable resin are common. means equal to or greater than

The configuration of the resin composition of the present invention will be described below.

(Type of biodegradable resin)
The biodegradable resin in the present invention includes at least polybutylene adipate terephthalate (hereinafter also referred to as "PBAT") or polybutylene succinate adipate (hereinafter also referred to as "PBSA"). That is, the biodegradable resin in the invention may contain either PBAT or PBSA, or both.

The biodegradable resin in the present invention may or may not contain biodegradable resins other than PBAT and PBSA. The content of polybutylene adipate terephthalate or polybutylene succinate adipate is preferably 50% by mass or more, particularly 70% by mass or more, relative to the biodegradable resin.

Examples of biodegradable resins other than PBAT and PBSA that can be contained in the resin composition of the present invention include polylactic acid, polyhydroxybutyrate, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). , polycaprolactone, polybutylene succinate, polyethylene succinate, polymalic acid, polyglycolic acid, polydioxanone, poly(2-oxetanone) and the like. Among these, polylactic acid is preferable from the viewpoint that the effects of the present invention are likely to be exhibited.

In the present invention, "polylactic acid" refers to a polylactic acid homopolymer obtained by condensation polymerization of only a lactic acid component as a raw material monomer, a lactic acid component as a raw material monomer, and other monomer components copolymerizable with the lactic acid component. It includes a polylactic acid copolymer obtained by condensation polymerization of and.
Any polymer known as polylactic acid can be used in the present invention.

Other monomer components that can be copolymerized with lactic acid are not particularly limited. The above polyvalent carboxylic acids, lactones and the like can be mentioned.

Examples of oxyacids include oxyacids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxybenzoic acid, and hydroxyheptanoic acid.

Examples of dihydric alcohols include ethylene glycol, propylene glycol, propanediol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, Examples include triethylene glycol, polyethylene glycol, polytetramethylene glycol and the like.

Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol.

Examples of aromatic hydroxy compounds include hydroquinone, resorcin, bisphenol A, and the like.

Examples of divalent carboxylic acids include oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid. acid, bis(4-carboxyphenyl)methane, anthracenedicarboxylic acid, bis(4-carboxyphenyl)ether, sodium 5-sulfoisophthalate and the like.

Examples of trivalent or higher polyvalent carboxylic acids include trimellitic acid and pyromellitic acid.

Examples of lactones include caprolactone, valerolactone, propiolactone, undecalactone, 1,5-oxepan-2-one and the like.

(Composition of biodegradable resin)
The composition of the biodegradable resin is not particularly limited as long as it contains at least PBAT and PBSA, but any one of the following aspects is particularly preferable.
(Mode 1) The biodegradable resin consists of PBAT.
(Mode 2) The biodegradable resin is PBSA.
(Mode 3) The biodegradable resin consists of PBAT and PBSA.
(Mode 4) The biodegradable resin consists of PBAT and/or PBSA and polylactic acid.

In the present invention, "the biodegradable resin consists of resin X" means that only resin X is included as the biodegradable resin in the resin composition.

Regarding the above (aspect 3), the mixing ratio of PBAT and PBSA is not particularly limited, but the mass ratio of PBAT and PBSA is preferably PBAT:PBSA=10:90 to 90:10.

Regarding the above (mode 4), the mixing ratio of PBAT and PBSA to polylactic acid is not particularly limited, but the mass ratio of PBAT and PBSA (total amount) to polylactic acid is preferably PBAT and PBSA: polylactic acid = 50. : 50 to 90:10, more preferably PBAT and PBSA: polylactic acid = 70:30 to 90:10.

Regarding the above (mode 4), the blending ratio of PBAT and polylactic acid is not particularly limited, but the mass ratio of PBAT and polylactic acid is preferably PBAT:polylactic acid = 50:50 to 90:10, more preferably is PBAT: polylactic acid = 70:30 to 90:10.

Regarding the above (mode 4), the blending ratio of PBSA and polylactic acid is not particularly limited, but the mass ratio of PBSA and polylactic acid is preferably PBSA:polylactic acid = 50:50 to 90:10, more preferably is PBSA: polylactic acid = 70:30 to 90:10.

(heavy calcium carbonate)
In the present invention, "heavy calcium carbonate" is obtained by mechanically pulverizing natural calcium carbonate. are distinct.

Heavy calcium carbonate can be obtained, for example, by crushing and classifying natural calcium carbonate such as calcite (limestone, chalk, marble, etc.), shells, and corals.

As the pulverization method in the method for producing heavy calcium carbonate, either wet pulverization or dry pulverization can be employed. Dry pulverization, which does not require a dehydration step, a drying step, or the like, is preferable from an economical point of view.
The pulverizer used for pulverization is not particularly limited, and examples thereof include impact pulverizers, pulverizers using pulverizing media (such as ball mills), and roller mills.

For classification in the manufacturing method of heavy calcium carbonate, conventionally known means such as air classification, wet cyclone, and decanter can be adopted.

The ground calcium carbonate may or may not be surface-treated. The surface treatment can be performed at any time (before pulverization, during pulverization, before classification, after classification, etc.) in the method for producing heavy calcium carbonate.

The surface treatment of heavy calcium carbonate includes physical methods (plasma treatment, etc.) and chemical methods (methods using coupling agents, surfactants, etc.).

Among the surface treatments of heavy calcium carbonate, coupling agents used in chemical methods include, for example, silane coupling agents and titanium coupling agents.

Among the surface treatments of heavy calcium carbonate, surfactants used in chemical methods include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. More specific examples include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

By applying the surface treatment as described above, the dispersibility of heavy calcium carbonate can be improved.
However, heavy calcium carbonate that has not been subjected to surface treatment is preferable in that it can reduce the risk of odor generation due to thermal decomposition of the surface treatment agent during molding.

The form of ground calcium carbonate is not particularly limited, but from the viewpoint of good dispersibility in the resin composition, it is preferably particulate.

When the ground calcium carbonate is particulate, its average particle size is preferably 0.7 μm or more and 6.0 μm or less, more preferably 1.0 μm or more and 5.0 μm or less, still more preferably 1.5 μm or more and 3.0 μm. It is below.
When the average particle size of the heavy calcium carbonate is within the above range, the dispersibility in the resin composition is good, and an excessive increase in viscosity of the resin composition can be prevented. Furthermore, the heavy calcium carbonate particles are less likely to protrude from the surface of the molded product obtained from the resin composition and fall off, or the surface properties, mechanical strength, etc. are less likely to be impaired, and the effects of the present invention are more likely to be achieved.

In the present invention, the "average particle size" means a value calculated from the measurement results of the specific surface area by the air permeation method according to JIS M-8511.
As a device for measuring the average particle diameter, for example, a specific surface area measuring device “SS-100 type” manufactured by Shimadzu Corporation can be preferably used.

When the heavy calcium carbonate is particulate, it is preferable that particles with a particle diameter of 45 μm or more are not included in the particle size distribution.

When ground calcium carbonate is particulate, its irregularity can be represented by the degree of spheroidization of the shape, ie, the degree of circularity. A lower roundness means a higher irregularity.
When the ground calcium carbonate is particulate, its circularity is preferably 0.50 or more and 0.95 or less, more preferably 0.55 or more and 0.93 or less, and still more preferably 0.60 or more and 0.90. It is below.

In the present invention, the term “roundness” refers to a value obtained by dividing the projected area of a particle by the area of a circle having the same perimeter as the projected perimeter of the particle ((projected area of the particle)/(projected perimeter of the particle) means the area of a circle with the same perimeter)).
The method of measuring the roundness is not particularly limited, but for example, the roundness can be specified by analyzing a projected image of particles obtained with a scanning microscope, a stereomicroscope, or the like, using commercially available image analysis software.
Specifically, the projected area of the particle (A), the area of the circle having the same perimeter as the projected perimeter of the particle (B), the radius of the circle having the same perimeter as the projected perimeter of the particle (r), the particle can be calculated by the following formula based on the measurement results of the projection perimeter (PM) of the .
"Roundness" = A/B = A/πr ² = A x 4π/(PM) ²

(Composition of resin composition)
The composition of the resin composition of the present invention is such that the mass ratio of biodegradable resin and ground calcium carbonate is biodegradable resin: ground calcium carbonate = 10:90 to 70:30, and a specific epoxy There is no particular limitation except that the content of the compound is 2.0 to 8.0% by mass.
According to the present invention, despite the high content of heavy calcium carbonate as described above, molding is excellent in moldability, mechanical properties, particularly good elongation at break, and bleeding to the surface of the molded product is less likely to occur. It is possible to provide a resin composition that provides a product.

In the resin composition of the present invention, the mass ratio of the biodegradable resin and the heavy calcium carbonate is preferably biodegradable resin: heavy calcium carbonate = 10:90 to 50:50, and 20:80 to 50:50. is more preferred, and 30:70 to 50:50 is even more preferred.

The upper limit of the content of the biodegradable resin is preferably 70% by mass or less, more preferably 50% by mass or less, relative to the resin composition.

The lower limit of the content of the biodegradable resin is preferably 10% by mass or more, more preferably 20% by mass or more, relative to the resin composition.

The upper limit of the content of heavy calcium carbonate is preferably 90% by mass or less, more preferably 80% by mass or less, relative to the resin composition.

The lower limit of the content of heavy calcium carbonate is preferably 30% by mass or more, more preferably 50% by mass or more, relative to the resin composition.

(epoxy compound)
In addition to the above biodegradable resin and ground calcium carbonate, the resin composition of the present invention contains epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A type epoxy resin, and One or more epoxy compounds selected from the group consisting of bisphenol F type epoxy resins are contained in an amount of 2.0% by mass or more and 8.0% by mass or less based on 100% by mass of the resin composition.

Epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, and epoxidized palm oil are known and commercially available. Both are epoxidized vegetable oils such as soybean oil, linseed oil, castor oil, and palm oil. In this specification, epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, and epoxidized palm oil may be collectively referred to as "epoxidized vegetable oil".

These epoxidized vegetable oils are made from natural oils, and the degree of epoxidation varies between varieties, between lots, and between molecules within the same lot. over. In addition, there are cases where oils not made solely from soybean oil or flax are supplied as "epoxidized soybean oil" or the like because they have a similar structure, but such epoxidized products are also epoxy compounds used in the present invention. subsumed in Examples of representative chemical structures of epoxidized soybean oil and epoxidized linseed oil are shown below, but the epoxidized vegetable oil that can be used in the present invention is not limited to these.

An example of a representative chemical structure of epoxidized soybean oil:

An example of a representative chemical structure of epoxidized linseed oil:

The molecular weights of epoxidized soybean oil and epoxidized linseed oil shown in the above formula are 960 and 974, respectively. In the present invention, an epoxidized vegetable oil of any molecular weight can be used, but considering the balance between the molding processability of the resin composition and the mechanical properties of the molded product, the average molecular weight is preferably about 500 to 2000. , more preferably about 700 to 1,500, and particularly preferably about 800 to 1,200.

Bisphenol A-type epoxy resins and bisphenol F-type epoxy resins are also known, and various types are commercially available as general-purpose resin materials. Epoxy resin is a general term for thermosetting resins that can be cured by crosslinking epoxy groups remaining in the polymer. In a broad sense, it includes both prepolymers before cross-linking and curing and resins after curing, but prepolymers are used in the present invention. Hereinafter, the bisphenol A type epoxy resin and the bisphenol F type epoxy resin may be collectively referred to as "prepolymer". These prepolymers can generally be obtained by copolymerizing bisphenol A or bisphenol F with epichlorohydrin, and various types are available on the market depending on the state of polymerization. Their representative chemical structures are shown below.

An example of a representative chemical structure of a bisphenol A type epoxy resin:

An example of a representative chemical structure of a bisphenol F type epoxy resin:

These prepolymers generally tend to be solid at room temperature when "n" in the above formula is 2 to 3 or more and the molecular weight is about 700 to 1000 or more. Although any form of prepolymer can be used in the present invention, a liquid prepolymer is preferred from the viewpoint of improving the flexibility of the resin composition. More preferably, prepolymers in which "n" is 1 or less, especially 0 are used.

The above prepolymer is often used as a main raw material for thermosetting resins, that is, as a component that usually accounts for 50% by mass or more, or 70% by mass or more. Further, the epoxidized vegetable oil is frequently used as a resin plasticizer, and is usually blended in a resin composition in an amount of about 10 to 30% by mass. However, in the resin composition mainly composed of PBAT or PBSA and ground calcium carbonate as in the present invention, these epoxy compounds are added in an amount of 2.0% by mass or more and 8.0% by mass based on 100% by mass of the resin composition. Mechanical properties such as elongation at break are greatly improved by blending in a relatively small amount such as the following. This is a completely unexpected finding.

Although the present invention is not limited by any particular theory, one possible reason why the present invention is effective is that the epoxy compound reacts with the decomposition products of PBAT and PBSA. In general, ester resins such as PBAT and PBSA are hydrolyzed to reduce their molecular weights and produce decomposition products having carboxylic acid ends. When an epoxy compound coexists here, it reacts with the carboxy group of the generated decomposition product, resulting in suppression of a decrease in the molecular weight of the resin, and the reaction product can also function as a high-molecular-weight plasticizer. Furthermore, the risk of accelerated hydrolysis of PBAT and PBSA as a result of the reaction of the carboxylic acid, which is about to be generated by the decomposition of the resin, with the epoxy compound is reduced. The reason why the elongation at break can be greatly improved as shown in the examples described later even at a blending amount of 2.0 to 8.0% by mass, at which a large plasticizing effect is not normally obtained by blending the liquid component. is thought to be for this reason. The reason why it is difficult to bleed to the surface of the molded product, unlike ordinary plasticizers, can be attributed to the fact that part of the compounded epoxy compound bonds with the polymer component.

As described above, the molecular weight and chemical structure of the epoxidized vegetable oil and prepolymer to be blended in the resin composition of the present invention are not particularly limited, but compounds having an epoxy equivalent of 100 g/eq to 200 g/eq are preferred. . If the epoxy equivalent is 200 g/eq or less, even if the amount is small, a sufficient amount of epoxy groups relative to the biodegradable resin coexist in the resin composition. It reacts to suppress the reduction in molecular weight, and the mechanical properties of the molded product can be improved. Moreover, since it is possible to reduce the compounding amount, the risk of bleeding on the surface of the molded product is also reduced. If the epoxy equivalent is 100 g/eq or more, it is advantageous in terms of cost because various products are on the market. The epoxy equivalent of the epoxy compound is more preferably 120 g/eq or more and less than 200 g/eq, and particularly preferably 150 g/eq or more and 190 g/eq or less.

In addition, in order to enhance the effect of improving mechanical properties due to the inclusion of epoxy compounds, the content of these epoxy compounds is preferably 2.2% by mass or more relative to 100% by mass of the resin composition, and 2.5% by mass. More preferably, it should be 3.0% by mass or more, and particularly preferably 3.0% by mass or more.

On the other hand, from the viewpoint of reducing the risk of the epoxy compound bleeding onto the surface of the molded product, the content of these epoxy compounds is preferably 6.0% by mass or less with respect to 100% by mass of the resin composition. It is more preferably less than 0% by mass, even more preferably 4.5% by mass or less, and particularly preferably 4.0% by mass or less. In particular, an epoxy compound having an epoxy equivalent of more than 200 g/eq may bleed to the surface of the molded article if it is blended in a large amount, so the content is preferably less than 5.0% by mass.

(Other components in the resin composition)
In addition to the above components, the resin composition of the present invention may further contain optional components within a range that does not impair the effects of the present invention. Such ingredients can be used singly or in combination of two or more. Further, the type and blending amount of such components can be appropriately set according to the effect to be obtained.

Components that can be contained in the resin composition of the present invention include plasticizers, natural organic substances, resins other than biodegradable resins, antistatic agents, fillers (other than heavy calcium carbonate), coloring agents, lubricants, and antioxidants. , flame retardants, foaming agents, and the like.

[Plasticizer]
Examples of plasticizers include acetyltributyl citrate, triethyl citrate, acetyltriethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, o -benzoyl benzoic acid ester, diacetin and the like. Epoxy compounds such as the epoxidized soybean oil described above can also be used as plasticizers.

Among the above plasticizers, acetyltributyl citrate, in combination with heavy calcium carbonate, does not impair the biodegradability of the biodegradable resin and particularly suppresses the reduction in tensile strength and elongation at break of the molded product. It has the advantage of being easy.

The upper limit of the plasticizer content is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, relative to the resin composition of the present invention.

The resin composition of the present invention has improved mechanical properties such as elongation at break due to the action of the contained epoxy compound, and is flexible. In this case, the lower limit of the content is preferably 5.0% by mass or more, more preferably 7.5% by mass or more, relative to the resin composition of the present invention.

When acetyltributyl citrate is used as a plasticizer, the upper limit of its content is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, relative to the resin composition of the present invention.

When acetyltributyl citrate is used as a plasticizer, the lower limit of its content is preferably 5.0% by mass or more, more preferably 7.5% by mass or more, relative to the resin composition of the present invention.

[Natural organic matter]
Any component that can be incorporated into the resin composition can be used as the natural organic substance.

Among the natural organic substances, one or more selected from the group consisting of cellulose powder, wood flour, starch, rice husks, bean curd refuse, and wheat bran impairs the biodegradability of the biodegradable resin in combination with heavy calcium carbonate. It has the advantage that it is particularly easy to suppress the decrease in the tensile strength and elongation at break of the molded product.

In the present invention, "cellulose powder" is not particularly limited as long as it is powdered cellulose.
The average particle size of the cellulose powder is preferably 5 μm or more and 45 μm or less, more preferably 10 μm or more and 30 μm or less.
A commercially available product may be used as the cellulose powder.

In the present invention, "wood powder" is not particularly limited as long as it is powder obtained from any tree (cypress, Japanese cedar, etc.).
The average particle size of the wood flour is preferably 20 μm or more and 300 μm or less, more preferably 20 μm or more and 45 μm or less.
As wood flour, for example, what is known as "sawdust" can be used.

"Starch" in the present invention can be of any form that can be blended with a resin. The starch may be powdered, for example.

In the present invention, "rice husk" means the outermost hull of rice, and any form that can be blended with resin can be used. The rice hulls may be powdered, for example.

In the present invention, "okara" means soybean milk lees, and any form that can be blended with resin can be used. Okara is preferably a dried product, more preferably a dried powder.

In the present invention, "wheat bran" means the skin (outer skin, germ, etc.) removed during wheat milling, and any form that can be blended with resin can be used. The bran may be powdered, for example.

The upper limit of the content (total amount) of natural organic matter is preferably 20.0% by mass or less, more preferably 10.0% by mass or less, relative to the resin composition.

The lower limit of the content (total amount) of natural organic matter is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, relative to the resin composition.

[others]
Other components that can be contained in the resin composition of the present invention are exemplified below.

As resins other than biodegradable resins,
Polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, polymethyl-1-pentene, and ethylene-cyclic olefin copolymers;
Ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salt of ethylene-methacrylic acid copolymer (ionomer), ethylene-alkyl acrylate copolymer, ethylene- Functional group-containing polyolefin resins such as methacrylic acid alkyl ester copolymers, maleic acid-modified polyethylene, and maleic acid-modified polypropylene;
Polyamide resins such as nylon-6, nylon-6,6, nylon-6,10, nylon-6,12;
Aromatic polyester resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, and polybutylene terephthalate;
Polystyrene resins such as atactic polystyrene, syndiotactic polystyrene, acrylonitrile-styrene (AS) copolymer, acrylonitrile-butadiene-styrene (ABS) copolymer;
Polyvinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride;
polyphenylene sulfide;
Polyether-based resins such as polyether sulfone, polyether ketone, polyether ether ketone, and the like are included.
However, from the viewpoint that the effect of the present invention is likely to be exhibited, the resin composition of the present invention does not contain a resin other than a biodegradable resin, or even if it contains a small amount (for example, 1.0 % by mass or less).

Examples of the antistatic agent include fatty acid diethanolamides such as lauryl diethanolamide and stearyl diethanolamide, and hydroxyl group-containing compounds such as alcohol amine compounds. Alcohol amines such as monoethanolamine, diethanolamine, triethanolamine and the like are particularly preferred. Two or more antistatic agents can be used in combination. These antistatic agents may be supported on calcium silicate, calcium carbonate, or the like. It should be noted that the number of carbon atoms in the acyl group of the fatty acid diethanolamide is preferably in the range of about 8 to 22 from the viewpoint of exhibiting a sufficient antistatic effect.
The amount of such an antistatic agent is about 0.01 to 8.00% by mass, more preferably 0.02%, when the total mass of the inorganic powder-blended thermoplastic resin composition is 100% by mass. It is desired that the content be blended in a proportion of up to 4.00% by mass, more preferably 0.05 to 3.00% by mass, particularly about 0.10 to 1.50% by mass. By using it within this range, in addition to obtaining a sufficient antistatic effect, there is little possibility that the surface of the resin will become sticky or that the physical properties of the resin will be adversely affected.

Fillers can be either synthetic or of natural mineral origin.
Examples of fillers include carbonates (excluding heavy calcium carbonate) such as calcium, magnesium, aluminum, titanium, iron and zinc, sulfates, silicates, phosphates, borates, oxides, or these and hydrates of
More specifically, light calcium carbonate, magnesium carbonate, dolomite, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate , aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, graphite etc.
However, from the viewpoint that the effect of the present invention is likely to be exhibited, the resin composition of the present invention does not contain a filler other than heavy calcium carbonate, or if it does contain a small amount (for example, 0.00% of the resin composition). 1% by mass or less).

Any conventionally known organic pigment, inorganic pigment or dye can be used as the colorant.
Examples of organic pigments include azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, diosazine-based, perinone-based, quinophthalone-based, and perylene-based pigments.
Examples of inorganic pigments include ultramarine blue, titanium oxide, titanium yellow, iron oxide (rouge), chromium oxide, zinc white, and carbon black.

Examples of lubricants include fatty acid-based lubricants (stearic acid, hydroxystearic acid, complex stearic acid, oleic acid, sodium, potassium, magnesium, calcium salts thereof, etc.), fatty alcohol-based lubricants, and aliphatic amide-based lubricants. (Stearamide, oxystearamide, oleylamide, erucylamide, ricinolamide, behenamide, methylolamide, methylenebisstearamide, methylenebisstearobehenamide, higher fatty acid bisamic acids, complex amides, etc.), aliphatic esters Lubricants (n-butyl stearate, methyl hydroxystearate, polyhydric alcohol fatty acid esters, saturated fatty acid esters, ester waxes, etc.), fatty acid metal soap-based lubricants, and the like.

Examples of antioxidants include phosphorus antioxidants, phenolic antioxidants, and pentaerythritol antioxidants.

Examples of flame retardants include halogen-based flame retardants, phosphorus-based flame retardants, and non-phosphorus-based non-halogen flame retardants such as metal hydrates.

Examples of blowing agents include aliphatic hydrocarbons (propane, butane, pentane, hexane, heptane, etc.), alicyclic hydrocarbons (cyclobutane, cyclopentane, cyclohexane, etc.), halogenated hydrocarbons (chlorodifluoromethane , difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichloro tetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, perfluorocyclobutane, etc.), inorganic gases (carbon dioxide, nitrogen, air, etc.), water and the like.

(Preferred composition of resin composition)
As a preferred embodiment of the resin composition of the present invention, for example, 55 to 65% by mass of PBAT and/or PBSA; 25 to 35% by mass of heavy calcium carbonate: epoxidized soybean oil, epoxidized An epoxy compound selected from linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A type epoxy resin, and bisphenol F type epoxy resin is 2.0 to 8.0% by mass, particularly 2.2% by mass or more5 less than .0% by weight, including those containing 0 to 15% by weight, especially 5 to 10% by weight, of acetyltributyl citrate.

<Method for producing resin composition>
The resin composition of the present invention can be produced using the above-described components according to a conventionally known method for producing a resin composition.

The resin composition is obtained, for example, through mixing of components, melt-kneading, and the like.
The timing of mixing and melt-kneading can be appropriately set according to the molding method to be adopted (extrusion molding, injection molding, vacuum molding, etc.). For example, mixing may be performed before charging from the hopper of the molding machine or at the same time as molding.

Melt-kneading may be performed by, for example, a twin-screw kneader, a kneader, a Banbury mixer, or the like. In addition, there is no particular restriction on the order of adding each component to the kneader, and the biodegradable resin, ground calcium carbonate, and epoxy compound may be added at the same time, and two of these components may be used as a spare. You can knead it. It is also possible to melt-knead a biodegradable resin composition in which heavy calcium carbonate is kneaded and a biodegradable resin composition in which an epoxy compound is kneaded.

The form of the resin composition of the present invention can be, for example, pellets of any size and shape.

The shape of the pellet is not particularly limited, and may be, for example, cylindrical, spherical, or oval.

The size of the pellet is not particularly limited. For example, spherical pellets may be 1-10 mm in diameter. In the case of elliptical pellets, the aspect ratio can be 0.1 to 1.0 and the length and width can be 1 to 10 mm. For cylindrical pellets, they can be 1-10 mm in diameter and 1-10 mm in length.

A desired molded product can be obtained by molding after drying the resin composition of the present invention as necessary.

<Molded product>
The molded article of the present invention can be obtained by molding the resin composition of the present invention by any molding method.

The molded article of the present invention may have any shape according to its use.
The molded article of the present invention includes, for example, films, sheets, containers (food containers, etc.), daily necessities (various disposable products, etc.), automotive parts, electrical and electronic parts, various consumables (such as those in the field of construction materials, etc.). etc.

Because the resin composition of the present invention has good mechanical properties, it is particularly suitable for inflation molding or extrusion molding. Accordingly, the molded article of the present invention is preferably a blown or extruded article.

Examples of inflation-molded products include films, sheets, and bags (such as plastic shopping bags).
The thickness of the inflation molded product is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 30 μm to 100 μm.

Extruded products include films, sheets, and hollow products.

<Manufacturing method of molded product>
The method for producing the molded article of the present invention can be appropriately selected according to the molded article to be obtained.
Examples of methods for producing the molded article of the present invention include inflation molding, extrusion molding, injection molding, foam injection molding, injection compression molding, blow molding, press molding, calendar molding, and vacuum molding. etc.

The molding conditions can be appropriately set according to the composition of the resin composition, the type of molded product, etc.

When the molded product is a film, sheet, or the like, it may or may not be stretched uniaxially, biaxially, or multiaxially during or after molding.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

<Preparation of resin composition>
A resin composition containing each component shown in Tables 1 to 3 was prepared. In addition, the unit of the numerical value of a composition in a table|surface is a "mass part."

The details of each component in the resin composition are as follows. In addition, hereinafter, "average particle diameter" is a value calculated from the results of specific surface area measurement by an air permeation method according to JIS M-8511 using a specific surface area measuring device "SS-100 type" manufactured by Shimadzu Corporation. is.

(biodegradable resin)
Biodegradable resin 1: 70% by mass of polybutylene adipate terephthalate and 30% by mass of polylactic acid.
Biodegradable resin 2: 70% by mass of polybutylene succinate adipate and 30% by mass of polylactic acid.
Biodegradable resin 3: 100% by mass of polybutylene adipate terephthalate

(calcium carbonate)
CC1: heavy calcium carbonate particles (average particle size: 2.2 μm, no surface treatment)
CC2: Heavy calcium carbonate particles (average particle size: 2.3 μm, surface treated with stearic acid)
CC3: light calcium carbonate particles (average particle size: 1.5 μm, no surface treatment)

(epoxy compound)
EP1: epoxidized soybean oil (molecular weight about 920, oxirane oxygen 6.7-7.0%, epoxy equivalent 228-239 g/eq)
EP2: epoxidized linseed oil (molecular weight about 950, oxirane oxygen ≧8.5%, epoxy equivalent ≦188 g/eq)
EP3: bisphenol A type epoxy resin (epoxy equivalent 180-190 g/eq, liquid at room temperature)
EP4: Bisphenol F type epoxy resin (epoxy equivalent 160-180 g/eq, liquid at room temperature)
EP5: Bisphenol A type epoxy resin (epoxy equivalent 180-190 g/eq, liquid at room temperature, low chlorine type)

(Plasticizer)
Plasticizer 1: Glycerin fatty acid ester Plasticizer 2: Acetyltributyl citrate

(Antistatic agent)
HS15N: Antistatic agent containing lauryl diethanolamide and diethanolamine (manufactured by Kao Corporation)

(natural organic matter)
CP: cellulose powder with an average particle size of 20 μm

[Examples 1 to 4, Comparative Examples 1 to 4]
<Preparation of resin composition>
Each of the above raw materials was put into a co-rotating twin-screw kneading extruder HK-25D (φ25 mm, L/D=41) manufactured by Parker Corporation in the amounts shown in Table 1 below. After extruding strands at a cylinder temperature of 190 to 200° C., the strands were cooled and cut to produce pellets of resin compositions of various compositions.

<Preparation of inflation molded product>
A film was produced as an inflation molded product.
Specifically, the pellets were put into a blown film extrusion line (60 mm circular die, 1.2 mm die gap, 30 mm screw diameter, L/D ratio=30) to produce a 30 μm thick film. Films were processed at a BUR (blow-up ratio) of 2.5.
In addition, in the extruder, the temperature of each zone was set to 180° C. to 200° C., and the rotation speed was maintained at 20 rpm.

<Evaluation of resin composition/film>
The moldability, tensile strength, elongation at break, and bleeding state of the obtained resin composition and film were evaluated by the following methods. The results are shown in Table 1 below.

(Moldability)
Based on the state during kneading and extrusion molding, evaluation was made according to the following criteria. For some of the samples, the torque value of the extruder during molding was measured and used as a material for evaluating moldability.
· A: The kneading and extrusion operations proceeded extremely smoothly, and a film with a uniform thickness could be easily formed.
○: A film having a uniform thickness could be formed without uneven distribution of the inorganic substance powder.
Δ: Uneven distribution of the inorganic substance powder was observed, or it was difficult to form a uniform film.
x: Viscosity increased significantly during kneading and could not be extruded.

(Tensile strength and elongation at break)
A JIS K6251:2017 dumbbell-shaped No. 3 test piece was obtained from each film.
A tensile test of the obtained test piece was performed at 23° C. using a strograph (manufactured by Toyo Seiki Seisakusho Co., Ltd.). The drawing speed was set at 100 mm/min.
Based on the obtained stress-strain curve, tensile strength (Ts, unit: MPa) and elongation at break (EB, unit: %) were measured.

(bleed)
The appearance of each film was visually observed and evaluated according to the following criteria.
○: Bleeding was not observed at all on the surface of the film.
Δ: Slight bleeding occurred on the surface of the film.
x: Bleeding on the film surface was conspicuous.

(Biodegradable)
The size of each film was adjusted to 30 mm long×30 mm wide to obtain a test piece.
The obtained test piece was placed in a 25 ml vial with seawater (10 ml) temperature-controlled to the same temperature as room temperature (25° C.±5° C.), and allowed to stand for one month.
Next, the state of each test piece was visually observed and evaluated according to the following criteria.
A: The test piece is almost completely decomposed.
B: The test piece is partially decomposed, or no change is observed in the test piece.

According to the present invention, the resin compositions of Examples 1 to 4 containing 2.0% by mass or more and 8.0% by mass or less of a specific epoxy compound together with the biodegradable resin and heavy calcium carbonate have good workability. In addition, molded articles with good mechanical properties, especially elongation at break, were obtained, and no bleeding was observed. In addition, the addition of the epoxy compound did not impair the biodegradability.

[Examples 5-10, Comparative Examples 5-6]
The same operation as in Example 1 was performed, except that the types and blending amounts of the raw materials used were changed as shown in Table 2. Table 2 shows the evaluation results of each sample.

In accordance with the present invention, the resin compositions of Examples 5 to 10 containing specific epoxy compounds are excellent in moldability, give molded articles with good mechanical properties and particularly excellent elongation at break, and no bleeding is observed. I didn't. On the other hand, the resin composition of Comparative Example 5, which did not contain an epoxy compound, had low moldability and a small elongation at break of the molded product. Further, in the resin composition of Comparative Example 6 containing a general-purpose plasticizer, the moldability was good, but the mechanical properties of the molded product were low, and bleeding of the plasticizer was conspicuous. The advantages of using certain epoxy compounds are clear. Among them, the molded articles of Examples 6 to 9 using EP2 to EP5 having an epoxy equivalent of 100 g/eq to 200 g/eq or less, and the molded article of Example 10 having a blending amount of EP1 of 3% by mass, had poor mechanical properties. It was particularly good.

The same experiment as in Example 5 and Comparative Example 5 was conducted with the mass ratio of biodegradable resin to heavy calcium carbonate set to 90:10, but no significant improvement in elongation at break due to the addition of the epoxy compound was observed. rice field. The improvement of the mechanical properties in the resin composition of the present invention is not due to the plasticizing effect of the epoxy compound itself, but the decomposition product of the biodegradable resin component in the presence of heavy calcium carbonate reacts with the epoxy compound. It is suggested that it is brought about by

[Examples 11 to 12, Comparative Example 7]
The same operation as in Example 1 was performed with the types and blending amounts of the raw materials to be used changed as shown in Table 3. Table 3 shows the evaluation results of each sample.

According to the present invention, the resin composition of Example 11, which contains about 7% by mass of acetyltributyl citrate in addition to the biodegradable resin, ground calcium carbonate, and specific epoxy compound, has extremely excellent moldability and mechanical properties. gave good moldings. In addition, the molded article of Example 12 containing about 7% by mass of cellulose powder exhibited good mechanical properties.

According to the present invention, it is possible to provide a biodegradable resin-containing composition that has good molding processability, excellent mechanical properties, particularly excellent elongation at break, and that gives a molded article that is less likely to deteriorate in appearance due to bleeding. It became clear.

Claims

A resin composition containing a biodegradable resin, ground calcium carbonate, and an epoxy compound,
The biodegradable resin and the heavy calcium carbonate have a mass ratio of 10:90 to 70:30,
The biodegradable resin contains at least polybutylene adipate terephthalate or polybutylene succinate adipate,
The epoxy compound is one or more compounds selected from the group consisting of epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized palm oil, bisphenol A type epoxy resin, and bisphenol F type epoxy resin. can be,
The content of the epoxy compound is 2.0% by mass or more and 8.0% by mass or less with respect to 100% by mass of the resin composition.
Resin composition.
The resin composition according to claim 1, wherein the epoxy compound is a compound having an epoxy equivalent of 100 g/eq or more and 200 g/eq or less.
The resin composition according to claim 1 or 2, containing the biodegradable resin and the heavy calcium carbonate at a mass ratio of 10:90 to 50:50.
The biodegradable resin is composed of polybutylene adipate terephthalate and polylactic acid,
The mass ratio of the polybutylene adipate terephthalate and the polylactic acid is 50:50 to 90:10,
The resin composition according to any one of claims 1 to 3.
The biodegradable resin is composed of polybutylene succinate adipate and polylactic acid,
The mass ratio of the polybutylene succinate adipate and the polylactic acid is 50:50 to 90:10,
The resin composition according to any one of claims 1 to 3.
Further containing 5% by mass or more and 30% by mass or less of natural organic matter with respect to 100% by mass of the resin composition,
The natural organic matter is one or more selected from the group consisting of cellulose powder, wood flour, starch, rice husk, bean curd refuse, and wheat bran.
The resin composition according to any one of claims 1 to 5.
The resin composition according to any one of claims 1 to 6, wherein the ground calcium carbonate has an average particle size of 0.7 µm or more and 6.0 µm or less by an air permeation method according to JIS M-8511.
The resin composition according to any one of claims 1 to 7, further comprising acetyltributyl citrate in an amount of 5% by mass or more and 20% by mass or less with respect to 100% by mass of the resin composition.
A molded article obtained from the resin composition according to any one of claims 1 to 8.
The molded product according to claim 9, wherein the molded product is a blown film.
The molded product according to claim 9, wherein the molded product is an extruded sheet.