WO2021192427A1

WO2021192427A1 - Eggshell powder-containing thermoplastic resin composition and molded article

Info

Publication number: WO2021192427A1
Application number: PCT/JP2020/045063
Authority: WO
Inventors: 中村　宏; 英二水野
Original assignee: 株式会社Ｔｂｍ
Priority date: 2020-03-25
Filing date: 2020-12-03
Publication date: 2021-09-30
Also published as: JP6764210B1; JP2021152129A

Abstract

The present invention provides a thermoplastic resin composition in which an eggshell powder is highly filled in a thermoplastic resin while suppressing uneven distribution thereof and from which a molded article excellent in appearance and mechanical properties can be produced, and a molded article using the same.　The eggshell powder-containing thermoplastic resin composition, which contains a thermoplastic resin and an eggshell powder at a mass ratio of 50:50 to 10:90, is characterized in that: the mass ratio of the eggshell powder to the total eggshell powder-containing thermoplastic resin composition is 50/100 or more; the BET specific surface area of the eggshell powder is 0.1 m²/g to 10.0 m²/g inclusive; the roundness of the eggshell powder is 0.50-0.95 inclusive; and the eggshell powder contains at least two groups of particles, i.e., an eggshell powder group having an average particle size of 0.7 μm or more and less than 2.2 μm and an eggshell powder group having an average particle size of 2.2 μm or more and less than 6.0 μm. The molded article using the eggshell powder-containing thermoplastic resin composition.

Description

Eggshell powder-containing thermoplastic resin composition and molded product

The present invention relates to a thermoplastic resin composition containing eggshell powder and a molded product. More specifically, the present invention relates to a thermoplastic resin composition, which is suitable for producing a molded product having good appearance and mechanical properties, in which uneven distribution thereof is suppressed even though the eggshell powder is highly filled. And molded products using this.

Conventionally, thermoplastic resins have been widely used together with paper materials derived from forest resources as materials for various industrial and household molded products, food packaging and molding packaging for general products, but environmental protection is provided. Now that it has become an international issue, it is also being considered to reduce the consumption of thermoplastic resins and paper materials in parallel with the viewpoint of making them non-toxic, recyclable, and incinerated. From this point of view, an inorganic substance powder-blended thermoplastic resin composition in which an inorganic substance powder such as calcium carbonate is highly filled in a thermoplastic resin has been proposed and put into practical use (for example, Patent Documents). See 1st grade).

Similarly, from the viewpoint of environmental protection, the reuse of industrial waste and the utilization of biomass materials are also under consideration. For example, resin compositions containing calcium carbonate powder made from eggshells and shells are described in Patent Documents 2 to 7. Eggshell is an unmistakable biomass material, but the amount discarded from food processing factories and the like is more than 200,000 tons every year, and its effective utilization is desired. Eggshell is composed of 90% or more, and in many cases 95% or more, calcium carbonate, which is useful as a calcium source and has an advantage that impurities such as phosphorus are less than those of fish and animal bones. Calcium carbonate powder derived from eggshell is also porous, and is being studied as a functional material utilizing this point. For example, Patent Document 2 discloses that an eggshell powder-containing resin composition is used as a food packaging material by utilizing the harmful gas absorbing action derived from the pore structure as described above. Further, since the eggshell powder is porous as compared with general-purpose calcium carbonate having the same particle size, it has a large specific surface area and can be expected to have a reinforcing effect on the resin composition.

However, even if the eggshell powder is used without any particular adjustment, it is not possible to fill the thermoplastic resin in a large amount, and the resin composition that is forcibly highly filled is molded into a sheet, a film, or the like using a general-purpose molding machine. However, good physical properties cannot be obtained. Generally, in a molded product in which eggshell powder is highly filled by 50% by mass or more, there is a problem that eggshell powder is unevenly distributed, resulting in deterioration of mechanical properties and poor appearance. Also in the resin compositions described in Patent Documents 2 and 3, the content of eggshell powder is 50 parts by weight or less with respect to 100 parts by weight of the resin, that is, the entire composition, in consideration of the decrease in strength and the deterioration of the appearance of the molded product. It is stopped at 1/3 or less. In particular, eggshell powder having a small particle size exhibits reinforcing properties due to its large specific surface area, but increases the melt viscosity of the resin composition. As a result, there is a problem that the moldability is lowered and the physical properties of the molded product are deteriorated due to heat generation during kneading and molding, so that it is difficult to fill the resin with high filling. Patent Document 4 refers to a resin composition containing 1 to 50% by weight of eggshell powder having an average particle size of 3 μm or less, but what is actually prepared in the examples is an eggshell powder amount of 10% by weight. % Only resin composition. Patent Document 5 refers to a resin composition containing 46 to 65% by mass of calcium carbonate in eggshell powder, but does not describe an example in which such a resin composition is actually molded.

Patent Documents 6 and 7 disclose propylene-based composite resin compositions composed of 15 to 60% by weight of a specific propylene-based copolymer and 85 to 40% by weight of a filler such as eggshell powder, and 50% by mass in Examples. It is filled with eggshell powder in excess of%. However, the eggshell powder used in the examples described in these patent documents has a coarse particle size of 20 μm. The above-mentioned Patent Document 5 also describes that the particle size of the calcium carbonate fine powder is 80 to 100 μm. Such powders having a large particle size are often unevenly distributed in the resin composition, resulting in deterioration of physical properties. In a resin composition containing a powder having a large particle size, for example, when a sheet-shaped molded product is formed, the powder protrudes from the surface of the molded product, and the powder falls off or impairs the surface texture, mechanical strength, and the like. There is a risk. For the above reasons, it has been difficult to produce resin compositions and molded products that are highly filled with eggshell powder, suppress uneven distribution, and have good appearance and mechanical properties.

Japanese Unexamined Patent Publication No. 2013-1093 Japanese Unexamined Patent Publication No. 2-142840 Special Table 2019-503411 Gazette Japanese Unexamined Patent Publication No. 2011-256260 JP-A-2018-62579 Japanese Unexamined Patent Publication No. 2009-275087 Japanese Unexamined Patent Publication No. 2009-299024

The present invention has been made in view of the above circumstances, and is a thermoplastic resin composition capable of producing a molded product having a high filling of eggshell powder, suppressing uneven distribution thereof, and having good appearance and mechanical properties. An object of the present invention is to provide a product and a molded product using the product.

As a result of diligent studies to solve the above problems, the present inventors have made it possible to highly fill the thermoplastic resin by using a specific eggshell powder, suppress uneven distribution, and have an appearance and mechanical properties. It was found that a good molded product can be obtained. That is, when eggshell powder is highly filled in a thermoplastic resin, it has a predetermined BET specific surface area and roundness, and has a different particle size distribution, that is, a different average particle size within a range of a predetermined average particle size. The present invention has been reached based on the finding that the above-mentioned problems can be solved and a molded product having good appearance and mechanical properties can be obtained by using at least two groups of eggshell powders having.

That is, in the eggshell powder-containing thermoplastic resin composition containing the thermoplastic resin and the eggshell powder in a mass ratio of 50:50 to 10:90.
The mass ratio of the eggshell powder to the entire eggshell powder-containing thermoplastic resin composition is 50/100 or more.
The BET specific surface area of the eggshell powder is 0.1 m ² / g or more and 10.0 m ² / g or less.
The roundness of the eggshell powder is 0.50 or more and 0.95 or less.
The eggshell powder contains at least two groups of particles having different average particle diameters, and as the above-mentioned particle groups of at least two groups having different average particle diameters, the average particle diameter by the air permeation method is 0.7 μm or more and 2.2 μm. It is characterized in that it contains an eggshell powder group of less than 2 and an eggshell powder group having an average particle size of 2.2 μm or more and less than 6.0 μm by the air permeation method in a mass ratio of 1: 1 to 5: 1. It is a thermoplastic resin composition containing eggshell powder.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, the average particle size of the eggshell powder group A having a small average particle size is a, and the average particle size of the eggshell powder group B having a large average particle size is b. , The eggshell powder-containing thermoplastic resin composition having an a / b ratio of 0.85 or less is shown.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, the mass ratio of the thermoplastic resin to the eggshell powder in the eggshell powder-containing thermoplastic resin composition is 50:50 to 30:70. The thermoplastic resin composition contained is shown.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, the eggshell powder-containing thermoplastic resin composition in which the thermoplastic resin is a polypropylene-based resin and / or a polyethylene-based resin is shown.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, an eggshell further containing a plasticizer selected from the group consisting of lactic acid, a lactic acid oligomer having a weight average molecular weight of 3,000 or less, and branched polylactic acid. The powder-containing thermoplastic resin composition is shown.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, an eggshell powder-containing thermoplastic resin composition in which the eggshell powder is an unbaked eggshell powder is shown.

In one aspect of the eggshell powder-containing thermoplastic resin composition according to the present invention, an eggshell powder-containing thermoplastic resin composition in which the eggshell powder is not surface-treated is shown.

The present invention that solves the above-mentioned problems is also a molded product comprising the above-mentioned eggshell powder-containing thermoplastic resin composition.

In one aspect of the article according to the present invention, the article is a food container.

According to the present invention, the thermoplastic resin is highly filled with eggshell powder at a mass ratio of 50:50 to 10:90, while its uneven distribution is suppressed, and physical properties such as appearance and mechanical strength are good. Molded products can be manufactured.

Hereinafter, the present invention will be described in detail based on the embodiments.

≪Eggshell powder-containing thermoplastic resin composition≫
The eggshell powder-containing thermoplastic resin composition of the present invention contains the thermoplastic resin and eggshell powder in a mass ratio of 50:50 to 10:90, and will be described in detail below as the eggshell powder to be blended. Eggshell powder having such a predetermined particle size distribution, BET specific surface area, and roundness is used. Hereinafter, each component constituting the thermoplastic resin composition according to the present invention will be described in detail.

≪Thermoplastic resin≫
The thermoplastic resin that can be used in the eggshell powder-containing thermoplastic resin composition according to the present invention is not particularly limited, and various kinds can be used depending on the use, function, and the like of the composition. .. For example, polyolefin resins such as polyethylene resins, polypropylene resins, polymethyl-1-pentene, and ethylene-cyclic olefin copolymers; ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, and ethylene-methacrylic acid copolymers. Functional groups such as polymers, metal salts of ethylene-methacrylic acid copolymers (ionomers), ethylene-acrylic acid alkyl ester copolymers, ethylene-methacrylic acid alkyl ester copolymers, maleic acid-modified polyethylene, maleic acid-modified polypropylene, etc. Containing polyolefin resin; polyamide resin such as nylon-6, nylon-6,6, nylon-6,10, nylon-6,12; fragrance of polyethylene terephthalate and its copolymer, polyethylene naphthalate, polybutylene terephthalate, etc. Thermoplastic polyester resins such as aliphatic polyester resins such as group polyester resins, polybutylene succinates and polylactic acid; polycarbonate resins such as aromatic polycarbonates and aliphatic polycarbonates; atactic polystyrenes, syndiotactic polystyrenes, acrylonitrile- Polystyrene resins such as styrene (AS) copolymers and acrylonitrile-butadiene-styrene (ABS) copolymers; polyvinyl chloride resins such as polyvinyl chloride and vinylidene chloride; polyphenylene sulfides; polyether sulfone, polyether ketones , Polymer-based resins such as polyether ether ketones. These can be used individually by 1 type or in combination of 2 or more types.

Among these thermoplastic resins, it is preferable to use a polyolefin resin, an aromatic polyester resin, or an aliphatic polyester resin from the viewpoints of ease of molding, performance, economy, and the like.

Here, the polyolefin-based resin is a polyolefin-based resin containing an olefin component unit as a main component, and specifically, the polypropylene-based resin and the polyethylene-based resin described above, as well as polymethyl-1-pentene and ethylene-cyclic olefins. Examples thereof include copolymers and the like, as well as mixtures of two or more of them. The above-mentioned "main component" means that the polyolefin component unit contains 50% by mass or more of the olefin component unit, and the content thereof is preferably 75% by mass or more, more preferably 85% by mass. % Or more, more preferably 90% by mass or more. The method for producing the polyolefin resin used in the present invention is not particularly limited, and can be obtained by any of a method using a Ziegler-Natta catalyst, a metallocene catalyst, a radical initiator such as oxygen or peroxide, or the like. It may be a catalyst.

Examples of the polypropylene-based resin include resins having a propylene component unit of 50% by mass or more, and examples thereof include a propylene homopolymer and a copolymer with another α-olefin copolymerizable with propylene. Other α-olefins copolymerizable with propylene include, for example, ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene. , 1-Heptene, 3-Methyl-1-hexene and other α-olefins having 4 to 10 carbon atoms are exemplified. Propylene homopolymers include any of isotactics, syndiotactics, atactics, hemiisotactics and linear or branched polypropylenes exhibiting various stereoregularities. Further, the above-mentioned copolymer may be a random copolymer or a block copolymer, and may be not only a binary copolymer but also a ternary copolymer. Specifically, for example, an ethylene-propylene random copolymer, a butene-1-propylene random copolymer, an ethylene-butene-1-propylene random ternary copolymer, an ethylene-propylene block copolymer, and the like can be exemplified. .. The other olefin copolymerizable with propylene in the copolymer is 25% by mass or less, particularly 15% by mass or less, when the total mass of the eggshell powder-containing thermoplastic resin composition is 100% by mass. It is preferable that it is contained in, and the lower limit value is preferably 0.3% by mass. In addition, these polypropylene-based resins can be used alone or in combination of two or more.

Examples of the polyethylene-based resin include resins having an ethylene component unit of 50% by mass or more, and examples thereof include high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene, and linear low-density polyethylene (linear low-density polyethylene). LLDPE), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-butene 1 copolymer, ethylene-butene 1 copolymer, ethylene-hexene 1 copolymer, ethylene-4 methylpentene 1 Examples thereof include a copolymer, a polyethylene-octene 1 copolymer, and a mixture of two or more thereof.

Among the above-mentioned polyolefin resins, polypropylene resins and / or polyethylene resins, particularly polypropylene resins are preferably used because they are particularly excellent in the balance between mechanical strength and heat resistance.

≪Eggshell powder≫
In the present invention, as the eggshell powder to be blended in the thermoplastic resin composition, those having characteristics such as an average particle size are used. That is, the eggshell powder used in the present invention contains at least two particle groups having a predetermined BET specific surface area and roundness, and having different average particle size distributions. As long as the average particle size distribution is different, the combination is not limited to two groups, and may be a combination of three or more groups.

Although not particularly limited, it is desirable that eggshell powder groups having different average particle sizes are produced separately and then kneaded into a resin material. In addition, at least two groups of eggshell powders having different average particle sizes may be mixed at the powder stage, or they may be added separately to the resin and mixed after kneading, but they are mixed at the powder stage. Is more preferable in terms of uniform dispersion.

Physical characteristics such as the appearance, mechanical strength, or viscosity of the thermoplastic resin composition during kneading of the molded product formed from the eggshell powder-containing thermoplastic resin composition obtained by adding the eggshell powder are the average of the added eggshell powder. It is affected by the particle size and the like. The appearance of the molded product tends to improve as the average particle size of the eggshell powder decreases, but the viscosity during kneading tends to increase as the average particle size decreases. Although it depends on the application, if the viscosity of the thermoplastic resin composition during kneading is high, the molding itself becomes difficult, or the original physical characteristics of the resin are difficult to be exhibited. The tendency becomes remarkable. On the other hand, the larger the average particle size of the eggshell powder, the easier it is to knead into the thermoplastic resin composition, and the lower the cost per unit mass of the particles, which is economically advantageous. Uneven distribution of particles in the resin composition is likely to occur, it is difficult to increase the blending amount, and when the molded product is formed from the eggshell powder-containing thermoplastic resin composition, the appearance of the molded product is deteriorated. There is a risk. Therefore, the present invention is excellent in the properties of the eggshell powder having a small outer diameter and the properties of the eggshell powder having a large outer diameter by blending a plurality of particle groups having different average particle diameters in the thermoplastic resin composition and kneading them. It is intended to bring out the above-mentioned properties to both parties.

For example, when eggshell powder group A having a certain average particle size is mixed with eggshell powder group B having an average particle size larger than this, eggshell powder group B alone is coarsely dispersed in a thermoplastic resin in a composite state. In the above, the space between the eggshell powder of the eggshell powder group B and the resin can be filled with the eggshell powder of the eggshell powder group A, thereby suppressing the uneven distribution of the eggshell powder and effectively improving the addition amount thereof. Can be done. Further, by dispersing the eggshell powder of the eggshell powder group A in the gap where the eggshell powder of the eggshell powder group B is dispersed, the distribution of the eggshell powder in the resin composition is densified and the three-dimensional arrangement relationship between the particles. Is complicated, and the mechanical strength is also increased.

As the eggshell powder used in the present invention, at least two groups of eggshell powders having different average particle size distributions are used as described above, and the average particle size of each powder group is 0.7 μm or more. It is desirable that it is within the range of 0 μm or less. This is because even if at least a plurality of groups of eggshell powders having different average particle size distributions are used, if an extremely fine or extremely coarse powder group is blended, the desired uneven distribution of the eggshell powder can be suppressed and the molded product can be mixed. This is because it is difficult to improve the appearance.

Further, although not particularly limited, when the average particle size of the eggshell powder group A having a small average particle size is a and the average particle size of the eggshell powder group B having a large average particle size is b, a / It is desirable that the b ratio can be roughly classified into 0.85 or less, more preferably 0.10 to 0.70, and even more preferably about 0.10 to 0.50. This is because a particularly excellent effect can be expected by using those having a certain difference in average particle size in combination.

Further, each eggshell powder group used in the present invention preferably has a coefficient of variation (Cv) of the distribution of its particle size (μm) of about 0.01 to 0.10, particularly 0.03 to 0. It is desirable that it is about 08. In the eggshell powder-containing thermoplastic resin composition using the eggshell powder group having a particle size variation coefficient (Cv) of about 0.01 to 0.10, the variation in the particle size defined by the variation coefficient (Cv) is Each particle of the eggshell powder group having a small average particle size and the eggshell powder group having a large average particle size suppresses and forms the uneven distribution of particles as described above in the eggshell powder-containing thermoplastic resin composition using the eggshell powder. It is considered that each powder group gives a more complementary effect in bringing about actions such as improvement of the appearance and mechanical strength of the product.

The eggshell powder groups of at least two groups having different average particle size distributions used in the present invention include an eggshell powder group having an average particle size of 0.7 μm or more and less than 2.2 μm and an average particle size of 2.2 μm or more and 6.0 μm. The combination is not particularly limited as long as it is a combination with an eggshell powder group of less than, but more preferably, an eggshell powder group A of 1.0 μm or more and less than 1.9 μm and an eggshell powder group B of 2.5 μm or more and 5.0 μm or less. It is preferable to combine them, and it is preferable to obtain a mixture obtained by substantially mixing and homogenizing the two. By mixing the two, uneven distribution of eggshell powder can be suppressed with better filling property than using only eggshell powder group A having a small average particle size or only eggshell powder group B having a large average particle size. It is possible to obtain a molded product having good appearance and mechanical properties such as elongation at break, and it is possible to reduce the dropping of eggshell powder from the composite material from the molded product made of the resin composition.

The average particle size of the eggshell powder described in the present specification refers to a value calculated from the measurement result of the specific surface area by the air permeation method according to JIS M-8511. As described above, the eggshell powder is porous, but the gas permeation method does not measure the pores that do not affect the fluid flow. Therefore, the eggshell powder with the same particle size as the general-purpose calcium carbonate powder can be measured by the air permeation method. Gives equivalent results. As the measuring device, for example, a specific surface area measuring device SS-100 manufactured by Shimadzu Corporation can be preferably used.

In the present invention, the boundary value between the eggshell powder group A having a small average particle size and the eggshell powder group B having a large average particle size being set to 2.2 μm has been studied diligently by the present inventors. As a result of experiments, by combining a particle group larger than this value and a particle group smaller than this value, it is possible to most effectively suppress the uneven distribution of the added eggshell powder and to produce a molded product having good appearance and mechanical properties. It is based on the conclusion that it can be done.

Further, the reason why the average particle size of the eggshell powder group A having a small average particle size is 0.7 μm or more is that when the average particle size becomes too small, it is combined with the eggshell powder group B having a large average particle size. However, this is because the viscosity may increase significantly when kneaded with the above-mentioned thermoplastic resin, which may make it difficult to manufacture a molded product.

On the other hand, the reason why the average particle size of the eggshell powder group B having a large average particle size is 6.0 μm or less is that when the average particle size becomes too large, it is combined with the eggshell powder group A having a small average particle size. Even so, there is a risk that the particles may be unevenly distributed when kneaded with the above-mentioned thermoplastic resin, or the appearance of the obtained molded product may be deteriorated.

In the present invention, even in the embodiment in which three or more eggshell powder groups having different average particle size distributions are used, one of the eggshell powder groups having a relatively small average particle size has an average particle size of 2. It is desirable that one of the eggshell powder groups having an average particle size of less than .2 μm and a relatively large average particle size has an average particle size of 2.2 μm or more.

As described above, in the present invention, at least two groups of eggshell powders having different average particle size distributions are used, but particles having a particle size exceeding 50 μm as a whole of the eggshell powders used, particularly in the particle size distribution, are used. It is preferably not contained substantially. On the other hand, if the particles become too fine, the viscosity may increase remarkably when kneaded with the above-mentioned thermoplastic resin, which may make it difficult to manufacture a molded product. Therefore, it is preferable that particles having a particle size of less than 0.5 μm are not substantially contained. Here, "substantially free" means an embodiment in which particles having the particle size are contained, for example, in an amount of less than 0.1% by mass, more preferably less than 0.01% by mass, based on the total particle mass. do.

Further, in the eggshell powder-containing thermoplastic resin composition according to the present invention, the blending ratio of at least two groups of eggshell powders having different average particle size distributions is as compared with the case where a single eggshell powder group is used. , Suppression of uneven distribution of eggshell powder as described above, improvement of appearance in the obtained molded product, improvement of mechanical strength, reduction of viscosity at the time of kneading the composition, reduction of dropping of eggshell powder from the molded product, etc. As long as the effect can be obtained, the mass ratio is A: when divided into the eggshell powder group A having a small average particle size and the eggshell powder group B having a large average particle size as described above. B is about 1: 1 to 5: 1. In particular, it is desirable that the ratio is about 3: 1 to 5: 1. This is because a particularly excellent effect can be expected by setting such a blending ratio.

In the present invention, the eggshell powder also has a BET specific surface area of ^{0.1 m 2} / g or more and 10.0 m ^{2 / g or less.} The BET adsorption method referred to here is a nitrogen gas adsorption method. The specific surface area also depends on the average particle size, and even if the particle size is the same, the eggshell powder generally has a large specific surface area, but if the specific surface area is within this range, a resin composition by blending a large amount of eggshell powder. It is possible to suppress a decrease in workability. In particular, when the average particle size of the eggshell powder is 0.7 μm or more and less than 2.2 μm, the average particle size of the eggshell powder is about 0.1 m ² / g or more and ^{less than 3.5 m 2} / g. However, when it is 2.2 μm or more and less than 6.0 μm, it is desirable that it is about ^{0.3 m 2} / g or more and 3.5 m ^{2 / g or less.}

The eggshell powder preferably has a low degree of spheroidization, and specifically, its roundness is 0.50 or more and 0.95 or less, preferably 0.55 or more and 0.93 or less, and more preferably 0. It is 60 or more and 0.90 or less. When the roundness of the eggshell powder is within this range, the strength and moldability of the product become appropriate when the eggshell powder is mixed with the thermoplastic resin composition to form a molded product.

Here, the roundness can be expressed by (projected area of particles) / (area of a circle having the same perimeter as the projected perimeter of particles). The method for measuring the roundness is not particularly limited, but for example, the projected area of the particles and the projected perimeter of the particles are measured from a micrograph and set as (A) and (PM), respectively, and the projected perimeter of the particles. Let (r) be the radius of a circle that has the same perimeter as the length.
PM = 2πr (1)
And if the area of a circle having the same perimeter as the projected perimeter of the particle is (B),
B = πr ² (2)
Is. When equation (1) is transformed, r = PM / 2π (3)
Therefore, when equation (3) is substituted into equation (2),
B = π × (PM / 2π) ² (4)
Then, roundness = A / B = A × 4π / (PM) ²
Will be. The particles to be measured are sampled so as to represent the particle size distribution of the powder. As the number of measurement particles increases, the reliability of the measured value increases, but in consideration of the measurement time, it is generally expressed as the average value of about 100 particles, and 100 particles are also used in this specification. Was taken as the average value of. In these measurements, the roundness can be obtained by drawing a projection drawing of each particle obtained by a scanning microscope or a stereomicroscope using commercially available image analysis software.

The eggshell powder as described above can be prepared by using a conventional manufacturing method. Eggshell powder is also commercially available, and commercially available products such as Calhope (registered trademark) manufactured by Kewpie Co., Ltd. and eggshell calcium manufactured by Sanshu Foods Co., Ltd. may be finely pulverized to adjust the particle size to a desired value. The eggshell raw material may be any animal egg, but the use of chicken eggs is recommended from the viewpoint of availability and quality stability. When preparing powder from eggshell, first remove the eggshell membrane from the eggshell after collecting the egg liquid, and then grind it. Specifically, the eggshell is stirred in hot water to remove the eggshell membrane, then coarsely pulverized, washed again, and at a temperature of 20 to 200 ° C. under vacuum or at a temperature of about 100 to 400 ° C. under normal pressure. Eggshell powder can be produced by drying for several minutes and then finely grinding to a desired particle size. When the eggshell membrane is removed or washed, alkali treatment or the like facilitates the removal of impurities such as proteins. Alternatively, the eggshell membrane can be removed by heating to, for example, 200 to 500 ° C. instead of stirring in hot water. Further, it may be heated to a high temperature, for example, 500 to 800 ° C. to completely remove organic substances such as eggshell membranes and oxidize a part of the powder surface. When the surface of the powder is partially oxidized in this way and partially contains the composition of calcium oxide, it is possible to add functions such as biodegradability and halogen adsorption. For example, a halogen system from a halogen-containing resin It is also possible to prevent the release of gas.

However, in the present invention, the eggshell powder is preferably unbaked. Since eggshells generally have few impurities, they can be kneaded with a thermoplastic resin as a high-purity calcium carbonate raw material without any treatment such as firing. The use of unbaked eggshell powder eliminates the need to spend energy and time on firing, which is advantageous in terms of both environmental protection and economy. By not firing, it is expected that the reinforcing effect derived from the pores in the eggshell powder and the function of absorbing harmful gas and the like will be exhibited.

There are two crushing methods for obtaining eggshell powder, a dry method and a wet method. Economically, the dry method is preferable because it can be washed with water at the same time. For example, it is possible to combine a dry method and a wet method, perform coarse pulverization by the dry method, and then finely pulverize by the wet method, and vice versa. After pulverization, the foreign matter may be removed by using a commercially available foreign matter removing device or the like. The crusher is not particularly limited, and an impact crusher, a crusher using a crushing medium such as a ball mill, a roller mill, or the like can be used. In addition, the classification may be performed using an air classification, a wet cyclone, a decanter, or the like.

Further, in order to enhance the dispersibility of the eggshell powder in the thermoplastic resin, the surface of the eggshell powder may be surface-modified in advance according to a conventional method. Examples of the surface modification method include a physical method such as plasma treatment and a method of chemically surface-treating the surface with a coupling agent or a surfactant. Examples of the coupling agent include a silane coupling agent and a titanium coupling agent. The surfactant may be any of anionic, cationic, nonionic and amphoteric, and examples thereof include higher fatty acids, higher fatty acid esters, higher fatty acid amides and higher fatty acid salts.

However, in a preferred embodiment of the present invention, it is preferable to use as the eggshell powder to be used, which has not been surface-treated with a chemical treatment agent, or at least not surface-treated with the above-mentioned fatty acid-based compound. By using an eggshell powder that has not been surface-treated, it is possible to eliminate the fact that the surface treatment agent adhering to the surface of the eggshell powder at the time of molding is thermally decomposed and causes a slight odor. be. Therefore, in a particularly preferable embodiment of the present invention, an eggshell powder that has not been surface-treated is preferably used.

In the eggshell powder-containing thermoplastic resin composition according to the present invention, as long as the action and effect of using at least two eggshell powder groups having different average particle diameters as described above are not substantially impaired, the above is described. In addition to the at least two eggshell powder groups, it is also possible to modify the color tone, mechanical properties, etc. of the resin composition by adding other inorganic substance powders, if necessary.

The powder of other inorganic substances other than these eggshell powders is not particularly limited, but for example, calcium carbonate such as heavy calcium carbonate and light calcium carbonate, dolomite, magnesium carbonate, zinc oxide, titanium oxide, silica. , Alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, wallastnite and the like.

In the eggshell powder-containing thermoplastic resin composition according to the present invention, the above-mentioned eggshell powder is contained in an amount of 50% by mass or more based on 100% by mass of the total amount of the eggshell powder-containing thermoplastic resin composition. The compounding ratio (mass%) of the above-mentioned thermoplastic resin and eggshell powder is not particularly limited as long as it is a ratio of 50:50 to 10:90, but it should be a ratio of 40:60 to 10:90. Is preferable, and the ratio is more preferably 35:65 to 20:80. When other inorganic substance powders such as the above-mentioned heavy or light calcium carbonate are added, the total amount of the other inorganic substance powders and at least two eggshell powder groups is the above-mentioned amount with respect to the blending amount of the thermoplastic resin. Is preferably the mass ratio of. When the ratio of the total amount of the inorganic substance powder including the eggshell powder is lower than 50% by mass in the blending ratio of the thermoplastic resin and the total inorganic substance powder, the predetermined texture and impact resistance of the thermoplastic resin composition containing the eggshell powder This is because it is difficult to obtain physical properties such as properties, while if it is higher than 90% by mass, molding processing by extrusion molding, vacuum molding, or the like becomes difficult.

≪Other additives≫
If necessary, other additives may be added to the eggshell powder-containing thermoplastic resin composition according to the present invention as an auxiliary agent. Other additives include, for example, colorants, lubricants, coupling agents, fluidity improvers, dispersants, antioxidants, UV absorbers, flame retardants, stabilizers, antistatic agents, foaming agents, plasticizers and the like. May be blended. These additives may be used alone or in combination of two or more. Further, these may be blended in the kneading step described later, or may be blended in the eggshell powder-containing thermoplastic resin composition in advance before the kneading step. In the eggshell powder-containing thermoplastic resin composition according to the present invention, the amount of these other additives added is a desired effect due to the combination of the above-mentioned thermoplastic resin and at least two eggshell powder groups having different average particle sizes. The content is not particularly limited as long as it does not inhibit In addition, it is desired that the other additives are blended in a proportion of 10% by mass or less in total.

The following is an explanation of what is considered to be important, but is not limited to these.

Examples of the plasticizer include triethyl citrate, acetyl triethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, and o-benzoylbenzoic acid. Examples thereof include esters, diacetin, epoxidized soybean oil, lactic acid, lactic acid oligomers having a weight average molecular weight of 3,000 or less, branched polylactic acid (see, for example, WO2010 / 082639, etc.). These plasticizers are usually blended in an amount of about several mass% with respect to the thermoplastic resin, but the amount is not limited to these ranges, and depending on the purpose of the molded product, about 20 to 50 parts by mass of epoxidized soybean oil or the like is blended. It is also possible to do. However, in the eggshell powder-containing thermoplastic resin composition of the present invention, it is preferable to blend lactic acid, a lactic acid oligomer having a weight average molecular weight of 3,000 or less, or branched polylactic acid as a plasticizer, and the blending amount is the thermoplastic resin. It is preferably about 0.5 to 10 parts by mass, particularly about 1 to 5 parts by mass with respect to 100 parts by mass.

As the colorant, any known organic pigment, inorganic pigment, or dye can be used. Specifically, organic pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, geoosazine-based, perinone-based, quinophthalone-based, and perylene-based pigments, ultramarine blue, titanium oxide, titanium yellow, and iron oxide. (Valve handle), chrome oxide, zinc flower, carbon black and other inorganic pigments can be mentioned.

Examples of the lubricant include fatty acid-based lubricants such as stearic acid, hydroxystearic acid, composite stearic acid, and oleic acid, aliphatic alcohol-based lubricants, stearoamide, oxystearoamide, oleylamide, elcilamide, ricinolamide, behenamide, and methylol. Adipose amide lubricants such as amides, methylene bisstearoamides, methylene bisstearobehenamides, higher fatty acid bisamide acids, complex amides, stearate-n-butyl, methyl hydroxystearate, polyhydric alcohol fatty acid esters, Examples thereof include saturated fatty acid esters, aliphatic ester-based lubricants such as ester-based waxes, fatty acid metal soap-based lubricants, and the like.

As the antioxidant, a phosphorus-based antioxidant, a phenol-based antioxidant, and a pentaerythritol-based antioxidant can be used. Phosphorus-based, more specifically, phosphorus-based antioxidant stabilizers such as phosphite ester and phosphoric acid ester are preferably used. Examples of the phosphite ester include triesters, diesters, monoesters and the like of phosphorous acids such as triphenylphosphite, trisnonylphenylphosphite and tris (2,4-di-t-butylphenyl) phosphite. Can be mentioned.

Examples of the phosphoric acid ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris (nonylphenyl) phosphate, 2-ethylphenyldiphenyl phosphate and the like. These phosphorus-based antioxidants may be used alone or in combination of two or more.

Examples of phenolic antioxidants include α-tocopherol, butylhydroxytoluene, cinapyl alcohol, vitamin E, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2-. t-Butyl-6- (3'-t-Butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenylacrylate, 2,6-di-t-butyl-4- (N, N-dimethyl) Aminomethyl) phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane Etc. are exemplified, and these can be used alone or in combination of two or more kinds.

The flame retardant is not particularly limited, but for example, a halogen-based flame retardant or a non-phosphorus-based halogen-based flame retardant such as a phosphorus-based flame retardant or a metal hydrate can be used. Specific examples of the halogen-based flame retardant include halogenated bisphenol compounds such as halogenated bisphenyl alkane, halogenated bisphenyl ether, halogenated bisphenyl thioether, and halogenated bisphenyl sulfone, brominated bisphenol A, and bromine. Bisphenol-bis (alkyl ether) -based compounds such as bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S, and as phosphorus-based flame retardants, tris (diethylphosphinic acid) aluminum, bisphenol A bis (diphenyl phosphate) , Triaryl isopropyl phosphate, cresildi 2,6-xylenyl phosphate, aromatic condensed phosphate, etc., as metal hydrates, for example, aluminum trihydrate, magnesium dihydride, or a combination thereof. Etc. can be exemplified respectively, and these can be used alone or in combination of two or more kinds. It works as a flame-retardant aid and can improve the flame-retardant effect more effectively. Further, for example, antimony oxide such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, magnesium oxide and the like can be used in combination as a flame retardant aid. ..

The foaming agent is a material that is mixed or press-fitted into an eggshell powder-containing thermoplastic resin composition that is a raw material that has been melted in a melt-kneader and undergoes a phase change from a solid to a gas, from a liquid to a gas, or the gas itself. , Mainly used to control the foaming ratio (foaming density) of a foamed sheet. The foaming agent dissolved in the eggshell powder-containing thermoplastic resin composition, which is the raw material, changes its phase to a gas at room temperature and dissolves in the molten resin, and the gas at room temperature does not change its phase. Dissolves in molten resin. When the molten resin is extruded into a sheet from an extrusion die, the foaming agent dispersed and dissolved in the molten resin expands inside the sheet because the pressure is released, and foams by forming a large number of fine closed cells in the sheet. A sheet is obtained. The foaming agent secondarily acts as a plasticizer for lowering the melt viscosity of the raw material resin composition, and lowers the temperature for bringing the raw material resin composition into a plasticized state.

Examples of the effervescent agent include aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptan; alicyclic hydrocarbons such as cyclobutane, cyclopentane and cyclohexane; chlorodifluoromethane, difluoromethane, trifluoromethane and trichlorofluoromethane. Methane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane , Tetrachlorodifluoroethane, perfluorocyclobutane and other halogenated hydrocarbons; carbon dioxide, nitrogen, air and other inorganic gases; water and the like.

As the foaming agent, for example, a carrier resin containing the active ingredient of the foaming agent can be preferably used. Examples of the carrier resin include crystalline olefin resins. Of these, crystalline polypropylene resin is preferable. In addition, examples of the active ingredient include hydrogen carbonate and the like. Of these, bicarbonate is preferred. A foaming agent concentrate containing a crystalline polypropylene resin as a carrier resin and a bicarbonate as a pyrolysis foaming agent is preferable.

The content of the foaming agent contained in the foaming agent in the molding step can be appropriately set according to the amount of the thermoplastic resin, the heavy calcium carbonate particles, etc., and is relative to the total mass of the eggshell powder-containing thermoplastic resin composition. It is preferably in the range of 0.04 to 5.00% by mass.

<Manufacturing method of thermoplastic resin composition containing eggshell powder>
As the method for producing the eggshell powder-containing thermoplastic resin composition of the present invention, a usual method can be used, and it may be appropriately set according to the molding method (extrusion molding, injection molding, vacuum molding, etc.), for example. The thermoplastic resin and at least two eggshell powder groups having different average particle diameters may be kneaded and melted before being charged into the molding machine from the hopper. May be kneaded and melted. In the melt-kneading, it is preferable to knead the eggshell powder uniformly in the thermoplastic resin by applying a high shear stress, for example, it is preferable to knead the eggshell powder with a twin-screw kneader.

In the method for producing an eggshell powder-containing thermoplastic resin composition of the present invention, the eggshell powder-containing thermoplastic resin composition may be in the form of pellets or not in the form of pellets, but in the form of pellets. The shape of the pellet is not particularly limited, and for example, pellets such as a cylinder, a sphere, and an elliptical sphere may be formed.

The size of the pellet may be appropriately set according to the shape, but for example, in the case of a spherical pellet, the diameter may be 1 to 10 mm. In the case of an elliptical spherical pellet, it may have an elliptical shape with an aspect ratio of 0.1 to 1.0 and an aspect ratio of 1 to 10 mm. In the case of cylindrical pellets, the diameter may be in the range of 1 to 10 mm and the length may be in the range of 1 to 10 mm. These shapes may be formed on the pellets after the kneading step described later. The shape of the pellet may be formed according to a conventional method.

≪Molded product≫
The molded product according to the present invention is a molded product molded by using the above-mentioned eggshell powder-containing thermoplastic resin composition.

The shape of the molded product according to the present invention is not particularly limited and may be of various forms, but for example, it is molded as various molded products such as sheets, food containers and other containers. Can be done. Since the molded product of the present invention contains eggshell, which is a sanitary-controlled waste mainly produced by a food manufacturer, as a raw material, it is suitable for use as a food container.

The wall thickness of the molded product according to the present invention is not particularly limited, and may vary from thin to thick depending on the form of the molded product. For example, the wall thickness is 40 μm. Molded articles having a wall thickness of up to 5,000 μm, more preferably a wall thickness of 50 μm to 1,000 μm are shown. If the wall thickness is within this range, it is possible to form a homogeneous and defect-free molded product without causing problems in moldability and workability and without causing uneven thickness.

In particular, when the form of the molded product is a sheet, it is more preferable that the wall thickness is 50 μm to 1,000 μm, and further preferably the wall thickness is 50 μm to 400 μm. A sheet having a wall thickness within such a range can be suitably used in place of general printing / information and packaging paper or synthetic paper.

≪Manufacturing method of molded products≫
The method for producing the molded product of the present invention is not particularly limited as long as it can be molded into a desired shape, and any of conventionally known methods such as extrusion molding, injection molding, vacuum molding, blow molding, and calendar molding can be used. Molding is possible. Furthermore, even when the eggshell powder-containing thermoplastic resin composition according to the present invention contains a foaming agent to obtain a molded product in the form of a foam, the foam can be molded as long as it can be molded into a desired shape. As a method, any of conventionally known liquid phase foaming methods such as injection foaming, extrusion foaming, and foam blowing, or solid phase foaming methods such as bead foaming, batch foaming, press foaming, and normal pressure secondary foaming are used. It can also be used. In one aspect of the above-mentioned thermoplastic composition containing crystalline polypropylene as a carrier resin and hydrogen carbonate as a pyrolytic foaming agent, an injection foaming method and an extrusion foaming method can be preferably used.

The molding temperature at the time of molding varies to some extent depending on the molding method, the type of thermoplastic resin used, and the like, and therefore cannot be unconditionally defined. However, for example, 180 to 260 ° C., more preferably 190 to At a temperature of 230 ° C., the eggshell powder-containing thermoplastic resin composition according to the present invention has good draw-down characteristics and ductility, and the composition has a predetermined shape without causing local modification. Can be molded.

<Sheet manufacturing method>
In the embodiment in which the molded product according to the present invention is a sheet, the manufacturing method thereof is not particularly limited as long as it is in the form of a sheet, and the conventional known molding method as described above can be used. In consideration of the smoothness of the sheet surface, it is preferable to adopt a method of making a sheet by extrusion molding with an extruder.

For molding, a direct method in which the kneading step and the step of molding into a sheet shape are continuously performed may be used, or for example, a method using a T-die type twin-screw extrusion molding machine may be used.
Further, in the case of molding into a sheet shape, it is possible to stretch in the uniaxial direction or the biaxial direction or in the multiaxial direction (stretching by the tubular method, etc.) at the time of the molding or after the molding. In the case of biaxial stretching, sequential biaxial stretching or simultaneous biaxial stretching may be used.

When the sheet after molding is stretched (for example, longitudinally and / or laterally stretched), the density of the sheet decreases. As the density decreases, the whiteness of the sheet becomes good.

Hereinafter, the present invention will be described in more detail based on examples. It should be noted that these examples are specific embodiments and practices in order to facilitate understanding of the concept and scope of the present invention disclosed in the present specification and described in the appended claims. The present invention is described only for the purpose of exemplifying the embodiments, and the present invention is not limited to these examples.

[Examples 1 and 2, Comparative Examples 1 to 5]
Sheets of various eggshell powder-containing thermoplastic resin compositions were prepared using the following raw materials, and the state at the time of extrusion was evaluated, and the appearance, smoothness, and mechanical strength were evaluated.
-Thermoplastic resin A: Polypropylene homopolymer (manufactured by Prime Polymer Co., Ltd .: Prime Polypro (trade name) E111G, melting point 160 ° C.)
Eggshell powder-O: Eggshell fine powder (manufactured by Sanshu Foods Co., Ltd .: Eggshell calcium (trade name), particle size 35 μm or less)
Eggshell powder-A: Eggshell fine powder with an average particle size of 1.0 μm (the above eggshell powder-O is finely pulverized and classified)
Eggshell powder-B: Eggshell fine powder with an average particle size of 3.6 μm (the above eggshell powder-O is finely pulverized and classified)
・ Light charcoal calcium powder: Light calcium carbonate particles with an average particle diameter of 1.0 μm ・ Plasticizer: Branched polylactic acid ・ Antistatic agent: Diethanolamide laurate ・ Antioxidant F1: Hindered phenolic antioxidant (pentaerythritol) Tetrakiss [3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate]
-Antioxidant F2: Tris (2,4-di-t-butylphenyl) phosphite

(Eggshell powder)
The eggshell powders-A and B were prepared by wet-pulverizing eggshell powder-O with a ball mill for 3 hours and 30 minutes, respectively, and further subjecting to spray drying. The characteristic values of each eggshell powder were evaluated by the following methods. The results are shown in Table 1.

(Average particle size of eggshell powder)
It was calculated from the measurement result of the specific surface area by the air permeation method according to JIS M-8511 using the specific surface area measuring device SS-100 manufactured by Shimadzu Corporation.

(Specific surface area of eggshell powder)
It was determined by a nitrogen gas adsorption method using BELSORP-mini manufactured by Microtrac Bell.

(Roundness of eggshell powder)
100 particles were sampled to represent the particle size distribution of eggshell powder, and a projection drawing of each of these particles was obtained using an optical microscope. The projected area and projected peripheral length of the particles of the image were measured using commercially available image analysis software, and the roundness was determined by the above measurement principle.

(Preparation of Eggshell Powder-Containing Thermoplastic Resin Composition / Sheet)
1 part by mass of plasticizer (branched polylactic acid), 2 parts by mass of antistatic agent, and 0.5 parts by mass of each of the amount (parts by mass) of thermoplastic resin A and various eggshell powders shown in Table 2. It was put into an extrusion molding machine equipped with a twin-screw screw (T-die extrusion molding apparatus (φ20 mm, L / D = 25) manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with the antioxidants F1 and F2, and kneaded at 200 ° C. The eggshell powder-containing thermoplastic resin composition was extruded from a T-die to a sheet at 220 ° C. (die temperature), wound up by a film sheet picker manufactured by Toyo Seiki Co., Ltd., and formed into a sheet having a wall thickness of about 200 μm.

(Evaluation method)
Each sheet obtained as described above was evaluated by the following method. The results are shown in Table 2 together with the state at the time of compounding and manufacturing.

(Appearance / surface smoothness)
The appearance of the sheet was visually observed, and the presence or absence of yellowing, unevenness, and scratches was observed. In addition, the smoothness of the surface of the molded product was evaluated visually and by touch according to the following evaluation criteria.
[Evaluation criteria]
◯: Has good smoothness with no irregularities or scratches on the surface.
Δ: Slight irregularities are observed on the surface.
X: Many irregularities are observed on the surface.

(Tensile strength, elongation)
Tensile strength and elongation were measured using Autograph AG-100kNXplus (Shimadzu Corporation) under the conditions of 23 ° C. and 50% RH according to JIS K 7161-2: 2014. The test piece had a dumbbell shape cut out from each of the obtained sheets. The stretching speed was 10 mm / min.

As shown from the results shown in Table 2, in the eggshell powder-containing thermoplastic resin compositions of Examples 1 and 2 according to the present invention, no problem occurs during extrusion even if the eggshell powder is highly filled by 70 parts by mass or more. A sheet having a smooth surface and high mechanical strength (tensile strength, elongation) was obtained. On the other hand, in the eggshell powder-containing thermoplastic resin compositions of Comparative Examples 2 and 3 in which only eggshell powder-A having a fine particle size was blended in the same amount, the melt viscosity increased, making extrusion difficult or impossible, and a sheet was obtained. Even in this case, the appearance was uneven. In the eggshell powder-containing thermoplastic resin compositions of Comparative Examples 1 and 4 in which eggshell powder-O and eggshell powder-B having a coarse particle size were blended, the obtained sheet was inferior in smoothness and had mechanical strength (tensile strength, elongation). Was also low. Further, in Comparative Example 5 in which a light calcium carbonate powder was used instead of the eggshell powder-A as the calcium carbonate powder having a fine particle size, there was no problem in smoothness, but the mechanical strength (tensile strength, elongation) was slightly inferior. The result was. Porous eggshell powder was shown to exhibit a higher reinforcing effect than general light calcium carbonate.

Based on the above, by using at least two groups of eggshell powders having a predetermined BET specific surface area and roundness and having different particle size distributions within a predetermined average particle size in accordance with the present invention, eggshell powder can be used. It has been found that a molded product having a good appearance and mechanical properties can be produced while being highly filled.

Claims

In an eggshell powder-containing thermoplastic resin composition containing a thermoplastic resin and eggshell powder in a mass ratio of 50:50 to 10:90.
The mass ratio of the eggshell powder to the entire eggshell powder-containing thermoplastic resin composition is 50/100 or more.
The BET specific surface area of the eggshell powder is 0.1 m 2 / g or more and 10.0 m 2 / g or less.
The roundness of the eggshell powder is 0.50 or more and 0.95 or less.
The eggshell powder contains at least two groups of particles having different average particle diameters, and as the above-mentioned particle groups of at least two groups having different average particle diameters, the average particle diameter by the air permeation method is 0.7 μm or more and 2.2 μm. It is characterized in that it contains an eggshell powder group of less than 2 and an eggshell powder group having an average particle size of 2.2 μm or more and less than 6.0 μm by the air permeation method in a mass ratio of 1: 1 to 5: 1. Eggshell powder-containing thermoplastic resin composition.
When the average particle size of the eggshell powder group A having a small average particle size is a and the average particle size of the eggshell powder group B having a large average particle size is b, the a / b ratio is 0.85 or less. The eggshell powder-containing thermoplastic resin composition according to claim 1.
The eggshell powder-containing thermoplastic resin composition according to claim 1 or 2, wherein the mass ratio of the thermoplastic resin to the eggshell powder in the eggshell powder-containing thermoplastic resin composition is 50:50 to 30:70.
The eggshell powder-containing thermoplastic resin composition according to any one of claims 1 to 3, wherein the thermoplastic resin is a polypropylene resin and / or a polyethylene resin.
The eggshell powder-containing thermoplastic according to any one of claims 1 to 3, further containing a plasticizer selected from the group consisting of lactic acid, a lactic acid oligomer having a weight average molecular weight of 3,000 or less, and branched polylactic acid. Resin composition.
The eggshell powder-containing thermoplastic resin composition according to any one of claims 1 to 5, wherein the eggshell powder is an unbaked eggshell powder.
The eggshell powder-containing thermoplastic resin composition according to claim 6, wherein the eggshell powder is an eggshell powder that has not been surface-treated.
A molded product comprising the eggshell powder-containing thermoplastic resin composition according to any one of claims 1 to 7.
The molded product according to claim 8, which is a food container.