JP7468954B1 - Resin composition and molded article - Google Patents

Abstract

[Problem] The object of the present invention is to provide a technology capable of suppressing screw wear during kneading for a resin composition highly filled with inorganic substance powder. [Solution] The present invention provides a resin composition containing a thermoplastic resin and an inorganic substance powder that satisfies certain requirements. [Selected Figures] None

Description

The present invention relates to a resin composition and a molded article.

In recent years, from the viewpoint of reducing the environmental load, etc., attempts have been made to highly fill resin products with inorganic powders.
Also known is a technique for surface treating an inorganic powder with a fatty acid-based surface treating agent or the like in order to improve dispersibility in a resin (see, for example, Patent Document 1).

Resin products highly filled with inorganic powders are usually obtained by melt-kneading a resin composition made up of the raw material components (resin, inorganic powder, etc.) and molding the resulting kneaded product.

JP 2007-169485 A

However, the present inventors have found that the inorganic powder easily causes wear of the screw during kneading of the resin composition, because, for example, the inorganic powder (such as heavy calcium carbonate) that is amorphous easily damages the surface of the screw.
A worn screw is likely to impair the stability of the kneading process, and may result in poor dispersion of the inorganic powder in the resin composition.
Furthermore, the present inventors have found that when an inorganic powder treated with a surface treatment agent (e.g., a fatty acid-based surface treatment agent) is used, the dispersibility of the inorganic powder may be improved while causing wear due to contact with the screw surface.

The present invention was made in consideration of the above situation, and aims to provide a technology that can suppress screw wear during kneading of resin compositions highly filled with inorganic powder.

The inventors discovered that the above problems can be solved by using an inorganic powder that has been surface-treated with a plant-derived material as the inorganic powder to be blended into the resin composition, and thus completed the present invention. More specifically, the present invention provides the following:

(1) A resin composition comprising a thermoplastic resin and an inorganic substance powder,
The content of the inorganic substance powder in the resin composition is 50% by mass or more and 90% by mass or less,
the thermoplastic resin includes a polyolefin resin,
A resin composition, wherein the inorganic substance powder is surface-treated with a plant-derived material.

(2) The resin composition according to (1), wherein the plant-derived material includes vegetable oil.

(3) The resin composition according to (2), wherein the vegetable oil comprises one or more vegetable oils selected from the group consisting of soybean oil, corn oil, and safflower oil.

(4) The resin composition according to (1), wherein the polyolefin resin comprises a polypropylene resin and/or a polyethylene resin.

(5) The resin composition according to (1), wherein the inorganic powder contains calcium carbonate powder.

(6) The resin composition according to (5), wherein the calcium carbonate powder includes ground calcium carbonate powder.

(7) The resin composition according to (6), in which the ground calcium carbonate powder contains ground calcium carbonate powder having an average particle size of 0.7 μm or more and 6.0 μm or less as measured by an air permeation method according to JIS M-8511.

(8) A molded article containing a thermoplastic resin and an inorganic substance powder,
The content of the inorganic substance powder in the molded article is 50% by mass or more and 90% by mass or less,
the thermoplastic resin comprises a polyolefin resin,
The inorganic powder is surface-treated with a plant-derived material.
Molding.

The present invention provides a technology that can suppress screw wear during kneading of a resin composition highly filled with inorganic powder.

The following describes an embodiment of the present invention, but the present invention is not limited to this.

<Resin Composition>
A resin composition according to one embodiment of the present invention contains a thermoplastic resin and an inorganic substance powder, and in particular has a major technical feature in that the inorganic substance powder is surface-treated with a plant-derived material.

The present inventors have conducted extensive research into techniques capable of reducing screw wear during kneading of a resin composition highly filled with inorganic substance powder.
As a result, it was found that screw wear could be significantly suppressed by blending inorganic powders that had been surface-treated with plant-derived materials. Surprisingly, this effect was not observed when using conventional fatty acid-based surface treatment agents (such as stearic acid) as the surface treatment agent.

In one embodiment of the present invention, "kneading the resin composition" includes a process of uniformly dispersing the components that make up the resin composition by mixing and stirring the components.

In one embodiment of the present invention, the "kneading" is performed by an apparatus equipped with a screw (such as a molding apparatus). The kneading is usually performed under heating in order to melt the resin contained in the resin composition and form a fluid.

In one embodiment of the present invention, the "screw" may be a part that rotates in a fluid and generates a flow of the fluid in the direction of the rotation axis. The screw comes into direct contact with the components contained in the resin composition during kneading.
The shape and material of the screw are not particularly limited, and any screw that is usually used in kneading a resin composition can be used.

In one embodiment of the present invention, "screw wear is suppressed" means that there is no or little wear scar on the screw surface compared to when a similar inorganic powder is used except that it has not been surface-treated with a plant-derived material.
The presence or absence of wear marks on the screw surface and the extent of such wear marks can be identified by microscopic or visual observation of the screw surface.

The presence or absence of screw wear during kneading and the extent of wear can be evaluated using the method shown in the examples.

In one embodiment of the present invention, "consisting of component A" means that it does not substantially contain any components other than component A.

In one embodiment of the present invention, "substantially free of component B" includes an embodiment in which the content of component B is less than 0.1% by mass, more preferably 0.01% by mass or less, based on the total blended target (e.g., resin composition), and even more preferably an embodiment in which component B is not included at all.

The composition of the resin composition according to one embodiment of the present invention is described in detail below.

(1) Thermoplastic resin The thermoplastic resin is not particularly limited except that it contains a polyolefin resin, and any resin that can be usually blended in a resin product can be used. The thermoplastic resin may be used alone or in combination of two or more kinds.

(1-1) Types of Thermoplastic Resins The thermoplastic resin includes at least a polyolefin resin, and is preferably made of a polyolefin resin. By combining the polyolefin resin with an inorganic substance powder described later, good antibacterial properties can be realized.
Examples of thermoplastic resins other than polyolefin resins include polyester resins and polystyrene resins.

In one embodiment of the present invention, the term "polyolefin-based resin" refers to a polyolefin-based resin containing an olefin component unit as a main component.
"Containing an olefin component unit as the main component" means that the olefin component unit is contained in the polyolefin resin at 50 mass % or more (preferably 75 mass % or more, more preferably 85 mass % or more, and even more preferably 90 mass % or more).
The method for producing the polyolefin resin used in the present invention is not particularly limited, and may be any method using a Ziegler-Natta catalyst, a metallocene catalyst, a radical initiator (oxygen, peroxide, etc.), or the like.

Examples of polyolefin resins include polypropylene resins and polyethylene resins.
From the viewpoint of easily achieving the effects of the present invention and further easily realizing a good appearance, the thermoplastic resin preferably contains a polypropylene-based resin and/or a polyethylene-based resin, and more preferably consists of a polypropylene-based resin and/or a polyethylene-based resin.

(1-1-1) Polypropylene Resin The polypropylene resin in the present invention includes a resin containing propylene component units in an amount of preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and most preferably 80% by mass or more.

Examples of polypropylene-based resins include polypropylene homopolymers (propylene homopolymers), copolymers of propylene and other α-olefins (copolymerizable with propylene), and the like.
Examples of the "other α-olefins" include α-olefins having 4 to 10 carbon atoms (such as ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, and 3-methyl-1-hexene).

Propylene homopolymers include linear or branched polypropylenes exhibiting various stereoregularities (isotactic, syndiotactic, atactic, hemiisotactic, etc.).

The propylene copolymer may be any of polypropylene random copolymers (random copolymers), polypropylene block copolymers (block copolymers), binary copolymers, ternary copolymers, etc. Specific examples include ethylene-propylene random copolymers, butene-1-propylene random copolymers, ethylene-butene-1-propylene random terpolymers, ethylene-propylene block copolymers, etc.

Among the above polypropylene-based resins, resins containing polypropylene block polymers are preferred, and resins made of polypropylene block polymers are more preferred.

(1-1-2) Polyethylene Resin The polyethylene resin in the present invention includes a resin containing ethylene component units in an amount of preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and most preferably 80% by mass or more.

Examples of polyethylene resins include high density polyethylene (HDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), 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 copolymer, and ethylene-octene 1 copolymer.

As the polyethylene-based resin, a resin containing high-density polyethylene and/or linear low-density polyethylene is preferable, and a resin consisting of high-density polyethylene and/or linear low-density polyethylene is more preferable.

The high-density polyethylene preferably has an MFR (190°C, 21.6 kg) according to JIS K 6922-1 (ISO1133) of 5 g/10 min or more and 15 g/10 min or less, more preferably 7 g/10 min or more and 13 g/10 min or less.

The linear low-density polyethylene preferably has an MFR (190°C, 2.16 kg) according to JIS K 6922-1 (ISO1133) of 0.5 g/10 min or more and 1.5 g/10 min or less, more preferably 0.7 g/10 min or more and 1.3 g/10 min or less.

In resins containing high-density polyethylene and linear low-density polyethylene, the mass ratio of the two (high-density polyethylene:linear low-density polyethylene) is preferably 90:10 to 50:50, more preferably 92:8 to 50:50, and even more preferably 94:6 to 50:50.

(1-2) Amount of Thermoplastic Resin Added The amount of the thermoplastic resin added can be appropriately set depending on the amount of the inorganic substance powder added, etc.

From the viewpoint of moldability, the content of the thermoplastic resin is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the resin composition.

The content of the thermoplastic resin is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the viewpoint that a sufficient amount of inorganic powder can be blended and that good mechanical properties, etc. can be easily obtained.

(2) Inorganic Powder By blending a predetermined ratio of inorganic powder that has been surface-treated with a plant-derived material together with a thermoplastic resin, screw wear during kneading can be suppressed even in the case of a resin composition that is highly filled with inorganic powder.

(2-1) Kind of Inorganic Powder There is no particular limitation on the inorganic powder, and it is possible to use those contained in ordinary resin molded products, etc. The inorganic powder may be one type of substance alone or two or more types of substances in combination.
However, from the viewpoint of easily achieving the effects of the present invention, preferred embodiments of the present invention include an embodiment containing calcium carbonate powder as the inorganic substance powder, and an embodiment containing only calcium carbonate powder.

(2-1-1) Calcium Carbonate The calcium carbonate may be either heavy calcium carbonate or light calcium carbonate.
"Heavy calcium carbonate" is calcium carbonate obtained by mechanically grinding (dry method, wet method, etc.) natural raw materials (limestone, etc.) whose main component is _CaCO3 .
"Light calcium carbonate" refers to calcium carbonate prepared by a synthetic method (such as a chemical precipitation reaction).
Thus, ground calcium carbonate and light calcium carbonate are clearly distinguished from each other.

The difference between ground calcium carbonate and light calcium carbonate can be identified, for example, from the circularity calculated based on the analysis of SEM images.
The roundness of the ground calcium carbonate powder is, for example, in the range of 0.50 to 0.95, and the roundness of the light calcium carbonate powder is, for example, approximately 1.00.

In one embodiment of the present invention, "circularity" is a value represented by the following formula, and is an index of the degree of irregularity of a particle. The closer the circularity is to "1" (maximum value), the closer it is to a perfect circle, and the lower the value, the higher the degree of irregularity.
"Circularity" = (projected area of particle) / (area of a circle with the same perimeter as the projected perimeter of the particle)

Heavy calcium carbonate, due to its manufacturing process, does not have a uniform shape, and is low cost, but it is easy to stably impart good mechanical properties to resin molded products.
On the other hand, due to its shape, heavy calcium carbonate is a component that is likely to cause wear of the screw during kneading. However, according to the present invention, by using heavy calcium carbonate that has been surface-treated with a plant-derived material, such wear can be effectively suppressed.
Therefore, preferred embodiments of the present invention include those in which the calcium carbonate contains ground calcium carbonate or those in which the calcium carbonate consists of ground calcium carbonate.

(2-1-2) Inorganic substance powder other than calcium carbonate Examples of inorganic substance powder other than calcium carbonate include the following.
Metal (magnesium, aluminum, titanium, iron, zinc, etc.) carbonates, sulfates, silicates, phosphates, or borates;
Oxides of metals (calcium, magnesium, aluminum, titanium, iron, zinc, etc.);
Hydrates of the above salts or oxides.

Examples of inorganic powders other than calcium carbonate include magnesium carbonate, 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, and graphite.

The inorganic powder may be synthetic or derived from natural minerals.

(2-2) Surface Treatment of Inorganic Powder The inorganic powder of the present invention has a technical feature in that its surface is treated with a plant-derived material.

In one embodiment of the present invention, the phrase "the surface of the inorganic substance powder is surface-treated with a plant-derived material" encompasses the surface of the inorganic substance powder being covered with a plant-derived material.
This includes an embodiment in which all (100%) or a part of the surface of the powder of an inorganic substance is surface-treated with a plant-derived material.
When a portion of the surface of the inorganic substance powder is surface-treated, preferably 50%, more preferably 75%, and even more preferably 95% or more of the total surface area of the inorganic substance powder may be surface-treated.

In one embodiment of the present invention, the term "plant-derived material" includes materials whose raw material is derived from any plant and which are capable of maintaining a state in which they cover the surface of the inorganic substance powder.
The plant-derived material may be used alone or in combination of two or more kinds of substances.

In one embodiment of the present invention, the plant-derived material is preferably a vegetable oil.
Preferred examples of the vegetable oil include soybean oil, corn oil, safflower oil, rapeseed oil, coconut oil, palm kernel oil, and olive oil.
Of these vegetable oils, from the viewpoint that the effects of the present invention are particularly easily achieved, one or more selected from the group consisting of soybean oil, corn oil, and safflower oil are more preferable.

The surface treatment of the inorganic powder can be carried out by any method known in the art.
For example, a method of immersing an inorganic substance powder in a plant-derived material, a method of spraying a plant-derived material onto an inorganic substance powder, and the like can be mentioned.

The thickness of the surface treatment layer in the surface-treated inorganic substance powder (i.e., the thickness of the plant-derived material covering the surface of the inorganic substance powder) is not particularly limited, but is preferably 0.1 μm or more and 5 μm or less, more preferably 0.5 μm or more and 2 μm or less.
The thickness of the surface treatment layer may be uniform or non-uniform, but from the viewpoint of easily achieving the effects of the present invention stably, it is preferable that the thickness of the surface treatment layer is uniform (for example, the difference between the thickest and thinnest points is 0.3 μm or less).

(2-3) Average Particle Size, etc. of Inorganic Powder The average particle size of the inorganic powder can be appropriately set depending on the moldability, etc. of the resin composition to be obtained.
However, from the viewpoint of easily realizing stable dispersibility and easily achieving uniform mechanical properties throughout the resin molded article, the average particle size of the inorganic substance powder as measured by an air permeation method in accordance with JIS M-8511 is preferably 0.7 μm or more and 6.0 μm or less, more preferably 1.0 μm or more and 5.5 μm or less.
The average particle size of the inorganic substance powder may be any size as long as the entire inorganic substance powder satisfies the above requirement.

The shape of the inorganic powder is not particularly limited, and may be any of particles (spherical, irregular, etc.), flakes, granules, fibers, etc.

(2-4) Amount of Inorganic Powder The content of the inorganic powder surface-treated with a plant-derived material is not particularly limited as long as the content of the inorganic powder relative to the resin composition is 50% by mass or more and 90% by mass or less.
As long as the content of the inorganic powder surface-treated with a plant-derived material falls within the above range, the inorganic powder may further contain an inorganic powder that is not surface-treated or an inorganic powder surface-treated with a material other than a plant-derived material. However, from the viewpoint of easily achieving the effects of the present invention, the inorganic powder in the present invention is composed of an inorganic powder surface-treated with a plant-derived material.

From the viewpoint of easily improving mechanical properties, the lower limit of the content of the inorganic powder is 50% by mass or more, preferably 52% by mass or more, more preferably 54% by mass or more, and even more preferably 56% by mass or more, relative to the resin composition.

From the viewpoint of moldability, the upper limit of the content of the inorganic powder is 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, based on the resin composition.

The content of calcium carbonate in the inorganic powder is preferably 70% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass, based on the total inorganic powder, from the viewpoint of easily achieving good mechanical properties.

Whether or not an inorganic powder contains calcium carbonate and how much it contains can be determined by firing the resin molded product and analyzing its ash content.

(3) Other Components The resin composition may contain, or may not contain, other components than the inorganic substance powder and the thermoplastic resin, as long as the effects of the present invention are not impaired.

As the other components, any components that can be usually blended in resin molded products can be used.
Such components include colorants, lubricants, dispersants, antistatic agents, antioxidants, heat stabilizers, and ultraviolet absorbing agents.
The types and amounts of these components can be appropriately determined depending on the effects to be obtained.

In a preferred embodiment of the present invention, the resin composition includes those consisting only of a thermoplastic resin and an inorganic powder.

(4) Ratio of Thermoplastic Resin to Inorganic Powder In the resin composition, the mass ratio of the thermoplastic resin to the inorganic powder (thermoplastic resin:inorganic powder) is preferably 50:50 to 15:85, more preferably 45:55 to 15:85, and even more preferably 40:60 to 20:80.
In this way, by making the ratio of the inorganic substance powder to the thermoplastic resin equal to or greater than the above, the effect of improving the mechanical properties by the inorganic substance powder can be easily achieved.

<Method of producing resin composition>
As a method for producing the resin composition, conventionally known methods and conditions can be adopted depending on the form and application of the resin composition.

The resin composition can be obtained, for example, by mixing, melt-kneading, or the like, the constituent components using an apparatus equipped with a screw.
The machine for producing the resin composition can be selected according to the form and use of the resin composition as long as it is a device equipped with a screw, and examples of the machine include an extruder, a kneader, a Banbury mixer, and a kneader (such as a twin-screw kneader).

The material, shape, etc. of the screw may be any of those usually used for kneading resins, etc.
For example, the screw may be made of aluminum chromium molybdenum steel, stainless steel, or the like.

The form of the resin composition is not particularly limited, and any form that can be molded into the desired resin molded product (sheet, container, etc.) can be adopted.

<Resin molded products>
The present invention also includes the following resin molded article.
A molded article comprising a thermoplastic resin and an inorganic powder,
The content of the inorganic substance powder in the molded article is 50% by mass or more and 90% by mass or less,
The thermoplastic resin includes a polyolefin resin,
Inorganic powder is surface-treated with plant-derived material.
Molding.

The details of each component constituting the molded article of the present invention may be the same as those of the resin composition of the present invention.

The molded article of the present invention can be obtained, for example, by molding the resin composition of the present invention using a method appropriate for the type of molded article.

Examples of molding methods for obtaining the molded article of the present invention include injection molding, extrusion molding, inflation molding, vacuum molding, blow molding, calendar molding, compressed air molding, match mold molding, and press molding.
Therefore, the molded article of the present invention includes any of injection molded articles, extrusion molded articles, inflation molded articles, vacuum molded articles, blow molded articles, calendar molded articles, compressed air molded articles, match mold molded articles, and press molded articles.

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 and evaluation of resin composition>
In the process of producing a resin composition by the following method, the presence or absence and the degree of wear of the screw during kneading were evaluated.

(1) Preparation of Materials Materials for each layer were prepared as follows.

(1-1) Inorganic Powder As the inorganic powder, calcium carbonate particles (ground calcium carbonate particles) were used. The average particle size of the calcium carbonate particles was set to 2.5 μm by the air permeability method according to JIS M-8511.
The entire surface of the inorganic powder was uniformly coated with any one of the following surface treatment agents to a thickness of about 1 μm.
Surface treatment agent made from plant-derived materials: soybean oil, corn oil, safflower oil, or rapeseed oil Fatty acid-based surface treatment agent: stearic acid In addition, inorganic substance powder that was not treated with a surface treatment agent (untreated) was also prepared.

(1-2) Thermoplastic Resin Any of the following thermoplastic resins (all of which correspond to polyolefin-based resins) was used.
Polypropylene resin (PP): Polypropylene block copolymer (melting point 160°C)
Polyethylene resin (PE): a blend of HDPE and LLDPE (HDPE:LLDPE (mass ratio) = 70:30)
The MFR (190° C., 21.6 kg) of the above HDPE is 7.5 g/10 min according to JIS K 6922-1 (ISO 1133).
The LLDPE has an MFR (190° C., 2.16 kg) according to JIS K 6922-1 (ISO 1133) of 0.8 g/10 min.

(2) Preparation of resin composition and molded article Thermoplastic resin (PP or PE) and inorganic substance powder were melt-kneaded in the ratios shown in Tables 1 and 2, and then pellet-shaped resin compositions were prepared.
A small twin-screw extruder (screw diameter = ψ 25 mm, L/D = 41) equipped with a screw was used to prepare the resin composition. The screw used was made of sacm645 (aluminum chromium molybdenum steel).
The kneading conditions were set to a screw rotation speed of 50 rpm, 200° C., 20 minutes, and a resin composition discharge amount of 800 g, and kneading was performed a total of 20 times under these conditions (i.e., each resin composition was operated for a total of 400 minutes). Next, extrusion molding was performed to prepare a molded product from the resin composition.
The screw was replaced with an unused screw each time kneading of each resin composition was completed.

(3) Evaluation of Screw Wear After the production of the molded product, the screw was removed from the small twin-screw extruder, washed and dried, and the presence or absence and the degree of wear marks on the surface were visually evaluated according to the following criteria. The results are shown in Tables 1 and 2.
A: No wear marks were observed on the screw surface.
B: Slight wear marks were observed on the screw surface.
C: Wear marks were clearly observed on the screw surface.

As shown in the table, when the inorganic powder having its surface treated with a plant-derived material was used, the wear of the screw was effectively suppressed.
In this example, heavy calcium carbonate powder was used as the inorganic powder, but the same tendency was observed even when other inorganic powders (talc, etc.) were used.

When soybean oil, corn oil, or safflower oil was used as a plant-derived material, there was a tendency for a stable effect of suppressing screw wear.

In contrast, when inorganic powders that had been surface-treated with stearic acid were used, the dispersibility during melt kneading was good, but the effect of suppressing screw wear could not be confirmed.

In this example, the average particle size of the inorganic powder was set to 2.5 μm, but even with a higher average particle size (i.e., an inorganic powder that is more susceptible to causing screw wear), the effect of suppressing screw wear was observed to have a similar tendency to this example.

Claims (7)

A resin composition comprising a thermoplastic resin and an inorganic substance powder,
The content of the inorganic substance powder in the resin composition is 50% by mass or more and 90% by mass or less,
the thermoplastic resin comprises a polyolefin resin,
The inorganic substance powder includes calcium carbonate powder,
The inorganic powder is surface-treated with a plant-derived material ;
The plant-derived material comprises vegetable oil.
Resin composition. The resin composition according to claim 1 , wherein the vegetable oil comprises one or more vegetable oils selected from the group consisting of soybean oil, corn oil, and safflower oil. The resin composition according to claim 1, wherein the polyolefin resin comprises a polypropylene resin and/or a polyethylene resin. The resin composition according to claim 1 , wherein the calcium carbonate powder comprises ground calcium carbonate powder. The resin composition according to claim 4 , wherein the ground calcium carbonate powder contains ground calcium carbonate powder having an average particle size of 0.7 μm or more and 6.0 μm or less as measured by an air permeation method in accordance with JIS M-8511. A molded article comprising a thermoplastic resin and an inorganic powder,
The content of the inorganic substance powder in the molded article is 50% by mass or more and 90% by mass or less,
the thermoplastic resin comprises a polyolefin resin,
The inorganic substance powder includes calcium carbonate powder,
The inorganic powder is surface-treated with a plant-derived material ;
The plant-derived material comprises vegetable oil.
Molding. A method for producing a resin composition, comprising a mixing step of a thermoplastic resin and an inorganic substance powder,
The content of the inorganic substance powder in the resin composition is 50% by mass or more and 90% by mass or less,
the thermoplastic resin comprises a polyolefin resin,
The inorganic substance powder includes calcium carbonate powder,
The inorganic powder is surface-treated with a plant-derived material before the mixing step;
The plant-derived material comprises vegetable oil.
Production method.