Resin composition and molded article thereof

Abstract

To provide a resin composition which is excellent in moldability, can correspond to various molding methods, especially, both injection molding and inflation molding, is excellent in a percentage content of cellulose powder, and can reduce environmental loads, and a molding of the same.SOLUTION: A resin composition contains at least a thermoplastic resin and cellulose powder, wherein the cellulose powder content to the whole resin composition is more than 50 mass%, and an aspect ratio (Str) of a surface quality is 0.80 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition containing cellulose powder.

Background Art

[0002] In recent years, problems with synthetic resin products, starting with the marine plastic problem, have been regarded as issues. Therefore, there is a demand to convert at least a part of the raw materials of synthetic resin products, especially products that are discarded after use, to raw materials other than synthetic resins and reduce the amount of synthetic resin used.

[0003] Examples of raw materials other than such synthetic resins include cellulose materials such as paper. Since this cellulose material is inexpensive and has excellent recyclability, it is widely used as a reinforcing material for thermoplastic resins and elastomers that are molding materials such as films.

[0004] Examples of such resin compositions containing cellulose materials include cellulose powder (fine paper powder) in an amount of 20 to 70 parts by mass and a thermoplastic resin such as polypropylene in an amount of 30 to 80 parts by mass, and a resin composition in which the total of cellulose powder and the thermoplastic resin is 100 parts by mass has been proposed. It is described that by using such a resin composition, a resin composition having good fluidity and suitable as a material for molding can be obtained. (For example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, the above-mentioned conventional cellulose powderIn a resin composition containing cellulose, the cellulose is present in the entirety of the resin composition. powder If the content exceeds 50% by mass, it can be treated as paper under the Container and Packaging Recycling Law, but cellulose powder When the content of this substance increases, problems arise such as holes appearing during the molding process of films, making it impossible to obtain good molded products.

[0007] Furthermore, since the conventional resin composition containing cellulose powder described above uses polypropylene as its base material, the resin composition is hard, and in order to prevent the occurrence of the aforementioned porosity, cellulose is used. powder Because it was necessary to reduce the content of synthetic resins, there was a problem in that the effect of reducing the amount of synthetic resin used was diminished.

[0008] Therefore, the present invention has been made in view of the above-mentioned problems, and aims to provide a resin composition and a molded article thereof that has excellent moldability, can be used with various molding methods, in particular injection molding and inflation molding, has an excellent cellulose powder content, and can reduce environmental impact. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a resin composition comprising at least a thermoplastic resin and cellulose powder, wherein the cellulose powder content relative to the total resin composition is more than 50% by mass, and the aspect ratio (Str) of the surface properties determined by the following measurement procedure is 0.80 or higher.

[0010] (Procedure for measuring the aspect ratio (Str) of surface texture) 1. The resin composition pellets are injection molded at 150-180°C to obtain a sheet-like molded product measuring 100mm x 100mm x 3mm thick.

[0011] 2. On one 100mm x 100mm surface of the molded product, arbitrarily set six measuring circles with a diameter of 2cm, such that the measuring circles do not extend beyond the surface and do not overlap with each other.

[0012] 3. Measure the aspect ratio of the surface properties on the surface of the molded product according to [texture aspect ratio] specified in ISO25178-2:2012 within the range of 1 mm square at the center of the measurement circle.

[0013] 4. Measure the aspect ratio of the surface properties six times, calculate the average value of the aspect ratios of the surface properties for the six measurements, and define it as the aspect ratio (Str) of the surface properties of the molded product.

[0014] Moreover, the molded body of the present invention can be obtained by molding the resin composition of the present invention by various methods (injection, inflation, blow, etc.).

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a resin composition that is excellent in the cellulose powder content and can reduce the environmental load. In addition, it is possible to provide a resin composition that is excellent in moldability and can be applied to various molding methods, particularly both injection molding and inflation molding. Furthermore, the molded body using this resin composition can be treated as "paper" under the container recycling method.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram (top view) for explaining the measurement procedure of the aspect ratio (Str) of the surface properties in the molded product of the resin composition of the present invention. [Figure 2] It is a schematic diagram (side view) for explaining the measurement procedure of the aspect ratio (Str) of the surface properties in the molded product of the resin composition of the present invention.

Modes for Carrying Out the Invention

[0017] Hereinafter, the resin composition of the present invention will be specifically described. Note that the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.

[0018] The resin composition of the present invention contains at least cellulose powder and a thermoplastic resin.

[0019] <Cellulose powder > The cellulose of the present invention powder can be produced, for example, by using pulp derived from purified high-purity cotton linter, wood, bamboo, bagasse, etc., and classifying the powder pulp obtained by pulverizing these pulps with a pulverizer such as a knife mill, a vertical roller mill, or a jet mill so as to have the target average particle size.

[0020] Also, the average particle size of the cellulose powder is preferably 10 μm or less. If the average particle size is 10 μm or less, the surface of the resin composition becomes smooth, and the cellulose powder is uniformly dispersed. Therefore, there are no holes due to drawdown during extrusion, and it becomes easy to cope with fine structures during injection. Accordingly, the resin composition has excellent moldability and excellent toughness.

[0021] Also, the average particle size of the cellulose powder is more preferably 5 μm or more. If the average particle size is 5 μm or more, the resin composition has excellent rigidity.

[0022] The "average particle size" refers to the 50% particle size (D50), and can be measured as the volume average particle size by a laser diffraction particle size distribution measuring device (dry particle size distribution meter manufactured by Malvern Panalytical, trade name: MASTER SIZER 3000), etc.

[0023] Also, commercially available products may be used as the cellulose powder. Examples of commercially available cellulose powders include KC Flock manufactured by Nippon Paper Industries Co., Ltd., and Cellulose Microfiber 1 manufactured by Rettenmaier Japan Co., Ltd.

[0024] Also, the whole of the resin composition (that is, cellulose powderThe content of cellulose powder relative to the total mass of polyethylene resin, the olefin elastomer described later, and the maleic anhydride-modified polyolefin described later is more than 50% by mass of the entire resin composition (i.e., out of 100% by mass of the resin composition). If the cellulose powder content is more than 50% by mass, then cellulose powder Because of its excellent content, it is highly effective in reducing the amount of synthetic resin used in molded products, thereby reducing the environmental burden. Furthermore, it can achieve sufficient rigidity even when the thermoplastic resin content is low. In addition, the molded product can be treated as "paper" under the Container Recycling Law.

[0025] Furthermore, from the viewpoint of further improving the moldability and rigidity of the resin composition, the content of cellulose powder in the total resin composition is preferably 70% by mass or less, and more preferably 60% by mass or less.

[0026] <Thermoplastic resin> Examples of thermoplastic resins include polyethylene resins, polypropylene resins, polystyrene resins, polyurethane resins, polyvinyl alcohol resins, and ethylene-vinyl acetate copolymer resins. Note that thermoplastic resins may be used individually or in combination of two or more types.

[0027] Furthermore, polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (ULDPE) can be used. One type of polyethylene resin may be used alone, or two or more types may be used in combination.

[0028] Furthermore, low-density polyethylene (density: 0.900~0.930 g / cm³) is used as a polyethylene-based resin because it does not easily impair flexibility when combined with cellulose powder and is easily compatible with elastomers. 3 It is preferable to use ).

[0029] Furthermore, when using low-density polyethylene as the polyethylene resin, cellulose powder The low-density polyethylene content per 100 parts by mass is preferably 15 to 50 parts by mass. This is because if it is less than 15 parts by mass, the resin composition becomes too soft, resulting in poor release properties and reduced moldability. If it is more than 50 parts by mass, the resin composition becomes hard and brittle, also reducing moldability.

[0030] Furthermore, using linear low-density polyethylene (LLDPE) or low-density polyethylene obtained with a metallocene catalyst as the low-density polyethylene improves sliding properties. Therefore, the resin composition of the present invention is particularly suitable for molded products having a screw shape, such as lids for containers that are frequently opened and closed.

[0031] <Olefin-based elastomer> The resin composition of the present invention may contain an olefin-based elastomer. Examples of olefin-based elastomers used in the present invention include copolymers or homopolymers mainly composed of olefins having 3 or more carbon atoms, and copolymers of ethylene and olefins having 3 or more carbon atoms.

[0032] More specifically, examples include propylene-ethylene copolymers and ethylene-propylene-diene terpolymers. Note that olefin elastomers may be used individually or in combination of two or more.

[0033] Furthermore, olefin-based elastomers are generally composed of a hard segment that governs basic physical properties such as mechanical properties, and a soft segment that governs rubber-like properties such as elasticity. Olefin-based elastomers in which the hard segment is made of polypropylene are called propylene-based elastomers, and those in which the hard segment is made of polyethylene are called ethylene-based elastomers. Examples of soft segments of olefin-based elastomers include EPDM, EPM, EBM, IIR, hydrogenated styrene-butadiene rubber (HSBR), NBR, and acrylic rubber (ACM).

[0034] Furthermore, propylene-based elastomers, which are copolymers mainly composed of propylene (for example, the "propylene-ethylene copolymer" mentioned above) or homopolymers of propylene, are preferred because they offer excellent moldability and toughness.

[0035] Furthermore, in the case of propylene-based elastomers, the propylene unit content relative to the total units is preferably 70% to 95% by mass, and more preferably 80% to 90% by mass. If the propylene unit content of the hard segment is 70% by mass or more, the strength is improved, resulting in excellent moldability. If it is 95% by mass or less, the elasticity of the soft segment provides excellent stretchability.

[0036] Furthermore, when using a propylene-based elastomer as an olefin-based elastomer, cellulose powder The preferred content of propylene-based elastomer per 100 parts by mass is 25 to 65 parts by mass. This is because if the content is less than 25 parts by mass, the resin composition becomes hard and brittle, resulting in reduced moldability, and if it is more than 65 parts by mass, the resin composition becomes too soft, resulting in poor release properties and reduced moldability.

[0037] Furthermore, the melt mass flow rate (MFR) of the propylene-based elastomer is preferably 15 to 200 g / 10 min. If the MFR of the propylene-based elastomer is 15 g / 10 min or higher, the resin composition will have excellent moldability and rigidity, and if it is 200 g / 10 min or lower, the resin composition will have excellent moldability and toughness.

[0038] Furthermore, as shown in the examples below, when two types of propylene-based elastomers are used in combination, the MFR of the propylene-based elastomer (i.e., a mixture of the two types of propylene-based elastomers) can be determined by the following formula (1).

[0039] [Mathematics 1] Z=X a ×Y(1-a) (1)

[0040] Here, Z is the MFR of the propylene elastomer (i.e., a mixture of two types of propylene elastomers), X is the MFR of the first type of propylene elastomer, Y is the MFR of the second type of propylene elastomer, a is the content ratio (mass ratio) of the first type of propylene elastomer in the mixture of the two types of propylene elastomers, and (1-a) is the content ratio (mass ratio) of the second type of propylene elastomer in the mixture of the two types of propylene elastomers.

[0041] Furthermore, this equation (1) is a modified version of the empirical formula (logZ = a × logX + (1-a) × logY) used when determining the MFR of a mixture containing multiple types of components. It is commonly used and well known in this industry that the logarithm of the MFR value when multiple types of components are used together is given by the sum of the products of the mass ratios of each component and the logarithms of the MFR values.

[0042] Furthermore, from the viewpoint of improving the moldability of the resin composition, it is preferable that the mass ratio of low-density polyethylene to propylene-based elastomer in the resin composition is such that the mass of low-density polyethylene : the mass of propylene-based elastomer = 1:0.7 to 1:2.8.

[0043] Furthermore, the melting point of the propylene-based elastomer is preferably 50 to 160°C, and more preferably 50 to 80°C. If the melting point of the propylene-based elastomer is 50°C or higher, the toughness of the resin composition is superior, and if it is 160°C or lower, the rigidity of the resin composition is superior.

[0044] Note that "melting point" refers to the melting onset temperature on a differential scanning calorimeter (DSC) chart.

[0045] Furthermore, the flexural modulus of the propylene-based elastomer is preferably 5 to 50 MPa, and more preferably 5 to 10 MPa. If the flexural modulus of the propylene-based elastomer is 5 to 50 MPa, the flexural modulus of the resin composition tends to fall within the preferred range described later.

[0046] <Maleic anhydride-modified polyolefin> The resin composition of the present invention may contain maleic anhydride-modified polyolefin (hereinafter sometimes referred to as "MA-PO"). MA-PO functions as a compatibilizer, and the inclusion of MA-PO in the resin composition facilitates the dispersion of cellulose powder within the resin composition.

[0047] Examples of MA-PO include α-olefin-maleic anhydride copolymers, mixtures of α-olefin polymers and maleic anhydride, and mixtures of α-olefins, α-olefin-maleic anhydride copolymers, and maleic anhydride. Examples of α-olefins include ethylene and propylene.

[0048] Also, cellulose powder The MA-PO content per 100 parts by mass is preferably 4 to 18 parts by mass. This is because if the content is less than 4 parts by mass, the dispersibility of the cellulose powder in the resin composition decreases, resulting in reduced moldability. If the content is more than 18 parts by mass, the MA-PO components aggregate, which, similar to the case where the MA-PO content is less than 4 parts by mass, reduces the dispersibility of the cellulose powder in the resin composition and reduces moldability.

[0049] The melt viscosity of MA-PO is preferably 100 to 15,000 mPa·s, and more preferably 200 to 5,000 mPa·s. If the melt viscosity of MA-PO is 100 mPa·s or higher, the resin composition will have excellent moldability and toughness, and if it is 15,000 mPa·s or lower, the rigidity of the resin composition will be even better.

[0050] "Melting viscosity" refers to the viscosity measured using a capillary rheometer.

[0051] The acid value of MA-PO is preferably 5 to 150 mg KOH / g, and more preferably 30 to 100 mg KOH / g. If the acid value of MA-PO is 5 mg KOH / g or higher, the moldability of the resin composition is excellent, and if it is 150 mg KOH / g or lower, the appearance of the resin composition is even better.

[0052] Note that "acid value" refers to the value measured by neutralization titration.

[0053] <Other ingredients> The resin composition may include the cellulose described above, if necessary. powder The material may further contain other components besides thermoplastic resins, olefin-based elastomers, and maleic anhydride-modified polyolefins. Examples of other components include additives such as stabilizers, antioxidants, lubricants, antistatic agents, and colorants.

[0054] Furthermore, the content of other components relative to the total resin composition is preferably 0% by mass or more and less than 5% by mass, and more preferably 0% by mass or more and less than 2% by mass.

[0055] <Aspect ratio of surface texture (Str)> Here, the aspect ratio (Str) of the surface properties of the resin composition of the present invention is 0.80 or higher. When the aspect ratio (Str) of the surface properties is 0.80 or higher, the surface roughness of the resin composition (molded product) does not depend on the direction, and the isotropy of the surface properties of the resin composition is improved, so that the resin composition flows appropriately during molding. Therefore, it is possible to provide a resin composition that has excellent moldability and can be used with various molding methods, in particular, both injection molding and inflation molding.

[0056] The "aspect ratio (Str) of the surface texture" is determined by the following method (measurement procedures 1-4).

[0057] (Procedure for measuring the aspect ratio (Str) of surface texture) 1. Pellets of the resin composition of the present invention are injection molded at 150-180°C to obtain a sheet-like molded product 1 measuring 100 mm × 100 mm × 3 mm thick, as shown in Figures 1 and 2.

[0058] 2. As shown in Figure 1, six measuring circles 2 with a diameter of 2 cm are arbitrarily set on one surface 1a of the molded product 1, which measures 100 mm x 100 mm, such that the measuring circles 2 do not extend beyond the surface 1a and do not overlap with each other.

[0059] 3. Using a measuring instrument (shape analysis laser microscope (manufactured by Keyence Corporation, product name: VK-X1050) 4) positioned above the molded product 1 as shown in Figure 2, the aspect ratio of the surface texture on surface 1a of the molded product 1 is measured in accordance with the [texture aspect ratio] specified in ISO 25178-2:2012, within a 1 mm square area (measurement range) 3 at the center of the measurement circle 2 as shown in Figures 1 and 2.

[0060] Note that in Figure 1, the 1mm square area (measurement range) 3 at the center of measurement circle 2 is schematically illustrated (and is shown larger than its actual size).

[0061] 4. The aspect ratio of the surface texture is measured six times (i.e., the aspect ratio of the surface texture is measured within a 1 mm square area 3 at the center of each of the six measurement circles 2), and the average value of the surface texture aspect ratios from the six measurements is calculated and taken as the surface texture aspect ratio (Str) of the molded product 1 (i.e., the resin composition of the present invention).

[0062] <Flexural modulus> The flexural modulus of the resin composition is preferably 150 to 1000 MPa, and more preferably 300 to 600 MPa. If the flexural modulus is 150 MPa or higher, the rigidity of the resin composition is better, and if it is 1000 MPa or lower, the toughness of the resin composition is better.

[0063] The "flexural modulus" is measured in accordance with JIS K 7171, under conditions of 23°C, 50% relative humidity, and a test speed of 1 mm / min ± 20%.

[0064] <Tensile yield stress> The tensile yield stress of the resin composition is preferably 4 to 10 MPa, and more preferably 4.9 to 7.2 MPa. If the tensile yield stress is 4 MPa or higher, the moldability and toughness of the resin composition are better, and if it is 10 MPa or lower, the rigidity of the resin composition is better.

[0065] The "tensile yield stress" is measured in accordance with JIS K 7161-1, under conditions of 23°C, 50% relative humidity, and a test speed of 50 mm / min ± 10%.

[0066] <Maximum stretching ratio> The maximum stretch ratio of the resin composition is preferably 200 to 1100%, and more preferably 350 to 1080%. If the maximum stretch ratio of the resin composition is 200% or more, the toughness of the resin composition is better, and if it is 1100% or less, the moldability of the resin composition is better.

[0067] The "maximum stretching ratio" is determined in accordance with the provisions of JIS K 7199 and is determined by the following method.

[0068] 1. A cylinder equipped with a die at the outlet is filled with pellets of a resin composition, and heated to 170°C to melt them.

[0069] 2. The piston is lowered from the cylinder inlet at a constant speed of 10 mm / min, and the molten material is pushed out from the die outlet with a diameter of 1 mm at a speed of 10 mm / min.

[0070] 3. The strand-shaped molten material extruded from the die is passed through a pulley and held between the take-up rolls.

[0071] 4. Start the take-up roll speed at 1 m / min and gradually increase it. During this process, the acceleration of the take-up speed should be 0.1 m / min. 2 Let's assume that.

[0072] 5. Record the take-up speed when the molten material at the die exit breaks.

[0073] 6. Repeat steps 1-5 above a total of three times (N=3), and the minimum recorded pull-up speed will be taken as the maximum pull-up speed. The maximum extension ratio will then be calculated using the following formula (2).

[0074] [Math 2] Maximum stretching ratio = Maximum take-up speed (mm / min) / Extrusion speed (mm / min) (2)

[0075] For example, if the maximum pickup speed is 2 m / min (2 × 10 3 For mm / min, the maximum stretching ratio = 2 × 10 3 / 10 = 200.

[0076] <Method for manufacturing molded products> Next, an example of a method for manufacturing a molded article using the resin composition of the present invention will be described.

[0077] First, cellulose powder and MA-PO are mixed in a predetermined ratio. Then, the resulting mixture is mixed with a thermoplastic resin and an olefin-based elastomer in a predetermined ratio. The mixture is then melt-kneaded in a twin-screw extruder equipped with a strand die and extruded into strands. The extruded mixture is then cut to obtain pellets of the resin composition.

[0078] Regarding mixing methods, dry mixing using a super mixer, Henschel mixer, etc., is one option.

[0079] Then, by molding these pellets, a molded article using the resin composition of the present invention is manufactured.

[0080] For example, when injection molding is used as the molding method, molded articles using the resin composition of the present invention (e.g., containers for cream-type cosmetics, cups, plates, forks, spoons, and other tableware) are manufactured by injection molding pellets of the resin composition at a predetermined temperature.

[0081] Furthermore, for example, when using inflation molding as the molding method, the resin composition pellets are melt-extruded at a predetermined temperature in a twin-screw extruder equipped with a circular die to form a film, and the film is wound up on a winding roll to produce a molded product using the resin composition of the present invention (for example, an outer bag for packaging hygiene products such as diapers, a shopping bag, etc.).

[0082] Furthermore, for example, when blow molding is used as the molding method, a cylindrical parison is formed by melting and extruding a pellet of the resin composition at a predetermined temperature in an extruder. After sandwiching the parison in a blow molding die, air is blown in to form a hollow body, thereby producing a molded product using the resin composition of the present invention (for example, a container for pharmaceuticals or cosmetics that holds liquids or highly fluid substances).

[0083] Furthermore, in the resin composition of the present invention, since the cellulose powder content relative to the total resin composition exceeds 50% by mass, the environmental impact can be reduced, and the molded article can be treated as "paper" under the Container Recycling Law. In addition, in the resin composition of the present invention, the aspect ratio (Str) of the surface properties determined by the measurement procedures 1 to 4 described above is 0.80 or higher, resulting in excellent moldability, and as shown in the examples described later, it can be used for various molding methods, particularly injection molding and inflation molding. [Examples]

[0084] The present invention will be described below based on examples. However, the present invention is not limited to these examples, and these examples can be modified and altered in accordance with the spirit of the invention; such modifications do not exclude them from the scope of the present invention.

[0085] The materials used in this embodiment are shown below. (1) LDPE (Low-density polyethylene, density: 0.921 g / cm³) 3 MFR: 5g / 10min, manufactured by Sumitomo Chemical Co., Ltd., product name: Sumikasen, F412-1) (2) Propylene-based elastomer 1 (propylene-ethylene copolymer, ethylene unit content: 16% by mass, MFR: 3g / 10min, melting point: 55℃, manufactured by ExxonMobil, trade name: Vistamaxx(registered trademark) 6102FL) (3) Propylene-based elastomer 2 (propylene-ethylene copolymer, ethylene unit content: 6% by mass, MFR: 10,000 g / 10 min, melting point: 97°C, manufactured by ExxonMobil, trade name: Vistamaxx(registered trademark) 8880) (4) MA-PO (Olefin wax, α-olefin-maleic anhydride copolymer: 66.8% by mass, α-olefin polymer: 32.9% by mass, maleic anhydride: 0.3% by mass, melting point: 70-76℃, melt viscosity: 140-210 mPa·s, acid value: 95-110 mgKOH / g, manufactured by Mitsubishi Chemical Corporation, product name: DiaCarna 30M) (5) Cellulose powder 1 (Average particle size: 10 μm, manufactured by Rettenmeyer Japan Co., Ltd., product name: ARBOCEL UFC100) (6) Cellulose powder 2 (Average particle size: 28 μm, manufactured by Nippon Paper Industries Co., Ltd., product name: KC Floc W-300F)

[0086] Note that each cellulose powder The average particle size was measured using a laser diffraction particle size distribution analyzer (Malvern dry particle size distribution analyzer, product name: MASTER SIZER 3000).

[0087] (Examples 1-2, Comparative Examples 1-5) <Preparation of resin composition> The resin composition was prepared according to the formulation shown in Table 1 using the following procedure.

[0088] First, cellulose powder and MA-PO were mixed in a super mixer to obtain a mixture. Next, the obtained mixture and the remaining raw materials (LDPE, propylene-based elastomer) were melt-kneaded in a co-direction twin-screw extruder under conditions of a molding temperature of 150-210°C and a screw rotation speed of 40-120 rpm, extruded into strands with a diameter of 2-4 mm, and the extruded kneaded material was cut to obtain resin composition pellets.

[0089] <Moldability Evaluation> The moldability (injection molding, inflation molding) of the prepared resin composition pellets was evaluated.

[0090] More specifically, for injection molding, resin composition pellets were injection molded at 150-180°C to obtain sheet-like molded products measuring 100mm x 100mm x 3mm thick. These molded products were rated as follows: ○ (mold successfully) if they were molded without problems, △ (molded successfully, but with problems) if the shape of the ejector pins was clearly visible, and × (unmold) if the shape was distorted upon removal from the mold, or if it cracked due to brittleness. The results are shown in Table 1.

[0091] Furthermore, for inflation molding, resin composition pellets were melted and kneaded in a twin-screw extruder equipped with a circular die at a molding temperature of 150-210°C, guided into the circular die to form a film, cooled and solidified by air cooling, and wound onto a winding roll to obtain a film-like molded product. The film thickness was set to 0.2 mm ± 0.05 mm. For the molded products, those that were molded without problems were marked with ○ (moldable), and those that did not stretch, did not reach the specified thickness, had holes during the process, or were brittle were marked with × (molded unsuitable). The results are shown in Table 1.

[0092] <Measurement of surface texture aspect ratio (Str)> A resin composition pellet was injection molded at 150-180°C to obtain a sheet-like molded product measuring 100mm x 100mm x 3mm thick. Six measurement circles with a diameter of 2cm were arbitrarily placed on one 100mm x 100mm surface of the molded product, ensuring that the measurement circles did not extend beyond the surface and did not overlap. Next, the aspect ratio of the surface texture on the surface of the molded product was measured within a 1mm square area at the center of each measurement circle, according to the [texture aspect ratio] specified in ISO 25178-2:2012. This surface texture aspect ratio measurement was performed six times, and the average value of the six surface texture aspect ratios was calculated and defined as the surface texture aspect ratio (Str) of the molded product. The results are shown in Table 1. In Comparative Examples 1-4, where the injection molding evaluation was negative, measurement points were extracted from smooth areas of the surface, avoiding areas where the shape was distorted.

[0093] Furthermore, the standard deviation σ was calculated using the aspect ratio (Str) of the six measured surface textures. More specifically, the six measured surface roughnesses were designated Str1, Str2, Str3, Str4, Str5, and Str6, and the standard deviation was calculated using the following formula (3). The results are shown in Table 1.

[0094]

number

[0095] <Measurement of flexural modulus> Pellets of the resin composition were injection molded at a temperature of 150-180°C to obtain a 3mm thick sheet, which was then cut into test specimens measuring 25±0.5mm in width and 60±3mm in length. The flexural modulus of the obtained test specimens was then determined in accordance with JIS K 7171, under conditions of 23°C, 50% relative humidity, and a test speed of 1mm / min±20%. The results are shown in Table 1.

[0096] <Measurement of tensile yield stress> Pellets of the resin composition were injection molded at a temperature of 150-180°C to obtain a 3 mm thick sheet, and then 1B type test specimens were cut out in accordance with JIS K 7161-2. The tensile yield stress of the obtained test specimens was then determined in accordance with JIS K 7161-1 under conditions of 23°C, 50% relative humidity, and a test speed of 50 mm / min ± 10%. The results are shown in Table 1.

[0097] <Measurement of maximum stretch ratio> For the resin composition pellets, the maximum stretch ratio was determined using a capillary rheometer manufactured by Toyo Seiki Seisakusho Co., Ltd., in accordance with JIS K 7199, following the procedure below.

[0098] 1. A cylinder equipped with a die at the outlet was filled with pellets of a resin composition and heated to 170°C to melt them.

[0099] 2. The piston was lowered from the cylinder inlet at a constant speed of 10 mm / min, and the molten material was pushed out from the die outlet with a diameter of 1 mm at a speed of 10 mm / min.

[0100] 3. The strand-shaped molten material extruded from the die was passed through a pulley and then sandwiched between take-up rolls.

[0101] 4. The speed of the take-up roll was started at 1 m / min and gradually increased. During this process, the acceleration of the take-up speed was 0.1 m / min. 2 That's what I decided.

[0102] 5. The take-up speed at the time the molten material at the die exit fractured was recorded.

[0103] 6. The above steps 1-5 were repeated a total of three times (N=3), and the minimum recorded pull-up speed was taken as the maximum pull-up speed. The maximum stretching ratio was then calculated using formula (2) above. The results are shown in Table 1. Cases where the pull-up speed could not be measured were marked as "unmeasurable".

[0104] <Measurement of nominal strain at tensile fracture> Pellets of the resin composition were injection molded at a temperature of 150-180°C to obtain a 3 mm thick sheet, and then 1B type test specimens were cut out in accordance with JIS K 7161-2. The nominal strain at tensile fracture of the obtained test specimens was then determined in accordance with JIS K 7161-1, under conditions of 23°C, 50% relative humidity, and a test speed of 50 mm / min ± 10%. The results are shown in Table 1.

[0105] <Measurement of bending stress> Pellets of the resin composition were injection molded at a temperature of 150-180°C to obtain a 3mm thick sheet, which was then cut into test specimens measuring 25±0.5mm in width and 60±3mm in length. The bending stress of the obtained test specimens was then determined in accordance with JIS K 7171, under conditions of 23°C, 50% relative humidity, and a test speed of 1mm / min±20%. The results are shown in Table 1.

[0106] [Table 1]

[0107] As shown in Table 1, the resin compositions of Examples 1 and 2 have a surface aspect ratio (Str) of 0.80 or higher. Therefore, even when the cellulose powder content in the resin composition exceeds 50% by mass, it can be used for both injection molding and inflation molding, demonstrating excellent moldability.

[0108] On the other hand, as shown in Table 1, in the resin compositions of Comparative Examples 1 to 5, the aspect ratio (Str) of the surface properties is less than 0.80, so the surface roughness of the resin composition (molded product) is direction-dependent, and the isotropy of the surface properties of the resin composition decreases (i.e., anisotropy improves), so the fluidity of the resin composition decreases during molding, resulting in cellulose formation. powder It appears that the material aggregates, resulting in poor moldability.

[0109] In comparative examples 2 and 4, the strands were brittle and broke when placed on the pulley, making it impossible to measure the maximum stretch ratio.

[0110] Furthermore, in Comparative Example 5, cellulose powder Because the average particle size is larger than 10 μm (it is 28 μm), the cellulose is extruded in the same direction (extrusion direction). powder As the particles become more easily aligned, the surface roughness of the resin composition (molded product) becomes direction-dependent, and the isotropy of the surface properties of the resin composition decreases. Therefore, when molded thinly like a film, the surface becomes rough, which can cause holes, and thus it is clear that the moldability is particularly poor in inflation molding. [Industrial applicability]

[0111] As described above, the present invention is suitable for resin compositions containing cellulose powder and molded articles thereof. [Explanation of Symbols]

[0112] 1 Molded product 1a One side of the molded product 2. Measurement circle 3. Measurement circle centered within a 1mm square area 4 Measuring instrument

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