JP7661006B2 - Polypropylene resin composition - Google Patents

Description

The present invention relates to a polypropylene resin composition containing a biomass material, and to an extruded foam, an injected foam, a sheet, a thermoformed product, and a blow molded product made from the polypropylene resin composition.

Polypropylene is used in all industrial sectors because it has excellent physical properties including heat resistance and can be produced inexpensively. In recent years, there has been a demand for reducing CO2 emissions from the perspective of global warming and environmental protection, and as a countermeasure, the use of biomass materials that can adsorb and fix CO2 in the atmosphere has been proposed in many fields. For example, a composition has been proposed in which polypropylene is composited with biomass materials such as wood flour (Patent Document 1). Polypropylene resin compositions in which polypropylene is composited with wood flour are semi-plastic, giving the feeling of warmth of wood that cannot be expressed with plastic, and are able to retain the properties of wood such as scent and color, and are therefore being used for a wide range of applications, such as artificial wood.

When biomass materials are compounded with polypropylene and the compounded polypropylene resin composition is molded into various molded products, a processing temperature of, for example, about 180 to 200°C is required. However, at such high temperatures, the biomass materials give off a strong odor, which has a significant adverse effect on workers. If the processing temperature is lowered to suppress the generation of odor, problems arise in that processing becomes difficult in the first place and the appearance quality of the resulting molded product deteriorates.

To solve these problems during molding, a propylene-based resin composition has been proposed that consists of 10 to 90 parts by weight of a propylene-based resin with a melting point of 110 to 150°C and 90 to 10 parts by weight of a lignocellulosic or cellulose-based material (Patent Document 2). The propylene-based resin composition of Patent Document 2 not only allows the molding temperature to be lowered and suppresses odor generation, but also shows that odor can be improved even at high molding temperatures.

Japanese Patent Application Publication No. 6-80832 JP 2007-169612 A

The propylene resin composition of Patent Document 2 has an improved odor, but has a problem in that the color tone and other aspects give it a strong plastic feel. The present invention therefore aims to provide a polypropylene resin composition that has an improved odor and a reduced plastic feel.

The polypropylene resin composition of the present invention comprises 5 to 85 mass% of a polypropylene resin (A) having a melting point of 150°C or higher, 5 to 85 mass% of a polypropylene resin (B) having a melting point of 110°C or higher and 140 °C or lower, and 10 to 80 mass% of a biomass material (C) (wherein the total mass of (A), (B) and (C) is 100 mass%), wherein the polypropylene resin (B) is one or more polypropylene resins selected from the group consisting of a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-ethylene-1-butene random copolymer, a propylene-ethylene random block copolymer and a propylene-ethylene-1-butene random block copolymer, and the biomass material (C) is one or more selected from the group consisting of a cellulosic material and a lignocellulosic material .

The polypropylene resin (A) may be one or more polypropylene resins selected from the group consisting of propylene homopolymer, propylene-ethylene block copolymer, and propylene-ethylene-1-butene block copolymer.

Furthermore, the polypropylene resin (B) may have the following properties (b-1) and/or (b-2).
(b-1) The Q value is 5.0 or less. (b-2) The soluble matter at 40°C or less measured by temperature rising elution fractionation (TREF) is 4.0% by mass or less.

The biomass material (C) may be one or more plant-derived fillers selected from the group consisting of wood, pulp, bamboo , bagasse, and rice husks .

A polypropylene resin composition is also preferred that contains 1 to 50 parts by mass of a thermoplastic elastomer (D) per 100 parts by mass of the above-mentioned polypropylene resin (A), polypropylene resin (B), and biomass material (C), which together make up 100% by mass.

Furthermore, it is preferable that the extrusion foam molding, injection foam molding, sheet molding, thermoformed body, or blow molded body is made of the polypropylene resin composition described above.

The polypropylene resin composition of the present invention has excellent environmental protection performance and can reduce odor and plastic feel.

Polypropylene resin (A)
The polypropylene resin (A) has a melting point of 150° C. or higher, preferably 153° C. or higher, and more preferably 155° C. or higher. The melting point of the polypropylene resin (A) is preferably 170° C. or lower. By making the melting point of the polypropylene resin (A) 150° C. or higher, the rigidity and heat resistance are increased. The melting point can be adjusted by the amount of comonomer such as ethylene or butene introduced during propylene polymerization.

In this specification, the melting point is a value measured by a differential scanning calorimeter (DSC). Using a Seiko differential scanning calorimeter, about 5 mg of a sample is taken, held at 200°C for 5 minutes, cooled to 40°C at a temperature drop rate of 10°C/min, and then melted at a temperature increase rate of 10°C/min. The melting point is obtained from the heat of fusion curve obtained when the sample is heated at a rate of 10°C/min. In other words, the maximum peak temperature of the heat of fusion curve is regarded as the melting point.

The polypropylene resin (A) preferably has a melt flow rate (MFR) measured at 230°C under a load of 2.16 kg of 0.1 to 150 g/10 min, more preferably 1 to 100 g/10 min. Here, the MFR is a value measured at 230°C under a load of 2.16 kg in accordance with JIS K7210. The MFR of the polypropylene resin (A) can be adjusted by controlling the hydrogen concentration during polymerization, etc. If the MFR is 0.1 g/10 min or more, the load on the extruder is reduced when extruding a sheet, improving productivity, and is therefore preferable.

The relationship between the melt flow rate (MFR) and the melt tension (MT) (unit: g) of the polypropylene resin (A) preferably satisfies log(MT)<-0.9 x log(MFR)+0.7 and log(MT)<1.15, more preferably log(MT)<-0.9 x log(MFR)+0.6 and log(MT)<1.04 (MT<11), and even more preferably log(MT)<-0.9 x log(MFR)+0.5 and log(MT)<0.85 (MT<7).

There is no lower limit for the melt tension of polypropylene resin (A), but if it is too small, the drawdown resistance decreases and the moldable temperature range during thermoforming may become narrow, so log(MT)>0.48 (MT>3) is preferable.

Here, melt tension (MT) is a value measured using a capillograph. Resin is placed in a 9.6 mm diameter cylinder heated to a temperature of 230°C, and the molten resin is extruded from an orifice 2.0 mm in diameter and 40 mm in length at a pushing speed of 20 mm/min. The tension detected by the pulley when the extruded resin is taken up at a speed of 4.0 m/min is measured, and this is taken as the melt tension (MT).

The polypropylene resin (A) preferably has a Q value (Mw/Mn) calculated from the weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of 3.5 to 10, more preferably 3.7 to 8, and even more preferably 4 to 6. When the Q value of the polypropylene resin (A) is in the above range, the polypropylene resin has particularly excellent moldability when extruding a sheet, and is therefore preferred.

The polypropylene resin (A) preferably does not have a long chain branching structure. The branching index g' of the polypropylene resin (A) is preferably 1 when the absolute molecular weight Mabs is 1,000,000 as determined by a light scattering meter.

The branching index g' can be used as a direct indicator of whether or not a polypropylene resin has a long chain branching structure. The branching index g' is given by the ratio of the intrinsic viscosity [η]br of a polymer having a long chain branching structure to the intrinsic viscosity [η]lin of a linear polymer having the same molecular weight, i.e., [η]br/[η]lin, and if g'<1, it can be said to have a long chain branching structure.

The definition of the branching index g' is described, for example, in "Developments in Polymer Characterization-4" (J.V. Dawkins ed. Applied Science Publishers, 1983), and is an index known to those skilled in the art.

The branching index g' can be obtained as a function of the absolute molecular weight Mabs, for example, by using a light scattering meter and GPC equipped with a viscometer as a detector, as described below.

The branching index g' is calculated as follows.
Alliance GPCV2000 manufactured by Waters is used as a GPC device equipped with a differential refractometer (RI) and a viscosity detector (Viscometer). In addition, a multi-angle laser light scattering detector (MALLS) DAWN-E manufactured by Wyatt Technology is used as a light scattering detector. The detectors are connected in the order of MALLS, RI, and Viscometer. The mobile phase solvent is 1,2,4-trichlorobenzene (with antioxidant Irganox 1076 manufactured by BASF Japan added at a concentration of 0.5 mg/mL).

The flow rate of the mobile phase solvent is 1 mL/min, and two Tosoh GMHHR-H(S) HT columns are used in combination. The temperature of the column, sample injection section, and each detector is 140°C. The sample concentration is 1 mg/mL, and the injection volume (sample loop volume) is 0.2175 mL.

The absolute molecular weight (Mabs), the root mean square radius of gyration (Rg) and the intrinsic viscosity ([η]) are calculated using the data processing software ASTRA (version 4.73.04) attached to MALLS, with reference to the following literature:
References 1. Developments in Polymer Characterization-4 (J.V. Dawkins ed. Applied Science Publishers, 1983. Chapter 1.)
References 2. Polymer, 45, 6495-6505 (2004)
Reference 3. Macromolecules, 33, 2424-2436 (2000)
Reference 4. Macromolecules, 33, 6945-6952 (2000)

The branching index g' is calculated as the ratio ([η]br/[η]lin) of the intrinsic viscosity ([η]br) obtained by measuring a sample with a viscometer to the intrinsic viscosity ([η]lin) obtained by separately measuring a linear polymer.

Here, a commercially available homopolypropylene (Novatec (registered trademark) PP grade name: FY6, manufactured by Japan Polypropylene Corporation) is used as the linear polymer to obtain [η]lin. It is known that the logarithm of [η]lin of a linear polymer has a linear relationship with the logarithm of the molecular weight, as known by the Mark-Houwink-Sakurada equation, so the value of [η]lin can be obtained by appropriately extrapolating to the low molecular weight side or the high molecular weight side.

Polypropylene resin (A) is a propylene homopolymer obtained by homopolymerizing propylene in a single stage or two or more multistage polymerization, a propylene-α-olefin random copolymer obtained by copolymerizing propylene and an α-olefin in a single stage or two or more multistage polymerization, a polymerization step (1) in which propylene is homopolymerized in a single stage or two or more multistage polymerization to obtain a propylene homopolymer, a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more multistage polymerization to obtain a propylene-α-olefin random copolymer, or a copolymerization step (2-2) in which two or more α-olefins are copolymerized in a single stage or two or more multistage polymerization to obtain an α-olefin random copolymer. Examples of the propylene-α-olefin random block copolymer include a propylene-α-olefin block copolymer obtained by polymerization including a copolymerization step (2-2) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, or a copolymerization step (2-2) in which two or more α-olefins are copolymerized in a single stage or two or more stages to obtain an α-olefin random copolymer. The polypropylene resin (A) may be one type or a combination of two or more types.

The α-olefin is preferably ethylene or an α-olefin having 4 to 18 carbon atoms. Specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, and 4,4-dimethylpentene-1. The α-olefin may be one type or a combination of two or more types.

The polypropylene resin (A) is preferably one or more polypropylene resins selected from the group consisting of propylene homopolymers, propylene-ethylene block copolymers, and propylene-ethylene-1-butene block copolymers.

Examples of the polypropylene resin (A) include those polymerized by a Ziegler-Natta catalyst, those polymerized by a metallocene catalyst, and those polymerized by a post-metallocene catalyst. Examples of the Ziegler-Natta catalyst include a catalyst containing a solid component essentially containing titanium, magnesium, and a halogen, an organoaluminum, and an electron donor used as needed. Examples of the metallocene catalyst include a catalyst containing a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, and an organometallic compound and a carrier used as needed. Examples of the post-metallocene catalyst include a catalyst containing an organometallic compound such as a bisamide compound of a metal of Group 4 of the periodic table, a bisimino compound of a metal of Groups 8 to 10 of the periodic table, and a salicylaldiminato compound of a metal of Groups 4 to 10 of the periodic table, a cocatalyst, and an organometallic compound and a carrier used as needed.
As the polypropylene resin (A), commercially available products can be used, for example, the Novatec PP series manufactured by Japan Polypropylene Corporation.

Polypropylene resin (B)
The polypropylene resin (B) has a melting point of 110 to less than 150°C, preferably 115 to 145°C, and more preferably 120 to 140°C. By making the melting point of the polypropylene resin (B) 110°C or higher, it is possible to reduce stickiness caused by low crystallinity components. In addition, by making the melting point of the polypropylene resin (B) less than 150°C, the temperature when molding the polypropylene resin composition can be relatively low, the generation of odor can be suppressed, and moldability and product quality can be ensured. The melting point can be adjusted by the amount of comonomers such as ethylene and butene introduced during propylene polymerization, as with the polypropylene resin (A). Here, the melting point is a value measured by the same method as that for measuring the melting point of the polypropylene resin (A).

The polypropylene resin (B) preferably has a melt flow rate (MFR) measured at 230°C under a load of 2.16 kg of 0.1 to 150 g/10 min, more preferably 1 to 100 g/10 min. If the MFR is 0.1 g/10 min or more, the load on the extruder is reduced during extrusion molding of the sheet, improving productivity. Here, the MFR is a value measured at 230°C under a load of 2.16 kg in accordance with JIS K7210. The MFR of the polypropylene resin (B) can be adjusted by controlling the hydrogen concentration during polymerization, etc.

The MFR of polypropylene resin (B) preferably satisfies the following relationship. That is, when the melt flow rate of polypropylene resin (A) is MFRa and the melt flow rate of polypropylene resin (B) is MFRb, MFRa/MFRb preferably satisfies 30>MFRa/MFRb>1, and more preferably satisfies 15>MFRa/MFRb>1.5. When MFRa/MFRb is within the above value range, a molded product with smaller wall thickness deviation can be obtained.

The relationship between the melt flow rate (MFR) and the melt tension (MT) (unit: g) of the polypropylene resin (B) preferably satisfies log(MT)<-0.9 x log(MFR)+0.7 and log(MT)<1.15, more preferably log(MT)<-0.9 x log(MFR)+0.6 and log(MT)<1.04 (MT<11), and even more preferably log(MT)<-0.9 x log(MFR)+0.5 and log(MT)<0.85 (MT<7).

There is no lower limit for the melt tension of polypropylene resin (B), but if it is too small, the drawdown resistance decreases and the moldable temperature range during thermoforming may become narrow, so it is preferably log(MT)>0.48 (MT>3). Here, the melt tension (MT) is a value measured using the same method as for measuring the melt tension of polypropylene resin (A).

(b-1) Q value The polypropylene resin (B) preferably has a Q value of 5.0 or less, more preferably 2.0 to 4.0, even more preferably 2.3 to 3.5, and even more preferably 2.6 to 3.3. Here, the Q value is defined as the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC. By making the Q value of the polypropylene resin (B) 5.0 or less, a molded product having excellent mechanical properties can be obtained, which is preferable.

(b-2) Amount of soluble matter at 40 ° C. or less measured by temperature rising elution fractionation (TREF) method The amount of components soluble in orthodichlorobenzene at 40 ° C. or less measured by temperature rising elution fractionation (TREF) method in polypropylene resin (B) is preferably 4.0 mass% or less, more preferably 3.0 mass% or less, and even more preferably 1.5 mass% or less. By making the amount of soluble matter at 40 ° C. or less measured by temperature rising elution fractionation (TREF) method 4.0 mass% or less, affinity with biomass material (C) is improved and bleeding from the molded article is suppressed, which is preferable.

Components soluble in orthodichlorobenzene at 40°C include so-called low crystallinity components, such as low molecular weight components such as oligomers, components with low stereoregularity such as atactic polypropylene, and components with extremely high comonomer content. Here, components with low stereoregularity such as atactic polypropylene and low crystallinity components with extremely high comonomer content can be soluble even if they have a high molecular weight. Therefore, in order to obtain the polypropylene resin (B) preferably used in the present invention, it is necessary to avoid using catalysts or polymerization methods that can produce polypropylene with a wide composition distribution that contains polypropylene with low stereoregularity or low crystallinity components with extremely high comonomer content.

Here, the amount of components soluble in orthodichlorobenzene at 40° C. or less as measured by temperature rising elution fractionation (TREF) is a value measured according to the following procedure.
A sample is dissolved in orthodichlorobenzene at 140° C. to obtain a solution. This is introduced into a TREF column at 140° C. under the following conditions, and then cooled to 100° C. at a temperature drop rate of 8° C./min, and then cooled to 40° C. at a temperature drop rate of 4° C./min, and then held for 10 minutes. Thereafter, orthodichlorobenzene, which is a solvent, is passed through the column at a flow rate of 1 mL/min to elute the components dissolved in orthodichlorobenzene at 40° C. in the TREF column for 10 minutes, and then the column is linearly heated to 140° C. at a temperature increase rate of 100° C./hour to obtain an elution curve.
Column size: 4.3 mmφ×150 mm
Column packing material: 100 μm surface deactivated glass beads Solvent: orthodichlorobenzene Sample concentration: 5 mg/mL
Sample injection volume: 0.2 mL
Solvent flow rate: 1 mL/min Detector: Fixed wavelength infrared detector FOXBORO MIRAN 1A
Measurement wavelength: 3.42μm
From the elution curve obtained under the above conditions, the ratio (mass %) of the amount of the component eluted at 40° C. to the total amount of the sample is calculated.

Polypropylene resin (B) is a propylene homopolymer obtained by homopolymerizing propylene in a single stage or two or more multistage polymerization, a propylene-α-olefin random copolymer obtained by copolymerizing propylene and an α-olefin in a single stage or two or more multistage polymerization, a polymerization step (1) in which propylene is homopolymerized in a single stage or two or more multistage polymerization to obtain a propylene homopolymer, a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more multistage polymerization to obtain a propylene-α-olefin random copolymer, or a copolymerization step (2-2) in which two or more α-olefins are copolymerized in a single stage or two or more multistage polymerization to obtain an α-olefin random copolymer. Examples of the propylene-α-olefin random block copolymer include a propylene-α-olefin block copolymer obtained by polymerization including a copolymerization step (2-2) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, or a copolymerization step (2-2) in which two or more α-olefins are copolymerized in a single stage or two or more stages to obtain an α-olefin random copolymer. The polypropylene resin (B) may be one type or a combination of two or more types.

The α-olefin is preferably ethylene or an α-olefin having 4 to 18 carbon atoms. Specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, and 4,4-dimethylpentene-1. The α-olefin may be one type or a combination of two or more types.

The polypropylene resin (B) is preferably one or more polypropylene resins selected from the group consisting of propylene-ethylene random copolymers, propylene-1-butene random copolymers, propylene-ethylene-1-butene random copolymers, propylene-ethylene random block copolymers, and propylene-ethylene-1-butene random block copolymers.

The polypropylene resin (B) contains 85 to 100 mol %, preferably 90 to 99.5 mol %, and more preferably 92 to 98.5 mol % of propylene units, and 0 to 15 mol %, preferably 0.5 to 10 mol %, and more preferably 1.5 to 8 mol % of ethylene units and/or 1-butene units.
The amounts of propylene units and ethylene and/or 1-butene units are values measured by Fourier transform infrared analysis.

Examples of the polypropylene resin (B) include those polymerized by a Ziegler-Natta catalyst, those polymerized by a metallocene catalyst, and those polymerized by a post-metallocene catalyst. Examples of the Ziegler-Natta catalyst include a catalyst containing a solid component essentially containing titanium, magnesium, and a halogen, an organoaluminum, and an electron donor used as needed. Examples of the metallocene catalyst include a catalyst containing a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, and an organometallic compound and a carrier used as needed. Examples of the post-metallocene catalyst include a catalyst containing an organometallic compound such as a bisamide compound of a metal of Group 4 of the periodic table, a bisimino compound of a metal of Groups 8 to 10 of the periodic table, and a salicylaldiminato compound of a metal of Groups 4 to 10 of the periodic table, a cocatalyst, and an organometallic compound and a carrier used as needed.
As the polypropylene resin (B), commercially available products can be used, for example, the WINTEC series manufactured by Japan Polypropylene Corporation.

Biomass material (C)
The biomass material (C) is an organic resource derived from animals and plants, excluding fossil resources, and is preferably an organic resource derived from plants, excluding fossil resources. Examples of the organic resource derived from plants, excluding fossil resources, include cellulosic materials, lignocellulosic materials, and starch materials.

Examples of cellulosic materials include alpha fiber flocks made by mechanically shredding wood pulp after alkali treatment, cotton linters and cotton flocks obtained from cottonseeds, and rayon flocks made by shredding rayon. Examples of lignocellulosic materials include lignocellulosic fibers and lignocellulosic powders. Specific examples include wood pulp, refiner graft pulp (RGP), paper pulp, waste paper, crushed wood chips, wood flour, and fruit shell powder. There are no particular limitations on the shape of these cellulosic and lignocellulosic materials, and fibrous or powdered materials can be used. Specific examples of wood flour include crushed pine, fir, poplar, bamboo, bagasse, and oil palm trunks, as well as sawdust and canna dust, and fruit shell powder includes crushed fruits such as walnuts, peanuts, and coconuts.

The cellulosic or lignocellulosic material may be an esterified cellulosic or lignocellulosic material in which a polybasic acid anhydride is added to the hydroxyl groups of the cellulosic or lignocellulosic material, an oligoesterified cellulosic or lignocellulosic material in which a polybasic acid anhydride and a monoepoxy compound are added to the hydroxyl groups of the cellulosic or lignocellulosic material, or an oligoesterified cellulosic or lignocellulosic material in which a polybasic acid anhydride and a polyhydric alcohol are added to the hydroxyl groups of the cellulosic or lignocellulosic material.

Examples of polybasic acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dichloromaleic anhydride, itaconic anhydride, tetrabromophthalic anhydride, HET anhydride, trimellitic anhydride, pyromellitic anhydride, etc., but maleic anhydride, succinic anhydride, and phthalic anhydride are particularly preferred because they are industrially advantageous and inexpensive.

The monoepoxy compound may be any compound containing one epoxy group in the molecule, such as phenyl glycidyl ether, allyl glycidyl ether, styrene oxide, octylene oxide, methyl glycidyl ether, butyl glycidyl ether, cresyl glycidyl ether, etc.

Examples of polyhydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, pinacol, hydrobenzoin, benzpinacol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, glycerin, polyethylene glycol 400, etc.

A typical method for carrying out the esterification involves mixing the polybasic acid anhydride (or the polybasic acid anhydride and the monoepoxy compound, or the polybasic acid anhydride and the polyhydric alcohol) in the presence of a cellulosic or lignocellulosic material and reacting at a temperature of 60 to 150°C for 0.5 to 8 hours.

In the case of a reaction in which the polybasic acid anhydride and the monoepoxy compound are alternately added and esterified to hydroxyl groups in a cellulosic or lignocellulosic material component, the reaction proceeds sufficiently without a catalyst, but a basic catalyst such as sodium carbonate, dimethylbenzylamine, tetramethylammonium chloride, or pyridine may be used to promote the reaction. An addition esterification catalyst may also be used.

From the standpoint of ease of use and effectiveness, the molecular weight of the oligomer of the polybasic acid anhydride and the monoepoxy compound is preferably about 20 to 1000 (with a degree of polymerization of preferably 5 or less, including 1), which allows the oligomer to be liquid.

The amounts of the polybasic acid anhydride and the monoepoxy compound are as follows: First, the polybasic acid anhydride is used in an amount of 5 to 120 parts by mass, preferably 10 to 100 parts by mass, per 100 parts by mass of dried cellulosic or lignocellulosic material. The monoepoxy compound is preferably used in an amount of 0.5 to 2.0 equivalents of epoxy groups per equivalent of anhydride acid group of the polybasic acid anhydride used. This is because if more than 120 parts by mass of the polybasic acid anhydride is used per 100 parts by mass of dried cellulosic or lignocellulosic material, the content of the lignocellulosic or cellulose-based substance component will be low, which is undesirable as it will cause bleeding during hot-press molding, and if the amount is less than 5 parts by mass, the hot-press fluidity will be low, and furthermore, a uniform molded product will not be obtained, which is undesirable.

In the case of a reaction in which the polybasic acid anhydride and the polyhydric alcohol are alternately added and esterified to the hydroxyl groups of a cellulosic or lignocellulosic material, the monoepoxy compound may be replaced with the polyhydric alcohol.

Specific examples of starch-based materials that can be used include rice, wheat, corn, sugar cane, potato, sweet potato, tapioca, corn starch, potato starch, potato starch, tapioca starch, and lightly acetylated products thereof. Any agricultural product that contains starch can be used without being limited to these. Furthermore, these starch-based materials can be used in the general state in which they are stored, or after simple pretreatment such as washing, removing parts that do not contain starch such as the husk, and cutting into appropriate sizes. Starch-based materials are usually obtained in granular form, and can be used as is.

Furthermore, it is even more preferable that the starch-based material used as the raw material is subjected to such a simple pretreatment and then to a gelatinization treatment as described below. In other words, the starch that constitutes the starch-based material initially has a crystalline structure (β structure), but when placed in a temperature environment of 70°C or higher in the presence of an appropriate amount of moisture, this β structure collapses and changes to an amorphous structure (α structure). In this way, the change from β structure to α structure caused by raw starch containing moisture and being heated is called gelatinization. The starch granules that exhibit the α structure of this gelatinized system material are dissolved at the molecular level of the starch in the thermally flowing polypropylene resin and become in a state that is easier to disperse finely and uniformly, compared to when they were in the β structure in the initial heated state (raw state).

Specific examples of processes for converting starch with a β structure to an α structure include heat treatments that are generally used when preparing starch for consumption, such as soaking it in water and boiling it or steaming it with water vapor.

It is generally known that when starch in an amorphous α-structure is left at low temperatures while still containing moisture, it undergoes a phenomenon known as retrogradation, in which it reverts to its original β-structure crystalline state over time. On the other hand, it is known that if moisture is removed from starch in an amorphous α-structure, the starch maintains its α-structure and does not reversibly transition to a β-structure (does not retrogradate), even if it is then left at low temperatures for a long period of time.

The starch-based material used as the raw material in the present invention is one in which the starch structure is an α-structure (amorphous structure), and includes both a moist and dehydrated (dehydrated) state. In any case, if the starch structure of the starch-based material blended with the polypropylene resin is an α-structure (amorphous structure), the molecular chains of the starch are loosened in the polypropylene resin matrix during the kneading process described below, making it easier to disperse in finer particles. This is an effect that cannot be obtained when blending an unheated starch-based material with a β-structure (crystalline structure).

Specifically, a method for obtaining a dehydrated α-structure starch-based material is to heat it in the presence of moisture to gelatinize it, and then reduce the pressure of the atmosphere using a vacuum device. If such a dehydrated α-structure starch-based material is used, it will be possible to store the starch-based material alone for long periods of time since it is less prone to aging, which will contribute to shortening the production time and reducing the production costs of polypropylene resin compositions.

The water used to convert the starch having a β structure to an α structure as described above contains dissolved trehalose. The effect of this is that, for example, when rice is used as the starch-based material, the trehalose acts to inhibit the decomposition of the lipid components of the rice by impregnating the raw rice with an aqueous trehalose solution, and the deterioration over time of the polypropylene resin composition produced using the rice is suppressed. The reason for this is said to be that trehalose has the effect of coating the rice components and protecting the fatty acids from oxidative decomposition.

This effect is not limited to rice, but can also be achieved with general starch-based materials, and in addition to the above-mentioned trehalose, other substances that have this effect include salt, sucrose, antioxidants, protein decomposition promoters, and cellulosic decomposition promoters. By adding these substances to water to create an α-structure in the starch-based material, the effect of preventing the characteristic odor, burning, and coloring of the manufactured polypropylene resin composition can also be achieved.

So far, we have explained that starch-based materials that have already been gelatinized are used as raw materials, but by using the manufacturing method described below, starch-based materials with a β structure that contain moisture can also be used.

Specifically, raw rice is soaked in water for a specified time, the water is drained off, and then it is put into a kneader together with polypropylene resin and kneaded at the thermal flow temperature of the polypropylene resin. This thermal flow temperature (usually 100-170°C) is sufficient to transition the starch structure of the raw rice from a beta structure to an alpha structure, so the raw rice is gelatinized during the kneading process. After the raw rice has changed to an alpha structure in this way, as already mentioned above, the molecular chains of the starch are loosened, refined, and dispersed into the polypropylene resin matrix.

Here, in order for raw rice with a β structure to be heated and turn into an α structure, it is desirable for the moisture content to be 17% by mass or more, and to achieve this, it is necessary to soak the rice in water for 5 minutes or more. In addition, for starch-based materials such as potatoes, which contain enough moisture to turn their starch into an α structure on their own, there is no need to soak the potatoes in water like rice, and they can be put directly into the kneader.

The biomass material (C) is preferably one or more plant-derived fillers selected from the group consisting of wood, pulp, bamboo, sugarcane (bagasse), rice husks, and rice (starch).

The polypropylene resin composition of the present invention contains 5 to 85% by mass of polypropylene resin (A), 5 to 85% by mass of polypropylene resin (B), and 10 to 80% by mass of biomass material (C), preferably contains 10 to 75% by mass of polypropylene resin (A), 10 to 75% by mass of polypropylene resin (B), and 15 to 70% by mass of biomass material (C), more preferably contains 15 to 65% by mass of polypropylene resin (A), 15 to 65% by mass of polypropylene resin (B), and 20 to 60% by mass of biomass material (C), and even more preferably contains 20 to 55% by mass of polypropylene resin (A), 20 to 55% by mass of polypropylene resin (B), and 25 to 55% by mass of biomass material (C). Here, the total amount of the mass proportions of (A), (B), and (C) is 100% by mass.

Thermoplastic elastomer (D)
The polypropylene resin composition may optionally contain a thermoplastic elastomer (D). Examples of the thermoplastic elastomer (D) include olefin-based elastomers, styrene-based elastomers, etc. These may be used alone or in combination of two or more.

Examples of olefin-based elastomers include ethylene-propylene copolymer elastomers (EPR), ethylene-butene copolymer elastomers (EBR), ethylene-hexene copolymer elastomers (EHR), ethylene-octene copolymer elastomers (EOR), ethylene-α-olefin-diene terpolymer elastomers such as ethylene-propylene-ethylidenenorbornene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-isoprene copolymer, and hydrogenated polymer-based elastomers such as ethylene-ethylene-butylene-ethylene copolymer (CEBC). Of these, ethylene-propylene copolymer elastomers, ethylene-butene copolymer elastomers, and ethylene-hexene copolymer elastomers are preferred.

Examples of styrene-based elastomers include styrene-butadiene-styrene triblock copolymer elastomer (SBS), styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene-butylene copolymer elastomer (SEB), styrene-ethylene-propylene copolymer elastomer (SEP), styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene-styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, partially hydrogenated styrene-isoprene-butadiene-styrene copolymer elastomer, etc.

The thermoplastic elastomer (D) preferably has an MFR of 0.01 to 10 g/10 min, more preferably 0.1 to 3 g/10 min, measured at 190°C under a load of 2.16 kg. If the MFR of the thermoplastic elastomer (D) is 0.1 g/10 min or more, the load on the extruder is reduced during extrusion molding of the sheet, improving productivity. In addition, if the MFR is 10 g/10 min or less, the melt tension of the sheet can be kept high, and the molded body does not sag under its own weight during extrusion molding or thermoforming, which is preferable.

The polypropylene resin composition of the present invention can preferably contain 1 to 50 parts by mass, more preferably 2 to 44 parts by mass, even more preferably 4 to 38 parts by mass, and even more preferably 8 to 32 parts by mass of the thermoplastic elastomer (D) per 100 parts by mass of the total of 100% by mass of the polypropylene resin (A), the polypropylene resin (B), and the biomass material (C).

(3) Compatibilizer In the polypropylene resin composition, a compatibilizer can be blended as necessary. Examples of the compatibilizer preferably used include saturated carboxylic acid, unsaturated carboxylic acid or their derivatives, thermoplastic resins modified with unsaturated carboxylic acid or their derivatives, and cellulose-based materials, lignocellulose-based materials, and starch-based materials modified with unsaturated carboxylic acid or their derivatives. In addition, oil-modified alkyd resins or their derivatives, and modified starch or their derivatives can also be used.

Examples of saturated carboxylic acids include succinic anhydride, succinic acid, phthalic anhydride, phthalic acid, tetrahydrophthalic anhydride, adipic anhydride, etc. Examples of unsaturated carboxylic acids include maleic anhydride, maleic acid, nadic anhydride, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, sorbic acid, acrylic acid, etc. Examples of derivatives of saturated or unsaturated carboxylic acids that can be used include metal salts, amides, imides, esters, etc. of saturated or unsaturated carboxylic acids.

In addition, thermoplastic resins modified with unsaturated carboxylic acids or their derivatives, as well as cellulose-based materials, lignocellulose-based materials, starch-based materials, and the like, modified with unsaturated carboxylic acids or their derivatives, can be used. There are no particular limitations on the thermoplastic resin before modification used in the thermoplastic resin modified with unsaturated carboxylic acids or their derivatives, so long as it does not significantly impair the effects of the present invention. Specific examples include low-density polyethylene, ethylene-α-olefin copolymers, high-density polyethylene, polypropylene, propylene block copolymers, and propylene random copolymers. Of these, it is preferable that the resin is the same as the polypropylene resin (A) and/or the polypropylene resin (B).

These are obtained by heating and mixing a thermoplastic resin or a cellulose-based material, a lignocellulose-based material, a starch-based material, or the like with an unsaturated carboxylic acid or its derivative, and a radical generator in the presence or absence of a solvent. The amount of unsaturated carboxylic acid or its derivative added is preferably 0.1 to 15 mass%, and particularly preferably 1 to 10 mass%. As the compatibilizer used in the present invention, preferred are thermoplastic resins modified with unsaturated carboxylic acid or its derivatives, which are odorless and have low acidity, as well as cellulose-based materials, lignocellulose-based materials, starch-based materials, and the like modified with unsaturated carboxylic acid or its derivatives.

The polypropylene resin composition may contain, as optional components, various additives, such as nucleating agents, heat stabilizers, antioxidants, weather stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, slip agents, antiblocking agents, antifogging agents, neutralizing agents, metal deactivators, surfactants, compatibilizing agents, colorants, antibacterial and antifungal agents, flame retardants, plasticizers, dispersants, fillers, conductive agents, preservatives, fragrances, deodorizers, insect repellents, elastomers, etc., as long as the effects of the present invention are not significantly impaired. Two or more of these optional components may be used in combination.
In addition, these optional components may be blended into the polypropylene resin (A) or into the polypropylene resin (B), and two or more of each of the resin components may be used in combination.

The propylene resin composition of the present invention can be prepared by mixing powdered or pelletized polypropylene resin (A), polypropylene resin (B), biomass material (C) and other compounding agents used as necessary using a dry blend or Henschel mixer. Depending on the situation, the biomass material (C) and polypropylene resin (A) and/or polypropylene resin (B) may be bonded together in advance using a gelation method or the like. These may also be kneaded in a single-screw or twin-screw extruder or kneaded to a high filler content to form a master batch, which is then diluted to the required concentration during molding.

The polypropylene resin composition of the present invention can be produced by mixing polypropylene resin (A), polypropylene resin (B) and biomass material (C), or polypropylene resin (A), polypropylene resin (B), biomass material (C) and thermoplastic elastomer (D), and optional components that are blended as necessary, or by heating and kneading them using a single-screw extruder, a twin-screw extruder, or the like. The resin temperature for heating and kneading can be appropriately determined in the range of 100°C to 300°C, taking into consideration the load of kneading, the color and odor of the resin composition, etc.

The polypropylene resin composition of the present invention can be molded into the desired shape by means of pressure molding, film molding, vacuum molding, extrusion molding, injection molding, or other suitable means to produce various molded products. The molding temperature can be appropriately set in the range of 100°C to 300°C, taking into consideration the load of kneading, the color and odor of the resin composition, etc.

The polypropylene resin composition of the present invention can be effectively used as a material for various film and sheet materials, disposable molded products (e.g., containers, pipes, timber, bars, artificial wood, trays, concrete panels, foams, etc.), furniture, building materials, interior and exterior materials for automobiles, chassis and housings for home appliances, civil engineering and construction materials, materials for the agricultural, dairy and fishery industries, recreational materials, and sports materials.

The polypropylene resin composition of the present invention is also suitable for use in fields such as electrical insulating materials, industrial parts and materials, and building materials, and is particularly suitable as a raw material for housing components, building materials, and home appliances. Specific examples include trays, tableware, speakers, bathroom unit floor pans, buckets, toilet seats, cabinets, stereo cabinets, baseboards, door materials, counter materials, window frames, soundproofing boards, shelves, civil engineering timber, pillars, structural materials, kitchen components, floors, bathrooms, underlayment boards, piano organ main boards, and building and ceiling materials.

The polypropylene resin composition of the present invention allows for the effective disposal of large quantities of excess agricultural produce that are difficult to dispose of, and reduces the amount of polypropylene resin produced from fossil fuels used. Furthermore, when molded products made from the polypropylene resin composition of the present invention are incinerated after use, charcoal remains as a residue, which contributes greatly to the conservation of the global environment, as it generates less combustion heat and carbon dioxide. Even when the product is disposed of in a landfill, the return rate to the soil is high, making it environmentally friendly.

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

1. Evaluation Method (1) Melting Point (Tm)
Measurement was performed using a differential scanning calorimeter DSC6200 manufactured by Seiko Corp. Approximately 5 mg of a sheet-shaped sample was packed in an aluminum pan, and the sample was heated from room temperature to 200° C. at a heating rate of 100° C./min, held for 5 minutes, cooled to 40° C. at 10° C./min, and then heated to 200° C. at 10° C./min. The maximum melting peak temperature was determined as the melting point Tm (° C.) from the melting calorific curve obtained when the sample was heated.

(2) Melt flow rate (MFR)
The MFR of polypropylene resins (A) and (B) was measured at 230°C and a load of 2.16 kg in accordance with JIS K7210. The MFR of thermoplastic elastomer (D) was measured at 190°C and a load of 21.6 kg in accordance with JIS K6922-2. The unit is g/10 min.

(3) Melt tension MT
The measurement was carried out using a Capillograph manufactured by Toyo Seiki Seisakusho Co., Ltd.
(Measurement conditions)
Capillary: diameter 2.0 mm, length 40 mm
Cylinder diameter: 9.55 mm
Cylinder extrusion speed: 20 mm/min. Take-up speed: 4.0 m/min. Temperature: 230° C.
When the melt tension MT is extremely high, the resin may break at a take-up speed of 4.0 m/min. In such a case, the take-up speed is decreased by 0.1 m/min, and the melt tension at the highest possible take-up speed is taken as MT. The unit is grams.

(4) Q value (Mw/Mn)
It was determined by GPC measurement according to the following method.
Apparatus: Waters GPC (ALC/GPC 150C)
Detector: FOXBORO MIRAN 1A IR detector (measurement wavelength: 3.42 μm)
Column: Showa Denko AD806M/S (3 columns)
Mobile phase solvent: orthodichlorobenzene (ODCB)
・Measurement temperature: 140℃
・Flow rate: 1.0ml/min ・Injection volume: 0.2ml
Sample preparation: A 1 mg/mL solution of the sample is prepared using ODCB (containing 0.5 mg/mL BHT), and dissolved at 140° C. for approximately 1 hour.
The retention volume obtained by GPC measurement is converted to the molecular weight using a calibration curve prepared in advance using standard polystyrene. The following brands of standard polystyrene manufactured by Tosoh Corporation are used.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000

(5) Soluble matter at 40° C. or less measured by temperature rising elution fractionation (TREF) method: Measured according to the method described above.

(6) Pellet odor 100 g of pellets were weighed out and placed in a 500 ml glass container, which was then kept at 80° C. for 3 hours. The lid of the glass container was then opened, and the odor of the pellets inside was evaluated sensorily. The odor intensity was judged as follows:
: Almost no odor is detected.
○: Slight odor is felt.
△: There is an unpleasant odor.
×: The odor is strong.

(7) Extruded Sheet Molded Product and Its Plastic Feel The pellets were fed into an extruder having a screw diameter of 40 mm, extruded through a T-die at a resin temperature of 200°C, sandwiched between a mirror-finished metal casting roll having a surface temperature of 60°C, and continuously taken up at a speed of 1.2 m/min while being cooled and solidified, to obtain a sheet of polypropylene resin composition having a width of 500 mm and a thickness of 1.0 mm.
The plastic feel of the obtained molded body was evaluated based on the loss of gloss caused by the biomass material and the appearance of a pattern. The strength of the plastic feel was judged as follows.
○: Almost no plastic feel.
△: Has a slight plastic feel.
×: It feels just like plastic.

(8) Extrusion foam molding and its plasticity 100 parts by weight of the pellets of the polypropylene resin composition and 0.5 parts by weight of a chemical foaming agent (trade name: Hydrocellol CF40E-J, manufactured by Clariant Japan Co., Ltd.) as a cell regulator were uniformly mixed and stirred by a ribbon blender, and the resulting mixture was fed into a single-screw extruder having a barrel hole for injecting a physical foaming agent in the middle of the barrel. While the polypropylene resin composition was heated and melted in the front stage of the extruder to be plasticized and the cell regulator was decomposed, 0.50 parts by weight of liquefied carbon dioxide was injected and kneaded with a high-pressure pump relative to 100 parts by weight of the polypropylene resin composition, and then the polypropylene resin foam molding material was quickly cooled in the rear stage of the extruder and extruded from a T-shaped die with a width of 750 mm and a lip width of 0.4 mm. The extruded foam sheet was first cooled on one side by a roll installed immediately adjacent to the die, and then cooled on both sides by three rolls installed thereafter, and taken up at a constant speed by a pinch roll to obtain a foam sheet with a thickness of 1.3 mm. The operating conditions of the extruder are as follows.
Extruder: Diameter: 65 mmφ, L/D = 42, Physical foaming agent injection port: L/D = 20 position Screw rotation speed: 75 rpm
Discharge amount: approx. 65kg/h
The evaluation of the resulting plastic feeling was carried out as described in (7) above.

(9) Injection Molded Product and Its Plastic Feel Using a molding machine (Toshiba Machine Co., Ltd. EC20 type injection molding machine) and the following mold, flat test pieces for evaluating physical properties were prepared under the following conditions and used for evaluating the "tensile modulus" described later.
Mold = for taking two flat test pieces for evaluating physical properties (10 x 80 x 4t (mm)).
Molding conditions: molding temperature 220°C, mold temperature 30°C, injection pressure 50 MPa, injection time 5 seconds, cooling time 20 seconds.
The evaluation of the resulting plastic feeling was carried out as described in (7) above.

(10) Tensile Modulus of Elasticity: Using the flat test piece prepared in (9) above, a test piece was prepared by machining in accordance with JIS K7162, and measured at a test temperature of 23° C. The tensile modulus of elasticity was judged to be high or low as follows.
○: Tensile modulus of elasticity is 1,200 MPa or more ×: Tensile modulus of elasticity is less than 1,200 MPa

2. Raw materials The raw materials used in the evaluation are as follows. The physical properties of the raw materials are summarized in Table 1.
- Polypropylene resin (A-1): Novatec BC6C (product name) manufactured by Japan Polypropylene Corporation
- Polypropylene resin (A-2): Novatec BC03C (product name) manufactured by Japan Polypropylene Corporation
- Polypropylene resin (B-1): Wintech WFX6 (product name) manufactured by Japan Polypropylene Corporation
- Polypropylene resin (B-2): Wintech WSX03 (product name) manufactured by Japan Polypropylene Corporation
- Biomass material (C-1): Wood flour (100 mesh), manufactured by Casino Co. - Biomass material (C-2): Wood flour (45 mesh), manufactured by Casino Co. - Thermoplastic elastomer (D-1): Toughmer (registered trademark) A4050 manufactured by Mitsui Chemicals, Inc.

(Examples 1 to 12, Comparative Examples 1 to 5)
Seventeen types of polypropylene resin compositions (Examples 1 to 12, Comparative Examples 1 to 5) shown in Tables 2 and 3 were weighed and uniformly mixed by stirring using a ribbon blender. The resulting mixture was fed into a twin-screw extruder with a screw diameter of 15 mm, kneaded at a resin temperature of 200° C., extruded into a strand shape, cooled with water, and pelletized to obtain a polypropylene resin composition.

The resulting polypropylene resin composition was evaluated for pellet odor, extrusion sheet molding (plastic feel), extrusion foam molding (plastic feel), injection molding (plastic feel), and strength using the methods described above. The evaluation results are summarized in Tables 2 and 3.

Claims (6)

A polypropylene resin composition comprising 5 to 85 mass% of polypropylene resin (A) having a melting point of 150°C or higher, 5 to 85 mass% of polypropylene resin (B) having a melting point of 110°C or higher and 140 °C or lower, and 10 to 80 mass% of a biomass material (C) (wherein the total mass of (A), (B) and (C) is 100 mass%), wherein the polypropylene resin (B) is one or more polypropylene resins selected from the group consisting of a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-ethylene-1-butene random copolymer, a propylene-ethylene random block copolymer and a propylene-ethylene-1-butene random block copolymer, and the biomass material (C) is one or more polypropylene resins selected from the group consisting of a cellulose-based material and a lignocellulosic material . The polypropylene resin composition according to claim 1, characterized in that the polypropylene resin (A) is one or more polypropylene resins selected from the group consisting of propylene homopolymer, propylene-ethylene block copolymer, and propylene-ethylene-1-butene block copolymer. The polypropylene resin composition according to claim 1 or 2 , characterized in that the polypropylene resin (B) has the following property (b-1) and/or (b-2).
(b-1) The Q value is 5.0 or less. (b-2) The soluble matter at 40°C or less measured by temperature rising elution fractionation (TREF) is 4.0% by mass or less. The polypropylene resin composition according to any one of claims 1 to 3 , characterized in that the biomass material (C) is one or more plant-derived fillers selected from the group consisting of wood, pulp, bamboo , bagasse, and rice husks . The polypropylene resin composition according to any one of claims 1 to 4, further comprising 1 to 50 parts by mass of a thermoplastic elastomer (D) per 100 parts by mass consisting of 100% by total mass of the polypropylene resin (A), the polypropylene resin ( B ), and the biomass material (C). 6. An extrusion foam molded product, an injection foam molded product, a sheet molded product, a thermoformed product, or a blow molded product, comprising the polypropylene resin composition according to any one of claims 1 to 5 .