WO2024014545A1 - Resin material for molding, resin molded article, and method for producing resin material for molding - Google Patents

Abstract

This resin material for molding contains biodegradable plastic and cellulose microfibers and has a biomass ratio of 90 mass% or more.

Description

Production method of resin material for molding, resin molded product, and resin material for molding

The present invention relates to a resin material for molding, a resin molded product, and a method for producing a resin material for molding.

In recent years, bioplastics (also called bioresins), which have a lower environmental impact, have been attracting attention compared to conventional plastics derived from fossils such as petroleum. Bioplastics are broadly divided into biomass plastics (also called biomass resins), which are made from renewable organic resources such as plants, and biodegradable plastics, which can be broken down into carbon dioxide and water through the action of microorganisms. . Note that among bioplastics, there are also plastics that are biodegradable.

For example, a biomass resin composition containing a biomass resin and a hydroxyalkyl (alkyl) cellulose compound has been developed (see Patent Document 1). In Patent Document 1, by including a biomass resin and a hydroxyalkyl (alkyl) cellulose compound, an attempt is made to realize a biomass resin composition that has excellent transparency, strength, and heat resistance without adding a non-biomass filler. . Furthermore, strength is maintained by including cellulose nanofibers (hereinafter referred to as CNF) in this biomass resin composition.

Japanese Patent Application Publication No. 2021-155665

As in the technology of Patent Document 1, CNF is included to compensate for the lack of strength in biomass plastics, but in molding (e.g. injection molding) using biomass plastics mixed with CNF, the molding itself Problems have arisen in that it is difficult and the CNF is unevenly dispersed, which impairs the appearance of the molded product.

The present invention was made to solve these problems, and its purpose is to create a molding resin material that can realize bioplastics with improved moldability and good dispersibility without impairing the appearance. , a resin molded product, and a method for producing a resin material for molding.

In order to achieve the above object, the molding resin material according to the present disclosure contains biodegradable plastic and cellulose microfibers, and has a biomass ratio of 90% by mass or more.

The resin molded product according to the present disclosure is molded using the above molding resin material.

The method for producing a molding resin material according to the present disclosure includes a drying step of drying cellulose microfibers to a moisture content of 5% by weight or less, a cellulose microfiber dried in the drying step, and a biodegradable plastic. , and a kneading step of kneading with a pressure kneader.

According to the present invention using the above means, there is provided a molding resin material, a method for producing a molding resin material, and a method for producing a molding resin material that can realize a bioplastic with improved moldability and good dispersibility without impairing the appearance. We can provide molded products made from materials.

This is a classification table of plastics. FIG. 1 is a schematic configuration diagram of a pellet manufacturing apparatus used for manufacturing a molding resin according to the present embodiment. It is a table showing manufacturing conditions of each example and each comparative example. It is a table showing the results of each example and each comparative example. 3 is a photograph showing molded products using the molding resin materials of (a) Comparative Example 3, (b) Comparative Example 4, and (c) Comparative Example 5. 3 is a photograph showing molded products using the molding resin materials of (a) Example 2, (b) Example 2, and (c) Comparative Example 1. 3 is a photograph showing molded products using molding resin materials of (a) Example 5, (b) Example 6, and (c) Comparative Example 2. It is a table showing the evaluation of the appearance of a resin material for molding using a press sheet. 1 is a table showing evaluation of the appearance of molding resin materials using a scanning electron microscope (SEM). It is a table and a graph showing the biomass degree of CMF and molding resin material.

The molding resin of this embodiment is a molding resin material that contains biodegradable plastic and cellulose microfibers and has a biomass ratio of 90% by mass or more. The biodegradable plastic is preferably a bio-based biomass plastic. Further, the molding resin material preferably has a biomass ratio of 100% by mass. The plastic in this embodiment is a thermoplastic resin. In this specification, when a numerical range is expressed as A to B, it indicates a range of A or more and B or less.

Figure 1 shows a classification table of plastics. In Figure 1, plastics are classified according to whether they are biodegradable or not, and the material from which they are derived.

Specifically, plastics made of fossil-derived materials that are not biodegradable are non-bioplastics, and representative examples include PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), and PTT (polytrisate). (methylene terephthalate), PVC (polyvinyl chloride), PS (polystyrene), ABS (acrylonitrile-butadiene-styrene resin), PC (polycarbonate), PBT (polybutylene terephthalate), POM (polyacetal), PMMA (polymethyl methacrylate) , PPS (polyphenylene sulfide), PA6 (polyamide 6), PA66 (polyamide 66), PU (polyurethane), phenol resin, and epoxy resin.

Representative examples of plastics made from biodegradable fossil-derived materials include PVA (polyvinyl alcohol), PGA (polyglycolic acid), PBS (polybutylene succinate), PBSA (polybutylene succinate-co-adipate), There are PBAT (polybutylene adipate terephthalate) and PETS (polyethylene terephthalate succinate).

Typical examples of plastics that are not biodegradable and are made of fossil-derived and bio-derived materials include bio-PET (polyethylene terephthalate), bio-PPT (polytrimethylene terephthalate), and bio-PA (polyamide) 610, 410, 510. , Bio PA (Polyamide) 1012, 10T, Bio PA (Polyamide) 11T, MXD10 (Nylon MXD6), Bio PA56 (Polyamide 56), Bio PC (Polystyrene), Bio PU (Polyurethane), Aromatic Polyester, Bio Unsaturated Polyester , biophenolic resin, and bioepoxy resin.

Typical examples of biodegradable plastics made from fossil- and bio-derived materials include bio-PBS (polybutylene succinate), PBAT (polybutylene adipate terephthalate), PLA (polylactic acid) compounds, and starch polyester resins. There is.

Typical examples of plastics that are not biodegradable and are made of bio-derived materials include Bio-PE, Bio-PA11, and Bio-PA1010.

Typical examples of biodegradable plastics made from bio-derived materials include PLA (polylactic acid), PHA (polyhydroxyalkanoate) (PHBH (3-hydroxybutyric acid/3-hydroxyhexanoic acid copolymer polyester) ), etc.).

The plastics surrounded by the dashed line in Figure 1 are biomass plastics, and the plastics surrounded by dotted lines are biodegradable plastics.

<Binder>
The binder of the molding resin of this embodiment is a biodegradable plastic, particularly a biomass plastic derived only from bio-based materials. Specifically, they are PLA, PHA type (PHBH), bio-PBS, PBAT/PLA (polylactic acid) compound, and starch polyester resin, and preferably PLA and PHA type (PHBH). Further, it is preferable to use a pellet-shaped binder.

<Filler>
The filler of the molding resin of this embodiment is cellulose micro fiber (hereinafter abbreviated as CMF). Specifically, the fiber length is 20 to 50 μm, preferably 35 to 45 μm, and the particle size distribution (D50) is 20 to 50 μm, preferably 30 to 40 μm. For example, in this embodiment, the CMF is a cellulose fiber made from coniferous wood that has been subjected to pulverized and classified products, and has an average fiber length of 45 μm, an average fiber diameter of 35 μm, and a tentative ratio of 0.25. Note that CMF may be made from broad-leaved trees or other plants.

<Manufacturing method>
FIG. 2 shows a schematic explanatory diagram showing the manufacturing mechanism of the molding resin material of this embodiment, and the method for manufacturing the molding resin will be described below based on the diagram.

The method for producing molding resin of the present embodiment mainly uses a pellet manufacturing apparatus 1 having a kneader 2 for kneading a binder and a filler, and an extruder 3 for producing pellet-shaped molding resin from a kneaded material K. .

The kneader 2 is a pressure kneader. The kneader 2 has a pair of kneader screws 21 rotatably installed in a barrel 20 with an open top that allows temperature adjustment. Further, the pressure press 22 of the kneader 2 can be moved up and down to open and close the upper opening, and during kneading, the pressure press 22 can be lowered to pressurize the inside of the barrel 20. Materials to be kneaded can be introduced into the barrel 20 through an input port 23 . Moreover, the barrel 20 is rotatable as shown by the dotted line in FIG. 2 so as to discharge the kneaded material K.

A conveyor 4 is provided between the kneader 2 and the extruder 3. The conveyor 4 has a bucket 40 that accommodates the kneaded material K discharged from the barrel 20 of the kneader 2. The bucket 40 can be moved above the hopper 30 of the extruder 3, which will be described later, and the kneaded material K can be thrown into the hopper 30 from above the hopper 30.

The extruder 3 has a hopper 30 into which the kneaded material K is charged, and a hopper screw 31 is rotatably provided within the hopper 30. The hopper 30 is connected to a horizontally extending hollow cylinder 32, and a straight screw 33 is rotatably provided within the cylinder 32.

The temperature of the cylinder 32 can be adjusted, and by rotating the straight screw 33 inside, the kneaded material K can be melted and extruded toward the tip side. A pelletizer 34 is provided on the distal end side of the straight screw 33. The pelletizer 34 has a die 34a that forms the molten resin into a small diameter rod, and a rotary cutter 34b that cuts the resin coming out of the die 34a into pellets.

Although not shown, a sorter or the like for sorting pellets may be provided downstream of the extruder 3.

The molding resin of this embodiment is granulated by the manufacturing apparatus 1 configured as described above in the following procedure.

First, in step S1, CMF, which is a filler, is introduced into the barrel 20 from the input port 23 of the kneader 2.

In step S2, the kneader screw 21 is driven to rotate while heating the barrel 20 in a non-pressurized state to reduce the water content of the CMF (drying step). In this drying step, it is preferable to dry the CMF to a moisture content of 5% by weight or less. CMF generally contains a water content of about 7 to 10% by weight, but in order to improve its moldability as a molding resin material and to prevent steam explosions, the water content of CMF must be adjusted before kneading with the binder. It is effective to provide a drying step in which the amount of the carbon dioxide is dried to 5% by weight or less.

In step S3, after the drying of the CMF in step S2 is completed, a resin material as a binder is charged into the barrel 20 from the input port 23.

In step S4, the pressure press 22 is lowered to pressurize and heat the inside of the barrel 20, while rotating the kneader screw 21 to knead the CMF and the binder resin material (kneading step).

In step S5, after the kneading in step S4 is completed, the kneaded material K is taken out from the barrel 20 and put into the bucket 40 of the conveyor 4.

In step S6, the kneaded material K is transported by the conveyor 4 to the hopper 30 of the extruder 3, and the kneaded material K is introduced into the hopper 30.

In step S7, the hopper screw 31 is driven to draw the kneaded material K into the cylinder 32.

In step S8, the straight screw 33 rotates while heating the inside of the cylinder 32, thereby transferring the kneaded material K to the tip side while melting it.

In step S9, in the pelletizer 34, the resin is extruded into a rod shape from the die 34a, and the resin coming out from the die 34a is cut by the rotary cutter 34b to form a pellet-shaped molding resin material.

As described above, the pellet-shaped molding resin material of this embodiment is produced using the pellet manufacturing apparatus 1 by the production method including steps S1 to S9. Although the pellet manufacturing apparatus 1 of this embodiment uses a pressure kneader to knead the binder and filler, the kneader is not limited to this. For example, kneading may be performed using an extruder (for example, a twin-screw extruder).

<Molded products using molding resin>
A molded article using the molding resin material of this embodiment is formed by injection molding the above-mentioned pellet-shaped molding resin material. That is, although not shown, a pellet-shaped molding resin material is kneaded using a kneader, and then injection molded using an extruder for molded products. Existing kneaders and injection molding machines can be used.

<Example>
Examples of molded articles made of a molding resin material according to the present invention, comparative examples of molded articles made of a molding resin material whose filler is CNF, and molded articles made of a molding resin material made of bioplastics including those derived from fossils are shown below. Evaluations of moldability, appearance, and physical properties of a comparative example of a molded article and a comparative example of a molded article made of a conventional non-bioplastic molding resin material will be described with reference to FIGS. 3 to 9.

FIG. 3 shows the manufacturing conditions of each example and each comparative example. As shown in the figure, in Examples 1 to 4 and Comparative Example 1, the binder was PLA resin, in Examples 5 to 7 and Comparative Example 2, the binder was PHA resin, and in Comparative Examples 3 to 5, the binder was bio-PBS. In Comparative Examples 6 to 10, the binder was PP resin. In each of the Examples and Comparative Examples, a molding resin material is manufactured using the pellet manufacturing apparatus 1 described above, and a molded product is molded using an injection molding machine using the molding resin material. The kneading conditions shown in FIG. 3 are the kneading conditions in the kneader 2 of the pellet manufacturing apparatus 1, and the molding conditions are the molding conditions in the injection molding machine.

Furthermore, as CMF as a filler, cellulose powder obtained by dry-pulverizing coniferous wood was used. The CNF used as the filler was cellulose fiber obtained by pulverizing coniferous wood using the TEMPO oxidation method, and had a water content of 7.96% by weight, a tentative specific gravity of 0.35, and a top size of 209.3 μm.

The PLA resins of Examples 1 to 4 and Comparative Example 1 are plant-derived PLA resins made from starch contained in corn, etc., and have an MFR (melt flow rate) of 10 to 15 (g/10min) and a specific gravity. 1.25 and a melting point of 165-175°C was used.

Specifically, in Example 1, a molding resin material was manufactured using 100% by weight of PLA resin, that is, only PLA resin without mixing filler. The molding conditions for a molded article using the molding resin material of Example 1 were injection time of 45 seconds, temperature of 180° C., and cooling time of 40 seconds.

In Example 2, a molding resin material was produced by mixing 80% by weight of PLA resin with 20% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Example 2 was produced by kneading at 190° C. and 40 rpm for 27 minutes. Further, the molding conditions for the molded product using the molding resin material of Example 2 were: injection time 15 seconds, temperature 180° C., and cooling time 5 seconds.

In Example 3, a molding resin material was produced by mixing 40% by weight of PLA resin with 60% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Example 3 was produced by kneading at 185° C. and a rotation speed of 40 rpm for 25 minutes.

In Example 4, a molding resin material was produced by mixing 30% by weight of PLA resin with 70% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Example 4 was produced by kneading at 195° C. and a rotation speed of 40 rpm for 25 minutes.

In Comparative Example 1, a molding resin material was produced by mixing 80% by weight of PLA resin with 20% by weight of CNF having a fiber length of 3 nm to 1 μm and a particle size distribution D50 of 26.30 μm as a filler. The molding resin material of Comparative Example 1 was manufactured by kneading at 180° C. and a rotation speed of 40 rpm for 15 minutes. However, the quality of the molding resin material of Comparative Example 1 was poor, and a molded article could not be molded.

The PHA resins (PHBV resins) of Examples 5 to 7 and Comparative Example 2 are plastics produced in vivo by microorganisms using biomass such as vegetable oil as raw materials, and have an MFR (melt flow rate) of 8 to 15. , specific gravity 1.25, and melting point 175 to 180°C.

Specifically, in Example 5, a molding resin material was manufactured using 100% by weight of PHA resin, that is, only PHA resin without mixing filler. The molding conditions for a molded article using the molding resin material of Example 5 were injection time of 12 seconds, temperature of 170° C., and cooling time of 40 seconds.

In Example 6, a molding resin material was produced by mixing 80% by weight of PHA resin with 20% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Example 6 was produced by kneading at 160° C. and a rotation speed of 40 rpm for 20 minutes. Further, the molding conditions for the molded product using the molding resin material of Example 6 were: injection time 12 seconds, temperature 160° C., and cooling time 40 seconds.

In Example 7, a molding resin material was produced by mixing 40% by weight of PHA resin with 60% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Example 7 was manufactured by kneading at 176° C. and a rotation speed of 40 rpm for 25 minutes.

In Comparative Example 2, a molding resin material was produced by mixing 80% by weight of PHA resin with 20% by weight of CNF having a fiber length of 3 nm to 1 μm and a particle size distribution D50 of 26.30 μm as a filler. The molding resin material of Example 9 was produced by kneading at 145° C. and 40 rpm for 15 minutes. Furthermore, the molding conditions for the molded product using the molding resin material of Comparative Example 2 were: injection time 12 seconds, temperature 170° C., and cooling time 40 seconds.

The bio-PBS of Comparative Examples 3 to 5 is a bioplastic with a biomass ratio of 50% by weight produced from biosuccinic acid and 1,4-butanediol from corn, cassava, sugarcane, etc., and has an MFR (melt flow rate) of 50% by weight. 5, a specific gravity of 1.26 and a melting point of 115°C was used.

Specifically, in Comparative Example 3, the molding resin material was manufactured using 100% by weight of bio-PBS, that is, only bio-PBS without mixing filler. The molding conditions for the molded article using the molding resin material of Comparative Example 3 were injection time of 30 seconds, temperature of 130° C., and cooling time of 40 seconds.

In Comparative Example 4, a molding resin material was produced by mixing 80% by weight of bio-PBS with 20% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Comparative Example 2 was manufactured by kneading at 130° C. and a rotation speed of 40 rpm for 25 minutes. The molding conditions for the molded article using the molding resin material of Comparative Example 4 are the same as in Example 1: injection time 30 seconds, temperature 130° C., and cooling time 40 seconds.

In Comparative Example 5, 66.2% by weight of bio-PBS was mixed with 28.4% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler, and 5.7% by weight of rubber and wax. A resin material for molding was produced by adding % by weight. The molding resin material of Comparative Example 5 was manufactured by kneading at 130° C. and a rotation speed of 40 rpm for 25 minutes. Further, the molding conditions for the molded product using the molding resin material of Example 2 were: injection time 12 seconds, temperature 190° C., and cooling time 40 seconds.

The PP resin used in Comparative Examples 6 to 10 was homopolypropylene F113G manufactured by Prime Polymer Co., Ltd., which had an MFR (melt flow rate) of 3, a specific gravity of 0.90, and a melting point of 165°C.

Specifically, in Comparative Example 6, a molding resin material was manufactured using 100% by weight of PP resin, that is, only PP resin without mixing filler. The molding conditions for the molded article using the molding resin material of Comparative Example 6 were injection time of 14 seconds, temperature of 200° C., and cooling time of 40 seconds.

In Comparative Example 7, a molding resin material was produced by mixing 80% by weight of PP resin with 20% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler. The molding resin material of Comparative Example 8 was manufactured by kneading at 200° C. and a rotation speed of 40 rpm for 26 minutes. Furthermore, the molding conditions for the molded product using the molding resin material of Comparative Example 8 were: injection time 14 seconds, temperature 200° C., and cooling time 60 seconds.

In Comparative Example 8, 59.2% by weight of PP resin was mixed with 39.5% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler, and 1.3% of wax was added as an additive. A resin material for molding was produced by adding % by weight. The molding resin material of Comparative Example 9 was manufactured by kneading at 175° C. and a rotation speed of 40 rpm for 45 minutes. Furthermore, the molding conditions for the molded product using the molding resin material of Comparative Example 9 were: injection time 14 seconds, temperature 200° C., and cooling time 60 seconds.

In Comparative Example 9, 39.2% by weight of PP resin was mixed with 58.8% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler, and 2.0% of wax was added as an additive. % was added to produce a molding resin material. The molding resin material of Comparative Example 9 was manufactured by kneading at 175° C. and a rotation speed of 40 rpm for 45 minutes. Furthermore, the molding conditions for the molded product using the molding resin material of Comparative Example 9 were: injection time 14 seconds, temperature 200° C., and cooling time 60 seconds.

In Comparative Example 10, 19.6% by weight of PP resin was mixed with 78.4% by weight of CMF having a fiber length of 35 to 45 μm and a particle size distribution D50 of 33.09 μm as a filler, and 2.0% of wax was added as an additive. A resin material for molding was produced by adding % by weight. The molding resin material of Comparative Example 9 was manufactured by kneading at 176° C. and a rotation speed of 40 rpm for 44 minutes.

FIG. 4 shows the results of each example and each comparative example for each molding resin material and molded product manufactured under such manufacturing conditions. In addition, Figures 5 to 7 show photographs of the molded products of each example and each comparison, Figure 8 shows a table showing the appearance of the resin material for molding using press sheets, and Figure 9 shows the appearance of the molded products using a scanning electron microscope. A table showing the appearance properties of the molding resin material by (SEM) is shown, and the characteristics of the molding resin material and molded product of this embodiment will be described below based on FIGS. 4 to 9.

The moldability will be explained based on FIGS. 4 to 7. The moldability is based on the presence or absence of defects such as burrs, short shots, warping, sink marks, voids, flow marks, weld lines, and silver streaks in the molded product (test piece).

As shown in FIG. 4, in Comparative Examples 6 to 10, which use PP resin that has been commonly used, there is no problem in moldability. Furthermore, Comparative Examples 3 to 5, in which bio-PBS of which 50% is derived from fossils, have no problems in moldability. On the other hand, regarding Examples 1 to 7 and Comparative Examples 1 and 2, which are bioplastics with a biomass ratio of 100%, only Examples 3 to 7, in which CMF is mixed, meet the moldability as a product. It is.

Specifically, Comparative Example 3 (Bio PBS 100% by weight) shown in FIG. 5(a), Comparative Example 4 (Bio PBS 80% by weight, CMF 20%) shown in FIG. 5(b), and Comparative Example 4 shown in FIG. 5(c) In Comparative Example 5 (Bio PBS 66, 2% by weight, CMF 28.4%, rubber, wax 5.7% by weight), there were no defects in the molded products (test pieces), and there was no problem in moldability.

In addition, in Example 1 (100% by weight of PLA resin) shown in FIG. 6(a), some of the test pieces contained air bubbles, which caused problems in moldability. In Example 2 (PLA resin 80% by weight, CMF 20%) shown in FIG. 6(b), there were no defects in the molded product (test piece) and no problems in moldability. As shown in FIG. 6(c), in Comparative Example 1 (PLA resin 80% by weight, CNF 20%), the test piece broke during molding, and molding could not be performed.

Example 5 (PHA 100% by weight) shown in FIG. 7(a), Example 6 (PHA 80% by weight, CMF 20%) shown in FIG. 7(b), and Comparative Example 2 (PHA 80% by weight) shown in FIG. 7(c). , CNF 20%), there were no defects in the molded products (test pieces), and there was no problem in moldability.

The appearance will be explained based on FIGS. 4, 8, and 9. Regarding the appearance, a regular appearance is judged as a good product, and a powdery or gradated appearance is judged as poor. In terms of appearance, products that retain their shape are considered good, and products that become brittle and break when touched are considered defective.

As shown in FIG. 4, Comparative Examples 6 to 11 using PP resin have no problems in appearance. On the other hand, regarding Examples 1 to 7 and Comparative Examples 1 and 2, which are bioplastics with a biomass ratio of 100%, Examples 2 to 4, in which CMF is mixed, satisfy the appearance as a product. and Examples 6 and 7.

Specifically, FIG. 8 shows the evaluation of the appearance of the molding resin material using a press sheet.

The evaluation using this press sheet is performed according to the following procedure.

First, prepare the heat press machine, turn on the heat press machine, and raise the temperature for 2 hours. The heat press machine is equipped with one pressure detection section and one heater at the top and bottom. The set temperature was set at 200°C.

Next, prepare the molding resin material that will be the sample, and shake it with a Lumirror to remove any adhering dust. Then, place the Lumirror on a piece of paper, etc., place about a spatula's worth of the sample in the center of the Lumirror, and smooth it out. Note that if the resin content is high, it tends to spread when melted, so the sample size was kept small. Furthermore, shake another Lumirror in the same way to remove any adhering dust, and place the Lumirror on top of the sample.

Subsequently, the Lumirror containing the sample was placed in a heat press machine, a load of 0.95 to 1 t was applied, and it was heated for 1 minute. After 1 minute had passed, a load of 8.95 to 9 t was applied and heating was continued for 1 minute. Thereafter, immediately remove the Lumirror from the heat press.

The presence or absence of condensation was confirmed in the sample using the Lumirror, which was taken out, to confirm that the entire sample had cooled down, and the presence or absence of condensation was confirmed again by looking through the sample with light. We also checked for color abnormalities and foreign substances. If an abnormality was confirmed, another sheet was produced according to the above procedure.

As shown in Figure 8, the molding resin materials of PLA resin (Comparative Example 1) and PHA resin (Comparative Example 2) mixed with CNF as a filler had many aggregates and poor dispersibility in the press sheet evaluation. Recognize.

On the other hand, the molding resin materials of PLA resin (Examples 2 to 4) and PHA resin (Examples 6 and 7) mixed with CMF as a filler had almost no agglomerates in the press sheet evaluation, and had excellent dispersibility. I know that there is. In Examples 3, 4, and 7, some color unevenness occurred on the surface, but there were no agglomerates and no major problem occurred in terms of appearance quality.

Regarding PP resin, a similar press sheet evaluation was performed by mixing paper powder (actually measured particle size 55 to 65 μm) and paper pieces (catalog value particle size 1 to 2 mm, measured particle size 1000 to 2000 μm), but there were many aggregates. Dispersibility was poor. On the other hand, the molding resin materials of bio-PBS resin (Comparative Examples 4 and 5) and PP resin (Comparative Examples 9 and 10) mixed with CMF (catalog value particle size 35 to 45 μm, measured particle size 25 to 35 μm) as a filler are as follows: In the press sheet evaluation, there were almost no agglomerates, indicating excellent dispersibility.

Further, FIG. 9 shows a table showing the evaluation of the appearance of the molding resin material using a scanning electron microscope (SEM). Note that the molding resin material to be evaluated in FIG. 9 is obtained by observing pellets using an SEM.

As shown in Figure 9, the molding resin materials of PLA resin (Comparative Example 1) and PHA resin (Comparative Example 2) mixed with CNF as a filler have large variations in particle size and poor dispersibility as seen from the SEM images. I understand.

On the other hand, the molding resin materials of PLA resin (Example 2), PHA resin (Example 6), and bio-PBS (Example 2) mixed with CMF as a filler have small variations in particle size as seen from SEM images, and are dispersed. It turns out that he has excellent sex. Note that FIG. 9 also shows an SEM image of bio-PBS (comparative example 4) mixed with CMF as a filler, which also had small variations in particle size and excellent dispersibility.

Note that when PP resin was mixed with paper powder and pieces of paper, the particle size varied widely and the dispersibility was poor. Similar paper powder was mixed with PLA resin and observed under SEM, but the particle size varied widely and the dispersibility was poor. On the other hand, the molding resin material of PP resin (Comparative Example 10) mixed with CMF (catalog particle size 35 to 45 μm, measured particle size 25 μm to 35 μm) as a filler had small variations in particle size and had excellent dispersibility.

The physical property evaluation will be explained based on FIG. 4. In physical property evaluation, the required physical properties and their values change depending on the use of the molded product. For example, strength is primarily required for molded products such as automobile parts. On the other hand, items that do not require much strength include so-called daily necessities. Indices for determining strength include bending strength and bending elasticity. IZOD impact strength is important for things that affect impact, such as car bumpers. Additionally, molding shrinkage is generally evaluated as dimensional formability.

As shown in Fig. 4, Examples 2 and 6, which have a biomass ratio of 100% by weight (CMF 20% by weight) and satisfy moldability and appearance, have the bending strength and bending elasticity of the PP resin mixed with talc. It has been possible to achieve physical properties that are equivalent to or better than Comparative Example 7, which is a mixture of PP resin and CMF, and Comparative Example 8, which is a mixture of PP resin and CMF.For molded products that require strength, the biomass ratio of PP resin molded products is 100% by weight. It turns out that it can be replaced. In addition, Examples 2 and 6 are superior in bending elasticity and bending strength to bio-PBS with a biomass ratio of 50% by weight and a mixture of 20% by weight of CMF. For this reason, Examples 2 and 6, for example, can be applied to molded products that require a certain strength, such as automobile parts.

Furthermore, the molding shrinkage rates of Examples 2 and 6 were 1.00% or less, indicating that they had relatively excellent dimensional stability.

Although the required physical properties differ depending on the product to be molded, the molding resin material of this embodiment achieves a biomass ratio of 100% by weight (a high biomass ratio of at least 90% by weight) while maintaining moldability and appearance. It is characterized by its ability to be molded while satisfying its properties.

From the above results, by mixing CMF as a filler with biodegradable plastics as a molding resin material for bioplastics, moldability can be improved, and the resin material has good dispersibility and biodegradability without impairing appearance. It is possible to realize a molding resin material with a high biomass ratio.

Furthermore, by using biodegradable plastics as bioplastics made only from bio-derived materials, it is possible to realize molding resin materials with lower environmental impact.

In particular, by setting the biomass ratio to 100% by weight, the environmental load reduction effect can be maximized.

Furthermore, by setting the biodegradable plastic to 30% by weight or more and the CMF to 20% by weight or more, it is possible to realize a bioplastic molding resin material with sufficient moldability and appearance.

Furthermore, from FIGS. 3 and 4 above, PLA (polylactic acid) resin is suitable as the biodegradable plastic. Further, from FIGS. 3 and 4 above, PHA (PHBV) resin is suitable as the biodegradable plastic. Further, from FIGS. 3 and 4 above, it is suitable that CMF (cellulose microfiber) has a fiber length of 35 μm or more and 45 μm or less.

The resin molded product molded using the molding resin material of this embodiment has excellent moldability and appearance.

In addition, the production method for resin materials for molding includes a drying process in which the moisture content of CMF is dried to 5% by weight or less, and a pressure kneading machine to mix the CMF dried in the drying process and biodegradable plastic. By having the kneading step of kneading, it is possible to produce a molding resin material with a high biomass ratio while preventing problems such as steam explosion.

<Radiocarbon concentration measurement (AMS measurement)>
As samples, the first sample is CMF (sample name: ARBOCEL FD600/30), the second sample is a molding resin material (sample name: PHA(CMF60)-MB), and the third sample is a molding resin material. A sample (sample name: PLA(CMF70)-MB) was prepared. The second sample contained PHA resin and CMF in a weight percent ratio of 40:60. The third sample contained PLA resin and CMF in a weight percent ratio of 30:70. Carbon dioxide was generated by burning each sample without pretreatment, and the generated carbon dioxide was purified using a vacuum line. Furthermore, graphite was produced by reducing purified carbon dioxide with hydrogen using iron as a catalyst. The produced graphite was packed into a cathode with an inner diameter of 1 mm using a hand press machine, which was fitted into a wheel and attached to a measuring device.

The measuring device used was a ¹⁴ C-AMS dedicated device (manufactured by NEC Corporation) based on a tandem accelerator, which counted ¹⁴ C, ¹³ C concentration ( ¹³ C/ ¹² C), and ¹⁴ C concentration ( ¹⁴ C/ ¹² C). C) was measured. In the measurements, oxalic acid (HOxII) provided by the US National Institute of Standards (NIST) was used as a standard sample, and measurements of this standard sample and a background sample were also performed at the same time. The measurement results are shown in Table 1 below.

In Table 1 below, δ ¹³ C is a value obtained by measuring the ¹³ C concentration ( ¹³ C/ ¹² C) of sample carbon and expressing the deviation from the standard sample in thousandth deviation (‰). This value is a value measured by an AMS device, and is also noted as "AMS" in Table 1 below. pMC (percent Modern Carbon) is the ratio of the ¹⁴ C concentration of sample carbon to standard modern carbon. Table 1 below shows values corrected by δ ¹³ C and values not corrected. δ ¹⁴ C is the deviation of the ¹⁴ C concentration of the sample carbon relative to standard modern carbon expressed in thousandths of a deviation (‰), and the value obtained by correcting this with δ ¹³ C is Δ ¹⁴ C.

Furthermore, the biomass degree of the sample calculated using δ ¹³ C-corrected pMC according to ASTM D6866-22 is shown in FIG. The standard value (atmospheric correction factor REF (pMC)) differs depending on the year in which the biomass raw material was produced, so if the origin of the raw material is clear, it is more accurate to use the REF (pMC) of that year. . If the carbon contained in the sample is derived from terrestrial plants, the carbon-based biomass degree for each year of production is as shown in Figure 10. However, if the carbon source is not a terrestrial plant, or if it is terrestrial but is expected to be older than 2004, the calculation will be different. As a reference for REF(pMC), plants around the Shirakawa Analysis Center (Fukushima Prefecture, Japan) showed pMC=98.9 in July 2022. Currently, in environments close to natural, pMC often shows around 99 to 102.

The bar graph in FIG. 10 shows the ratio of biomass-derived carbon and petroleum-derived carbon to the total carbon contained in the sample. Note that the mixing weight ratio of the biomass raw material and the petroleum raw material does not necessarily match the above ratio. IAAA-220645 shows very high pMC values for modern atmospheres. There is a high possibility that the biomass used as raw material, such as wood, is old, and in that case, it is not suitable to use the 2022 REF (pMC) in ASTM D6866-22.

As shown in FIG. 10, it was confirmed that the biomass degree of each of the first sample, second sample, and third sample was 90% by mass or more.

This concludes the description of the embodiments and examples of the present invention, but aspects of the present invention are not limited to these embodiments and examples.

Examples of the disclosure related to the above embodiments are as follows.
[1] A molding resin material containing biodegradable plastic and cellulose microfibers and having a biomass ratio of 90% by mass or more.
[2] The molding resin material according to [1], wherein the biodegradable plastic is a biomass plastic made only of bio-derived materials.
[3] The molding resin material according to [1] or [2], wherein the biomass ratio is 100% by mass.
[4] The molding resin material according to any one of [1] to [3], wherein the biodegradable plastic is 30% by weight or more, and the cellulose microfiber is 20% by weight or more.
[5] The molding resin material according to any one of [1] to [4], wherein the biodegradable plastic is a polylactic acid resin.
[6] The molding resin material according to any one of [1] to [4], wherein the biodegradable plastic is a polyhydroxyalkanoate resin.
[7] The molding resin material according to any one of [1] to [6], wherein the cellulose microfiber has a fiber length of 35 μm or more and 45 μm or less.
[8] A resin molded article molded using the molding resin material according to any one of [1] to [5] above.
[9] A drying step in which the water content of cellulose microfibers is dried to 5% by weight or less, and a kneading step in which the cellulose microfibers dried in the drying step and biodegradable plastic are kneaded using a pressure kneader. A method for producing a molding resin material, including a process.

1 Pellet production device 2 Kneader 3 Extruder 4 Conveyor 20 Barrel 21 Kneader screw 22 Pressure press 23 Inlet 30 Hopper 31 Hopper screw 32 Cylinder 33 Straight screw 34 Pelletizer 34a Die 34b Rotary cutter 40 Bucket

Claims (9)

1. A molding resin material containing biodegradable plastic and cellulose microfibers and having a biomass ratio of 90% by mass or more.
2. The molding resin material according to claim 1, wherein the biodegradable plastic is a biomass plastic made only of bio-derived materials.
3. The molding resin material according to claim 1, wherein the biomass ratio is 100% by mass.
4. The biodegradable plastic is 30% by weight or more,
   The molding resin material according to claim 1, wherein the cellulose microfiber is 20% by weight or more.
5. The molding resin material according to claim 1, wherein the biodegradable plastic is a polylactic acid resin.
6. The molding resin material according to claim 1, wherein the biodegradable plastic is a polyhydroxyalkanoate resin.
7. The molding resin material according to claim 1, wherein the cellulose microfiber has a fiber length of 35 μm or more and 45 μm or less.
8. A resin molded article molded using the molding resin material according to any one of claims 1 to 5.
9. a drying step of drying the cellulose microfiber to a moisture content of 5% by weight or less;
   a kneading step of kneading the cellulose microfibers dried in the drying step and biodegradable plastic using a pressure kneader;
   A method for producing a resin material for molding, including:
   

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