JP7433682B2 - Particles and resin compositions - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies TOKYO PACK 2018 (2018 Tokyo International Packaging Exhibition) Exhibition date October 2, 2018

The present invention relates to particles and resin compositions, and particularly to particles having a cellulose powder-containing coating layer and resin compositions produced using the particles.

Plastic molded products containing biomass materials are attracting attention. Since the plastic molded product contains biomass material as a substitute for petroleum-based materials, it is possible to reduce CO ₂ emitted during combustion. Examples of biomass materials include waste biomass (food waste, livestock excrement, construction waste, waste paper, etc.), unused biomass (inedible parts of agricultural crops, forest residue, etc.), and resource grains. can. More specific examples of biomass materials include wood flour, rice straw, bamboo, and old rice.

Regarding plastic molded products containing biomass materials, for example, Patent Document 1 below states that 50 to 70% by weight of starch, 20 to 40% by weight of thermoplastic resin, and 0.1 to 10% by weight of a plastic molded product having a melting point of 60 to 60% by weight. It contains a low melting point additive of 100°C and a high melting point additive of 1 to 15% by weight with a melting point of 100°C to 150°C, has a core part of a thermoplastic resin granule, and has a core part surface of the granule. A starch/resin composite molding formed by resin melt extrusion using a starch/resin composite intermediate granule as a raw material, which is provided with a coating layer of powder or granule containing starch containing at least a low melting point additive and adhered to by at least a high melting point additive. A processed material is disclosed.

JP 2018-104629 Publication

There is a need to improve the physical properties of plastic molded products containing biomass materials. For example, if physical properties such as rigidity, heat resistance, or dimensional stability can be improved, the applications of plastic molded products containing biomass materials will be further expanded, and it is thought that they can further contribute to the environment. Therefore, an object of the present invention is to improve the physical properties of plastic molded products containing biomass materials.

The present inventors have discovered that a resin composition having a high biomass material content and excellent physical properties can be produced by using particles having a specific configuration.

That is, the present invention provides particles that are composed of a particle core made of a thermoplastic resin and a cellulose powder-containing coating layer that covers at least a portion of the particle core.
According to one embodiment of the present invention, among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is greater than the total number of cellulose fibers constituting the cellulose powder. It can account for 65% to 100%.
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm may account for 0% to 30% of the total number of cellulose fibers constituting the cellulose powder.
The particles can be used to form films or sheets.
According to another embodiment of the invention, the cellulose powder may have a particle size with a 100 mesh pass of 90% or more.
The particles can be used for injection molding.
The coating layer may include a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant.
The second lubricant may contain at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, aliphatic amides, and fatty acid esters.
The first lubricant may include glycerin fatty acid ester.
The particles may have a generally spherical shape with a diameter of 3 mm to 10 mm.

Further, the present invention includes a thermoplastic resin and cellulose powder, and the content of the cellulose powder is 20% by mass to 50% by mass with respect to the mass of the resin composition,
A resin composition is also provided, further comprising a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant.
According to one embodiment of the present invention, among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is greater than the total number of cellulose fibers constituting the cellulose powder. It can account for 65% to 100%.
According to another embodiment of the invention, the cellulose powder may have a particle size with a 100 mesh pass of 90% or more.
The resin composition may include a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant.
The total mass of the cellulose powder and the thermoplastic resin may be 70% by mass to 98% by mass based on the mass of the resin composition.
Moreover, the present invention
A resin composition comprising a thermoplastic resin and cellulose powder,
The cellulose powder is contained in the resin composition at a content rate of 10 parts by mass to 60 parts by mass per 100 parts by mass of the resin composition,
The total mass of the cellulose powder and the thermoplastic resin contained in the resin composition is 70% by mass to 98% by mass with respect to the mass of the resin composition,
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm accounts for 65% to 100% of the total number of cellulose fibers constituting the cellulose powder,
further comprising a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant,
The resin composition includes a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant,
The content of the first lubricant in the resin composition is 0.5 parts by mass to 5 parts by mass based on 100 parts by mass of the cellulose powder,
The content of the second lubricant in the resin composition is 3 parts by mass to 20 parts by mass based on 100 parts by mass of the cellulose powder.
The resin composition is also provided.
The resin composition may be a thermoplastic resin composition.
The cellulose powder may have a particle size in which a 100 mesh pass is 90% or more.
The thermoplastic resin may be a polyolefin resin, a polystyrene resin, a polyamide resin, or a polyester resin.
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm may account for 0% to 30% of the total number of cellulose fibers constituting the cellulose powder.

Using the particles of the present invention, a resin composition with a high cellulose content can be produced. Furthermore, the resin composition has excellent physical properties such as rigidity, heat resistance, and dimensional stability.
Further, by employing a specific cellulose powder as the cellulose powder contained in the coating layer of the particles, the physical properties can be further improved.
Note that the effects of the present invention are not necessarily limited to the effects described herein, and may be any of the effects described herein.

FIG. 1 is a schematic illustration of an example of particles according to the invention. It is a figure which shows the evaluation result of a bending elastic modulus. It is a figure which shows the evaluation result of load deflection temperature. It is a figure which shows the evaluation result of dimensional stability.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. Note that the embodiments described below are examples of typical embodiments of the present invention, and the present invention is not limited only to these embodiments.

1. particle

A schematic diagram of the particles of the present invention is shown in FIG. As shown in FIG. 1, the particles 1 of the present invention are composed of a particle core portion 2 made of a thermoplastic resin and a cellulose powder-containing coating layer 3 that covers at least a portion of the particle core portion. The particles of the present invention are suitable for producing cellulose-containing resin compositions, and are particularly suitable for producing resin compositions with a high cellulose content. Furthermore, by using the particles of the present invention, it is also possible to improve the dispersibility of cellulose powder within the resin composition. The particle core portion and the coating layer will be explained below.

1-1. Particle core part

The particle core portion is made of thermoplastic resin. The thermoplastic resin may be, for example, a polyolefin resin, a polystyrene resin, a polyamide resin, or a polyester resin, and preferably a polyolefin resin.

Polyolefin resins are polymers obtained by polymerization using olefins (eg, α-olefins) as main monomers. The polyolefin resin may be, for example, a polyethylene resin, a polypropylene resin, or a mixture thereof. The polyethylene resin is a resin whose main component is polyethylene, and may contain polyethylene in a proportion of, for example, 90% by mass or more, preferably 95% by mass or more, preferably 98% by mass or more based on the mass of the resin. The polypropylene resin is a resin containing polypropylene as a main component, and may contain, for example, polypropylene in a proportion of 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more based on the mass of the resin.
More specifically, polyethylene includes low density polyethylene (LDPE), high density polyethylene (HDPE), very low density polyethylene (VLDPE), and linear low density polyethylene ( It may be LLDPE (Linear Low Density Polyethylene), ultra high molecular weight polyethylene (UHMW-PE), or a combination of two or more of these.
The polypropylene may more particularly be a homopolymer polypropylene or a random copolymer or block copolymer polypropylene (such as an ethylene-propylene copolymer).

The polyolefin resin may preferably be a biomass-derived polyolefin resin, for example, biomass polyethylene and/or biomass polypropylene. The biomass polyethylene can be, for example, LDPE, LLDPE, or HDPE. By employing a biomass-derived polyolefin resin as the polyolefin resin, CO2 emissions can be reduced.

The polyolefin resin may be a polyolefin resin manufactured using a metallocene catalyst. For example, the polyolefin resin may be, for example, metallocene-catalyzed polyethylene or polypropylene, or a combination thereof.

The polystyrene resin is a resin containing polystyrene as a main component, and may contain polystyrene in a proportion of, for example, 90% by mass or more, preferably 95% by mass or more, preferably 98% by mass or more based on the mass of the resin. Examples of polystyrene include, for example, general purpose polystyrene (GPPS) and high impact polystyrene (HIPS).

The polyamide resin is a resin containing polyamide as a main component, and may contain polyamide in a proportion of, for example, 90% by mass or more, preferably 95% by mass or more, preferably 98% by mass or more based on the mass of the resin. The polyamide may be, for example, an aliphatic polyamide, more specifically polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 11, polyamide 12, or polyamide 6.12.

The polyester resin is a resin containing polyester as a main component, and may contain polyester in a proportion of, for example, 90% by mass or more, preferably 95% by mass or more, preferably 98% by mass or more based on the mass of the resin. Examples of polyesters include polyethylene terephthalate (hereinafter also referred to as PET), polybutylene succinate (hereinafter also referred to as PBS), polybutylene succinate adipate (hereinafter also referred to as PBSA), polybutylene adipate terephthalate (hereinafter also referred to as PBAT), polyhydroxy Alkanoic acid (hereinafter also referred to as PHA), polylactic acid (hereinafter also referred to as PLA), polybutylene terephthalate (hereinafter also referred to as PBT), polyethylene naphthalate (hereinafter also referred to as PEN), polyarylate (hereinafter also referred to as PAR), polycarbonate (hereinafter also referred to as PEN), (hereinafter also referred to as PC), and one or a combination of two or more of these may be used as the polyester.

In the present invention, the thermoplastic resin preferably has a melting point higher than that of the second lubricant described below. That is, the thermoplastic resin has a melting point higher than either of the first lubricant and the second lubricant. As a result, when producing the particles of the present invention, the materials can be mixed at a temperature where the first lubricant and the second lubricant melt but the thermoplastic resin does not melt, and the particle core portion can be mixed more easily. A cellulose powder-containing coating layer can be formed around it. The thermoplastic resin may preferably have a melting point of 110°C to 250°C, more preferably 115°C to 230°C, even more preferably 120°C to 210°C.

The particle core preferably has a substantially spherical shape, more preferably has a diameter of 2 mm to 9 mm, more preferably has a diameter of 2 mm to 7 mm, and particularly preferably has a diameter of 3 mm to 5 mm. . By employing a particle core having such a shape, it becomes easier to cover the entire particle core with cellulose powder.
The particles of the present invention preferably have a substantially spherical morphology, more preferably a substantially spherical morphology with a diameter of 3 mm to 10 mm, and even more preferably a substantially spherical morphology with a diameter of 4 mm to 7 mm.
By having the above dimensions, each component can be easily mixed in the production of the resin composition described below, and the resin composition can be produced more easily.

The particle core portion may preferably account for 20% to 90% by weight, more preferably 20% to 80% by weight, and even more preferably 30% to 70% by weight of the weight of the particles of the present invention. That is, the content of the thermoplastic resin constituting the particle core is preferably 20% by mass to 90% by mass, more preferably 20% to 80% by mass, and even more preferably Preferably, it may be 30% by mass to 70% by mass.

1-2. Covering layer containing cellulose powder

The cellulose powder-containing coating layer covers at least a portion of the particle core, preferably covers 80% or more of the surface area of the particle core, more preferably covers 90% or more, and particularly preferably The entire surface of the particle core portion is covered.

The cellulose powder-containing coating layer preferably includes a lubricant. The cellulose powder constituting the coating layer can be attached to the surface of the particle core by the lubricant. The lubricant can reduce the friction between the resin composition and the molding machine and/or the friction between particles. The fluidity and/or mold releasability of the resin composition can be improved by the lubricant.

According to a preferred embodiment of the present invention, the cellulose powder-containing coating layer includes a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant. By including these two types of lubricants having different melting points, the cellulose powder can be more easily attached to the particle core portion. The first lubricant may have a melting point of, for example, 50°C to 100°C, preferably 55°C to 90°C, more preferably 60°C to 80°C. The second lubricant may have a melting point of, for example, 100°C to 160°C, preferably 100°C to 150°C, more preferably 100°C to 140°C.

As the first lubricant, for example, an ester-based lubricant can be used, and in particular, an ester-based lubricant having a melting point within the numerical range described above can be used. Examples of ester-based lubricants include glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, special fatty acid esters, and higher alcohol fatty acid esters. The glycerin fatty acid ester includes monoglyceride, diglyceride, triglyceride, acetylated monoglyceride, organic acid monoglyceride, and medium chain fatty acid monoglyceride.
According to a preferred embodiment of the present invention, the first lubricant comprises an ester-based lubricant, more preferably a glycerin fatty acid ester, and even more preferably a glycerin monostearate. The first lubricant may be only an ester-based lubricant, more preferably only glycerin fatty acid ester, and even more preferably only glycerin monostearate.

The second lubricant may include at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, aliphatic amides, and fatty acid esters. The second lubricant is at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, aliphatic amides, and fatty acid esters, particularly having a melting point within the numerical range mentioned above. It can be.
Examples of the fatty acid metal salt include metal salts of saturated or unsaturated fatty acids having 10 to 30 carbon atoms, particularly 12 to 25 carbon atoms. More specifically, the second lubricant is selected from the group consisting of magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, sodium lauryl sulfate, magnesium lauryl sulfate, potassium benzoate, and sodium benzoate. It can be at least one species.

According to a particularly preferred embodiment of the present invention, the first lubricant may be the glycerin fatty acid ester, and the second lubricant may be the fatty acid metal salt. By using these compounds as the first and second lubricants, the melt viscosity in extrusion for producing a resin composition from the particles of the present invention can be made more appropriate.

The content of the first lubricant in the particles may be, for example, 0.5 parts by mass to 5 parts by mass, preferably 1 part by mass to 4 parts by mass, based on 100 parts by mass of the cellulose powder.
The content of the second lubricant in the particles may be, for example, 3 parts by mass to 20 parts by mass, preferably 5 parts by mass to 15 parts by mass, based on 100 parts by mass of the cellulose powder. In particular, the content of the fatty acid metal salt in the particles may be, for example, 3 parts by mass to 20 parts by mass, preferably 5 parts by mass to 15 parts by mass, based on 100 parts by mass of the cellulose powder.
Setting the amounts of the first and second lubricants within the numerical range described above contributes to making the melt viscosity of the resin composition produced from the particles of the present invention suitable for molding.
Furthermore, it is suitable for the production of the particles of the present invention that the amounts of the first and second lubricants are within the numerical range described above. It becomes easier to attach the powder, that is, it becomes possible to manufacture the particles of the present invention more efficiently.

The particle size D50 (median diameter) of the cellulose powder contained in the cellulose powder-containing coating layer may be, for example, 15 μm to 150 μm, particularly preferably 20 μm to 100 μm. The particle size D50 is determined by wet measurement using a laser diffraction particle size distribution analyzer (SALD-3100, Shimadzu Corporation). Cellulose powders having particle sizes within the above numerical ranges are suitable for forming the particles of the present invention. Furthermore, having the particle size of the cellulose powder within the above numerical range can contribute to improving the dispersibility of the cellulose powder in the resin composition of the present invention.

According to one preferred embodiment of the present invention, among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is the total number of cellulose fibers constituting the cellulose powder. 65% to 100%, preferably 70% to 100%, more preferably 80% to 100%, even more preferably 85% to 100%. The above ratio regarding the number of cellulose fibers is the ratio of the number of cellulose fibers having a particle size of 0 μm to 9.8 μm (hereinafter referred to as "first ratio") out of the total number of cellulose fibers in the cellulose powder, and the ratio of the number of cellulose fibers having a particle size of 0 μm to 9.8 μm (hereinafter referred to as "first ratio"). The ratio of the number of cellulose fibers having a particle size of 110.6 μm (hereinafter referred to as "second ratio") is determined by wet measurement using the laser diffraction particle size distribution analyzer, and It is determined by subtracting the first ratio from . The numerical ranges "0 μm to 9.8 μm" and "0 μm to 110.6 μm" are both numerical ranges input to the laser diffraction particle size distribution measuring device in the wet measurement.
In this embodiment, particularly preferably, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder is greater than the total number of cellulose fibers constituting the cellulose powder. It accounts for 0% to 30%, preferably 0% to 25%, more preferably 0% to 20%, even more preferably 0% to 15%. The above ratio regarding the number of cellulose fibers is the ratio of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (the above “second ratio”) out of the total number of cellulose fibers of the cellulose powder, and the ratio of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (the above “second ratio”) The ratio of the number of cellulose fibers having a particle size of 998.4 μm (hereinafter referred to as the "third ratio") is determined by wet measurement using the laser diffraction particle size distribution analyzer, and the third ratio is determined by wet measurement using the laser diffraction particle size distribution measuring device. It is determined by subtracting the second ratio from . The numerical ranges "0 μm to 110.6 μm" and "0 μm to 998.4 μm" are both numerical ranges input to the laser diffraction particle size distribution measuring device in the wet measurement.
Cellulose powder having the above particle size distribution can be produced, for example, by treating pulp with chemicals such as acids. An example of the cellulose powder having the above particle size distribution is KC Flock W400 (Nippon Paper Industries Co., Ltd.).
The particles of the invention can be used to form films or sheets. In particular, by using a cellulose powder having the particle size distribution in this embodiment, better formability (especially in vacuum forming) is achieved when thin molded articles such as films and sheets are manufactured using the particles of the present invention. gender) is brought about.
In particular, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm among the cellulose fibers constituting the cellulose powder is 80% to 100% of the total number of cellulose fibers constituting the cellulose powder, Even more preferably, by accounting for 85% to 100%, it is possible to prevent the occurrence of tears or holes in a molded product obtained by subjecting a resin composition produced using the particles of the present invention to vacuum forming. In order to prevent the formation of tears or holes in the molded product, it is particularly preferable that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder constitute the cellulose powder. 0% to 20%, even more preferably 0% to 15% of the total number of cellulose fibers.
As mentioned above, the particles according to this embodiment are suitable for the production of resin compositions for forming films or sheets, ie can be used for producing films or sheets. It should be noted that particles according to this embodiment may be used for injection molding.

According to another preferred embodiment of the present invention, the cellulose powder may have a particle size with a 100 mesh pass of 90% or more. In this embodiment, more preferably, the cellulose powder has a particle size with a 100 mesh pass of 90% or more, and the apparent specific gravity of the cellulose powder is 0.30 g/ml to 0.40 g/ml. It's possible.

The particle size is measured by a standard sieve method, specifically as follows. That is, 10 g of the sample is placed in a 100-mesh standard sieve, a saucer and a lid are set on the standard sieve, and the sample is shaken for 40 minutes using a low-tap shaker. Then, the particle size is determined from the sample mass (10 g) and the mass of the sieve residue using the following formula.
Particle size (%) = [(sample mass (g) - sieve residue (g)) / sample mass (g)] x 100

The apparent specific gravity is measured as follows. That is, 10 g of the sample is accurately weighed using a balance and placed in a 50 ml graduated cylinder. Place the bottom of the graduated cylinder on a table covered with a rubber sheet and tap it to prevent the sample from scattering. Continue this tapping operation until the sample is no longer clogged. After the tapping operation, the surface of the sample is leveled and its scale (volume, ml) is read. Then, the apparent specific gravity can be calculated using the following formula.
Apparent specific gravity (g/ml) = sample (10g)/volume (ml)

Cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity) can be produced, for example, by mechanically pulverizing pulp (for example, by jet milling). As the cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity), for example, KC Flock 100GK can be mentioned.
The particles of the invention can be used for injection molding. In particular, the use of cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity) provides good moldability when the particles of the invention are subjected to injection molding. Furthermore, the cellulose powder contributes to improving the strength and/or heat resistance of the resin composition produced using the particles of the present invention.

The total mass of the cellulose powder and the thermoplastic resin constituting the particles of the present invention is, for example, 70% to 98% by mass, preferably 80% to 97% by mass, more preferably can be from 85% to 95% by weight. When the total mass is within this range, the amount of resin in the resin composition produced from the particles can be increased, and further the content of cellulose powder can be increased.

The cellulose powder-containing resin layer may further contain other components. Examples of the other components include a compatibilizer and a coloring agent.

The compatibilizer can be used to more uniformly disperse cellulose in a resin composition made from the particles. The compatibilizer may be selected depending on the type of thermoplastic resin. Examples of the compatibilizer include acid-modified polyolefin, acid-modified nylon, acid-modified polystyrene, acid-modified EVA, acid-modified ethylene copolymer, acid-modified acrylate, acrylic acid-modified EVA, and modified ethylene acrylate.

When the thermoplastic resin is a polyolefin-based resin, the compatibilizing agent is preferably an acid-modified polyolefin, and in particular may be a carboxylic anhydride-modified polyolefin or an olefin-based comonomer.
The carboxylic anhydride constituting the carboxylic anhydride-modified polyolefin may preferably be maleic anhydride. The compatibilizer is, for example, a maleic anhydride-grafted polyolefin resin, more particularly one selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer. It may be one or a combination of two or more. A rubber component may be dispersed in the compatibilizer.
The compatibilizer may be contained in the particles at a content rate of, for example, 0.1 parts by mass to 10 parts by mass, more preferably 0.5 parts by mass to 6 parts by mass, per 100 parts by mass of the particles.

The coloring agent can be used to color a resin composition produced from the particles. Examples of the coloring agent include titanium oxide, carbon black, dyes, and pigments.

Further, as the other components, for example, an antioxidant and an impact resistance agent may be used. As the antioxidant, for example, a phenolic antioxidant can be used. The impact agent may be, for example, a styrene thermoplastic elastomer, more specifically, for example, a styrene-ethylene-butylene-styrene block copolymer (SEBS), a styrene-ethylene-ethylene-propylene-styrene block copolymer. (SEEPS), and styrene-ethylene-propylene-styrene block copolymer (SEPS).

1-3. Method for producing particles of the present invention

The method for producing particles of the present invention may include the following steps:
(1) The cellulose powder, the first lubricant, the second lubricant, and the thermoplastic resin that will become the particle core are heated to a temperature that is higher than the melting point of the second lubricant and lower than the temperature of the thermoplastic resin. A mixing step of mixing to obtain a mixture containing the melted first lubricant, the second lubricant, the cellulose powder, and the thermoplastic resin; and (2) the mixture obtained in the mixing step, A cooling step of cooling while stirring to a temperature that is higher than the melting point of the first lubricant and lower than the melting point of the second lubricant.
In the cooling step, the second lubricant is solidified, and a cellulose powder-containing coating layer containing the first lubricant, the second lubricant, and the cellulose powder is formed on the surface of the particle core part, Particles of the invention are obtained.
Each step will be explained in more detail below.

(1) Mixing process

In the mixing step, the cellulose powder, the first lubricant, the second lubricant, and the thermoplastic resin forming the particle core are mixed. In the mixing step, the above 1-2. Other ingredients mentioned above (such as compatibilizers, colorants, antioxidants, and impact stabilizers) may also be mixed.

Said mixing step may be carried out, for example, with a stirring device known in the art, whose mixing temperature can be set to the above-mentioned temperature. As described above, the mixing step is performed at a temperature that is higher than the melting point of the second lubricant and lower than the temperature of the thermoplastic resin. The mixing step may be performed, for example, at a temperature of 100°C to 160°C, preferably 100°C to 150°C, more preferably 100°C to 140°C.

In the mixing step, by mixing at the above temperature, the first lubricant and the second lubricant melt, but the thermoplastic resin does not melt. In the mixing step, a state is formed in which the cellulose powder, the solid thermoplastic resin, and the melted first lubricant and second lubricant are mixed.

The cooling step is performed such that the mixture obtained in the mixing step does not reach a temperature lower than the melting point of the second lubricant (in particular, while maintaining the temperature adopted in the mixing step). can be supplied to the device.

(2) Cooling process

In the cooling step, the mixture obtained in the mixing step may be cooled while being stirred to a temperature that is higher than the melting point of the first lubricant and lower than the melting point of the second lubricant. By performing cooling while stirring, a more uniform cellulose powder-containing coating layer is formed around the particle core, and the particles of the present invention can be obtained.

The cooling step may be performed using a stirring device capable of cooling the mixture obtained in the mixing step to a temperature that is higher than the melting point of the first lubricant and lower than the melting point of the second lubricant.

The particles of the present invention obtained by the above production method are preferably maintained at a temperature that is higher than the melting point of the first lubricant and lower than the melting point of the second lubricant. This can prevent the cellulose powder from peeling off from the particles.

1-4. Methods of using the particles of the invention

The particles of the present invention can be used, for example, to produce a resin composition containing cellulose powder and a thermoplastic resin. For example, by heating the particles of the present invention to a temperature higher than the melting point of the thermoplastic resin constituting the particles and kneading them, a resin composition in which cellulose powder constituting the particles is dispersed in the thermoplastic resin can be created. can get. By manufacturing the resin composition using the particles of the present invention, a resin composition in which cellulose powder is well dispersed can be manufactured. The resin composition obtained using the particles of the present invention may be the resin composition according to the present invention described below in "2. Resin Composition".

2. resin composition

The resin composition of the present invention includes a thermoplastic resin and cellulose powder, and the content of the cellulose powder is 20% by mass to 50% by mass with respect to the mass of the resin composition. Furthermore, the resin composition of the present invention further includes a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant.

2-1. Composition of resin composition

The thermoplastic resin and cellulose powder contained in the resin composition of the present invention are as explained in "1-1. Particle core part" and "1-2. Cellulose powder-containing coating layer" above, and the explanation is in accordance with the main text. This also applies to the resin compositions of the invention.

The content of the cellulose powder in the resin composition of the present invention is 20% by mass to 50% by mass, preferably 22% by mass to 48% by mass, more preferably 25% by mass, based on the mass of the resin composition. ~45% by weight.

The total mass of the cellulose powder and the thermoplastic resin contained in the resin composition of the present invention is, for example, 70% to 98% by mass, preferably 80% to 97% by mass, based on the mass of the resin composition. %, more preferably 85% to 95% by weight. When the total mass is within the range, the amount of resin in the resin composition can be increased, and the content of cellulose powder can also be increased.

The ratio of the mass of the cellulose powder to the mass of the thermoplastic resin contained in the resin composition of the present invention is preferably 1:1 to 1:4, more preferably 1:1 to 1:3, and even more preferably may be 1:1 to 1:2.5. By adjusting the ratio within the range, the dispersibility of the cellulose powder in the resin composition can be improved.

The resin composition of the present invention includes a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant. The first lubricant and the second lubricant are as explained in "1-2. Cellulose powder-containing coating layer" above, and the same explanation also applies to the resin composition of the present invention. According to a particularly preferred embodiment of the present invention, the first lubricant may be the glycerin fatty acid ester, and the second lubricant may be the fatty acid metal salt.

The content of the first lubricant in the resin composition of the present invention is, for example, 0.5 parts by mass to 5 parts by mass, preferably 1 part to 4 parts by mass, based on 100 parts by mass of the cellulose powder. It's possible.
The content of the second lubricant in the resin composition of the present invention may be, for example, 3 parts by mass to 20 parts by mass, preferably 5 parts by mass to 15 parts by mass, based on 100 parts by mass of the cellulose powder. .
Setting the amounts of the first and second lubricants within the numerical range described above contributes to making the melt viscosity of the resin composition of the present invention suitable for molding.

The particle size D50 (median diameter) of the cellulose powder contained in the resin composition of the present invention may be, for example, 15 μm to 150 μm, particularly preferably 20 μm to 100 μm. The particle size D50 is determined by wet measurement using a laser diffraction particle size distribution analyzer (SALD-3100, Shimadzu Corporation). Using cellulose powder having a particle size within the above numerical range can contribute to improving the dispersibility of cellulose powder in the resin composition of the present invention.

According to one preferred embodiment of the present invention, among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is the total number of cellulose fibers constituting the cellulose powder. 65% to 100%, preferably 70% to 100%, more preferably 80% to 100%, even more preferably 85% to 100%. The method for calculating the ratio regarding the number of cellulose fibers is as described in "1-2. Cellulose powder-containing coating layer" above.
In this embodiment, particularly preferably, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder is greater than the total number of cellulose fibers constituting the cellulose powder. It accounts for 0% to 30%, preferably 0% to 25%, more preferably 0% to 20%, even more preferably 0% to 15%. The method for calculating the ratio regarding the number of cellulose fibers is also the same as described in "1-2. Cellulose powder-containing coating layer" above.
By containing cellulose powder having such a particle size distribution, the resin composition of the present invention has better moldability (especially moldability in vacuum forming) when producing thin molded products such as films and sheets. is brought about.
In particular, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm among the cellulose fibers constituting the cellulose powder is 80% to 100% of the total number of cellulose fibers constituting the cellulose powder, Even more preferably, by accounting for 85% to 100%, it is possible to prevent the occurrence of tears or holes in a molded product obtained by subjecting the resin composition of the present invention to vacuum forming. In order to prevent the formation of tears or holes in the molded product, it is particularly preferable that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder constitute the cellulose powder. 0% to 20%, even more preferably 0% to 15% of the total number of cellulose fibers.
As described above, the resin composition of the present invention according to this embodiment can be used to form a film or sheet.

According to another preferred embodiment of the present invention, the cellulose powder may have a particle size with a 100 mesh pass of 90% or more. In this embodiment, more preferably, the cellulose powder has a particle size with a 100 mesh pass of 90% or more, and the apparent specific gravity of the cellulose powder is 0.30 g/ml to 0.40 g/ml. It's possible. The particle size and apparent specific gravity are measured as described in "1-2. Cellulose powder-containing coating layer" above.
By using a cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity), good moldability is provided when the resin composition of the present invention is subjected to injection molding. Furthermore, the cellulose powder contributes to improving the strength and/or heat resistance of the resin composition of the present invention.

The resin composition of the present invention may further contain other components. Examples of the other components include a compatibilizer and a coloring agent. The compatibilizer and colorant are as described in "1-2. Cellulose powder-containing coating layer" above. Further, as the other components, for example, an antioxidant and an impact resistance agent may be used.

The resin composition of the present invention can be used to form a film or sheet. That is, the present invention also provides the resin composition of the present invention in the form of a film or sheet. The thickness of the film may be, for example, from 10 μm to 500 μm, particularly from 10 μm to 300 μm, more particularly from 10 μm to 200 μm. The thickness of the sheet may be, for example, from 0.2 mm to 2 mm, especially from 0.3 mm to 1.5 mm, more particularly from 0.4 mm to 1 mm.

2-2. Physical properties of resin composition

The resin composition of the present invention has a dimensional change rate of preferably -0.5% to +0.5%, more preferably It may be -0.4% to +0.4%, more preferably -0.2% to +0.2%. The dimensional change rate is the dimensional change rate in the long side direction of a resin composition having dimensions of 32 cm long side x 14 cm short side x 0.4 mm thickness. The resin composition of the present invention thus has a low dimensional change rate.

The resin composition of the present invention has a flexural modulus of elasticity measured according to JIS K 7171, preferably 1.8 GPa or more, more preferably 1.8 GPa to 3 GPa, even more preferably 2 GPa to 2.8 GPa. It can be. The bending elastic modulus is measured for a resin composition having dimensions of 8 cm long side x 1 cm short side x 0.5 cm thickness. The resin composition of the present invention has such a bending modulus, that is, it has excellent rigidity.

The resin composition of the present invention has a deflection temperature under load when measured according to JIS K 7191, preferably 100°C or higher, more preferably 100°C to 150°C, even more preferably 105°C to 130°C. It's possible. The deflection temperature under load is measured for a resin composition having dimensions of 8 cm long side x 1 cm short side x 0.5 cm thickness. The load in the measurement was 0.45 MPa. The resin composition of the present invention has such a deflection temperature under load, that is, it has excellent heat resistance.

2-3. Method for manufacturing resin composition

The method for producing the resin composition of the present invention includes a kneading step of heating and kneading the particles of the present invention to a temperature equal to or higher than the melting point of the thermoplastic resin forming the particle core portion of the particles. The kneaded product obtained by the kneading step is the resin composition of the present invention. The manufacturing method may further include a molding step of molding the resin composition obtained in the kneading step. The molded resin composition is also included in the resin composition of the present invention. The kneading process and molding process will be explained below.

(1) Kneading process

The particles of the present invention used in the kneading step are as explained in "1. Particles" above, and the explanation also applies to the manufacturing method of the present invention. In the kneading step, the thermoplastic resin contained in the particles of the present invention is melted, and the cellulose powder contained in the cellulose powder-containing coating layer of the particles of the present invention is dispersed in the melted thermoplastic resin. . Further, in the kneading step, the first lubricant and the second lubricant that may be included in the particles of the present invention may also be melted and mixed with the thermoplastic resin.

Preferably, the particles of the present invention obtained in the cooling step described in "1-3. Method for producing particles of the present invention" have a melting point higher than the melting point of the first lubricant and a melting point of the second lubricant. While being maintained at a lower temperature, it may be fed to a device for performing the kneading step (such as an extruder described below).

The kneading step may be performed at a temperature at which the thermoplastic resin contained in the particles of the present invention can be melted. The temperature may be appropriately selected by those skilled in the art depending on the melting point of the thermoplastic resin used. The kneading step is performed at, for example, 100°C to 250°C, preferably 110°C to 250°C, more preferably 115°C to 230°C, even more preferably 120°C to 210°C, particularly preferably 120°C to 190°C. I can.

The kneading step may be performed using, for example, a twin-screw kneading extruder or a single-screw kneading extruder. As these extruders, equipment known in the art may be used. Preferably, the kneading step includes at least heating and kneading treatment using a twin-screw kneading extruder. As the twin-screw kneading extruder, a co-rotating twin-screw kneading extruder or a counter-rotating twin-screw kneading extruder may be used. By performing the kneading process using a twin-screw kneading extruder, a resin composition in which cellulose powder is more uniformly dispersed can be obtained.

The kneaded product obtained in the kneading step may be directly subjected to the molding step without being pelletized. Thereby, the pelletizing step can be omitted.
Note that the kneading product obtained in the kneading step may be pelletized. The pelletized resin composition may be subjected to a molding process.

(2) Molding process

In the molding step, the resin composition produced in the kneading step is molded. The resin composition of the present invention is suitable for molding a molded article having a thickness of, for example, 20 μm to 5 mm, that is, it can be used to mold the molded article.

In the molding step, the resin composition of the present invention can be molded into, for example, a film or a sheet. The thickness of the film or sheet may be, for example, 0.01 mm to 5 mm. Inflation molding can be performed to produce the film. The inflation molding can be performed using a ring die, for example. Further, in order to manufacture the sheet, molding using a T-die may be performed. In these moldings, for example, the kneaded product may be extruded as is from these dies without being pelletized, or the pelletized resin composition may be melted, and the molten resin composition may be It may be extruded from these dies.

Alternatively, in the molding step, the resin composition of the present invention may be molded by injection molding or vacuum molding. For example, the resin composition of the present invention can be molded into the shape of a container. Injection molding or vacuum forming may be used to form the shape of the container. In the injection molding, the resin composition of the present invention can be injected in a molten state into a mold for giving the resin composition a desired shape (for example, a container). The resin composition is cooled in the mold, and a resin composition (molded article) having a desired shape is obtained. In the vacuum forming, the sheet is softened by heating, and the softened sheet is brought into close contact with a mold by suction to form the sheet.

2-4. Specific examples of resin compositions

The resin composition of the present invention may be thermoplastic. Since the resin composition of the present invention is thermoplastic, molded articles having various shapes can be manufactured. More detailed specific examples of the composition and uses of the resin composition according to the present invention will be explained below.

(1) Thermoplastic resin composition for sheet molding

According to one embodiment of the present invention, the thermoplastic resin composition may include cellulose powder and polypropylene.
The cellulose powder is, for example, 10 parts by mass to 60 parts by mass, preferably 15 parts by mass to 55 parts by mass, more preferably 20 parts by mass to 50 parts by mass, and even more preferably, per 100 parts by mass of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 25 parts by mass to 45 parts by mass.
The polypropylene is, for example, 30 parts to 80 parts by weight, preferably 35 parts to 75 parts by weight, more preferably 40 parts to 70 parts by weight, and even more preferably 45 parts by weight, per 100 parts by weight of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 65 parts by mass.

Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is 65% to 100% of the total number of cellulose fibers constituting the cellulose powder, preferably 70%. % to 100%, more preferably 80% to 100%, even more preferably 85% to 100%. Particularly preferably, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder is 0% to 30% of the total number of cellulose fibers constituting the cellulose powder. , preferably 0% to 25%, more preferably 0% to 20%, even more preferably 0% to 15%.

The resin composition may further include a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant.
The glycerin fatty acid ester can be, for example, glycerin monostearate. The glycerin fatty acid ester is, for example, 0.3 parts by mass to 3 parts by mass, preferably 0.4 parts to 2 parts by mass, more preferably 0.5 parts by mass to 1 part by mass, per 100 parts by mass of the thermoplastic resin composition. It may be included in the resin composition at a content rate of .5 parts by mass.
The fatty acid metal salt is, for example, 2 parts by mass to 6 parts by mass, preferably 2.5 parts by mass to 5.5 parts by mass, and more preferably 3 parts by mass to 5 parts by mass, per 100 parts by mass of the thermoplastic resin composition. may be included in the resin composition at a content ratio of
Examples of the fatty acid metal salt include metal salts of saturated or unsaturated fatty acids having 10 to 30 carbon atoms, particularly 12 to 25 carbon atoms. More specifically, the second lubricant is selected from the group consisting of magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, sodium lauryl sulfate, magnesium lauryl sulfate, potassium benzoate, and sodium benzoate. It can be at least one species.

The resin composition may further include an impact agent. The impact agent may include a styrenic thermoplastic elastomer. The impact-resistant agent is, for example, 0.3 parts by mass to 3 parts by mass, preferably 0.4 parts by mass to 2 parts by mass, and more preferably 0.5 parts by mass to 1 part by mass, per 100 parts by mass of the thermoplastic resin composition. It may be included in the resin composition at a content rate of .5 parts by mass.

The resin composition may further include other components such as a compatibilizer, an antioxidant, and a colorant. As a compatibilizer, preferably a maleic anhydride grafted polyolefin resin may be included. The compatibilizer may be used in an amount of, for example, 0.1 parts by mass to 3 parts by mass, preferably 0.2 parts by mass to 2 parts by mass, and more preferably 0.5 parts by mass to 1 part by mass, per 100 parts by mass of the thermoplastic resin composition. It may be included in the resin composition at a content rate of .5 parts by mass.

The thermoplastic resin composition according to this embodiment is suitable for forming sheets, for example from 0.2 mm to 2 mm, especially from 0.3 mm to 1.5 mm, more particularly from 0.3 mm to 1.4 mm, and even More particularly, it is used to form sheets having a thickness of 0.4 mm to 1 mm.
Since the thermoplastic resin composition according to this embodiment has excellent dispersibility of cellulose powder, it is difficult to cause tears or holes even when molded into an extremely thin sheet of, for example, 0.2 mm to 0.4 mm.
The thermoplastic resin composition according to this embodiment can also be used for vacuum forming. By the vacuum forming, a molded article (for example, a container) having a desired shape can be manufactured.

(2) Thermoplastic resin composition for injection molding

According to another embodiment of the invention, the thermoplastic resin composition may include cellulose powder and polypropylene.
The cellulose powder is, for example, 10 parts by mass to 60 parts by mass, preferably 15 parts by mass to 55 parts by mass, more preferably 20 parts by mass to 50 parts by mass, and even more preferably, per 100 parts by mass of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 25 parts by mass to 45 parts by mass.
The polypropylene is, for example, 30 parts to 80 parts by weight, preferably 35 parts to 75 parts by weight, more preferably 40 parts to 70 parts by weight, and even more preferably 45 parts by weight, per 100 parts by weight of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 65 parts by mass.

The cellulose powder may have a particle size in which a 100 mesh pass is 90% or more. More preferably, the cellulose powder has a particle size with a 100 mesh pass of 90% or more, and has an apparent specific gravity of 0.30 g/ml to 0.40 g/ml.

The resin composition may further include a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant.
The glycerin fatty acid ester can be, for example, glycerin monostearate. The glycerin fatty acid ester is, for example, 0.3 parts by mass to 3 parts by mass, preferably 0.4 parts to 2 parts by mass, more preferably 0.5 parts by mass to 1 part by mass, per 100 parts by mass of the thermoplastic resin composition. It may be included in the resin composition at a content rate of .5 parts by mass.
The fatty acid metal salt is, for example, 2 parts by mass to 6 parts by mass, preferably 2.5 parts by mass to 5.5 parts by mass, and more preferably 3 parts by mass to 5 parts by mass, per 100 parts by mass of the thermoplastic resin composition. may be included in the resin composition at a content ratio of
Examples of the fatty acid metal salt include metal salts of saturated or unsaturated fatty acids having 10 to 30 carbon atoms, particularly 12 to 25 carbon atoms. More specifically, the second lubricant is selected from the group consisting of magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, sodium lauryl sulfate, magnesium lauryl sulfate, potassium benzoate, and sodium benzoate. It can be at least one species.

The resin composition may further include other components such as a compatibilizer, an antioxidant, and a colorant. As a compatibilizer, preferably a maleic anhydride grafted polyolefin resin may be included. The compatibilizer may be used in an amount of, for example, 0.5 parts by mass to 5 parts by mass, preferably 1 part to 4 parts by mass, and more preferably 1.5 parts by mass to 3.5 parts by mass, per 100 parts by mass of the thermoplastic resin composition. It may be contained in the resin composition at a content ratio of parts by mass.

The resin composition according to this embodiment is suitable for injection molding and can be used, for example, to form containers by injection molding.

(3) Thermoplastic resin composition for film molding

According to another embodiment of the invention, the thermoplastic resin composition may include cellulose powder and polyethylene.
The cellulose powder is, for example, 10 parts by mass to 60 parts by mass, preferably 15 parts by mass to 55 parts by mass, more preferably 20 parts by mass to 50 parts by mass, and even more preferably, per 100 parts by mass of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 25 parts by mass to 45 parts by mass.
The polyethylene is, for example, 30 parts to 80 parts by weight, preferably 35 parts to 75 parts by weight, more preferably 40 parts to 70 parts by weight, and even more preferably 45 parts by weight, per 100 parts by weight of the thermoplastic resin composition. It is contained in the resin composition at a content rate of 65 parts by mass.

Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is 65% to 100% of the total number of cellulose fibers constituting the cellulose powder, preferably 70%. % to 100%, more preferably 80% to 100%, even more preferably 85% to 100%. Particularly preferably, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm among the cellulose fibers constituting the cellulose powder is 0% to 30% of the total number of cellulose fibers constituting the cellulose powder. , preferably 0% to 25%, more preferably 0% to 20%, even more preferably 0% to 15%.

The resin composition may further include a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant.
The glycerin fatty acid ester can be, for example, glycerin monostearate. The glycerin fatty acid ester is, for example, 0.1 part by mass to 1 part by mass, preferably 0.2 part to 0.9 part by mass, more preferably 0.3 part by mass, per 100 parts by mass of the thermoplastic resin composition. It may be contained in the resin composition at a content rate of 0.8 parts by mass.
The fatty acid metal salt is contained in the resin composition at a content rate of, for example, 1 part by mass to 3 parts by mass, preferably 1.5 parts by mass to 2.5 parts by mass, per 100 parts by mass of the thermoplastic resin composition. It can be done.
Examples of the fatty acid metal salt include metal salts of saturated or unsaturated fatty acids having 10 to 30 carbon atoms, particularly 12 to 25 carbon atoms. More specifically, the second lubricant is selected from the group consisting of magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, sodium lauryl sulfate, magnesium lauryl sulfate, potassium benzoate, and sodium benzoate. It can be at least one species.

The resin composition may further include other components such as a compatibilizer, an antioxidant, and a colorant. As a compatibilizer, preferably a maleic anhydride grafted polyolefin resin may be included. The compatibilizer is contained at a content rate of, for example, 1 part by mass to 10 parts by mass, preferably 3 parts by mass to 7 parts by mass, and more preferably 4 parts by mass to 6 parts by mass, per 100 parts by mass of the thermoplastic resin composition. , may be included in the resin composition.

The thermoplastic resin composition according to this embodiment is suitable for forming films by inflation molding, for example from 10 μm to 500 μm, in particular from 10 μm to 300 μm, more particularly from 10 μm to 200 μm, even more particularly from 60 μm to 100 μm. Used to form thick films.
The thermoplastic resin composition according to this embodiment has excellent dispersibility of cellulose powder, so even when an extremely thin film of, for example, 50 μm to 100 μm is molded, tearing or holes are unlikely to occur.

Hereinafter, the present invention will be explained in more detail based on Examples. The examples described below are representative examples of the present invention, and the scope of the present invention is not limited only to these examples. Furthermore, "Example 1-3" and "Example 1-5" described below shall be read as "Reference Example 1-3" and "Reference Example 1-5", respectively.

Test Example 1: Production of a resin composition containing cellulose powder and evaluation of a sheet molded from the resin composition

(Example 1-1)

(Manufacture of particles)

As shown in Table 1 below, 30 parts by mass of cellulose powder (KC Flock W400, Nippon Paper Industries Co., Ltd.), 59 parts by mass of polypropylene (PP, FL6632G, Sumitomo Chemical Co., Ltd.), glycerin fatty acid ester (S-100, Riken Vitamin Co., Ltd.), 4 parts by mass of fatty acid metal salt, 1 part by mass of impact agent, 1 part by mass of compatibilizer, 1 part by mass of antioxidant, and 3 parts by mass of white MB. Table 2 below shows the percentage of cellulose fibers having a particle size of 0 μm to 9.8 μm, the percentage of cellulose fibers having a particle size of 0 μm to 110.6 μm, and the percentage of cellulose fibers having a particle size of 9.8 μm to 110 μm in the cellulose powder. The percentage of the number of cellulose fibers with a particle size of 6 μm is shown. Table 3 below also shows the ratio of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm, the ratio of the number of cellulose fibers having a particle size of 0 μm to 998.4 μm, and 110 μm of each cellulose powder. The percentage of the number of cellulose fibers with particle size from .6 μm to 998.4 μm is shown. Further, the melting point of the fatty acid metal salt is higher than the melting point of the glycerin fatty acid ester. The ratios listed in Tables 2 and 3 were measured by wet measurement using a laser diffraction particle size distribution analyzer (SALD-3100, Shimadzu Corporation).
Using these materials, particles in which polypropylene was coated with cellulose powder (hereinafter referred to as "particles of Example 1-1") were manufactured. The method for producing the particles will be explained below.

(1) Mixing process In a stirring device (high-temperature stirrer, Kawata Co., Ltd.), 30 parts by mass of cellulose powder, 59 parts by mass of polypropylene particles, 1 part by mass of glycerin fatty acid ester (first lubricant), fatty acid metal salt (metal 4 parts by mass of soap, second lubricant), 1 part by mass of impact agent, 1 part by mass of compatibilizer, 1 part by mass of antioxidant, and 3 parts by mass of white MB were mixed. The rotation speed of the stirring device during the mixing was 45 Hz. Further, while performing the mixing, the temperature of the stirring device was raised to 120°C. 120°C is higher than both the melting point of the glycerin fatty acid ester and the fatty acid metal, and lower than the melting point of the polypropylene. In the mixing, the glycerin fatty acid ester and the fatty acid metal were melted, and the lubricants were distributed throughout the cellulose powder and the polypropylene particles.

(2) Cooling step The high-temperature mixture obtained in the mixing step was put into a cooling stirrer (cooling stirrer, Kawata Co., Ltd.), and stirred at a rotational speed of 25 Hz in the stirrer for 70 minutes. Cooled to °C. 70°C is higher than the melting point of the glycerin fatty acid ester and lower than the melting point of the fatty acid metal. By cooling while stirring, particles (particles of Example 1-1) in which the polypropylene particle core portion was covered with a cellulose powder-containing coating layer were obtained.
The particles were transferred into a stock tank and maintained at approximately 70°C.

(Manufacture of resin composition)

Using a kneading extruder, the particles of Example 1-1 maintained at about 70°C in a stock tank were heated to a temperature higher than the melting point of the thermoplastic resin (polypropylene) contained in the particles. A resin composition (hereinafter also referred to as "resin composition of Example 1-1") was obtained by kneading. The cylinder temperature during the kneading was 160°C to 200°C. The resin composition was extruded from a T-die provided in the kneading extruder and formed into a sheet. The obtained sheet-like resin composition was taken up by a take-up roll. During the taking-up process, the sheet-like resin composition was cooled. The thickness of the sheet-shaped resin composition (hereinafter also referred to as "sheet of Example 1-1") after cooling was 0.5 mm. The sheet of Example 1-1 had excellent rigidity, heat resistance, and dimensional stability.

(Examples 1-2 to 1-6)

A sheet formed from a resin composition was produced in the same manner as in Example 1-1, except that the cellulose powder shown in Table 2 below was used instead of KC floc as the cellulose powder. The sheets of each example are referred to as the "sheet of Example 1-2", the "sheet of Example 1-3", etc. in the same way as the sheet of Example 1-1. All of the sheets of Examples 1-2 to 1-6 were excellent in rigidity, heat resistance, and dimensional stability.
Table 2 also shows the ratio of the number of cellulose fibers with a particle size of 0 μm to 9.8 μm, the ratio of the number of cellulose fibers with a particle size of 0 μm to 110.6 μm, and the ratio of cellulose fibers with a particle size of 9.8 μm in each cellulose powder. The percentage of the number of cellulose fibers with a particle size of ˜110.6 μm is shown. Table 3 below also shows the ratio of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm, the ratio of the number of cellulose fibers having a particle size of 0 μm to 998.4 μm, and 110 μm of each cellulose powder. .6 μm to 998.4 μm particle size.

Vacuum forming was performed using each of the sheets of Examples 1-1 to 1-6. The vacuum forming was performed as follows. That is, each sheet was heated for about 25 seconds to soften it in a vacuum forming device (FVS-500P, Wakisaka Engineering Co., Ltd.) set at 450° C., and the softened sheet was molded in the same device. The mold used in the molding had a rectangular parallelepiped shape with dimensions of 9.7 cm in length, 9.7 cm in width, and 3.0 cm in height. In this molding, a container with a length of 9.7 cm, a width of 9.7 cm, and a depth of 3.0 cm was molded.

The moldability of each sheet (whether it could be applied to vacuum forming) and the molded product formed from each sheet by vacuum forming were evaluated according to the following evaluation criteria.
<Moldability>
Acceptable: Applicable (the molded product had a shape that conformed to the mold)
Not applicable: Not applicable (there were many holes and the molded product did not have a shape that conformed to the mold)
<Evaluation of molded products>
A: A molded product with a smooth surface and no holes or tears B: A molded product with a slightly rough surface and a few holes C: A rough surface It was a molded product with a hole.

The evaluation results are shown in Table 4 below.

As shown in Table 4, all of the sheets of Example 1-1, Example 1-2, Example 1-4, and Example 1-6 could be applied to vacuum forming. Sheets 1-3 and 1-5 could not be applied to vacuum forming. From this result, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is 65% to 100%, preferably 70% to 100% of the total number of cellulose fibers constituting the cellulose powder. It can be seen that the resin composition of the present invention has excellent moldability for vacuum forming.
More particularly, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm is 0% to 30%, preferably 0% to 25% of the total number of cellulose fibers constituting the cellulose powder. It can be seen that particularly excellent molded products can be obtained.

Further, among Examples 1-1 to 1-6, the evaluation result of the molded product in Example 1-1 was A, and a particularly excellent molded product could be molded. From this result, it is found that among the particles of the present invention, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm is 80% to 100% of the total number of cellulose fibers constituting the cellulose powder, more preferably It has been found that particularly excellent molded articles can be obtained by using cellulose powder that accounts for 85% to 100%.
More particularly, among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm is 0% to 20% of the total number of cellulose fibers constituting the cellulose powder, It has been found that particularly excellent molded articles can be obtained by using cellulose powder, which preferably accounts for 0% to 15%.

Test example 2: Changing the ratio of thermoplastic resin and cellulose powder

(Example 2-1)

As shown in Table 5 below, a sheet (hereinafter referred to as , "Sheet of Example 2-1") was produced.

The sheet of Example 2-1 could also be applied to vacuum forming. Furthermore, when the sheet of Example 2-1 was evaluated according to the evaluation criteria described in Test Example 1 above, it was rated A.

Note that from the viewpoint of ease of particle production, Example 1-1 was superior to Example 2-1. This is considered to be because the amount of lubricant (especially the amount of the second lubricant) relative to the amount of cellulose powder in Example 1-1 was greater than that in Example 2-1. Therefore, the content of the second lubricant (especially fatty acid metal salt) in the particles of the present invention (or the resin composition of the present invention) is preferably more than 10 parts by mass based on 100 parts by mass of cellulose powder. , more preferably 11 parts by mass or more.

Test Example 3: Production of resin composition and evaluation of sheet molded from the resin composition

(Example 3)

As shown in the column of Example 3 in Table 6 below, 30 parts by mass of cellulose powder (KC Flock 100GK, Nippon Paper Industries Co., Ltd.), 62.5 parts by mass of polypropylene (homopropylene, J108M, Prime Polymer Co., Ltd.), fatty acids 4 parts by mass of a metal salt and 2.5 parts by mass of a compatibilizer were prepared. These materials were mixed and pelletized using a twin screw kneading extruder. The kneading temperature was about 140°C, and the rotation speed was 12 rpm. From the obtained pellets, using an injection molding device (injection molding machine, Sumitomo Heavy Industries, Ltd.), the shape of the test piece used in the following flexural modulus evaluation, load deflection temperature evaluation, and dimensional stability evaluation was made. Injection molded. The thickness of the test piece was 1.0 mm. In the injection molding, the temperature for melting the pellets was 170°C.

(Comparative example 3)

By injection molding similar to Example 3, polypropylene (homopropylene, J108M, Prime Polymer Co., Ltd.) was injection molded into the shape of the test piece.

(evaluation)

(1) Evaluation of bending elastic modulus The bending elastic modulus of the sheet of Example 3 and the sheet of Comparative Example 3 was measured. The measurement was performed according to JIS K 7171. The test piece used in the measurement had dimensions of 8 cm long side x 1 cm short side x 0.5 cm thickness. The measurement results are shown in Figure 2. As shown in FIG. 2, the sheet of Example 3 had a higher flexural modulus than the sheet of Comparative Example 3. This result shows that the rigidity of the sheet is improved by including cellulose powder.
In addition, polyolefin resin compositions containing biomass materials tend to have lower rigidity (flexural modulus) than polyolefin resin compositions that do not contain biomass materials, but by using cellulose powder as the biomass material, , it can be seen that the rigidity is improved.

(2) Evaluation of deflection temperature under load The deflection temperature under load of the sheet of Example 3 and the sheet of Comparative Example 3 was measured. The measurement was performed flatwise under a load of 0.45 MPa in accordance with JIS K 7191. The test piece used in the measurement had dimensions of 8 cm long side x 1 cm short side x 0.5 cm thickness. The measurement results are shown in Figure 3. As shown in FIG. 3, the sheet of Example 3 had a higher deflection temperature under load than the sheet of Comparative Example 3. This result shows that the heat resistance of the sheet is improved by including cellulose powder.
Additionally, polyolefin resin compositions containing biomass materials tend to have lower heat resistance (deflection temperature under load) than polyolefin resin compositions that do not contain biomass materials. It can be seen that the heat resistance is improved.

(3) Evaluation of dimensional stability The dimensional stability of the sheet of Example 3 was evaluated. The test piece used in the evaluation had dimensions of 32 cm long side x 14 cm short side x 0.4 mm thickness. For the evaluation, the dimension in the long side direction was measured when the sheet of Example 3 was left for 30 days at a temperature of 23 degrees Celsius and a humidity of 50%, and the dimensional change rate was calculated from the measured dimension. The dimensional change rate is calculated by the following formula: dimensional change rate (%) = [L ₁ - L ₀ ]/L ₀ ×100
Here, L ₁ is the dimension measured after being left, and L ₀ is the dimension before starting to be left.
The measurement results of the dimensional change rate are shown in FIG. As shown in FIG. 4, the dimensional change rate (legend "30%" in FIG. 4) of the sheet of Example 3 was within the range of -0.2% to +0.2% over the 30 days. . This result shows that the sheet of Example 3 has excellent dimensional stability.
The cellulose powder content in the sheet of Example 3 is 30% by mass, but even if this percentage is 40% by mass (legend "40%" in FIG. 4), over the 30 days - It was within the range of 0.2% to +0.2%. This result shows that even if the content of cellulose powder is 40% by mass, the dimensional stability is excellent.
In addition, polyolefin resin compositions containing biomass materials tend to have inferior dimensional stability compared to polyolefin resin compositions that do not contain biomass materials, but by using cellulose powder as the biomass material, it is possible to achieve better dimensional stability. It can be seen that dimensional stability is improved.

Note that the present invention also provides the following.
[1]
A particle comprising a particle core made of a thermoplastic resin and a cellulose powder-containing coating layer covering at least a portion of the particle core.
[2]
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm accounts for 65% to 100% of the total number of cellulose fibers constituting the cellulose powder, [ 1].
[3]
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm accounts for 0% to 30% of the total number of cellulose fibers constituting the cellulose powder, [ 1] or the particle according to [2].
[4]
The particles according to any one of [1] to [3], which are used to form a film or sheet.
[5]
The particles according to [1], wherein the cellulose powder has a particle size in which a 100 mesh pass is 90% or more.
[6]
The particles according to any one of [1] to [3] and [5], which are used for injection molding.
[7]
The particle according to any one of [1] to [6], wherein the coating layer includes a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant. .
[8]
The particles according to claim 7, wherein the second lubricant contains at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, aliphatic amides, and fatty acid esters.
[9]
The particles according to [7] or [8], wherein the first lubricant contains a glycerin fatty acid ester.
[10]
The particles according to any one of [1] to [9], wherein the particles have a substantially spherical shape with a diameter of 3 mm to 10 mm.

Claims (5)

A resin composition comprising a thermoplastic resin and cellulose powder,
The cellulose powder is contained in the resin composition at a content rate of 10 parts by mass to 60 parts by mass per 100 parts by mass of the resin composition,
The total mass of the cellulose powder and the thermoplastic resin contained in the resin composition is 70% by mass to 98% by mass with respect to the mass of the resin composition,
Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm accounts for 65% to 100% of the total number of cellulose fibers constituting the cellulose powder,
further comprising a first lubricant and a second lubricant having a melting point higher than the melting point of the first lubricant,
The resin composition includes a glycerin fatty acid ester as the first lubricant, and a fatty acid metal salt as the second lubricant,
The content of the first lubricant in the resin composition is 0.5 parts by mass to 5 parts by mass based on 100 parts by mass of the cellulose powder,
The content of the second lubricant in the resin composition is 3 parts by mass to 20 parts by mass based on 100 parts by mass of the cellulose powder.
The resin composition. The resin composition according to claim 1, wherein the resin composition is a thermoplastic resin composition. The resin composition according to claim 1, wherein the cellulose powder has a particle size with a 100 mesh pass of 90% or more. The resin composition according to any one of claims 1 to 3, wherein the thermoplastic resin is a polyolefin resin, a polystyrene resin, a polyamide resin, or a polyester resin. Among the cellulose fibers constituting the cellulose powder, the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm accounts for 0% to 30% of the total number of cellulose fibers constituting the cellulose powder. The resin composition according to any one of Items 1 to 4.