Sheet containing biomass material

Abstract

To provide a sheet containing a biomass material that can be molded in-line at low temperature even when using the sheet containing the biomass material.SOLUTION: An in-line molding method of the present invention includes a molding step, an article-to-be-packaged filling step, and a sealing step, and the molding step, the article-to-be-packaged filling step, and the sealing step are performed on a single line. In the molding step, a biomass material-containing sheet is molded into a shape having a recessed part; in the article-to-be-packaged filling step, the article to be packaged is filled into the recessed part of the biomass material-containing sheet; in the sealing step, the recessed part filled with the article to be packaged is sealed with a film; the biomass material-containing sheet is formed from a biomass material and a resin composition containing a thermoplastic resin, the thermoplastic resin being a random copolymer, the content of the thermoplastic resin being 30 mass% or more and 45 mass% or less with respect to the mass of the biomass material-containing sheet; and a deflection temperature under load of the biomass material-containing sheet measured in accordance with JIS K 7191 "Plastics - Test method for deflection temperature under load" is 65°C or more and 80°C or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present technology relates to a biomass material-containing sheet. [Background technology]

[0002] Food products and the like are usually distributed in a state where they are contained in a packaging container or the like. In recent years, packaging containers in which a lid material and a base material are heat-sealed have been widely used for packaging food products and the like. Such packaging containers are usually produced in-line by forming the base material from a plastic bottom sheet by vacuum forming or the like, filling the recess in the formed base material with the food product or other contents, covering the recess in the base material with a lid material of a top sheet, and then heat-sealing the base material and the lid material to hermetically seal the contents.

[0003] In-line molding uses rolled flat sheets to make food packaging into three-dimensional containers, which reduces the labor and space required for purchasing flat sheets, which are packaging materials.Furthermore, since the flat sheets are heated and molded at the time of packaging, food products can be packaged hygienically and efficiently.

[0004] The base and lid materials used in inline molding are plastic molded products made from petroleum-derived raw materials. However, the manufacturing and disposal processes for plastic molded products consume a huge amount of energy, and global warming due to the greenhouse gases emitted and the depletion of petroleum resources due to the mass consumption of plastic molded products are important long-term issues that need to be addressed on a global scale. Furthermore, when plastic molded products made from petroleum-derived raw materials are discarded, they are difficult to decompose or disintegrate in the natural environment, remaining in nature for long periods of time and polluting the natural environment, which is a problem.

[0005] Against this background, natural materials have been attracting attention in recent years as new environmentally friendly materials that do not contribute to global warming, decompose relatively quickly in the natural environment, and the use of biomass materials, which are organic resources derived from living organisms, as raw materials for plastic molded products is being considered.

[0006] As such biomass materials, the use of natural materials such as polylactic acid, starch, modified starch, and cellulose has been proposed.

[0007] However, in order to use biomass materials for a wide range of applications, they require mechanical properties, thermal properties, melt processability, etc., and many biomass materials do not have sufficient physical properties and are difficult to mold.

[0008] Therefore, in order to improve the physical properties and processability and enable substitution of petroleum-derived raw materials in the production of plastic molded products, composite materials have been proposed in which biomass-derived raw materials such as polylactic acid, biopolyethylene, starch, and cellulose are combined with synthetic resins such as polyolefins (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-64458 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-155842 Summary of the Invention [Problem to be solved by the invention]

[0010] To solve the problems associated with petroleum resources, the use of sheets containing biomass materials for the base material, which constitutes the main portion of packaging containers, has been considered. However, until now, there have been no biomass materials that are suitable for vacuum molding. Furthermore, in in-line molding, when the efficiency and speed of product filling and packaging are achieved on the same line, molding at low temperatures of 155°C or less has been required to improve the speed and efficiency of molding. However, there has been a problem in that the melting points of the resins used in the base material of sheets have been high, making low-temperature in-line molding impossible. An object of the present invention is to provide a biomass material-containing sheet that can be molded in-line at low temperatures while using a biomass material-containing sheet. [Means for solving the problem]

[0011] The present technology provides a biomass material-containing sheet formed from a biomass material and a resin composition containing a thermoplastic resin, wherein the thermoplastic resin is a random copolymer, and the sheet is intended for in-line molding. The inline molding can involve a molding process of molding the biomass material-containing sheet into a shape having a recess, a packaging material filling process of filling the recess in the biomass material-containing sheet with the packaging material, and a sealing process of sealing the recess filled with the packaging material with a film, all on one line. In the molding step, the biomass material-containing sheet can be molded at 135°C to 145°C. The present technology provides a biomass material-containing sheet formed from a biomass material and a resin composition containing a thermoplastic resin, wherein the thermoplastic resin is a random copolymer and the content of the biomass material is 50% by mass or more. The deflection temperature under load may be 65°C or higher and 80°C or lower. The biomass material can be starch. The thermoplastic resin may be a polyolefin resin. The polyolefin resin may be a polypropylene resin. [Effects of the Invention]

[0012] This technology makes it possible to provide a biomass material-containing sheet that can be molded inline at low temperatures while still using a biomass material-containing sheet, and that can ensure that the resulting packaging container has sufficient strength. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a flowchart of in-line molding using a biomass material-containing sheet according to the present embodiment. [Figure 2] 1 is a schematic diagram showing one embodiment of a method for manufacturing a packaging container by in-line molding. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments for carrying out the present technology will be described below. Note that the embodiments described below are representative embodiments of the present technology, and the scope of the present technology is not limited to these embodiments.

[0015] This technology will be described in the following order. 1. First embodiment (example of biomass material-containing sheet) (1) Composition of biomass material-containing sheet (2) Physical properties (3) Manufacturing method of biomass material-containing sheet 2. Uses of biomass material-containing sheets 3. Working Example

[0016] 1. First embodiment (example of biomass material-containing sheet)

[0017] (1) Composition of biomass material-containing sheet The biomass material-containing sheet according to this embodiment is formed from a resin composition. The resin composition contains a biomass material and a thermoplastic resin. The thermoplastic resin is a random copolymer. Because the thermoplastic resin is a random copolymer, in-line molding at low temperatures is possible. Furthermore, by using such a random copolymer thermoplastic resin, the processing temperature (set temperature) of the extruder can be lowered, which suppresses browning of biomass materials such as starch and improves the whiteness of the biomass material-containing sheet. The thermoplastic resin may also contain a biodegradable material to prevent a decrease in biodegradability.

[0018] The thermoplastic resin may be a polyolefin resin, a polyester resin, or a mixture of these resins. The thermoplastic resin may also be a polystyrene resin.

[0019] The polyolefin resin is a polymer obtained by polymerization of olefins (e.g., α-olefins) as a main monomer. The polyolefin resin may be, for example, a polyethylene (PE) resin, a polypropylene (PP) resin, or a combination thereof.

[0020] The polyethylene resin may be, for example, an ethylene copolymer such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), very-low-density polyethylene (VLDPE), linear-low-density polyethylene (LLDPE), or ethylene-vinyl acetate copolymer (EVA resin), or an ultra-high-molecular-weight polyethylene (UHMW-PE), or a combination thereof.

[0021] In order to lower the melting point of the thermoplastic resin and enable in-line molding at low temperatures, the polypropylene resin is a random copolymer. Examples of such a copolymer include ethylene-propylene copolymers. To enable low-temperature in-line molding, the melting point of the random copolymer is preferably 155°C or lower, more preferably 140°C or lower. Furthermore, the melting point of the random copolymer is preferably 120°C or higher, more preferably 130°C or higher.

[0022] The polyolefin resin may preferably be a biomass-derived polyolefin resin (e.g., a biomass-derived polyethylene resin), such as a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0023] The polyolefin resin may be a polyolefin resin produced using a metallocene catalyst, i.e., the thermoplastic resin may be, for example, a metallocene-catalyzed polyethylene resin or polypropylene resin, or a combination thereof. The polystyrene-based resin may be a metallocene-catalyzed polystyrene-based resin.

[0024] The polyester resin is a polymer formed by polymerizing monomers through ester bonds. Examples of the polyester resin include polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid resin (PLA), polycarbonate resin (PC), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), and combinations of two or more of these.

[0025] The polystyrene resin is a polymer formed by polymerization of a styrene monomer. Examples of the polystyrene resin include polystyrene resin, rubber-reinforced polystyrene resin (high impact polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylate ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene propylene-styrene copolymer, or a combination of two or more of these.

[0026] In this embodiment, the type of thermoplastic resin may be appropriately selected by a person skilled in the art depending on, for example, the application of the molded product to be in-line molded from the biomass material-containing sheet formed from the thermoplastic resin, and a thermoplastic resin with a low processing temperature is preferred. For example, in the case of a sheet used as a base material for food packaging containers, the thermoplastic resin is a polypropylene resin, which is a random copolymer.

[0027] In this embodiment, the melting point of the thermoplastic resin is preferably 155°C or lower, and more preferably 140°C or lower. By using a thermoplastic resin with a lower melting point, the molding temperature can be lowered. The melting point of the thermoplastic resin is preferably 120°C or higher, and more preferably 130°C or higher.

[0028] The thermoplastic resin may be in the form of pellets, and the content of the thermoplastic resin relative to the mass of the biomass material-containing sheet is preferably 30% by mass or more and 45% by mass or less, more preferably 35% by mass or more and 45% by mass or less, and even more preferably 40% by mass or more and 45% by mass or less.

[0029] Examples of the biodegradable material include cellulose derivatives such as methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and hydroxybutyl methyl cellulose; hydrophilic polymer materials such as polyvinyl alcohol, carboxymethyl cellulose, polyacrylic acid polymers, and polyacrylamide; emulsions of various acrylates, ethylene / vinyl acetate copolymers, and polyurethanes; and aliphatic polyester resins such as caprolactone, polylactic acid, polybutylene adipate, polybutylene succinate, and polyhydroxybutyrate-valerate copolymers.

[0030] In the biomass material-containing sheet according to this embodiment, the thermoplastic resin contains a biomass material. The biomass material is preferably a plant-derived biomass material, more specifically, a starch material and a cellulose material. The starch material and the cellulose material may be classified as waste biomass, unused biomass, or resource grain. The biomass material may also be animal-derived, such as eggshells.

[0031] The starch material used in this embodiment may be raw starch, including, for example, starch from underground sources and starch from aboveground sources. Underground starch is starch accumulated underground, such as in rhizomes or roots. Examples of underground starches include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch.

[0032] Terrestrial starch refers to starch accumulated above ground, for example, starch accumulated in seeds, etc. Examples of terrestrial starches include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0033] In this embodiment, ground starch is preferably used. By producing the biomass material-containing sheet of this embodiment using ground starch, in-line moldability can be further improved.

[0034] The starch material may be a modified starch (i.e., modified starch). Such modified starches include physically modified starches and chemically modified starches. Examples of physically modified starches include pregelatinized starch and heat-moisture starch. Examples of chemically modified starches include acetoacetate-esterified starch, acetate-esterified starch, hydroxymethyl-etherified starch, hydroxypropyl-etherified starch, carboxymethyl-etherified starch, allyl-etherified starch, methyl-etherified starch, succinate-esterified starch, xanthogen acetate-esterified starch, nitrate-esterified starch, urea phosphate-esterified starch, phosphate-esterified starch, phosphate-crosslinked starch, formaldehyde-crosslinked starch, acrolein-crosslinked starch, and epichlorohydrin-crosslinked starch.

[0035] When the starch material is corn starch, the particle size is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of improving in-line moldability. The upper limit of the particle size is not particularly limited, but is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0036] When the starch material is tapioca starch, the particle size is preferably 2 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of improving in-line moldability. The upper limit of the particle size is not particularly limited, but is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less.

[0037] When the starch material is potato starch, the particle size is preferably 2 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, from the viewpoint of improving in-line moldability. The upper limit of the particle size is not particularly limited, but is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less.

[0038] The starch material may preferably contain equilibrium moisture, which may be, for example, preferably 10% to 15% by mass, more preferably 10% to 14% by mass, even more preferably 10% to 13% by mass, and even more preferably 11% to 13% by mass, relative to the mass of the starch material.

[0039] In this embodiment, the content of the starch material is 50% by mass or more, preferably 55% by mass or more, more preferably 57% by mass or more, and even more preferably 59% by mass or more, relative to the mass of the starch-containing sheet. The content of the starch material is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, relative to the mass of the starch-containing sheet. The content of the starch material is preferably 50% by mass or more and 90% by mass or less, more preferably 55% by mass or more and 80% by mass or less, and even more preferably 57% by mass or more and 70% by mass or less, relative to the mass of the starch-containing sheet.

[0040] The cellulose material used in this embodiment may be paper, paper pulp, cotton, or ground cloth.

[0041] The particle size D50 (median diameter) of the cellulose material can be, for example, 15 μm to 150 μm, and particularly preferably 20 μm to 100 μm. The particle size D50 is determined by wet measurement using a laser diffraction particle size analyzer (SALD-3100, Shimadzu Corporation). Having the cellulose material have a particle size within the above numerical range can contribute to improving the dispersibility of the cellulose material contained in the thermoplastic resin.

[0042] According to this embodiment, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm accounts for 65% to 100%, preferably 70% to 100%, more preferably 80% to 100%, and even more preferably 85% to 100% of the total number of cellulose fibers constituting the cellulose material. The above percentage of the number of cellulose fibers is calculated by determining the percentage of the number of cellulose fibers having a particle size of 0 μm to 9.8 μm (hereinafter referred to as the "first percentage") and the percentage of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (hereinafter referred to as the "second percentage") among the total number of cellulose fibers in the cellulose material by wet measurement using the laser diffraction particle size analyzer, and then subtracting the first percentage from the second percentage. 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 analyzer during the wet measurement.

[0043] In this embodiment, it is particularly preferred that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm account for 0% to 30%, preferably 0% to 25%, more preferably 0% to 20%, and even more preferably 0% to 15% of the total number of cellulose fibers constituting the cellulose material. The above percentage of the number of cellulose fibers is calculated by determining the percentage of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (the "second percentage") and the percentage of the number of cellulose fibers having a particle size of 0 μm to 998.4 μm (hereinafter referred to as the "third percentage") among the total number of cellulose fibers in the cellulose material by wet measurement using the laser diffraction particle size analyzer, and then subtracting the second percentage from the third percentage. 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 analyzer during the wet measurement.

[0044] A cellulose material having the above particle size distribution can be produced, for example, by treating pulp with a chemical such as an acid. An example of a cellulose material having the above particle size distribution is KC Flock W400 (Nippon Paper Industries Co., Ltd.). The use of cellulose powder having the above particle size distribution provides better moldability when producing sheets containing cellulose material.

[0045] In particular, by having the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm account for 80% to 100%, and even more preferably 85% to 100%, of the total number of cellulose fibers constituting the cellulose powder, it is possible to prevent tears or holes from occurring in the cellulose material-containing sheet obtained by molding the thermoplastic resin.To prevent tears or holes from occurring in the cellulose material-containing sheet, it is particularly preferable that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm account for 0% to 20%, and even more preferably 0% to 15%, of the total number of cellulose fibers constituting the cellulose powder.

[0046] According to another preferred embodiment of the present invention, the cellulose powder may have a particle size in which 90% or more pass through a 100 mesh. In this embodiment, more preferably, the cellulose powder may have a particle size in which 90% or more pass through a 100 mesh, and the apparent specific gravity of the cellulose powder may be 0.30 g / ml to 0.40 g / ml.

[0047] The particle size is measured by the standard sieve method, specifically as follows: 10 g of sample is placed on a 100-mesh standard sieve, a tray and a lid are attached to the standard sieve, and the sample is shaken for 40 minutes in a low-tap shaker. The particle size is then calculated from the sample mass (10 g) and the mass of the residue on the sieve using the following formula: Particle size (%) = [((sample mass (g) - sieve residue (g)) / sample mass (g)] × 100

[0048] The apparent specific gravity is measured as follows. That is, 10 g of sample is accurately weighed on a balance and placed in a 50 ml measuring cylinder. The bottom of the measuring cylinder is placed on a rubber sheet-covered table and tapped, taking care not to scatter the sample. This tapping operation is continued until the sample no longer clogs the cylinder. After this tapping operation, the surface of the sample is flattened and the scale (volume, ml) is read. The apparent specific gravity is then calculated using the following formula: Apparent specific gravity (g / ml) = sample (10g) / volume (ml)

[0049] The 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 mill pulp). An example of the cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity) is KC Floc 100GK.

[0050] In this embodiment, the content of the cellulose material is preferably 20% by mass or more, more preferably 22% by mass or more, and even more preferably 25% by mass or more, relative to the mass of the cellulose material-containing sheet. Furthermore, the content of the cellulose material is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less, relative to the mass of the cellulose material-containing sheet. Furthermore, the content of the cellulose material is preferably 20% by mass or more and 50% by mass or less, more preferably 22% by mass or more and 48% by mass or less, and even more preferably 25% by mass or more and 45% by mass or less, relative to the mass of the cellulose material-containing sheet.

[0051] The resin composition may further contain additives. As the additive, a low-melting additive having a melting point lower than the melting temperature of the thermoplastic resin and melting at a relatively low temperature may be used. Such low-melting additives preferably melt at 100°C or below, more preferably at 60 to 100°C. The low-melting additive may have a melting point of preferably 50 to 100°C, more preferably 55 to 90°C, and even more preferably 60 to 80°C. Specific examples of the low-melting additive 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 esters include monoglycerides, diglycerides, triglycerides, acetylated monoglycerides, organic acid monoglycerides, and medium-chain fatty acid monoglycerides.

[0052] According to this embodiment, the low-melting point additive preferably comprises a glycerin fatty acid ester, and more preferably comprises glycerin monostearate. The low-melting point additive may preferably consist solely of a glycerin fatty acid ester, and more preferably, solely of glycerin monostearate. The low-melting point additive melts at a relatively low temperature, has viscosity, and can function to entangle and adhere to the biomass material powder.

[0053] The low melting point additive may be contained in the resin composition in a content ratio of, for example, preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the resin composition.

[0054] The resin composition may also contain a high-melting-point additive having a melting point higher than that of the low-melting-point additive. Such a high-melting-point additive may have a melting point higher than that of the low-melting-point additive, preferably in the range of 100 to 150°C, solidify earlier than the low-melting-point additive, and have a melting point lower than the melting temperature of the thermoplastic resin. The high-melting-point additive may have a melting point of preferably 100 to 160°C, more preferably 100 to 150°C, and even more preferably 100 to 140°C. Specifically, the high-melting-point additive may include at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, fatty amides, and fatty acid esters. The high-melting-point additive may be at least one compound selected from the group consisting of fatty acid metal salts, hydrocarbons, higher alcohols, fatty amides, and fatty acid esters, particularly having a melting point within the above-mentioned range.

[0055] Examples of the fatty acid metal salt include metal salts of saturated or unsaturated fatty acids having a carbon number of 10 to 30, particularly 12 to 25. More specifically, the high-melting point additive may be at least one 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.

[0056] The high-melting point additive may be contained in the resin composition in a content ratio of, for example, preferably 1 to 15 parts by mass, more preferably 3 to 15 parts by mass, per 100 parts by mass of the resin composition.

[0057] Other additives include compatibilizers that improve the affinity between the biomass material and the thermoplastic resin and allow the biomass material to be uniformly dispersed in the resin composition. The compatibilizer may be selected depending on the type of thermoplastic resin. Examples of such compatibilizers include acid-modified polyolefins, acid-modified nylons, acid-modified polystyrenes, acid-modified EVAs, acid-modified ethylene copolymers, acid-modified acrylates, acrylic acid-modified EVAs, and modified ethylene acrylates.

[0058] When the thermoplastic resin is a polyolefin-based resin, the compatibilizer is preferably an acid-modified polyolefin, and in particular may be a carboxylic acid anhydride-modified polyolefin or an olefin-based comonomer.

[0059] The carboxylic acid anhydride constituting the carboxylic acid anhydride-modified polyolefin may preferably be maleic anhydride. The compatibilizer may be, for example, a maleic anhydride-grafted polyolefin resin, more particularly, one or a combination of two or more selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer. A rubber component may be dispersed in the compatibilizer.

[0060] The compatibilizer may be contained in the resin composition in an amount of, for example, 0.1 to 10 parts by mass, more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of the resin composition.

[0061] As other additives, colorants may be used.

[0062] The colorant can be used to impart color to the resin composition. Examples of the colorant include titanium oxide, carbon black, dyes, and pigments.

[0063] Furthermore, the other components may include, for example, an antioxidant, a crosslinking agent, an ultraviolet absorber, a foaming agent, an impact resistance agent, etc. Commercially available additives may be used as these additives.

[0064] (2) Physical properties <Deflection temperature under load> The biomass material-containing sheet according to this embodiment has a deflection temperature under load of preferably 65° C. or higher, more preferably 67° C. or higher, and even more preferably 70° C. or higher. The deflection temperature under load is preferably 80° C. or lower, more preferably 75° C. or lower. If the deflection temperature under load exceeds 80° C., low-temperature in-line molding may become difficult.

[0065] The deflection temperature under load can be measured, for example, in accordance with JIS K 7191 "Plastics - Test method for deflection temperature under load." An injection-molded piece injection-molded using an injection molding machine (model number SH-125, manufactured by Sumitomo Heavy Industries, Ltd.) was used as the test sample. The deflection temperature under load is measured for an injection-molded piece having dimensions of 8 cm long x 1 cm short x 0.5 cm thick. The deflection temperature under load can be measured by applying a bending stress load of 0.45 MPa and performing a flatwise test.

[0066] (3) Manufacturing method of biomass material-containing sheet The biomass material-containing sheet according to this embodiment may include a resin composition production step of producing a resin composition and a sheet molding step.

[0067] The resin composition production process may include a particle production process having a particle core portion made of a thermoplastic resin and a biomass material-containing coating layer covering at least a portion of the particle core portion, and a kneading process in which the particles obtained in the particle production process are heated to a temperature equal to or higher than the melting point of the thermoplastic resin that forms the particle core portion of the particles and kneaded.

[0068] The particle production process may include a mixing step of mixing a biomass material, a low-melting point additive, a high-melting point additive, and a thermoplastic resin at a temperature equal to or higher than the melting point of the high-melting point additive and lower than the melting point of the thermoplastic resin to obtain a mixture containing the melted low-melting point additive and high-melting point additive, the biomass material, and the thermoplastic resin; and a cooling step of cooling the mixture obtained in the mixing step to a temperature equal to or higher than the melting point of the low-melting point additive and lower than the melting point of the high-melting point additive while stirring.

[0069] The mixing step may be carried out, for example, by a stirring device known in the art that can set the mixing temperature to the above-mentioned temperature. As described above, the mixing step is carried out at a temperature equal to or higher than the melting point of the high-melting-point additive and lower than the melting point of the thermoplastic resin. The mixing step may be carried out at a temperature preferably between 100°C and 160°C, more preferably between 100°C and 150°C, and even more preferably between 100°C and 140°C.

[0070] In the mixing step, by performing mixing at the above temperature, the low-melting point additive and the high-melting point additive are melted, while the thermoplastic resin is not melted. In the mixing step, a mixed state of the biomass material, the solid thermoplastic resin, and the melted low-melting point additive and the high-melting point additive is formed.

[0071] The mixture obtained in the mixing step can be fed to an apparatus in which the cooling step is carried out, preferably so as not to be at a temperature lower than the melting point of the high-melting point additive (particularly while maintaining the temperature employed in the mixing step).

[0072] In the cooling step, the mixture obtained in the mixing step can be cooled to a temperature equal to or higher than the melting point of the low-melting-point additive and lower than the melting point of the high-melting-point additive while being stirred. By cooling with stirring, a more uniform biomass material-containing coating layer can be formed around the particle core, and particles can be obtained.

[0073] The cooling step can be performed using a stirring device that can cool the mixture obtained in the mixing step to a temperature that is equal to or higher than the melting point of the low-melting-point additive and lower than the melting point of the high-melting-point additive.

[0074] The particles obtained by the above-described manufacturing method are preferably maintained at a temperature equal to or higher than the melting point of the low-melting additive and lower than the melting point of the high-melting additive, thereby preventing the biomass material from peeling off from the particles.

[0075] The particles obtained in the particle production step are heated to a temperature equal to or higher than the melting point of the thermoplastic resin forming the particle core portion of the particles, and kneaded to obtain a resin composition.

[0076] The kneading step can be carried out at a temperature at which the thermoplastic resin contained in the particles can melt. The temperature can be appropriately selected by those skilled in the art depending on the melting point of the thermoplastic resin used. The kneading step can be carried out at a temperature of preferably 100°C to 250°C, more preferably 110°C to 250°C, even more preferably 115°C to 230°C, still more preferably 120°C to 210°C, and particularly preferably 120°C to 190°C.

[0077] The kneading step may be performed, for example, using a twin-screw extruder or a single-screw extruder. Any device known in the art may be used as the extruder. Preferably, the kneading step includes at least heating and kneading using a twin-screw extruder. A co-rotating twin-screw extruder or a counter-rotating twin-screw extruder may be used as the twin-screw extruder. By performing the kneading step using a twin-screw extruder, a resin composition in which the biomass material is more uniformly dispersed can be obtained.

[0078] The resin composition obtained in the kneading step may be directly subjected to the sheet molding step without being pelletized, thereby omitting the pelletizing step. The resin composition obtained in the kneading step may be pelletized, and the pelletized resin composition may be subjected to the sheet molding step.

[0079] In the sheet molding step, the resin composition produced in the kneading step is molded into a sheet. The temperature during molding of the sheet may be set to preferably a temperature equal to or higher than the melting temperature of the thermoplastic resin, for example, 150 to 180°C, and the extrusion pressure may be appropriately set. Note that, since the thermoplastic resin is a random copolymer, the temperature in this step can be lowered, which can suppress browning of the biomass material and improve the whiteness of the resulting sheet.

[0080] For extrusion, various extruders such as a T-die extruder or a calendar molding machine can be used. After extrusion, the biomass material-containing sheet formed into a sheet shape by the extruder may be cooled by setting the temperature of the take-up roll to 60°C or less, and the sheet formed to a predetermined thickness may be taken up and wound up as a raw roll. The thickness of the sheet may be, for example, 0.01 mm to 5 mm.

[0081] 2. Uses of biomass material-containing sheets

[0082] The biomass material-containing sheet according to this embodiment is used for in-line molding. Preferably, the biomass material-containing sheet according to this embodiment is used for low-temperature in-line molding at 135 to 145°C.

[0083] In-line molding is a molding method in which a bottom sheet with good thermoformability is heated and vacuum molded to form a recess (depression) that fits the packaged item, such as a food product, and then the packaged item is filled into the recess, after which a top film is placed over it to seal, and then cut. Figure 1 is a flowchart of in-line molding using a biomass material-containing sheet according to this embodiment.

[0084] As shown in Figure 1, in-line molding involves a molding step (S1), a packaging material filling step (S2), and a sealing step (S3) all being carried out on a single line. In the molding step (S1), the biomass material-containing sheet that is supplied to the line as a bottom sheet can be molded into a shape with a recess. In the packaging material filling step (S2), the recess formed in the molding step (S1) can be filled with a packaging material such as a food product. In the sealing step (S3), the recess filled with the packaging material is sealed with a top film.

[0085] Fig. 2 is a schematic diagram showing one embodiment of a method for producing a packaging container by in-line molding. As shown in Fig. 2, packaging containers produced by in-line molding using an in-line molding machine 101 are produced by heating and softening a bottom sheet 102 made of a biomass material-containing sheet according to this embodiment, and then vacuum-molding a recess for accommodating an item 104 to be packaged into the bottom container 105 by suctioning the softened bottom sheet 102 and bringing it into close contact with a molding die 103 to form a bottom container 105. In a filling area, the item 104 to be packaged is filled into the bottom container 105 through an opening in the bottom container 105, and a top film 106 is placed over the bottom container 105, which is then heat-sealed with a sealing die 107, and the bottom container 105 is individually cut in a cutting unit 108.

[0086] The biomass material-containing sheet according to this embodiment is heated in a forming die 103, and recesses can be formed by various forming methods such as compressed air, vacuum, or plug assist, so as to accurately fit the shape of the packaged item. The depth of the recesses can be set appropriately depending on the application, and may be, for example, preferably 1 to 5 cm. Deep drawing molding may also be used, which has a large drawing ratio, which is the value obtained by dividing the depth of the container by the inner dimensions of the opening of the container. The heating temperature in the forming die 103 is preferably set to 135 to 145°C, the heating time is preferably set to 2 to 5 seconds, and the forming time is preferably set to 1 to 5 seconds.

[0087] Furthermore, the method of filling the bottom container 105 with the packaged item 104 can be carried out manually or by an automatic filling device.

[0088] The top film 106 can be supplied to a sealing mold 107 together with a bottom container 105 filled with an item to be packaged 104. Such a top film 106 can be made of, but is not particularly limited to, polyethylene resin, polypropylene resin, polyamide resin, ethylene-vinyl alcohol copolymer resin, polyethylene terephthalate resin, or the like.

[0089] In the sealing mold 107, the date, lot number, etc. may be printed by thermal printing, inkjet printing, hot printing, etc. Furthermore, after vacuuming or gas replacement is performed appropriately in the sealing mold 107, the top film 106 and the bottom container 105 may be heat sealed. Examples of packaging that can be performed in the sealing mold 107 include vacuum packing, gas replacement packing, steam flash packing (hot packing), steam shrink packing, and skin packing.

[0090] In the cutting unit 108, cutting can be performed in the running direction of the in-line molding machine 101 and in a direction perpendicular to the running direction. Examples of cutting methods include straight cut, corner cut, complete cut, perforation cut, zigzag cut, etc. Also, the cutting unit 108 may be equipped with an automatic labeler.

[0091] 3. Working Example

[0092] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples. The evaluation methods and evaluation criteria used in the examples are as follows:

[0093] (1) Deflection temperature under load In accordance with JIS K 7191 "Plastics - Test method for deflection temperature under load," the deflection temperature under load was measured for an injection-molded specimen having dimensions of 8 cm long x 1 cm short x 0.5 cm thick. The deflection temperature under load was measured by a flatwise test under a bending stress load of 0.45 MPa. Specifically, the deflection temperature under load was measured under the following conditions: Equipment used: HDT test equipment (Toyo Seiki Seisakusho Co., Ltd., model "3M-2")

[0094] (2) Melting point of thermoplastic resin The melting point of the thermoplastic resin was measured using a differential scanning calorimeter (DSC) (DSC8000, manufactured by PerkinElmer).

[0095] (3) Sheet whiteness The WI (White Index) of the sheet was measured using a spectrophotometer (product name "CM-600d", manufactured by Konica Minolta, Inc.) in accordance with JIS Z 8722. The WI of the sheet was used as an index of whiteness.

[0096] 1. Biomass material-containing sheet

[0097] [Sheet containing starch as biomass material] Test Example 1: Sheet manufacturing

[0098] Example 1

[0099] 59 parts by mass of cornstarch and 0.7 parts by mass of glyceric acid ester were mixed in a high-temperature mixer, heated and stirred at a temperature of 110 to 150°C for 20 to 40 minutes, and then 32.3 parts by mass of random copolymer polypropylene (product name: Sumitomo Noblen FL6632G, manufactured by Sumitomo Chemical Co., Ltd. (melting point 138.5°C)) and 1 part by mass of zinc stearate and 3 parts by mass of magnesium stearate as high-melting point additives were added. 1 part by mass of white pigment MB and 3 parts by mass of a compatibilizer were then added, and the mixture was heated and stirred at a temperature of 110 to 150°C for 1 to 10 minutes.

[0100] The heated and stirred mixture was discharged from the high-temperature mixer and transferred to a coolable mixer (cooling mixer), where it was cooled to 60-100°C while being stirred and cooled, and the temperature was lowered to obtain particles in which the particle core was a granular body of random copolymer polypropylene, a thermoplastic resin, and the surface of the particle core was coated with a cornstarch-containing coating layer.The particles were transferred to a stock tank and maintained at approximately 70°C.

[0101] Particles maintained at approximately 70°C in a stock tank were fed into a first-stage twin-screw extruder, where they were kneaded at a cylinder temperature of 120-190°C and a resin pressure of 1-4 MPa. The particles kneaded in the twin-screw extruder were then fed into a second-stage single-screw extruder, where the heating zone temperature was set to 140-190°C (a temperature higher than the melting point of the random copolymer polypropylene) and the resin pressure was set to 3-20 MPa, to obtain a starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 1"). The starch-containing resin composition was extruded into a sheet form through a T-die equipped in the single-screw extruder, and the temperature of the take-up roll was set to 40-60°C. The starch-containing sheet molded to a predetermined thickness of 0.7 mm was cooled, taken up, and wound onto a paper tube.

[0102] Furthermore, the starch-containing resin composition of Example 1 was injection molded using an injection molding machine to obtain an injection-molded piece as a sample for measuring deflection temperature under load.

[0103] The deflection temperature under load of the injection-molded piece was measured in accordance with JIS K 7191. The deflection temperature under load was measured by a flatwise test under a bending stress load of 0.45 MPa. The measurement results are shown in Table 1 below.

[0104] [Table 1]

[0105] Examples 2 to 4

[0106] Starch-containing sheets were produced in the same manner as in Example 1, except that the amounts of corn starch and random copolymer polypropylene (product name: Sumitomo Noblen FL6632G, manufactured by Sumitomo Chemical Co., Ltd. (melting point 138.5°C)) added were changed as shown in Table 1 above.

[0107] In Examples 2 to 4, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 1 above.

[0108] (Comparative Example 1)

[0109] A sheet was produced in the same manner as in Example 1, except that only homopolymer polypropylene (product name: Sumitomo Noblen D101, manufactured by Sumitomo Chemical Co., Ltd.) was added and supplied to a second-stage single-screw extruder with a heating zone temperature set to 170°C to 190°C and a resin pressure set to 3 MPa to 20 MPa.

[0110] In Comparative Example 1, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 1 above.

[0111] (Comparative Example 2)

[0112] A sheet was produced in the same manner as in Example 1, except that only block copolymer polypropylene (trade name: SunAllomer VB170A, manufactured by SunAllomer Co., Ltd.) was added and supplied to a second-stage single-screw extruder with a heating zone temperature set to 170°C to 190°C and a resin pressure set to 3 MPa to 20 MPa.

[0113] In Comparative Example 2, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 1 above.

[0114] (Comparative Example 3)

[0115] A starch-containing sheet was produced in the same manner as in Example 1, except that 32.3 parts by mass of homopolymer polypropylene (product name: Sumitomo Noblen D101, manufactured by Sumitomo Chemical Co., Ltd.) was added instead of random copolymer polypropylene (product name: Sumitomo Noblen FL6632G, manufactured by Sumitomo Chemical Co., Ltd. (melting point 138.5°C)), and the mixture was supplied to a second-stage single-screw extruder with a heating zone temperature set to 170°C to 190°C and a resin pressure set to 3 MPa to 20 MPa.

[0116] In Comparative Example 1, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 1 above.

[0117] Comparative Example 4

[0118] A starch-containing sheet was produced in the same manner as in Example 1, except that 32.3 parts by mass of block copolymer polypropylene (trade name: SunAllomer VB170A, manufactured by SunAllomer Co., Ltd.) was added instead of the random copolymer polypropylene (trade name: Sumitomo Noblen FL6632G, manufactured by Sumitomo Chemical Co., Ltd. (melting point: 138.5°C)).

[0119] In Comparative Example 4, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 1 above.

[0120] The starch-containing sheets of Examples 1 to 4 all had deflection temperatures under load within the range of 65°C or higher and 80°C or lower, making them suitable for use in low-temperature in-line molding. On the other hand, the deflection temperatures under load of the sheets of Comparative Examples 1 to 4 were outside this range, making them unsuitable for use in low-temperature in-line molding. Furthermore, when Example 1, Comparative Example 3, and Comparative Example 4 are compared, it can be seen that the whiteness of Example 1 was improved over the whiteness of Comparative Examples 3 and 4, despite having the same starch content.

[0121] The configurations, methods, steps, shapes, materials, and numerical values, etc., described in the above-described embodiments and examples are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values, etc., may be used as necessary.

[0122] Furthermore, the configurations, methods, processes, shapes, materials, numerical values, etc. of the above-described embodiments and examples can be combined with one another without departing from the spirit of the present embodiments.

[0123] Furthermore, in this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage may be replaced with the upper or lower limit of a numerical range in another stage. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types. [Explanation of symbols]

[0124] 101 Inline molding machine 102 Bottom Sheet 103 Molding mold 104 Items to be packaged 105 Bottom container 106 Top Film 107 Sealing mold 108 Cutting section

Claims

1. An in-line molding method comprising a molding process, a packaging material filling process, and a sealing process, wherein the molding process, the packaging material filling process, and the sealing process are carried out on a single line, In the molding step, the biomass material-containing sheet is molded into a shape having a recess, In the packaging material filling step, the recesses of the biomass material-containing sheet are filled with packaging materials, In the sealing step, the recess filled with the packaged item is sealed with a film, The biomass material-containing sheet is formed from a biomass material and a resin composition containing a thermoplastic resin, the thermoplastic resin is a random copolymer, the content of the thermoplastic resin is 30% by mass or more and 45% by mass or less relative to the mass of the biomass material-containing sheet, and the deflection temperature under load of the biomass material-containing sheet measured in accordance with JIS K 7191 "Plastics - Test method for deflection temperature under load" is 65°C or more and 80°C or less.

2. An inline molding method as described in claim 1, wherein in the molding process, the biomass material-containing sheet is molded at 155°C or less.

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