Biomass fine particles

Abstract

To provide biomass fine particles which can be easily produced by a room temperature dry grinding method. The biomass fine particles are characterized by comprising a biomass plastic having a glass transition temperature of 75°C or higher and having a volume-average particle size of 10-200 μm. The biomass plastic is composed of a polyethylene furanoate resin, and the copolymer composition of the resin preferably includes biomass-derived furan dicarboxylic acid and biomass-derived ethylene glycol. The number-average molecular weight of the polyethylene furanoate resin is preferably 6,000-30,000. The biomass fine particles according to the present invention can be used in a wide range of fields such as polymer fine particles for light diffusion sheets for display and polymer fine particles for foundations.

Description

Biomass fine particles

[0001] The present invention relates to biomass fine particles made of biomass plastics having a polymer composition containing biomass-derived raw materials.

[0002] Polymer microparticles can be synthesized using a variety of methods, and various functions can be achieved by controlling the particle size, particle size distribution, shape, and surface condition. They are widely used in fields such as light diffusion plates and sheets for liquid crystal displays, external additives for toner, matting agents for paints, and cosmetic additives.

[0003] In recent years, with growing awareness of the need to prevent global warming and reduce the use of petroleum, a finite resource, there has been a desire to replace conventional fossil fuel-derived polymer particles with carbon-neutral plant-derived plastic materials, and the use of biomass plastics has been attracting attention.

[0004] Biomass plastics are plastics based on organic matter photosynthesized from carbon dioxide and water, and by using them they can be converted back into carbon dioxide and water, making them a so-called carbon-neutral renewable energy source. Recently, the practical use of biomass microparticles produced from these biomass plastics has progressed rapidly, and attempts are also being made to produce various resins from biomass-derived raw materials.

[0005] Conventional methods for producing biomass microparticles using biomass-derived raw materials include a method of polycondensation in an aqueous medium (Patent Document 1) and a method of microparticulating biomass resin synthesized by bulk polymerization using a dry grinding method (Patent Document 2).

[0006] JP 2007-291240 A JP 2001-288273 A

[0007] The method of polycondensation in an aqueous medium as disclosed in Patent Document 1 consists of a step of dispersing an oil phase containing polycondensable monomers including at least lactic acid in an aqueous medium and a step of polycondensing the polycondensable monomers. However, when actually extracting the product as dry fine particles, a dehydration step for separating the product from the aqueous medium, a washing step for removing the surfactant and unreacted polymer, and a drying step for completely removing the aqueous medium are required, which results in a complicated production process and high energy consumption.

[0008] On the other hand, a method of microparticulating biomass resin synthesized by bulk polymerization using a dry grinding method, as disclosed in Patent Document 2, can solve the problems associated with the polycondensation method in an aqueous medium. However, because biomass resins generally have a low glass transition temperature, if dry grinding is performed at room temperature, the mechanical grinding energy generated during the process causes collisions and friction, resulting in melting of the resin. As a result, thread-like or whisker-like protrusions with lengths of 1 mm or more are formed on the crushed particles, making the resulting product unusable as a powder.

[0009] Therefore, in order to increase the glass transition temperature, a method can be adopted in which a monomer that increases the glass transition temperature during the polycondensation reaction is copolymerized. However, if a monomer other than biomass-derived raw materials is used, the ratio of biomass-derived raw materials in the biomass microparticles decreases, and the original purpose cannot be achieved.

[0010] Therefore, as disclosed in Patent Document 2, a freeze-pulverization method in which freeze-dried resin is dry-pulverized has conventionally been used to pulverize and finely atomize biomass resins with low glass transition temperatures. However, the freeze-pulverization method requires a large amount of liquid nitrogen to freeze-dry the resin, and the pulverizer and other peripheral devices must also be specially designed to withstand low temperatures, resulting in large-scale equipment and high pulverization costs.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide biomass fine particles that can be easily produced by a room temperature dry grinding method.

[0012] To achieve the above-mentioned object, the present invention has the following features (1) to (4): (1) Biomass microparticles comprising a biomass plastic having a glass transition temperature of 75°C or higher and a volume average particle size of 10 to 200 μm. (2) Biomass microparticles according to (1), wherein the biomass plastic comprises a polyethylene furanoate-based resin, and the copolymer composition of the resin contains biomass-derived furandicarboxylic acid and biomass-derived ethylene glycol. (3) Biomass microparticles according to (2), wherein the polyethylene furanoate-based resin has a number average molecular weight of 6,000 to 30,000. (4) Biomass microparticles according to any one of (1) to (3), wherein the biomass plastic contains 10% by mass or more of a biomass-derived component as a copolymer composition.

[0013] The biomass microparticles of the present invention can be easily produced by a room-temperature dry grinding method, and therefore can be widely used, for example, as polymer microparticles in light diffusion sheets for displays, which are increasingly being replaced by carbon-neutral plant-derived plastic materials, or as polymer microparticles in foundations.

[0014] Next, an embodiment of the present invention will be described. First, the biomass plastic used in the biomass microparticles of the present invention has a glass transition temperature of 75°C or higher, more preferably 80°C or higher. If the glass transition temperature is below the lower limit, when micronization is performed using a room temperature dry grinder, collisions and frictional heat may cause the resin to melt. As a result, thread-like or whisker-like protrusions with a length of 1 mm or more may appear on the crushed particles, causing aggregation of the crushed particles or adhesion to the crushing equipment, making it difficult to extract the fine particles.

[0015] The volume-average particle diameter of the biomass particles of the present invention is 10 to 200 μm, preferably 20 to 130 μm. This volume-average particle diameter is suitable for use in fields such as light diffusion plates and sheets for liquid crystal displays, external additives for toners, matting agents for paints, and cosmetic additives. If the volume-average particle diameter is below the lower limit, not only will handling as a dry powder be difficult due to scattering, but as an additive, properties derived from the particle shape, such as smoothness and light diffusibility, may not be exhibited. On the other hand, if the volume-average particle diameter exceeds the upper limit, sedimentation may become a problem when used as an additive.

[0016] The room temperature dry grinding equipment used in producing the biomass fine particles of the present invention is not particularly limited as long as it is capable of grinding, and a jet mill, hammer mill, pin mill, turbo mill, turbo disc mill, cutter mill, etc. can be used.

[0017] A preferred biomass plastic with a glass transition temperature of 75° C. or higher is a polyethylene furanoate resin containing biomass-derived furan dicarboxylic acid and biomass-derived ethylene glycol. Polyethylene furanoate resins have a polymer structure in which the bond distance between aromatic rings is short and the resin has a specific bond angle, making them rigid, highly filled, and highly dense, and they have a high glass transition temperature among biomass plastics.

[0018] Polyethylene furanoate resins have a high glass transition temperature, but this glass transition temperature tends to depend on the molecular weight. When dry pulverization is performed at room temperature, a glass transition temperature of 75°C or higher is required. To achieve a glass transition temperature within this range, the number average molecular weight of the polyethylene furanoate resin is preferably in the range of 6,000 to 30,000, more preferably in the range of 11,000 to 20,000. As described below, the number average molecular weight of the polyethylene furanoate resin can be controlled by adjusting conditions in the production process, such as the polycondensation reaction time, monomer concentration, other raw material concentrations, reaction temperature, and degree of vacuum.

[0019] Biomass plastics is a general term for resins whose polymer composition is biomass-derived raw materials, but there is no clear definition of the composition ratio of the biomass-derived raw materials. In the present invention, biomass plastics are defined as those containing 10% by mass or more of biomass-derived components in the copolymer composition.

[0020] The biomass plastic of the present invention is preferably composed of a polyethylene furanoate-based resin, and contains a polycarboxylic acid having a furan skeleton as the polycarboxylic acid component and ethylene glycol as the polyhydric alcohol component. The polyethylene furanoate-based resin of the present invention preferably contains 80 mol % or more, more preferably 85 mol % or more, even more preferably 90 mol % or more, particularly preferably 95 mol % or more, and may even contain 100 mol % of units consisting of a polycarboxylic acid having a furan skeleton and ethylene glycol.

[0021] Examples of the furan skeleton of the polycarboxylic acid having a furan skeleton include furan and furan substitution products (i.e., furan in which one or two hydrogen atoms have been substituted with any substituent; the substituent does not include a carboxy group). Examples of the substituent introduced into the furan substitution product include an alkyl group having 1 to 10 carbon atoms, an aromatic group having 6 to 18 carbon atoms, a halogen, and an alkoxy group having 1 to 10 carbon atoms. A furan substitution product substituted with an alkyl group having 1 to 4 carbon atoms or unsubstituted furan is preferred, and unsubstituted furan is more preferred.

[0022] Furthermore, as a polycarboxylic acid component having a furan skeleton, furandicarboxylic acid having two carboxy groups is preferred. Furandicarboxylic acids include those having carboxy groups capable of reacting with other monomers at the 2- and 3-positions, the 2- and 4-positions, the 2- and 5-positions, or the 3- and 4-positions of the furan ring. Furandicarboxylic acid having carboxy groups at the 2- and 5-positions (2,5-furandicarboxylic acid) is particularly preferred in terms of heat resistance. Furandicarboxylic acid and its derivatives can be used as raw material monomers for producing polyethylene furanoate-based resins. Examples of derivatives include alkyl esters having 1 to 4 carbon atoms. Among these, methyl ester, ethyl ester, n-propyl ester, isopropyl ester, etc. are preferred, and methyl ester is more preferred. These may be used alone or in combination of two or more.

[0023] The proportion of the polycarboxylic acid component having a furan skeleton relative to 100 mol % of all polycarboxylic acid components constituting the polyethylene furanoate resin is not particularly limited, but is usually preferably 95 mol % or more, more preferably 96 mol % or more, and even more preferably 97 mol % or more. In another preferred embodiment, the polycarboxylic acid component is composed solely of polycarboxylic acid components having a furan skeleton.

[0024] The polyethylene furanoate resin of the present invention may contain, as the polycarboxylic acid component, an aliphatic polycarboxylic acid component in addition to a polycarboxylic acid component having a furan skeleton. The aliphatic polycarboxylic acid component is preferably an aliphatic dicarboxylic acid having two carboxy groups. The aliphatic dicarboxylic acid component may be a saturated aliphatic dicarboxylic acid or an unsaturated dicarboxylic acid, but is preferably a saturated aliphatic dicarboxylic acid. The saturated aliphatic dicarboxylic acid component may be a linear aliphatic dicarboxylic acid or a branched aliphatic dicarboxylic acid, but is preferably a linear saturated aliphatic dicarboxylic acid. The linear saturated aliphatic dicarboxylic acid component is preferably a linear saturated aliphatic dicarboxylic acid having 2 to 12 carbon atoms, more preferably a linear saturated aliphatic dicarboxylic acid having 2 to 10 carbon atoms, and even more preferably a linear saturated aliphatic dicarboxylic acid having 3 to 7 carbon atoms. Examples of such aliphatic polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid. In addition, as a raw material monomer for producing a polyethylene furanoate-based resin, a derivative of an aliphatic polycarboxylic acid can also be used. The derivative is the same as that described above.

[0025] The proportion of the aliphatic polycarboxylic acid component relative to 100 mol% of all polycarboxylic acid components constituting the polyethylene furanoate-based resin is preferably 5 mol% or less, more preferably 4 mol% or less, and even more preferably 3 mol% or less. The lower limit of the proportion of the aliphatic polycarboxylic acid component is preferably 0.1 mol% or more, more preferably 0.7 mol% or more, and even more preferably 1.5 mol% or more.

[0026] When the aliphatic polycarboxylic acid component is contained within the above-mentioned range, the decrease in heat resistance due to the copolymerization component can be suppressed, and the crystallization rate can be improved. The reason for this is thought to be that the inclusion of a flexible aliphatic polycarboxylic acid component within the above-mentioned optimal range increases the molecular mobility of the polyethylene furanoate-based resin, and the molecules are neatly arranged and densely packed so that crystal formation can occur. If the copolymerization amount of the aliphatic polycarboxylic acid component is higher than the above-mentioned range, molecular mobility increases, but the chain length of the block consisting of the polycarboxylic acid component having a furan skeleton and the polyhydric alcohol component becomes shorter, making crystal formation more difficult.

[0027] The polyethylene furanoate resin of the present invention may contain, as the polycarboxylic acid component, a carboxylic acid component other than the polycarboxylic acid component having a furan skeleton and the aliphatic polycarboxylic acid component, as long as the effects of the present invention are not impaired. Examples of the other carboxylic acid component include aromatic polycarboxylic acids and their esters, and alicyclic polycarboxylic acids and their esters.

[0028] Examples of aromatic polycarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, diphenic acid, 5-hydroxyisophthalic acid, trimellitic acid, pyromellitic acid, methylcyclohexene tricarboxylic acid, oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA). Other examples include aromatic dicarboxylic acids having a sulfonic acid group or a sulfonate salt group, such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, sulfoterephthalic acid, and / or metal salts or ammonium salts thereof.

[0029] Examples of alicyclic polycarboxylic acids include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,2-cyclohexanedicarboxylic acid and their anhydrides. These other carboxylic acid components may be used alone or in combination of two or more. They may also be ester-modified.

[0030] The proportion of the above-mentioned other carboxylic acid components relative to 100 mol% of all polycarboxylic acid components constituting the polyethylene furanoate-based resin of the present invention is preferably 3 mol% or less in total, more preferably 2 mol% or less, and even more preferably 1 mol% or less. It is also a preferred embodiment that the above-mentioned other carboxylic acid components are not contained, i.e., the polycarboxylic acid components consist only of polycarboxylic acid components having a furan skeleton and aliphatic polycarboxylic acid components. It is also a preferred embodiment that the polycarboxylic acid components consist only of polycarboxylic acid components having a furan skeleton.

[0031] Next, the polyhydric alcohol component of the polyethylene furanoate resin of the present invention contains ethylene glycol, as described above. The proportion of ethylene glycol in the total polyhydric alcohol components constituting the polyethylene furanoate resin of the present invention is not particularly limited, but is typically preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. It is also a preferred embodiment that the polyhydric alcohol component consists solely of ethylene glycol. Furthermore, it is preferably 99.5 mol% or less, more preferably 99 mol% or less, and even more preferably 98 mol% or less.

[0032] The polyethylene furanoate resin of the present invention may also contain diethylene glycol as a polyhydric alcohol component. The ratio of diethylene glycol to 100 mol% of all polyhydric alcohol components constituting the polyethylene furanoate resin of the present invention is preferably 5 mol% or less, more preferably 3 mol% or less, and even more preferably 2 mol% or less. The ratio of diethylene glycol to 100 mol% of all polyhydric alcohol components is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and even more preferably 1 mol% or more.

[0033] When the polyethylene furanoate resin of the present invention contains diethylene glycol as a polyhydric alcohol component, the ethylene glycol may be a by-product of condensation or may be added as a raw material. To suppress the amount of diethylene glycol by-product, a basic compound may be added as a diethylene glycol inhibitor. Examples of basic compounds include tertiary amines such as triethylamine and tri-n-butylamine, and quaternary ammonium salts such as tetraethylammonium hydroxide.

[0034] The polyethylene furanoate resin of the present invention may also contain a polyhydric alcohol component other than ethylene glycol or diethylene glycol. The polyhydric alcohol component other than ethylene glycol or diethylene glycol is preferably an aliphatic polyhydric alcohol, an alicyclic polyhydric alcohol, an ether bond-containing polyhydric alcohol, or an aromatic-containing polyhydric alcohol. Examples of aliphatic polyhydric alcohols include 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, hydroxypivalic acid neopentyl glycol ester, dimethylolheptane, 2,2,4-trimethyl-1,3-pentanediol, glycerin, pentaerythritol, trimethylolethane, trimethylolpentane, and trimethylolpropane.

[0035] Examples of the alicyclic polyhydric alcohol include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethylol, spiroglycol, hydrogenated bisphenol A, and ethylene oxide and propylene oxide adducts of hydrogenated bisphenol A.

[0036] Examples of ether bond-containing polyhydric alcohols that can be used, if necessary, include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, neopentyl glycol ethylene oxide adduct, and neopentyl glycol propylene oxide adduct.

[0037] Examples of aromatic polyhydric alcohols include glycols obtained by adding 1 to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols, such as paraxylene glycol, metaxylene glycol, orthoxylene glycol, 1,4-phenylene glycol, an ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct thereof. These may be used alone or in combination of two or more.

[0038] The polyethylene furanoate resin of the present invention can contain at least one metal element selected from antimony, aluminum, titanium, and germanium. This allows the polyethylene furanoate resin of the present invention to have excellent thermal stability. However, if the polyethylene furanoate resin contains a large amount of such metal element, it can accelerate the thermal decomposition reaction of the polyester at high temperatures, which can lead to a decrease in reduced viscosity, deterioration of the resin color, and thermal degradation. Therefore, the total content of such metal elements is preferably 350 ppm by mass or less, more preferably 300 ppm by mass or less, and even more preferably 250 ppm by mass or less.

[0039] The polyethylene furanoate resin of the present invention may contain a crystal nucleating agent. Examples of the crystal nucleating agent include inorganic materials such as talc, boron nitride, silica, and layered silicates, and organic materials such as polyester oligomers, polyethylene wax, and polypropylene wax. Talc and polyester oligomers are preferred. These may be used alone or in combination of two or more. By including a crystal nucleating agent in the polyethylene furanoate resin of the present invention, the crystallization rate can be accelerated. Specifically, the cold crystallization peak during the first heating cycle, as measured by differential scanning calorimetry (DSC) at a heating rate of 10°C / min, can be in the range of 145 to 185°C, and the calorific value can be 3 J / g or more. Another preferred embodiment involves including a crystal nucleating agent in the polyethylene furanoate resin to impart high shear stress.

[0040] The content of the nucleating agent is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more, based on the polyethylene furanoate-based resin. The upper limit of the content of the nucleating agent is 4% by mass, more preferably 3% by mass, even more preferably 2% by mass, and most preferably 1% by mass. If the content of the nucleating agent is less than the lower limit, the effect of promoting crystallization may not be sufficiently obtained, and if it is more than the upper limit, the mechanical properties of the polyethylene furanoate-based resin may be reduced, and flexibility may be impaired.

[0041] When the nucleating agent is an inorganic material, the smaller its particle size is, the better, in order to enhance the effect of the nucleating agent. The average particle size of the nucleating agent is preferably 5 μm or less, more preferably 3 μm or less, even more preferably 1 μm or less, and most preferably 0.5 μm or less. The lower limit of the average particle size of the nucleating agent is preferably 0.1 μm.

[0042] The method for producing the polyethylene furanoate resin of the present invention can be carried out by a method including the steps of a conventionally known method for producing a polyester resin, except that it includes a step of polycondensation reaction using a polycarboxylic acid having a furan skeleton as the polycarboxylic acid component and ethylene glycol as the polyhydric alcohol component.

[0043] In the method for producing the polyethylene furanoate resin of the present invention, the molar ratio of the polycarboxylic acid component containing a polycarboxylic acid having a furan skeleton and the polyhydric alcohol component containing ethylene glycol at the time of charging is not particularly limited as long as the polyethylene furanoate resin of the present invention can be produced. However, in terms of facilitating the production of a polyethylene furanoate resin with a high reduced viscosity, the diol is preferably 0.9 mol or more, more preferably 1.0 mol or more, and even more preferably 1.2 mol or more, per 1.0 mol of the dicarboxylic acid component. On the other hand, the ratio is preferably 4.0 mol or less, more preferably 3.0 mol or less, and even more preferably 2.5 mol or less.

[0044] When polymerizing the polyethylene furanoate resin of the present invention, it is preferable to use a polymerization catalyst. The timing and amount of catalyst addition may be adjusted as appropriate. That is, the polymerization catalyst may be added when the raw materials are charged, or may be added during the production process. Alternatively, the polymerization catalyst may be added both when the raw materials are charged and during the production process. As a method for charging the catalyst, the polymerization catalyst may be charged alone, or may be charged in a state where it is dissolved or dispersed in water, alcohol, or glycol such as ethylene glycol.

[0045] Examples of polymerization catalysts include titanium compounds (tetra-n-butyl titanate, tetraisopropyl titanate, titanium oxyacetylacetonate, etc.), antimony compounds (tributoxyantimony, antimony trioxide, etc.), germanium compounds (tetra-n-butoxygermanium, germanium oxide, etc.), zinc compounds (zinc acetate, etc.), and aluminum compounds (aluminum acetate, aluminum acetylacetate, etc.). When an aluminum compound is used as the polymerization catalyst, it is preferable to use a phosphorus compound in combination as a co-catalyst. One or more of the above polymerization catalysts may be used. From the standpoint of polymerization reactivity, antimony compounds, aluminum compounds, titanium compounds, and germanium compounds are preferred, and in consideration of the effect on the resin color, aluminum compounds and germanium compounds are more preferred.

[0046] The phosphorus compound is not particularly limited, but it is preferable to use a phosphonic acid compound or a phosphinic acid compound because it has a significant effect of improving catalytic activity, and among these, it is more preferable to use a phosphonic acid compound because it has a particularly significant effect of improving catalytic activity.

[0047] A large amount of polymerization catalyst is preferably used in terms of a fast polymerization reaction rate and high production efficiency. On the other hand, if the polyethylene furanoate-based resin contains a large amount of metal elements derived from the polymerization catalyst, this can accelerate the thermal decomposition reaction of the polyester at high temperatures, which can lead to deterioration of the resin color and thermal degradation. Even if the polymerization catalyst is placed in a reduced pressure environment during polymerization of the polyethylene furanoate-based resin, almost 100% of the amount initially added to the system as a catalyst remains in the polyethylene furanoate-based resin produced by polymerization. In other words, since the amount of polymerization catalyst remains almost unchanged before and after polycondensation, the amount of polymerization catalyst added to the resulting polyethylene furanoate-based resin is preferably 1 ppm by mass or more, more preferably 3 ppm by mass or more, and even more preferably 5 ppm by mass or more. On the other hand, the amount is preferably 350 ppm by mass or less, more preferably 300 ppm by mass or less, and even more preferably 250 ppm by mass or less.

[0048] From the viewpoint of thermal stability, it is preferable to produce the polymer using a polymerization catalyst containing an aluminum compound and a phosphorus compound.

[0049] When the polyethylene furanoate resin of the present invention contains a phosphorus compound derived from a polymerization catalyst, the content of phosphorus atoms is preferably 20 to 250 ppm by mass, more preferably 30 to 200 ppm by mass, even more preferably 40 to 150 ppm by mass, and particularly preferably 50 to 120 ppm by mass. If the phosphorus atom content is less than 20 ppm by mass, the polymerization activity may decrease and the amount of foreign matter may increase. On the other hand, if the content exceeds 250 ppm by mass, the catalyst cost may increase and the polymerization activity may decrease.

[0050] When a phosphorus compound that functions as a catalyst together with an aluminum compound is placed in a reduced pressure environment during polymerization of a polyethylene furanoate resin, a portion (about 10 to 40%) of the amount initially added to the system as a catalyst is generally removed from the system, and this removal rate varies depending on the molar ratio of phosphorus atoms to aluminum atoms added, the basicity or acidity of the aluminum-containing glycol solution or phosphorus-containing glycol solution added, the method of adding the aluminum-containing solution or phosphorus-containing solution (whether they are added as a single solution or added separately), etc. Therefore, the amount of phosphorus atoms added to the polyethylene furanoate resin to be produced is preferably 20 to 250 ppm by mass, more preferably 30 to 200 ppm by mass, and even more preferably 40 to 150 ppm by mass.

[0051] In the polyethylene furanoate-based resin of the present invention, the ratio of phosphorus atoms to aluminum atoms is preferably 1.1 to 2.8, more preferably 1.3 to 2.6, and even more preferably 1.5 to 2.5. As described above, the aluminum atoms and phosphorus atoms in the polyethylene furanoate-based resin are derived from the aluminum compound and phosphorus compound used as polymerization catalysts for the polyethylene furanoate-based resin, respectively. By using these aluminum compounds and phosphorus compounds in combination in a specific ratio, a complex having catalytic activity is functionally formed in the polymerization system, enabling sufficient polymerization activity to be exerted. If the ratio of phosphorus atoms to aluminum atoms is less than 1.1, there is a risk of reduced thermal stability and thermal oxidative stability, or an increase in the amount of foreign matter. On the other hand, if the ratio of phosphorus atoms to aluminum atoms exceeds 2.8, the amount of phosphorus compound added becomes too large, resulting in increased catalyst costs.

[0052] An example of the esterification reaction is a direct esterification method in which a polycarboxylic acid having a furan skeleton is directly reacted with ethylene glycol, and if necessary, other copolymerization components, and water is distilled off to carry out the esterification reaction, followed by a polycondensation reaction under normal pressure or reduced pressure.An example of the transesterification reaction is a production method in which dimethyl 2,5-furandicarboxylate is reacted with ethylene glycol, and if necessary, other copolymerization components, and methyl alcohol is distilled off to carry out the transesterification reaction, followed by a polycondensation reaction under normal pressure or reduced pressure.

[0053] The conditions for the esterification reaction and transesterification reaction, such as temperature, time, and pressure, can be within the ranges of conventionally known methods for producing polyethylene furanoate resins. The reaction temperature is usually 100°C or higher, preferably 120°C or higher. It is also usually 300°C or lower, preferably 290°C or lower, and more preferably 280°C or lower. By keeping the temperature within these ranges, the reaction can proceed efficiently. The reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. The reaction pressure is usually from atmospheric pressure to 0.3 MPa. The reaction time is usually 1 hour or longer, and on the other hand, it is usually 10 hours or shorter, preferably 8 hours or shorter.

[0054] The conditions for the polycondensation reaction, such as temperature, time, and pressure, can be within the ranges of conventionally known methods for producing polyester resins. The polycondensation reaction temperature is preferably 230°C or higher, more preferably 235°C or higher, and even more preferably 240°C or higher. On the other hand, it is preferably 300°C or lower, more preferably 290°C or lower, and even more preferably 280°C or lower. By setting the temperature within this range, a sufficient polymerization rate is ensured, and thermal decomposition, coloration, side reactions, etc. are suppressed, resulting in a polyethylene furanoate-based resin with a high reduced viscosity.

[0055] In any of these methods, the esterification reaction or transesterification reaction may be carried out in one step or in multiple steps, and the polycondensation reaction may be carried out in one step or in multiple steps.

[0056] The apparatus for producing the polyethylene furanoate resin of the present invention may be either a batch type or a continuous type.

[0057] The molecular weight of the polyethylene furanoate resin can be adjusted within the scope of conventionally known methods for producing polyester resins, i.e., by adjusting conditions such as polycondensation reaction time, monomer concentration, other raw material concentrations, reaction temperature, and degree of vacuum, or by lowering the molecular weight of the polyethylene furanoate resin through thermal decomposition, hydrolysis, transesterification, etc.

[0058] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The measurement methods used for evaluation in the examples are as follows.

[0059] (1) Biomass Ratio The mass ratio of biomass-derived components in the raw materials used was expressed as biomass ratio [mass %].

[0060] (2) Number average molecular weight (Mn) 2 mg of sample resin was weighed and dissolved in 4 ml of HFIP / sodium trifluoroacetate 10 mM. The solution was filtered through a 0.2 μm membrane filter, and the resulting sample solution was subjected to GPC analysis under the following conditions. The molecular weight was calculated in terms of standard polymethyl methacrylate (PMMA). The GPC analysis results show the analysis results for the entire peak. Apparatus: TOSOH HLC-8320GPC Column: TOSOH TSKgel Super HM-H x 2 + TSKgel Super H2000 Solvent: HFIP / sodium trifluoroacetate 10 mM Flow rate: 0.2 ml / min Sample concentration: 0.05% Injection volume: 10 μl Temperature: 40°C Detector: RI

[0061] (3) Glass Transition Temperature (Tg) Using a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation, 5 mg of sample resin was placed in an aluminum pan and sealed with a lid. Next, the temperature was increased to 250°C at 10°C / min and held at 250°C for 3 minutes. Thereafter, the temperature was decreased from 250°C to 25°C at 50°C / min and held at 25°C for 3 minutes. Next, the temperature was increased from 25°C to 250°C at 2°C / min, and a DSC curve was obtained during the second temperature increase. The glass transition temperature was determined from the DSC curve.

[0062] (4) Pulverization and Micronization The sample particles pulverized in a dry mill were subjected to a sieve test using a sieve with 4 mm openings and 4.7 mesh. If 90 mass % or more of the particles passed through the sieve, the result was judged as ◯; otherwise, the result was judged as ×.

[0063] (5) Volume-average particle size The dried sample particles were soaked in a surfactant and then dispersed in water to prepare a dispersion. The particle size distribution of the sample particles in this dispersion was measured using a laser diffraction particle size distribution analyzer, SALD-200V, manufactured by Shimadzu Corporation. The volume-average particle size was calculated from the obtained particle size distribution.

[0064] Next, the methods for preparing the various solutions used as catalysts will be described. <Preparation of aluminum-containing ethylene glycol solution> As an aluminum compound, a 20 g / L aqueous solution of basic aluminum acetate and an equal amount (volume ratio) of ethylene glycol were charged into a blending tank and stirred at room temperature (23°C) for several hours, and then the water was distilled off from the system while stirring under reduced pressure (3 kPa) at 50 to 90°C for several hours, to prepare an aluminum-containing ethylene glycol solution containing 20 g / L of the aluminum compound.

[0065] <Preparation of phosphorus-containing ethylene glycol solution> Irganox 1222 (manufactured by BASF Co., Ltd.) as a phosphorus compound was charged into a blending tank together with ethylene glycol, and the mixture was heat-treated at 175°C for 150 minutes while stirring under nitrogen substitution to prepare a phosphorus-containing ethylene glycol solution containing 50 g / L of the phosphorus compound.

[0066] <Preparation of antimony-containing ethylene glycol solution> Antimony trioxide as an antimony compound was charged into a blending tank together with ethylene glycol, and the mixture was heat-treated at 120°C for 150 minutes with stirring under nitrogen substitution to prepare an antimony-containing ethylene glycol solution containing 12 g / L of elemental antimony.

[0067] Next, the method for adjusting the molecular weight will be described. The molecular weight in each example and comparative example was adjusted by adjusting the polycondensation reaction time. However, as mentioned above, the molecular weight can also be adjusted by conditions such as temperature, time, and pressure in the polycondensation reaction, and the ranges used in conventionally known polyester production methods can be adopted.

[0068] Example 1 A 2-liter stainless steel autoclave equipped with a stirrer and an electric wire heater was charged with 2,5-furandicarboxylic acid (100 mol %) as a polycarboxylic acid component and ethylene glycol (200 mol %) as a polyalcohol component in an amount twice the molar amount of the polycarboxylic acid component, and triethylamine was added in an amount of 0.3 mol % relative to the polycarboxylic acid component. An esterification reaction was carried out for 120 minutes at 240°C under normal pressure while distilling water out of the system, to obtain an ester oligomer with an esterification rate of 95%.

[0069] The aluminum-containing ethylene glycol solution and phosphorus-containing ethylene glycol solution prepared by the above method were mixed and added to the resulting ester oligomer to form a single-component mixture. The mixture was added so that the aluminum and phosphorus contents were 30 ppm by mass and 74 ppm by mass, respectively, relative to the mass of the ester oligomer. The molar ratio of added phosphorus to aluminum was 2.15. The system temperature was then raised to 270°C over 1 hour, during which the system pressure was gradually reduced to 0.15 kPa. Under these conditions, a polycondensation reaction was carried out for 30 minutes. The number average molecular weight and Tg of the resulting polyethylene furanoate resin were measured, revealing a number average molecular weight of 6,500 and a Tg of 81°C.

[0070] The resulting polyethylene furanoate resin was then crushed into 2-3 cm resin pieces using a crusher. Dry crushing and classification were then carried out using a Disc Turbo Mill CD (manufactured by Freund Turbo). The results of this operation, including the determination of whether or not the resin could be crushed and pulverized, and the volume-average particle size of the resulting biomass fine particles, are shown in Table 1.

[0071] [Example 2] A polyethylene furanoate resin and biomass microparticles were obtained in the same manner as in Example 1, except that the polycondensation reaction time was adjusted. The number average molecular weight and Tg of the obtained polyethylene furanoate resin were measured, and the number average molecular weight was 11,000 and Tg was 80°C. The evaluation results are shown in Table 1.

[0072] [Example 3] A polyethylene furanoate resin and biomass microparticles were obtained in the same manner as in Example 1, except that the polycondensation reaction time was adjusted. The number average molecular weight and Tg of the obtained polyethylene furanoate resin were measured, and the number average molecular weight was 16,000 and Tg was 82°C. The evaluation results are shown in Table 1.

[0073] Example 4 A polyethylene furanoate resin and biomass microparticles were obtained in the same manner as in Example 2, except that the ethylene glycol used was changed to fossil fuel-derived ethylene glycol. The number average molecular weight and Tg of the obtained polyethylene furanoate resin were measured, and the number average molecular weight was 12,000 and the Tg was 81° C. The evaluation results are shown in Table 1.

[0074] Example 5 A polyethylene furanoate resin and biomass fine particles were obtained in the same manner as in Example 1, except that the polycarboxylic acid component was changed to 2,5-furandicarboxylic acid (98 mol%) and sebacic acid (SA; 2 mol%) and the polycondensation reaction time was adjusted. The number average molecular weight and Tg of the obtained polyethylene furanoate resin were measured, and the number average molecular weight was 12,500 and the Tg was 77°C. The evaluation results are shown in Table 1.

[0075] [Example 6] The antimony-containing ethylene glycol solution prepared by the above method was added to the ester oligomer of Example 1 so that the antimony content was 250 ppm by mass relative to the mass of the ester oligomer. The temperature of the system was then raised to 270°C over 1 hour, during which time the system pressure was gradually reduced to 0.15 kPa, and the polycondensation reaction time was adjusted under these conditions. A polyethylene furanoate-based resin and biomass microparticles were obtained in the same manner as in Example 1 except for the above. The number average molecular weight and Tg of the obtained polyethylene furanoate-based resin were measured, and the number average molecular weight was 7,000 and the Tg was 82°C. The evaluation results are shown in Table 1.

[0076] Comparative Example 1 A polyethylene furanoate resin and biomass microparticles were obtained in the same manner as in Example 1, except that the polycondensation reaction time was adjusted. The number average molecular weight and Tg of the obtained polyethylene furanoate resin were measured, and the number average molecular weight was 5,000 and the Tg was 68°C. The evaluation results are shown in Table 1. In this example, because the Tg of the polyethylene furanoate resin used was low, interparticle adhesion occurred due to melting, and the resin could not be recovered as primary particles.

[0077] Comparative Example 2 Commercially available polylactic acid (PLA) manufactured by Wako Pure Chemical Industries, Ltd., with a number-average molecular weight of 80,000 to 100,000 and a Tg of 57°C, was dry-pulverized and classified using a Disc Turbo Mill CD (manufactured by Freund Turbo). The results of this procedure to determine whether or not it could be pulverized and atomized, as well as the volume-average particle size of the resulting biomass microparticles, are shown in Table 1. In this example, because the Tg of the PLA used was low, interparticle adhesion occurred due to melting, and it was not possible to recover the biomass as primary particles.

[0078] Comparative Example 3: Commercially available polyhydroxybutyrate (PHB) with a Tg of 4°C (Biogreen, manufactured by Mitsubishi Gas Chemical Company) was crushed into 2-3 cm resin pieces using a crusher. Dry crushing and classification were then carried out using a Disc Turbo Mill CD (manufactured by Freund Turbo Corporation). The results of this operation to determine whether crushing and micronization were possible and the volume-average particle size of the resulting biomass microparticles are shown in Table 1. In this example, the Tg of the PHB used was low, so interparticle adhesion occurred due to melting, and the particles could not be recovered as primary particles.

[0079] Comparative Example 4 Commercially available polybutylene succinate (PBS) with a Tg of -31.2°C (BioPBS manufactured by Mitsubishi Chemical Corporation) was crushed into 2-3 cm resin pieces using a crusher. Dry crushing and classification were then carried out using a Disc Turbo Mill CD (manufactured by Freund Turbo Corporation). The results of this determination of whether crushing and micronization were possible and the volume-average particle size of the resulting biomass microparticles are shown in Table 1. In this example, the Tg of the PBS used was low, so interparticle adhesion occurred due to melting, and the particles could not be recovered as primary particles.

[0080] Comparative Example 5: Commercially available biomass polypropylene (manufactured by Iwatani Corporation) containing 50% biomass raw material and having a Tg of 0°C was crushed into resin pieces of 2 to 3 cm in size using a crusher. Dry crushing and classification were then carried out using a Disc Turbo Mill CD (manufactured by Freund Turbo Corporation). The results of this operation to determine whether or not the particles could be crushed and pulverized, as well as the volume-average particle size of the resulting biomass microparticles, are shown in Table 1. In this example, the Tg of the biomass polypropylene used was low, so interparticle adhesion occurred due to melting, and the particles could not be recovered as primary particles.

[0081]

[0082] From Table 1, it can be seen that in Examples 1 to 6, in which the Tg falls within the range of the present invention, the desired biomass fine particles can be obtained by room temperature dry grinding, but in Comparative Examples 1 to 5, in which the Tg does not fall within the range of the present invention, interparticle adhesion occurs due to melting during the room temperature dry grinding, making it impossible to grind and atomize the particles, and the desired biomass fine particles cannot be obtained.

[0083] The biomass microparticles of the present invention can be easily produced by a room temperature dry grinding method, and therefore can be used in a wide range of fields, such as polymer microparticles for light diffusion sheets for displays and polymer microparticles for foundations.

Claims

1. Biomass microparticles, characterized in that they are made of a biomass plastic having a glass transition temperature of 75°C or higher and have a volume average particle size of 10 to 200 μm.

2. Biomass microparticles according to claim 1, characterized in that the biomass plastic is made of a polyethylene furanoate-based resin, the copolymer composition of which contains biomass-derived furandicarboxylic acid and biomass-derived ethylene glycol.

3. Biomass fine particles according to claim 2, characterized in that the polyethylene furanoate resin has a number average molecular weight of 6,000 to 30,000.

4. Biomass microparticles according to any one of claims 1 to 3, characterized in that the biomass plastic contains 10 mass% or more of a biomass-derived component as a copolymer composition.

Images