WO2021054013A1 - Molding composition and molded body - Google Patents

Abstract

The present invention addresses the problem of providing a molded body with suppressed coloration and odor. The present invention relates to a molding composition made by mixing a pulp fiber and a biodegradable resin, wherein the content of the pulp fiber is 10-60 mass% with respect to the total mass of a molded body, the content of the biodegradable resin is 40-90 mass% with respect to the total mass of the molded body, and the pulp fiber has a cellulose purity of 90-98%.

Description

Molding composition and molded article

The present invention relates to a molding composition and a molded product.

Plastic is a useful substance that brings convenience and benefits to our lives, but usually, if it is spilled due to improper disposal, it will stay in the natural environment for a long period of time. In particular, it is estimated that the amount of plastic waste flowing into the ocean exceeds several million tons per year worldwide, and there is concern that global environmental pollution will adversely affect the ecosystem, living environment, fisheries, tourism, etc. ing. In order to solve these problems, it is desirable to suppress the outflow of plastic waste without restricting economic activities, but it is also expected to develop materials that will be decomposed even if they flow into the natural environment and to switch to such materials. Has been done. In recent years, the use of biodegradable plastics has been attracting attention in this trend, and it has begun to be used for applications such as agricultural mulch films, garbage bags, fishing lines, and vegetation nets.

Among plastic products, it is required to have mechanical strength in applications where durability is required, such as home appliances and automobile parts. Generally, in order to impart strength to the resin, a method of adding a reinforcing filler is adopted. So far, plastics to which reinforcing fibers such as glass fiber and carbon fiber have been added have been put into practical use as reinforcing fillers, but these are difficult to decompose in the natural environment, and there remains a problem in recyclability. There is.

On the other hand, since plant fibers are decomposed in a natural environment, biodegradable plastics reinforced with plant fibers have a small load even if they flow out into the environment, and are expected to be used in various applications.

For example, Patent Document 1 discloses a molded product made of a biodegradable composite material in which 5 to 60% by weight of pulp or cellulosic fiber is contained in a thermoplastic biodegradable resin. Here, a method is being studied in which beaten newspaper waste paper pulp and polycaprolactone fibers are dissociated in water to form columnar pellets by a wet granulation method, and the obtained pellets are heated and injection-molded to obtain a molded product. ..

Japanese Unexamined Patent Publication No. 06-345944

However, when ordinary pulp or cellulosic fibers are added as reinforcing fibers for reinforcement, there is a problem that the molded product is colored or has an odor due to the heat applied in the kneading and molding steps. In such a case, there is a concern that the obtained molded product itself or the contents of the molded product may give the consumer the illusion that the molded product itself is discolored or decomposed as compared with the original properties. Therefore, it has been difficult to use it in applications such as food containers that do not impair the original appearance and flavor of the contents and require a sense of cleanliness.

Therefore, in order to solve the problems of the prior art, the present inventors have proceeded with studies for the purpose of providing a molded product in which coloring and odor are suppressed.

As a result of diligent studies to solve the above problems, the present inventors have found that the content of pulp fibers and the biodegradable resin in a molding composition obtained by kneading pulp fibers and biodegradable resin. It has been found that a molded product in which coloring and odor are suppressed can be obtained by setting the content within a predetermined range and further setting the cellulose purity of the pulp fiber to 90% or more.
Specifically, the present invention has the following configuration.

[1] A molding composition obtained by kneading pulp fibers and a biodegradable resin.
The content of the pulp fiber is 10 to 60% by mass with respect to the total mass of the molding composition, and the content of the biodegradable resin is 40 to 90% by mass with respect to the total mass of the molding composition. Yes,
A molding composition having a cellulose purity of pulp fibers of 90 to 98%.
[2] The molding composition according to [1], wherein the pulp fiber has a crystallinity of 80 to 90%.
[3] The molding composition according to [1] or [2], wherein the pulp fiber is a fiber derived from wood or cotton.
[4] The molding according to any one of [1] to [3], wherein the weighted average fiber length of the pulp fiber is 0.2 to 3.0 mm, and the weighted average fiber width of the pulp fiber is 10 to 20 μm. Composition.
[5] The molding composition according to any one of [1] to [4], wherein the pulp fiber is a dissolving pulp obtained by an acidic sulfite steaming method or a pre-hydrolysis-craft steaming method.
[6] The molding composition according to any one of [1] to [5], wherein the Canadian standard pulp drainage degree measured according to JIS P 8121-1995 of pulp fiber is 600 ml to 750 ml.
[7] The molding composition according to any one of [1] to [6], wherein the biodegradable resin is a polyester resin having a melting point of 150 ° C. or lower.
[8] The molding composition according to any one of [1] to [7], wherein the biodegradable resin contains polybutylene succinate as a main component.
[9] A molded product obtained by molding the molding composition according to any one of [1] to [8].

According to the present invention, it is possible to obtain a molded product in which coloring and odor are suppressed.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.

(Composition for molding)
The present invention relates to a molding composition obtained by kneading pulp fibers and a biodegradable resin. Here, the content of the pulp fiber is 10 to 60% by mass with respect to the total mass of the molding composition, and the content of the biodegradable resin is 40 to 90 with respect to the total mass of the molding composition. It is mass%. The cellulose purity of pulp fibers is 90 to 98%.

Since the molding composition of the present invention has the above-mentioned structure, it is possible to mold a molded product in which coloring and odor are suppressed. Here, the suppression of the odor of the molded product can be evaluated by sensory evaluation of the odor of the molded product immediately after molding the molding composition. In general, pulp contains hemicellulose, lignin, etc. in addition to cellulose, and monosaccharides and disaccharides produced by hydrolysis of these contain odors, or reduced saccharides are amino compounds. It is presumed that it reacts with and emits an odor. In the present invention, it is considered that the odor of the molded product can be suppressed by reducing the proportion of hemicellulose and lignin in the pulp fiber as much as possible and setting the cellulose purity within the above range.

The fact that the coloring of the molded product is suppressed can be indexed by, for example, the lightness (L * value) or yellowness (b * value) of the color. Specifically, the brightness (L * value) of the molded product is preferably 75.0 or more, and more preferably 76.0 or more. Further, the yellowness (b * value) of the molded product is preferably 14.0 or less. When the lightness (L * value) and yellowness (b * value) of the molded product satisfy the above conditions, it can be determined that the coloring of the molded product is suppressed. Similar to odor, it is considered that monosaccharides and disaccharides produced by hydrolysis of hemicellulose and lignin, and reduced saccharides react with amino compounds to color them.

Since the molding composition of the present invention has the above-mentioned structure, the strength of the molded product can be increased. Specifically, the molded product molded from the molding composition of the present invention has higher bending strength and flexural modulus than the molded product molded only from resin. In addition, the molded product molded from the molding composition of the present invention is also excellent in impact resistance.

Further, the molding composition of the present invention is a molding composition in which pulp fiber, which is a biomass resource, and a biodegradable resin are kneaded. Therefore, it is possible to reduce the cost at the time of manufacturing, and because the production is a carbon-neutral material that does not depend on fossil resources, it is also possible to reduce the amount of carbon dioxide emitted at the time of disposal. Further, the molded product of the present invention can be biodegraded in a natural environment.

In the natural environment, many cellulolytic microorganisms exist. For example, in natural seawater at 30 ± 2 ° C., 80% or more of cellulose is decomposed into water and carbon dioxide in 6 months. Are known. Therefore, even if the resin is biodegraded relatively slowly in the natural environment, the biodegradation rate of the composition can be improved by adding cellulose. In addition, the decomposition of the cellulose constituting the composition creates voids in the molded product and increases the surface area of the resin, so that the biodegradation rate of the resin itself can be expected to be improved.

The melt flow rate (MFR) of the molding composition is preferably 1.0 g / 10 min or more, more preferably 3.0 g / 10 min or more, and further preferably 5.0 g / 10 min or more. .. The melt flow rate (MFR) of the molding composition is preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, and further preferably 20 g / 10 min or less. By setting the melt flow rate (MFR) of the molding composition within the above range, it is possible to suppress the frictional heat generated during kneading and molding and more effectively suppress the coloring of the molded product. The melt flow rate (MFR) of the molding composition is a value measured according to JIS K 7210 at 190 ° C. under a load of 10 kg.

The molding composition is a composition obtained by kneading pulp fibers and a biodegradable resin, and its properties may be a solid state or a molten liquid state. When the molding composition is a solid body, the molding composition may be in the form of pellets, flakes, or powders.

(Pulp fiber)
The pulp fiber is preferably a fiber derived from wood or cotton, and the cellulose purity of the pulp fiber is 90 to 98%. In the molding composition of the present invention, by using pulp fibers having a cellulose purity of 90% or more, it is possible to suppress coloring and odor generated when heating is performed in the kneading and molding steps. By setting the cellulose purity of the pulp fiber to 90% or more, it is possible to significantly reduce the content of hemicellulose and lignin contained in ordinary plant fibers, which occurs during the decomposition of hemicellulose and lignin. It is presumed that the generation of coloring and odor can be suppressed.

Examples of pulp fibers having a cellulose purity of 90% or more include dissolved pulp and cotton fibers. Among them, dissolved pulp is particularly preferably used. The cellulose purity of bleached kraft pulp of hardwoods and softwoods used in a normal papermaking process is about 85%.

Dissolving pulp can be obtained by selectively removing hemicellulose and lignin from lignocellulose substances contained in softwood pulp, hardwood pulp and the like. Among them, the dissolving pulp is preferably the dissolving pulp obtained by the acidic sulfite steaming method or the pre-hydrolysis-craft cooking method. The lignocellulosic substance used for the production of the dissolving pulp may be derived from any raw material of trees or non-trees, and even if a dissolved pulp processed by mixing lignocellulosic substances obtained from different tree species and different raw materials is used. Good. As the dissolving pulp, dissolved pulp obtained from different tree species and different raw materials may be mixed and used.

The dissolving pulp is preferably either softwood-derived pulp or hardwood-derived pulp, but more preferably hardwood-derived pulp. In general, hardwood is more suitable than softwood in that it can obtain dissolved pulp having a high volume weight and high treatment efficiency. Further, among hardwoods, eucalyptus and acacia, which have a high volume weight, are particularly preferably used. Examples of such hardwoods include eucalyptus globulus, eucalyptus grandis, eucalyptus eurograndis, eucalyptus perita, eucalyptus brasiana, acacia melansi, and the like, and eucalyptus perita is preferably used.

The volume weight of the hardwood ^{is preferably 450 to 700 kg / m 3} , more preferably 500 to 650 kg / m ³ . By setting the volume weight of the hardwood within the above range, the production efficiency of pulp can be increased, and further, the chemical solution sufficiently permeates during pre-hydrolysis or alkaline cooking, so that pulp having high cellulose purity can be obtained.

It is also preferable to use cotton fiber as the pulp fiber having a cellulose purity of 90% or more. Cotton fibers are obtained by using raw cotton collected from cotton as a raw material and loosening it while removing seed pieces, leaf pieces, dust and the like adhering to the raw cotton. The cotton fiber can be adjusted to a desired fiber length and diameter by performing treatments such as carding, combing, stretching, and cutting, if necessary.

Specifically, the cellulose purity of the pulp fiber can be calculated by the following method. First, the pulp fiber having an absolute dry amount of 5 g is placed in a beaker in a constant temperature water bath at 20 ° C., and then 17.5% by mass is obtained. Add 50 ml of sodium hydroxide solution uniformly. After leaving it for 3 minutes and 30 seconds, crush the sample with a glass rod for 5 minutes to allow it to sufficiently disintegrate. After flattening the surface of the sample and letting it sit for 20 minutes, add 50 ml of distilled water and stir the contents with a glass rod. Then, after filtering the contents, the contents are washed with water by repeating suction and dehydration with a total amount of washing water of 900 ml. Pour 40 ml of 10% acetic acid and leave it for 5 minutes to allow the acid solution to fully permeate, then wash with 1 L of boiling water to dry the contents. The ratio of the dry weight of the contents to the absolute dry amount of the sample is calculated as the α-cellulose content, and is defined as the cellulose purity (%).
Cellulose purity (%) = (weight of absolute dry α-cellulose / weight of absolute dry pulp fiber) × 100
When measuring the cellulose purity of pulp fibers, it is preferable to use the pulp fibers alone for the measurement, but a kneaded product of pulp and resin may be used for the measurement. In this case, it is preferable to extract only the pulp component using an organic solvent or the like that selectively dissolves the resin component in the kneaded product and subject it to the test. As the organic solvent used for extraction, a known one can be used. For example, a ketone-based organic solvent, an aromatic hydrocarbon-based organic solvent, an ether-based organic solvent, a halogen-containing organic solvent, an alcohol-based organic solvent, an ester-based organic solvent, a glycol-based organic solvent, and the like can be mentioned. The organic solvent can be used alone or in combination of two or more. Examples of organic solvents with good dissolution efficiency include acetone, methyl ethyl ketone (2-butanone) (hereinafter referred to as MEK), methyl isoptyl ketone (4-methyl-2-pentanone) (hereinafter referred to as MlBK), dioxane, tetrahydrofuran, and cyclohexanone alone. , Acetone ethylene glycol monobutyl ether mixed solution, MEK ethylene glycol monobutyl ether mixed solution, ΜΙΒΚ ethylene glycol monobutyl ether mixed solution, dioxane ethylene glycol monobutyl ether mixed solution, tetrahydrofuran ethylene glycol monobutyl ether mixed solution, cyclohexanone ethylene glycol monobutyl ether mixed solution A mixed solution, an acetone isopropanol mixed solution, a ΜΕΚ isopropanol mixed solution, a MIBK isopropanol mixed solution, a dioxane isopropanol mixed solution, a tetrahydrofuran isopropanol mixed solution, a cyclohexanone isopropanol mixed solution and the like can be preferably used.

The cellulose purity of the pulp fiber may be 90% or more, more preferably 95% or more. By setting the cellulose purity of the pulp fiber within the above range, it is possible to effectively suppress the coloring and odor generated when the pulp fiber is heated in the kneading and molding steps. The cellulose purity of the pulp fiber may be 98% or less, and the dispersibility of the pulp fiber can be improved by containing a very small amount of hemicellulose or lignin in the pulp fiber.

The crystallinity of the pulp fiber is preferably 80% or more, more preferably 85% or more. Further, the crystallinity of the pulp fiber is preferably 90% or less. By setting the crystallinity of the pulp fiber within the above range, the reactivity of the pulp fiber can be appropriately suppressed, and the coloring and odor generated when heated in the kneading and molding steps can be more effectively suppressed. ..

The crystallinity of the pulp fiber is the cellulose type I crystallinity calculated by the Segal method from the diffraction intensity value by the X-ray diffraction method. Specifically, the cellulose type I crystallinity is calculated based on the following formula (1) by measuring the X-ray diffraction intensity of the pulp fiber using "RINT Ultra III" manufactured by Rigaku Co., Ltd. under the following conditions. Value. The measurement sample is prepared by compressing the sheeted pulp fiber into an area of 320 mm ² × a thickness of 1 mm. For the measurement, it is preferable to use the pulp fiber alone before it is used for molding, but a kneaded product of pulp and resin may be used for the measurement. In this case, it is preferable that only the pulp component is extracted using a solvent that selectively dissolves the resin component in the kneaded product, and then subjected to the test.
(conditions)
X-ray source: Cu / Kα-radiation
Tube voltage: 40kv
Tube current: 120mA
Measurement range: Diffraction angle 2θ = 5 to 45 °
Scan speed: 10 ° / min
Formula (1): Cellulose type I crystallinity (%) = [(I _22.6- I _18.5 ) / I _22.6 ] x 100
In equation (1), I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the amorphous portion (diffraction angle 2θ). = 18.5 °).

Cellulose type I crystallinity means the ratio of the amount of crystalline region to the total cellulose. The cellulose type I is a crystalline form of natural cellulose, and the degree of cellulose type I crystallinity is related to the physical and chemical properties of cellulose, and the larger the value, the higher the hardness, density, etc. However, elongation, flexibility, and chemical reactivity are reduced.

In the present invention, two or more different pulp fibers may be used in combination, and the crystallinity of the pulp fibers in that case means the crystallinity obtained by the weighted average of the pulp fibers used, and the value thereof. Is preferably within the above range.

The Canadian standard pulp drainage measured according to JIS P 8121-1995 of pulp fibers is preferably 600 to 750 ml, more preferably 650 to 750 ml. By setting the Canadian standard pulp drainage degree of pulp fibers to the above upper limit or less, the pulp fibers can be appropriately entangled with each other to increase the strength of the molded product. Further, by setting the Canadian standard pulp drainage degree of the pulp fiber to the above lower limit value or more, the dispersibility of the biodegradable resin in the molding composition is enhanced, and a uniform molding composition can be obtained. In addition, it is possible to suppress the generation of frictional heat during kneading and molding of the molding composition and more effectively prevent the generation of coloration and odor derived from pulp fibers. When measuring the drainage degree of the pulp fiber, it is preferable to use the pulp alone for the measurement, but a kneaded product of the pulp and the resin may be used for the measurement. In this case, it is preferable to extract only the pulp component using a solvent that selectively dissolves the resin component in the kneaded product and subject it to the pulp drainage test.

The weighted average value of the pulp fiber length is preferably 0.2 to 3.0 mm, more preferably 0.3 to 2.5 mm, and even more preferably 0.5 to 2.0 mm. The weighted average fiber width of the pulp fibers is preferably 10 to 20 μm, more preferably 10 to 15 μm. By setting the fiber length of the pulp fiber within the above range, the impact resistance of the molded product can be enhanced. Further, by setting the fiber length and the average fiber width of the pulp fibers within the above ranges, it is possible to suppress the generation of frictional heat during kneading and more effectively prevent the generation of coloring and odor derived from the pulp fibers.

The content of the pulp fiber may be 10 to 60% by mass, preferably 15 to 55% by mass, and more preferably 20 to 50% by mass with respect to the total mass of the molding composition. By setting the content of the pulp fiber within the above range, the strength of the molded product can be increased more effectively. The content of the pulp fiber in the molding composition can be calculated from the blending amount of the pulp fiber added when the molding composition is produced, but it was obtained by subjecting the molding composition to X-ray diffraction. It is also possible to easily calculate from the diffraction intensity value. For example, pulp fibers have crystal peaks at diffraction angles of 2θ = 15.4 and 22.5, polybutylene succinate has crystal peaks at diffraction angles of 2θ = 19.6, 22.7, and 28.9, and the diffraction angles of 2θ = 15. .4 (pulp fiber) and 19.6 (polybutylene succinate) do not interfere with each other. By measuring the diffraction intensity of the non-interference peak portion of a plurality of samples having a known compounding ratio and drawing a calibration curve, it is possible to estimate the compounding ratio even for a sample having an unknown compounding ratio. Further, as a means for measuring the blending ratio of the pulp fiber and the molding resin, only the pulp component may be extracted using a solvent that selectively dissolves the resin component in the kneaded product, and the weight ratio may be measured.

(Biodegradable resin)
Biodegradable resin refers to a resin that is finally decomposed into water and carbon dioxide by the action of microorganisms. Examples of the biodegradable resin include polyhydroxyalkanoic acid, polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polyapple acid, polyglycolic acid, polydioxanone, and poly (2-oxetanone). ) And other aliphatic polyester resins; aliphatic aromatic copolyester resins such as polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate; starch, cellulose, chitin, chitosan, gluten, gelatin, zein , Natural polymers such as soybean protein, collagen, and keratin; a mixture with the above-mentioned aliphatic polyester resin or aliphatic aromatic copolyester resin; and biodegradable polyester resins and the like can be mentioned. As the biodegradable resin, a plurality of types of the above resins may be contained. Further, a copolymer of the above-mentioned monomer component constituting the biodegradable resin and the monomer component constituting the resin other than the biodegradable resin may be used as long as the biodegradability is not impaired, and the biodegradable resin may be used. And a mixture of resins other than the biodegradable resin may be used.

The biodegradable resin preferably contains at least one resin selected from an aliphatic polyester resin and an aliphatic aromatic copolyester resin. In this case, the total content of the aliphatic polyester resin and the aliphatic aromatic copolyester resin is preferably 40% by mass or more, preferably 50% by mass or more, based on the total mass of the biodegradable resin. More preferably, it is more preferably 60% by mass or more. By setting the total content of the aliphatic polyester resin and the aliphatic aromatic copolyester resin within the above range, the heat resistance and flexibility of the molded product can be enhanced.

The biodegradable resin is preferably a polyester resin having a melting point of 150 ° C. or lower. Thereby, it is possible to more effectively prevent the generation of coloring and odor when the molding composition is kneaded and molded. Further, by using a polyester resin having a melting point of 150 ° C. or lower as the biodegradable resin, the strength of the obtained molded product can be increased.

Examples of polyester resins having a melting point of 150 ° C. or lower include polyhydroxyalkanoic acid, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polyappleic acid, polydioxanone, poly (2-oxetanone), and polybutylene. Examples thereof include succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate and the like. Above all, it is particularly preferable to use polybutylene succinate from the viewpoint of the balance of strength and flexibility when kneaded with pulp fiber. As described above, the biodegradable resin is particularly preferably a resin containing polybutylene succinate as a main component.

The content of the biodegradable resin may be 40 to 90% by mass, preferably 50 to 85% by mass, and more preferably 60 to 80% by mass with respect to the total mass of the molding composition. preferable. By setting the content of the biodegradable resin within the above range, the strength of the molded product can be increased more effectively. Further, by setting the content of the biodegradable resin within the above range, the heat resistance and flexibility of the molded product can be improved.

(Arbitrary ingredient)
The molding composition of the present invention may contain other optional components in addition to the pulp fiber and the biodegradable resin. As an optional component, for example, a lubricant can be mentioned. Lubricants include aliphatic alcohols having 2 to 30 carbon atoms such as stearyl alcohol and cetyl alcohol, fatty acids having 12 to 30 carbon atoms such as lauric acid, stearic acid, oleic acid, and behenic acid, calcium stearate, magnesium stearate, and stearic acid. Metal salts of fatty acids having 12 to 30 carbon atoms such as zinc acid and calcium hydroxystearate and their complexes, aliphatic monoamides having 12 to 30 carbon atoms and ethylene bis of fatty acids such as oleic acid amide, erucic acid amide and ricinolic acid amide. Polyhydric alcohol fatty acids such as stearic acid amide, ethylene bislauric acid amide, ethylene bis 12-hydroxystearic acid amide and other fatty acid aliphatic alkylene bisamides having 12 to 22 carbon atoms, pentaerythritol sesquistearate and pentaerythritol tetrapalmitate. Esters, hydroxy fatty acid esters of fatty acids such as 12-hydroxystearate triglyceride having 12 to 22 carbon atoms, high molecular weight ester waxes such as pentaerythritol adipate stearate, polyolefin waxes such as polyethylene wax, tridodecyl phosphate, trioctadecyl phosphate , Sesquioctadecyl phosphate, organic phosphate such as di (polyoxyethylene (oxyethylene added molar number 2) lauryl ether) phosphate, organic phosphate metal salt such as bis (dioctadecyl phosphate) zinc salt, lauryl Examples thereof include cationic surfactants such as dihydroxyethylmethylammonium perchlorate.

Other optional ingredients include plasticizers; fillers (inorganic fillers, organic fillers); flame retardants; antioxidants; UV absorbers; antistatic agents; antifogging agents; light stabilizers; pigments; antifungal agents. Antibacterial agents; Effervescent agents; Surfactants; Polysaccharides such as starches and alginic acids; Natural proteins such as gelatin, glue and casein; Inorganic compounds such as tannins, zeolites, ceramics and metal powders; Fragrances; Flow conditioners; Leveling Agents; conductive agents; ultraviolet dispersants; deodorants and the like can be mentioned. Further, as an optional component, a polymer material or another thermoplastic resin may be added.

The content of the optional component in the molding composition is preferably 10% by mass or less, more preferably 5% by mass or less, and 3% by mass or less, based on the total mass of the molding composition. Is even more preferable. By setting the content of the optional component within the above range, the marine degradability can be enhanced.

(Manufacturing method of molding composition)
The molding composition of the present invention is obtained by melt-kneading pulp fibers and a biodegradable resin. As the melt-kneading device, known ones such as a single-screw extruder, a twin-screw extruder, a multi-screw extruder, and an extruder such as a twin-screw / single-screw compound extruder that combines them can be used. More specifically, KTK type twin-screw extruder (manufactured by Kobe Steel Works), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM type twin-screw extruder (manufactured by Ikegai Iron Works), TEX type twin-screw machine. Extruders (manufactured by Japan Steel Works, Ltd.) and the like can be mentioned.

As a method of supplying the raw material to the melt-kneading device, a method of directly supplying the pulp fiber and the biodegradable resin individually, a method of mixing the two in advance and then supplying them all at once, and a method of supplying the raw material using a high-speed mixer such as a Henschel mixer. Any method can be used, such as a method of aggregating (granulating) and then supplying the mixture. The raw material is preferably supplied to the melt-kneading apparatus by using a weight feeder whose supply amount can be adjusted to be constant.

The set temperature at the time of melt-kneading is not particularly limited, but in the present invention, from the viewpoint of suppressing fading of pulp fibers and generation of odor and producing a molded product having excellent strength, the temperature of the melt-kneaded product (T (° C.)). )) Is preferably 100 ° C. ≦ T ≦ 200 ° C., more preferably 100 ° C. ≦ T ≦ 180 ° C.

The kneaded molding composition is molded into strands, but from the viewpoint of operability during subsequent injection molding, the strands are cut with a strand cutter to pelletize them, or they are discharged from a die and at the same time a hot cutter or It may be pelletized using a cutting means such as an underwater cutter. When the strands are cut with a strand cutter and pelletized, the strands may be held in a liquid medium after the melt-kneading in order to increase the strength of the obtained melt-kneaded product. The temperature of the liquid medium at this time is preferably 15 to 40 ° C, more preferably 20 to 40 ° C, and even more preferably 25 to 30 ° C. The holding time in the liquid medium is preferably 0.5 to 10 seconds, more preferably 1 to 10 seconds. Examples of the liquid medium include low-viscosity liquids having a boiling point of 100 ° C. or higher, such as water, ethylene glycol, and silicone oil, and water is preferable from the viewpoint of safety and handleability. It is preferable that the temperature of the liquid medium is stably maintained by circulating the liquid medium with a temperature control device or the like.

(Manufacturing method of molded product)
Examples of the method for producing a molded product using the molding composition of the present invention include a molding method using an injection molding machine and a method for producing a sheet-shaped molded product using a melt extrusion die. The temperature of the molding composition to be injected into the injection molding die or the melt extrusion die is preferably 120 to 200 ° C., preferably 120 to 180 ° C., from the viewpoint of suppressing fading and odor generation of the obtained molded product and achieving both strength. More preferably, it is ° C.

The mold temperature during injection molding is preferably 10 to 90 ° C., more preferably 20 to 85 ° C., and more preferably 50 to 85 ° C. from the viewpoint of improving the crystallization rate of the resin composition. More preferred.

(Molded body)
The present invention also relates to a molded product obtained by molding the above-mentioned molding composition.

The flexural modulus of the molded product is preferably 0.5 to 5.0 GPa, more preferably 1.0 to 5.0 GPa, and even more preferably 1.5 to 5.0 GPa. The bending strength of the molded product is preferably 40 to 100 MPa, more preferably 50 to 100 MPa, and even more preferably 60 to 100 MPa. The flexural modulus and bending strength of the molded product are values measured according to JIS K7171.

The bending strain of the molded product is preferably 5 to 20%, more preferably 8 to 20%, and even more preferably 10 to 20%. The bending strain of the molded product is a value measured by JIS K7171. Further, the impact Charpy of moldings 3 ~ is preferably 20 kJ / ^{m 2,} more preferably 5 ~ 20 kJ / ^{m 2,} more preferably from 8 ~ 20kJ / ^{m 2.} The impact-resistant Charpy of the molded product is a value measured by JIS K7111-1.

The L * value of the molded product in the L ^* a ^* b ^* color space is preferably 75 to 80. Further, the b * value is more preferably -10 to 14, and further preferably -10 to 10.

The weight deflection temperature of the molded product is preferably 80 to 200 ° C, more preferably 100 to 200 ° C. The weight deflection temperature of the molded product is measured by the B method (flat wise, 0.45 MPa load) described in JIS K7191-1.

(Use of molded product)
Applications of the molded body of the present invention include, for example, housings for electronic devices and home appliances, reinforcing materials, civil engineering, building material parts, interior parts, automobiles, motorcycle parts, aircraft parts, railroad vehicle parts, and the like.
Examples thereof include daily necessities, packaging materials, and the like, but among them, it is suitable for disposable applications. It is desirable that the molded product of the present invention does not flow out into the natural environment, but even if it does flow out, it is decomposed in the natural environment, so that the load on the environment can be reduced.

The features of the present invention will be described in more detail below with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below.

(Example 1)
100 parts by mass of dissolved pulp derived from hardwood and 400 parts by mass of polybutylene succinate resin (Mitsubishi Chemical Co., Ltd., Bio-PBS FZ71PM) obtained by the pre-hydrolysis-craft cooking method were put into a twin-screw kneader and the temperature was adjusted. The mixture was stirred for 30 minutes at 160 ° C. and a rotation speed of 30 rpm to melt and knead. At this time, the pulp solid content was 20% by mass and the resin solid content was 80% by mass with respect to the total mass of the kneaded product.
The molding composition (resin composition) obtained by melt-kneading was solidified at room temperature and then pulverized into flakes. Then, it was molded into a standard shape (multipurpose test piece (A1) shape) for evaluating the physical characteristics of the plastic described in JIS K 7139 using an injection molding machine to obtain a molded product. At the time of injection molding, the cylinder temperature was uniformly set to 165 ° C, and the mold temperature was set to 30 ° C.

(Example 2)
As a raw material, a molding composition and a molded product were produced in the same manner as in Example 1 except that the pulp solid content was 40% by mass and the resin solid content was 60% by mass with respect to the total mass of the molding composition.

(Example 3)
A molding composition and a molded product were prepared in the same manner as in Example 1 except that cotton pulp was used as a raw material instead of dissolving pulp.

(Example 4)
As a raw material, polylactic acid (Nature works, ingeo 3251D) was used instead of polybutylene succinate resin, except that the temperature during kneading was set to 200 ° C and the cylinder temperature during injection molding was set to 180 ° C. A molding composition and a molded product were produced in the same manner as in Example 1.

(Comparative Example 1)
A molding composition and a molded product were prepared in the same manner as in Example 1 except that hardwood pulp was used as a raw material instead of dissolving pulp.

(Comparative Example 2)
As a raw material, hardwood pulp was used instead of dissolving pulp, and the pulp solid content was 40% by mass and 60% by mass of the resin solid content with respect to the total mass of the molding composition, as in Example 1. A molding composition and a molded product were prepared.

(Comparative Example 3)
A molding composition and a molded product were prepared in the same manner as in Example 1 except that hemp pulp was used as a raw material instead of dissolving pulp.

(Comparative Example 4)
A molding composition and a molded product were prepared in the same manner as in Example 1 except that straw pulp was used as a raw material instead of dissolving pulp.

(Comparative Example 5)
A molding composition and a molded product were prepared in the same manner as in Example 1 except that Kenaf pulp was used as a raw material instead of dissolving pulp.

(Reference example 1)
Using an injection molding machine, polybutylene succinate resin (Mitsubishi Chemical Co., Ltd., Bio-PBS FZ71PM) is molded into the standard shape (multipurpose test piece (A1) shape) for physical property evaluation of plastics described in JIS K 7139. A molded product was obtained. At the time of injection molding, the cylinder temperature was uniformly set to 165 ° C, and the mold temperature was set to 30 ° C.

(Measurement and evaluation method)
[Method for quantifying cellulose purity (α-cellulose content)]
After putting the pulp fiber in an absolute dry amount of 5 g into a beaker in a constant temperature water bath at 20 ° C., 50 ml of a 17.5 mass% sodium hydroxide solution was uniformly added. After leaving to stand for 3 minutes and 30 seconds, the sample was crushed for 5 minutes using a glass rod to sufficiently dissociate. The surface of the sample was flattened and allowed to stand for 20 minutes, then 50 ml of distilled water was added and the contents were stirred with a glass rod. After filtering the contents with a kanakin (pure cotton yarn 80 counts x 80 counts 127 yarns x 127 yarns / inch driving) having a known mass, the contents were washed with water by repeating suction and dehydration with a total amount of washing water of 900 ml. After pouring 40 ml of 10% acetic acid and leaving it for 5 minutes to allow the acid solution to fully permeate, the contents were washed with 1 L of boiling water to dry the contents. The ratio of the dry weight of the contents to the absolute dry amount of the sample was calculated as the α-cellulose content and used as the cellulose purity (%).
Cellulose purity (%) = (weight of absolute dry α-cellulose / weight of absolute dry pulp fiber) × 100
[Fiber length]
The fiber length of the pulp fiber was measured using "Valmet FS5HD" manufactured by Valmet.

[Crystallinity]
The crystallinity of the pulp fiber (cellulose type I crystallinity) is based on the following formula (1) by measuring the X-ray diffraction intensity of the pulp fiber using "RINT UltraIII" manufactured by Rigaku Co., Ltd. under the following conditions. Calculated. The measurement sample was prepared by compressing pulp fibers into an area of 320 mm ² × a thickness of 1 mm.
X-ray source: Cu / Kα-radiation
Tube voltage: 40kv
Tube current: 120mA
Measurement range: Diffraction angle 2θ = 5 to 45 °
Scan speed: 10 ° / min
Formula (1): Cellulose type I crystallinity (%) = [(I _22.6- I _18.5 ) / I _22.6 ] x 100
In equation (1), I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the amorphous portion (diffraction angle 2θ). = 18.5 °).

[Pulp drainage degree]
The degree of pulp drainage was measured according to JIS P 811-2.

[Melting point of resin]
The melting point of the resin was calculated from the crystal melting endothermic peak temperature by the temperature raising method of differential scanning calorimetry based on JIS K 7121 using a DSC device (DSC6200, manufactured by Seiko Instruments). The melting point of the resin was measured by raising the temperature from 20 ° C. to 250 ° C. at a heating rate of 10 ° C./min.

[Melt flow rate (MFR)]
The melt flow rate (MFR) of the molding composition of Example 2 and Comparative Example 2 was measured according to JIS K 7210 at 190 ° C. under a load of 10 kg. The melt flow rate (MFR) of the molding compositions other than Example 2 and Comparative Example 2 was measured according to JIS K 7210 at 190 ° C. under a load of 21.6 kg.

[Odor test]
The odor of the molded product obtained in Examples and Comparative Examples was evaluated according to the following criteria.
A: No odor is felt B: Slight odor is felt C: Smell is certainly felt D: Strong odor is felt

[Color evaluation]
The lightness and chromaticity of the molded articles obtained in Examples and Comparative Examples were measured using a spectrocolorimeter of "x-rite 939" manufactured by x-rite. The light source used was D65 / 2.

[Bending characteristics]
The flexural modulus and bending strength of the molded products obtained in Examples and Comparative Examples were measured according to JIS K7171.

[Impact resistance test]
The molded products obtained in Examples and Comparative Examples were notched according to JIS K 7144 using an "automatic notch processing machine A-4" manufactured by Toyo Seiki Co., Ltd., and then Charpy impact according to JIS K 7111. The characteristics were measured. The Charpy impact characteristics were measured using an "impact resistance tester IT" manufactured by Toyo Seiki Co., Ltd.

[Deflection temperature under load]
The deflection temperature under load of the molded product obtained in Examples and Comparative Examples was determined by method B (flat wise, 0.45 MPa load) described in JIS K7191-1 using "HDT tester 6M-2" manufactured by Toyo Seiki Co., Ltd. Measured at.

In the examples, the generation of odor was suppressed in the obtained molded product. Further, in the examples, coloring was suppressed.

In the examples, the generation of odor was suppressed in the obtained molded product. Further, in the examples, the brightness (L * value) was 75 or more, and the transparency was hardly impaired as compared with Reference Example 1 in which the resin alone was molded. The L * value of each of the molded articles described in the comparative examples was less than 75 due to the low purity of the pulp fibers.
Further, in the examples, the b * values indicating yellowness were all 14 or less. Further, in the molded products described in Examples 1 and 3, although the compounding ratio of the pulp fibers was the same as that of the molded products described in Comparative Examples, the b * value was remarkably low at 8 or less. The b * value of each of the molded articles described in the comparative examples exceeded 15 due to the low purity of the pulp fibers.

Claims (9)

A molding composition obtained by kneading pulp fibers and biodegradable resin.
The content of the pulp fiber is 10 to 60% by mass with respect to the total mass of the molding composition, and the content of the biodegradable resin is 40 to 60% by mass with respect to the total mass of the molding composition. 90% by mass,
A molding composition having a cellulose purity of 90 to 98% of the pulp fiber. The molding composition according to claim 1, wherein the pulp fiber has a crystallinity of 80 to 90%. The molding composition according to claim 1 or 2, wherein the pulp fiber is a fiber derived from wood or cotton. The molding composition according to any one of claims 1 to 3, wherein the weighted average fiber length of the pulp fiber is 0.2 to 3.0 mm, and the weighted average fiber width of the pulp fiber is 10 to 20 μm. Stuff. The molding composition according to any one of claims 1 to 4, wherein the pulp fiber is a dissolving pulp obtained by an acidic sulfite cooking method or a pre-hydrolysis-craft cooking method. The molding composition according to any one of claims 1 to 5, wherein the Canadian standard pulp drainage degree measured according to JIS P 8121-1995 of the pulp fiber is 600 ml to 750 ml. The molding composition according to any one of claims 1 to 6, wherein the biodegradable resin is a polyester resin having a melting point of 150 ° C. or lower. The molding composition according to any one of claims 1 to 7, wherein the biodegradable resin contains polybutylene succinate as a main component. A molded product obtained by molding the molding composition according to any one of claims 1 to 8.