JP7434871B2 - Molding composition and molded object - Google Patents

Description

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

Plastic is a useful material that brings convenience and benefits to our lives, but if it is improperly disposed of and is released, it usually remains in the natural environment for a long time. In particular, it is estimated that the amount of plastic waste flowing into the ocean exceeds several million tons annually worldwide, and there are concerns that global environmental pollution will have a negative impact on ecosystems, living environments, 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 we also hope to develop materials that can be decomposed even if they are released into the natural environment, or to switch to such materials. has been done. In recent years, the use of biodegradable plastics has been attracting attention in this trend, and they are beginning to be used in applications such as agricultural mulch films, garbage bags, fishing lines, and vegetation nets.

Among plastic products, mechanical strength is required for applications that require durability, such as home appliance parts and automobile parts. Generally, in order to impart strength to a resin, a reinforcing filler is added. So far, plastics with reinforcing fibers such as glass fiber and carbon fiber have been put into practical use as reinforcing fillers, but these are difficult to decompose in the natural environment, and there are still issues with recyclability. There is.

On the other hand, since plant fibers decompose in the natural environment, biodegradable plastics reinforced with plant fibers have less impact even if they are released into the environment, and are expected to be used in a variety of applications.

For example, Patent Document 1 discloses a molded article made of a biodegradable composite material containing 5 to 60% by weight of pulp or cellulose fibers in a thermoplastic biodegradable resin. Here, a method of disintegrating beaten newspaper pulp and polycaprolactone fibers in water, forming cylindrical pellets using a wet granulation method, and then heating and injection molding the resulting pellets to obtain a molded product is being considered. . Furthermore, Patent Document 2 describes that a thermoplastic resin that can be modified with a polybasic acid anhydride, 1 to 70% by weight of vegetable fibers containing cellulose and lignin, 0.05 to 8% by weight of an isocyanate-based resin, and a polybasic acid anhydride. A composite material is disclosed in which 0.05 to 30% by weight of an acid anhydride and 0.05 to 8% by weight of an organic peroxide are added and kneaded under heat.

Japanese Patent Application Publication No. 06-345944 Patent No. 4002942

In molded products with fibers such as pulp added as fillers, the interfacial adhesion between the resin and fibers is not sufficient, so the tensile strength and There was a problem that tensile properties such as tensile elongation at break were inferior. In particular, when producing products such as films and sheets by extrusion molding, molecular and fiber orientation occurs in the direction of stretching, which weakens the tensile strength in the direction perpendicular to the orientation, resulting in tearing. This is a problem because it occurs more easily.

In addition, when vacuum forming or pressure forming is performed after forming a molded product containing fibers such as pulp as a filler into a sheet, the pulp itself is difficult to stretch compared to resin, so it is difficult to follow the shape of a complex shape. This tends to cause a decrease in the strength of the member starting from the fiber portion and molding defects.

Therefore, in order to solve the problems of the prior art, the present inventors conducted studies with the aim of providing a molded article with good moldability and excellent tensile properties.

As a result of intensive studies to solve the above problems, the present inventors found that a molding composition in which pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant are kneaded, contains pulp fibers. It has been found that by adjusting the amount and content of the biodegradable resin within a predetermined range and further using a lubricant having a predetermined structure, a molded article with good moldability and excellent tensile properties can be obtained.
Specifically, the present invention has the following configuration.

[1] A molding composition obtained by kneading pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant,
When the content of pulp fiber is P and the content of biodegradable resin is Q, P:Q = 10:90 to 60:40,
A molding composition, wherein the lubricant is an aliphatic compound having 12 or more carbon atoms, and the aliphatic compound has at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amide group, and an ester bond.
[2] The molding composition according to [1], wherein the content of the hydrolysis inhibitor is 0.1 to 5.0% by mass based on the total mass of the molding composition.
[3] The molding composition according to [1] or [2], wherein the content of the lubricant is 0.1 to 5.0% by mass based on the total mass of the molding composition.
[4] The molding composition according to any one of [1] to [3], wherein the hydrolysis inhibitor is at least one selected from the group consisting of a carbodiimide compound, an isocyanate compound, an oxazoline compound, and an epoxy compound. .
[5] The molding composition according to any one of [1] to [4], wherein the biodegradable resin is a resin having a melting point of 160° C. or lower.
[6] The molding composition according to any one of [1] to [5], wherein the biodegradable resin contains polybutylene succinate as a main component.
[7] According to JIS K 7210, the melt flow rate of the molding composition measured under 190°C and 10 kg load condition is 4.0 to 20.0 g/10 min, [1] to [6]. The molding composition according to any one of the above.
[8] A molded article obtained by molding the molding composition according to any one of [1] to [7].

According to the present invention, a molded article having good moldability and excellent tensile properties can be obtained.

In the following, the present invention will be explained in detail. Although the constituent elements described below may be explained based on typical embodiments and specific examples, the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after the "~" as lower and upper limits.

(Molding composition)
The present invention relates to a molding composition obtained by kneading pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant. Here, when the content of pulp fiber in the molding composition is P and the content of biodegradable resin is Q, P:Q=10:90 to 60:40. Further, the lubricant is an aliphatic compound having 12 or more carbon atoms, and the aliphatic compound has at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amide group, and an ester bond.

Since the molding composition of the present invention has the above-mentioned structure, it can be molded into a molded article having good moldability and excellent tensile properties. Here, regarding the moldability of the molded object, whether there are no molding defects observed when the plate-shaped molded object molded from the molding composition is further heated and pressure-molded into a shape having a curved part, or whether there are molding defects. It can be determined that the condition is good if the occurrence of is small. The molding composition of the present invention can exhibit excellent moldability even when molding a molded article having a complicated shape, such as a shape having a curved part or a shape having uneven parts. Further, the tensile properties of the molded article can be evaluated by the tensile strength of the molded article measured according to JIS K 7161. Specifically, the tensile strength of the molded body is preferably 45 MPa or more, more preferably 50 MPa or more. In addition, although the upper limit of the tensile strength of a molded object is not specifically limited, it is preferable that it is 200 MPa or less, for example.

In the molding composition of the present invention, in addition to pulp fibers and biodegradable resin, a hydrolysis inhibitor and a lubricant having a predetermined structure are mixed, so that the fluidity of the molding composition (kneaded body) is significantly improved. It was very successful. Thereby, the moldability of the molded article can be significantly improved. Such improvement in moldability is achieved by at least one member selected from the group consisting of carboxy groups, hydroxyl groups, amide groups, and ester bonds possessed by the aliphatic compound reacting with the hydrolysis inhibitor and bonding with the resin. This is thought to be due to the fact that the aliphatic compound can enter between the molding composition or between the resin and the pulp, thereby increasing the fluidity of the molding composition.

Since the molding composition of the present invention has the above-mentioned structure, it is also possible to increase the strength of the molded article. Specifically, a molded article molded from the molding composition of the present invention has higher bending stress and bending elastic modulus than a molded article molded only from resin.

Further, the molding composition of the present invention is a molding composition obtained by kneading pulp fiber, which is a biomass resource, and a biodegradable resin. This makes it possible to reduce manufacturing costs and increase the proportion of carbon-neutral materials whose production does not rely on fossil resources, making it possible to reduce carbon dioxide emissions during disposal. Moreover, the molded article of the present invention can be biodegraded in the natural environment and has excellent biodegradability. The biodegradability of the molded article can be evaluated, for example, by a biodegradability test using natural seawater specified in ASTM D6691, and if the degree of biodegradation is above a predetermined value, the biodegradability is good. It can be evaluated as follows.

In addition, there are many cellulose-degrading microorganisms in the natural environment, and it is known that more than 80% of cellulose is decomposed into water and carbon dioxide in 6 months in natural seawater at 30 ± 2 degrees Celsius. ing. Therefore, even if the resin biodegrades relatively slowly in the natural environment, the biodegradation rate of the composition can be improved by incorporating cellulose. In addition, as the cellulose that makes up the composition is decomposed, voids are created in the molded body and the surface area of the resin increases, so an improvement in the biodegradation rate of the resin itself can be expected.

The melt flow rate (MFR) of the molding composition is preferably 4.0 g/10 min or more, more preferably 5.0 g/10 min or more, even more preferably 6.0 g/10 min or more. , 7.0 g/10 min or more is particularly preferable. Further, the upper limit of the melt flow rate (MFR) of the molding composition is not particularly limited, but is preferably 50.0 g/10 min or less. By setting the melt flow rate (MFR) of the molding composition within the above range, the moldability when molding a molded article from the molding composition can be more effectively improved. The melt flow rate (MFR) of the molding composition is a value measured according to JIS K 7210 at 190° C. and under a load of 10 kg.

The molding composition is a composition obtained by kneading pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant, and its properties may be a solid or a molten liquid. Good too. In addition, when the molding composition is a solid body, the molding composition may be in the form of pellets, flakes, or powder particles.

(Pulp fiber)
As the pulp fiber, wood pulp, non-wood pulp, deinked pulp, etc. can be used. Wood pulps include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), sulfite pulp (SP), hardwood dissolving pulp (LDKP, LDSP), softwood dissolving pulp (NDKP, NDSP), and soda pulp (AP). ), chemical pulps such as unbleached kraft pulp (UKP) and oxygen bleached kraft pulp (OKP), semi-chemical pulps such as semi-chemical pulp (SCP) and chemical ground wood pulp (CGP), ground wood pulp (GP) and thermomechanical pulp. Examples include mechanical pulp such as pulp (TMP, BCTMP). Examples of the non-wood pulp include cotton-based pulps such as cotton linters and cotton lint, non-wood-based pulps such as hemp, wheat straw, and bagasse. Examples of the deinked pulp include deinked pulp made from waste paper. Among these, the pulp fiber is preferably wood pulp or cotton pulp.

As the pulp fiber, it is preferable to use a pulp fiber having a cellulose purity of 90% or more. By using pulp fibers with a cellulose purity of 90% or more, it is possible to suppress coloration and odor that occur when heated during kneading and molding steps. This is because by increasing the cellulose purity of pulp fibers to 90% or more, it is possible to significantly reduce the content of hemicellulose and lignin contained in ordinary vegetable fibers. It is presumed that coloring and odor generation can be suppressed.

Examples of pulp fibers having a cellulose purity of 90% or more include dissolving pulp and cotton fibers. Among these, dissolving pulp is particularly preferably used. Note that the cellulose purity of bleached kraft pulp made from hardwood or softwood used in normal papermaking processes is about 85%.

Dissolving pulp can be obtained by selectively removing hemicellulose and lignin from lignocellulose materials contained in softwood pulp, hardwood pulp, and the like. Among these, the dissolving pulp is preferably one obtained by the acid sulfite cooking method or the prehydrolysis-kraft cooking method. The lignocellulosic material used in the production of dissolving pulp may be derived from either wood or non-wood raw materials, or dissolving pulp processed by mixing lignocellulosic materials obtained from different tree species and different raw materials may be used. good. As the dissolving pulp, dissolving pulps obtained from different tree species and different raw materials may be mixed and used.

The dissolving pulp is preferably either a softwood-derived pulp or a hardwood-derived pulp, and more preferably a hardwood-derived pulp. In general, hardwood materials are more suitable than softwood materials in that a dissolving pulp having a higher volumetric weight and higher processing efficiency can be obtained. Further, among broad-leaved trees, eucalyptus and acacia, which have a high volumetric weight, are particularly preferably used. Examples of such broad-leaved trees include Eucalyptus globulus, Eucalyptus grandis, Eucalyptus eurograndis, Eucalyptus pelita, Eucalyptus brassiana, and Acacia melanthi, among which Eucalyptus pelita is preferably used.

The volumetric weight of the hardwood is preferably 450 to 700 kg/m ³ , more preferably 500 to 650 kg/m ³ . By setting the volumetric weight of the hardwood within the above range, pulp production efficiency can be increased, and furthermore, the chemical solution can sufficiently penetrate during pre-hydrolysis and alkaline cooking, making it possible to obtain pulp with high cellulose purity.

It is also preferable to use cotton fibers as the pulp fibers having a cellulose purity of 90% or more. Cotton fibers are made from raw cotton collected from cotton plants, and are obtained by loosening the raw cotton while removing seeds, leaves, dust, etc. attached to it. Cotton fibers can be adjusted to desired fiber length and fiber diameter by performing treatments such as carding, combing, stretching, and cutting as necessary.

The cellulose purity of the pulp is preferably 90% or more, more preferably 95% or more. By controlling the cellulose purity of the pulp within the above range, it is possible to effectively suppress the coloration and odor that occur when heated during the kneading and molding steps. The cellulose purity of the pulp is preferably 98% or less. The presence of extremely small amounts of hemicellulose and lignin in the pulp improves the dispersibility of the pulp, and also facilitates bonding with the hydrolysis inhibitor via the hemicellulose-derived carboxy group.

Specifically, the cellulose purity of pulp fibers can be calculated by the following method. First, 5 g of pulp fibers are placed in a beaker in a constant temperature water bath at 20° C., and then 17.5% by mass of pulp fibers is added. 50 ml of sodium hydroxide solution are added evenly. After leaving for 3 minutes and 30 seconds, the sample was crushed for 5 minutes using a glass rod to fully disintegrate it. After leveling the surface of the sample and leaving it for 20 minutes, add 50 ml of distilled water and stir the contents with a glass rod. Thereafter, after filtering the contents, the contents are washed with water by repeating suction and dehydration using a total amount of 900 ml of washing water. Pour 40 ml of 10% acetic acid into the container and leave it for 5 minutes to allow the acid solution to fully penetrate, then wash with 1 L of boiled water and dry the contents. The ratio of the dry weight of the contents to the absolute dry weight of the sample is calculated as the α-cellulose content, and is defined as the cellulose purity (%).
Cellulose purity (%) = (weight of bone dry α-cellulose/weight of bone dry pulp fiber) x 100
In addition, when measuring the cellulose purity of pulp fibers, it is preferable to use the pulp fiber alone, but a kneaded product of pulp and resin may also be used for the measurement. In this case, it is preferable to extract only the pulp content using an organic solvent or the like that selectively dissolves the resin component in the kneaded material and use it for the test. Note that known organic solvents can be used for the extraction. Examples include ketone organic solvents, aromatic hydrocarbon organic solvents, ether organic solvents, halogen-containing organic solvents, alcohol organic solvents, ester organic solvents, and glycol organic solvents. The organic solvents can be used alone or in combination of two or more. Organic solvents with good dissolution efficiency include acetone, methyl ethyl ketone (2-butanone) (hereinafter referred to as MEK), methyl isobutyl ketone (4-methyl-2-pentanone) (hereinafter referred to as MIBK), dioxane, tetrahydrofuran, and cyclohexanone alone. , acetone Z ethylene glycol monobutyl ether mixed solution, MEKZ ethylene glycol monobutyl ether mixed solution, ΜΙΒΚΖ ethylene glycol monobutyl ether mixed solution, dioxane Ζ ethylene glycol monobutyl ether mixed solution, tetrahydrofuran Ζ ethylene glycol monobutyl ether mixed solution, cyclohexanone Ζ ethylene Glycol monobutyl ether mixed solution, acetone Z isopropanol mixed solution, ΜΕΚΖ isopropanol mixed solution, MIBKZ isopropanol mixed solution, dioxane Z isopropanol mixed solution, tetrahydrofuran Z isopropanol mixed solution, cyclohexanone Z isopropanol mixed solution, etc. can be suitably used.

The Canadian standard pulp freeness of pulp fibers measured according to JIS P 8121-1995 is preferably 600 to 750 ml, more preferably 650 to 750 ml. By controlling the Canadian standard pulp freeness of the pulp fibers to be less than or equal to the above upper limit, the pulp fibers are appropriately entangled with each other, and the strength of the molded article can be increased. Further, by setting the Canadian standard pulp freeness of the pulp fibers to the above lower limit value or more, the dispersibility of the biodegradable resin in the molding composition increases, and a uniform molding composition can be obtained. Moreover, generation of frictional heat during kneading and molding of the molding composition can be suppressed, and coloration and odor derived from pulp fibers can be more effectively prevented. In addition, when measuring the freeness of pulp fibers, it is preferable to use the pulp alone, but a mixture of pulp and resin may be used for the measurement. In this case, it is preferable to extract only the pulp content using a solvent that selectively dissolves the resin components in the kneaded material, and then to use the pulp freeness test.

The content of pulp fibers may be 10 to 60% by weight, preferably 15 to 55% by weight, and more preferably 20 to 50% by weight, based on the total weight of the molding composition. By controlling the content of pulp fibers within the above range, the moldability of the molded article can be improved more effectively. Furthermore, by controlling the content of pulp fibers within the above range, the strength of the molded product can be increased, and furthermore, the biodegradability of the molded product can be improved. The content of pulp fiber in the molding composition can be calculated from the amount of pulp fiber added when producing the molding composition, but the content of pulp fiber in the molding composition can be calculated from the amount of pulp fiber added when producing the molding composition. It is also possible to simply calculate from the diffraction intensity value. For example, pulp fiber has crystal peaks at diffraction angles 2θ = 15.4 and 22.5, and polybutylene succinate has crystal peaks at diffraction angles 2θ = 19.6, 22.7, and 28.9; .4 (pulp fiber) and 19.6 (polybutylene succinate) hardly interfere with each other. By measuring the diffraction intensities of non-interference peaks for multiple samples with known blending ratios and drawing a calibration curve, it is possible to estimate the blending ratio even for samples whose blending ratios are unknown. Alternatively, as a means of measuring the blending ratio of pulp fibers and molding resin, only the pulp content may be extracted using a solvent that selectively dissolves the resin component in the kneaded material, and the weight ratio may be measured.

(biodegradable resin)
Biodegradable resin refers to resin that is eventually decomposed into water and carbon dioxide by the action of microorganisms. Examples of biodegradable resins include polyhydroxyalkanoic acid, polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate/adipate, polyethylene succinate, polymalic acid, polyglycolic acid, polydioxanone, and poly(2-oxetanone). ); aliphatic aromatic copolyester resins such as polybutylene succinate/terephthalate, polybutylene adipate/terephthalate, polytetramethylene adipate/terephthalate; starch, cellulose, chitin, chitosan, gluten, gelatin, zein Biodegradable polyester resins such as natural polymers such as , soybean protein, collagen, and keratin; mixtures with the above-mentioned aliphatic polyester resins or aliphatic aromatic copolyester resins; The biodegradable resin may contain multiple types of the above resins. Additionally, a copolymer of a monomer component constituting the above-mentioned biodegradable resin and a monomer component constituting a resin other than the biodegradable resin may be used within a range that does not impair biodegradability. A mixture of resins other than biodegradable resins may also be used.

The biodegradable resin preferably contains at least one resin selected from aliphatic polyester resins and aliphatic aromatic copolyester resins. In this case, the total content of the aliphatic polyester resin and the aliphatic aromatic copolyester resin is preferably 40% by mass or more, and preferably 45% by mass or more, based on the total mass of the biodegradable resin. The content is more preferably 50% 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 article can be improved.

The biodegradable resin preferably has a melting point of 160°C or lower. This makes it possible to more effectively prevent coloring and odor from occurring during kneading and molding. Further, by using a polyester resin having a melting point of 160° C. or lower as the biodegradable resin, the tensile strength of the resulting molded article can be increased.

Examples of polyester resins with a melting point of 160°C or lower include polyhydroxyalkanoic acid, polycaprolactone, polybutylene succinate, polybutylene succinate/adipate, polyethylene succinate, polymalic acid, polydioxanone, poly(2-oxetanone), and polybutylene succinate. Examples include nate/terephthalate, polybutylene adipate/terephthalate, polytetramethylene adipate/terephthalate, polyurethane, and the like. Among these, polyhydroxyalkanoic acid, polycaprolactone, and polybutylene succinate, which are marine degradable, are preferred, and polybutylene succinate is particularly preferred from the viewpoint of the balance of strength and flexibility when kneaded with pulp. Thus, it is particularly preferable that the biodegradable resin is a resin containing polybutylene succinate as a main component.

The content of the biodegradable resin may be 40 to 90% by mass based on the total mass of the molding composition, preferably 50 to 85% by mass, and more preferably 60 to 80% by mass. preferable. By setting the content of the biodegradable resin within the above range, the tensile strength of the molded article can be increased more effectively. Further, by controlling the content of the biodegradable resin within the above range, the moldability of the molded article can be improved, and the heat resistance and flexibility of the molded article can also be improved. Furthermore, by controlling the content of the biodegradable resin within the above range, the biodegradability of the molded article can be improved.

(hydrolysis inhibitor)
Hydrolysis inhibitors are compounds that can react with carboxylic acids produced by hydrolysis of biodegradable resins. The hydrolysis inhibitor reacts with the terminal carboxylic acid produced by hydrolysis of the biodegradable resin, and therefore can function as an end-capping agent for the biodegradable resin. When the biodegradable resin is hydrolyzed, the molecular weight of the biodegradable resin decreases, but by containing a hydrolysis inhibitor in the molding composition, the decrease in the molecular weight of the biodegradable resin can be suppressed. Can be done. This is because the hydrolysis inhibitor reacts with the terminal carboxylic acid produced by hydrolysis of the biodegradable resin, sealing the terminal and inhibiting further hydrolysis chain. This is thought to be because the biodegradable resins crosslink with each other, thereby contributing to an increase in the molecular weight of the biodegradable resins. Thereby, the moldability and strength of the molded article can be improved.

Moreover, the hydrolysis inhibitor can also crosslink the terminal carboxylic acid produced by hydrolysis of the biodegradable resin and the hydroxyl group or carboxy group that the pulp fiber has. It is believed that by forming such a crosslinked structure, the strength and tensile properties of the obtained molded article can be improved.

The hydrolysis inhibitor is preferably at least one selected from the group consisting of carbodiimide compounds, isocyanate compounds, oxazoline compounds, and epoxy compounds. By using the above compound as a hydrolysis inhibitor, the initial acid value of the biodegradable resin during melt-kneading can be lowered. Furthermore, by reacting with the carboxylic acid produced by hydrolysis of the biodegradable resin, a decrease in molecular weight can be suppressed. Among these, the hydrolysis inhibitor is preferably at least one selected from the group consisting of carbodiimide compounds and isocyanate compounds, and more preferably a carbodiimide compound.

Commercially available products can also be used as the hydrolysis inhibitor. Specifically, carbodiimide compounds (Nisshinbo Chemical Co., Ltd., Carbodilyte HMV-15CA, Rhein Chemie Co., Ltd., Stabaxol I, Stavaxol P), carbodiimide-modified isocyanates (Nisshinbo Chemical Co., Ltd., Carbodilyte LA-1), cyclic carbodiimides (Teijin Co., Ltd.) , TCC-NP, TCC-FP100), glycidyl methacrylate (Mitsubishi Chemical Corporation, Metablen P-1901), oxazoline compound (Nippon Shokubai Co., Ltd., RPS1005), and the like.

The content of the hydrolysis inhibitor is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and 0.5% by mass based on the total mass of the molding composition. It is more preferable that it is above. Further, the content of the hydrolysis inhibitor is preferably 5.0% by mass or less based on the total mass of the molding composition. By controlling the content of the hydrolysis inhibitor within the above range, the moldability and strength of the molded article can be improved more effectively.

(Lubricant)
A lubricant is a modifier that reduces friction between components in a molding composition. The lubricant used in the present invention is an aliphatic compound having 12 or more carbon atoms, and the aliphatic compound has at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amide group, and an ester bond. In this specification, an aliphatic compound refers to a compound in which carbon atoms are connected in a chain. In the molding composition of the present invention, since a lubricant having such a predetermined structure is used, the moldability of the molded article can be improved.

Examples of the aliphatic compound having 12 or more carbon atoms and at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amide group, and an ester bond include aliphatic alcohols such as stearyl alcohol and cetyl alcohol; Fatty acids such as lauric acid, stearic acid, oleic acid, behenic acid, etc.; Metal salts of fatty acids such as calcium stearate, magnesium stearate, zinc stearate, calcium hydroxystearate, and complexes of such metal salts; oleic acid amide, erucic acid amide , aliphatic monoamides such as ricinoleic acid amide; aliphatic alkylene bisamides such as ethylene bisstearic acid amide, ethylene bislauric acid amide, ethylene bis 12-hydroxystearic acid amide; pentaerythritol sesquistearate, pentaerythritol tetrapalmitate, etc. Examples include polyhydric alcohol fatty acid esters; hydroxy fatty acid esters such as 12-hydroxystearic acid triglyceride; and the like.

The number of carbon atoms of the aliphatic compound having at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amide group, and an ester bond may be 12 or more, preferably 14 or more, and preferably 16 or more. More preferred. Further, it is preferable that the aliphatic compound having at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amide group, and an ester bond has 30 or less carbon atoms. By setting the carbon number of the aliphatic compound within the above range, the moldability of the molded article can be more effectively improved.

The aliphatic compound has at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amide group, and an ester bond. Among these, it is preferable that the aliphatic compound has at least one kind selected from the group consisting of a carboxy group and a hydroxyl group, and it is particularly preferable that the aliphatic compound has a carboxyl group. Note that aliphatic compounds having a carboxy group are sometimes called fatty acids.

In this specification, the aliphatic compound having at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amide group, and an ester bond includes salts and complexes of aliphatic compounds. For example, when the aliphatic compound is an aliphatic compound having a carboxy group, hydroxyl group, or amide group, the aliphatic compound includes salts and complexes of the aliphatic compound.

The aliphatic compound used in the present invention is preferably at least one selected from the group consisting of fatty acids having 12 or more carbon atoms and salts of fatty acids having 12 or more carbon atoms. By using the above compound as the aliphatic compound, the moldability of the molded article can be more effectively improved, and a molded article with better tensile properties can be obtained.

The content of the lubricant is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and 0.5% by mass or more based on the total mass of the molding composition. It is even more preferable. Further, the content of the lubricant is preferably 5.0% by mass or less based on the total mass of the molding composition. By controlling the content of the lubricant within the above range, the moldability of the molded article can be improved more effectively.

(optional ingredient)
The molding composition of the present invention may contain other optional components in addition to pulp fibers, biodegradable resins, hydrolysis inhibitors, and lubricants. Optional ingredients include plasticizer; filler (inorganic filler, organic filler); flame retardant; antioxidant; ultraviolet absorber; antistatic agent; antifogging agent; light stabilizer; pigment; antifungal agent; antibacterial agent. Foaming agents; Surfactants; Starches, polysaccharides such as alginic acid; Natural proteins such as gelatin, glue, and casein; Inorganic compounds such as tannins, zeolites, ceramics, and metal powders; Fragrances; Flow regulators; Leveling agents; Examples include a conductive agent; an ultraviolet dispersant; a deodorant, and the like. Furthermore, polymer materials other than biodegradable resins and other thermoplastic resins may be added as optional components.

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. It is even more preferable. By setting the content of optional components within the above range, biodegradability in the natural environment can be improved.

(Method for producing molding composition)
The molding composition of the present invention is obtained by melt-kneading pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant. As the melt-kneading device, known extruders such as a single-screw extruder, a twin-screw extruder, a multi-screw extruder, and a combination of these extruders such as a twin-screw/single-screw composite extruder can be used. More specifically, KTK type twin screw extruder (manufactured by Kobe Steel, Ltd.), TEM type twin screw extruder (manufactured by Toshiba Machinery Co., Ltd.), PCM type twin screw extruder (manufactured by Ikegai Iron Works), TEX type twin screw extruder Examples include an extruder (manufactured by Japan Steel Works).

Methods of supplying raw materials to the melt-kneading device include a method of directly supplying pulp fiber, biodegradable resin, hydrolysis inhibitor, and lubricant individually, a method of premixing the above components and then supplying them all at once, and a method of supplying the above components all at once. Any method can be used, such as a method in which a part of the raw materials is mixed in advance and then the other components are directly shared, or a method in which the raw materials are agglomerated (granulated) using a high-speed mixer such as a Henschel mixer and then supplied. It is preferable to supply the raw materials to the melt-kneading apparatus using a gravimetric feeder that can control the supply amount to a constant value.

Although the set temperature during melt-kneading is not particularly limited, in the present invention, the temperature of the melt-kneaded material (T (°C )) is preferably 100°C≦T≦200°C, more preferably 100°C≦T≦180°C.

The kneaded molding composition is molded into a strand, but from the viewpoint of operability during subsequent injection molding, the strand may be cut with a strand cutter to form pellets, or the strand may be pelletized with a hot cutter or It is also possible to pelletize using a cutting means such as an underwater cutter. Note that when cutting the strands with a strand cutter to pelletize them, the strands may be held in a liquid medium after melt-kneading in order to further increase the strength of the resulting melt-kneaded product. The temperature of the liquid medium at this time is preferably 15 to 40°C, more preferably 20 to 40°C, even more preferably 25 to 30°C. Further, the retention time in the liquid medium is preferably 0.5 to 10 seconds, more preferably 1 to 10 seconds. Note that examples of the liquid medium include low-viscosity liquids with a boiling point of 100° C. or higher, such as water, ethylene glycol, and silicone oil, and from the viewpoint of safety and ease of handling, water is preferable. The temperature of the liquid medium is preferably maintained stably by, for example, circulating the liquid medium using a temperature control device.

(Method for manufacturing molded body)
Examples of the method for manufacturing a molded object using the molding composition of the present invention include a molding method using an injection molding machine and a method for manufacturing a sheet-like molded object using a melt extrusion die. The temperature of the molding composition injected into the injection mold or melt extrusion die is preferably 120 to 200 °C, and 120 to 180 °C, from the viewpoint of suppressing discoloration and odor generation of the obtained molded product and achieving both strength. It is more preferable that the temperature is ℃.

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

The molded product of the present invention may be obtained by further heating and press-molding the molded product such as a sheet-like molded product obtained by the above method.

(molded object)
The present invention also relates to a molded article obtained by molding the above-mentioned molding composition. In addition, in the present invention, the molded body includes, in addition to the final molded product, a molded sheet obtained by processing a molding composition into a molded body, and which is further subjected to molding processing. By further molding such a molded sheet, it becomes easy to mold a final molded product having a complicated shape having curved portions and uneven portions. Such a molded sheet can also be called a precursor molded body.

The flexural modulus of the molded body is preferably 1.0 GPa or more, more preferably 1.5 GPa or more, and even more preferably 2.0 GPa or more. Although the upper limit of the flexural modulus of the molded body is not particularly limited, it is preferably 20.0 GPa or less. Further, the bending stress of the molded body is preferably 60 MPa or more, more preferably 70 MPa or more, and even more preferably 80 MPa or more. Although the upper limit of the bending stress of the molded body is not particularly limited, it is preferably 300 MPa or less. The bending elastic modulus and bending stress of the molded body are values measured according to JIS K7171.

The bending strain of the molded body is preferably 4% or more, more preferably 50% or more, and even more preferably 6% or more. Although the upper limit of the bending strain of the molded body is not particularly limited, it is preferably 20% or less. The bending strain of the molded body is a value measured according to JIS K 7171.

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

(Applications of molded body)
Applications of the molded article of the present invention include, for example, casings of electronic devices and home appliances, reinforcing materials, civil engineering, building material parts, interior parts, automobiles, motorcycle parts, aircraft parts, railway vehicle parts, and Japanese Examples include members for household goods, packaging materials, etc. Among them, disposable uses are suitable. It is desirable that the molded article of the present invention does not leak into the natural environment, but even if it does, it will decompose in the natural environment, reducing the burden on the environment.

EXAMPLES The features of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. In addition, in the following, Examples 2, 4, and 8 shall be read as Reference Examples 2, 4, and 8, respectively.

(Example 1)
30 parts by mass of hardwood-derived dissolving pulp (cellulose purity 95%) obtained by pre-hydrolysis-kraft cooking method, 70 parts by mass of polybutylene succinate resin (Bio PBS FZ71PM, Mitsubishi Chemical Corporation), carbodiimide compound ( Nisshinbo Chemical Co., Ltd., Carbodilite HMV-15CA) 1 part by mass and calcium stearate (NOF Corporation, Calcium Stearate) 1 part by mass were put into a twin-screw kneader and melted and kneaded at a temperature of 160°C and a rotation speed of 30 rpm. did.
The molding composition (resin composition) obtained by melt-kneading was extruded into a strand shape and then cut into pellets. Using an injection molding machine, it was molded into a standard shape (multipurpose test piece (A1) shape) for evaluating the physical properties of plastics described in JIS K 7139. During injection molding, the cylinder temperature was uniformly set at 165°C, and the mold temperature was set at 30°C.

(Example 2)
Except that polylactic acid resin (Nature works, ingeo 3251D) was used as a raw material instead of polybutylene succinate resin, the kneading temperature was set at 180°C, and the cylinder temperature during injection molding was set at 180°C. A molding composition and a molded article were produced in the same manner as in Example 1.

(Example 3)
A molding composition and a molded article were produced in the same manner as in Example 1, except that glycidyl methacrylate (Mitsubishi Chemical Corporation, Metablen P-1901) was used as a raw material instead of the carbodiimide compound.

(Example 4)
A molding composition and a molded article were produced in the same manner as in Example 1, except that oleic acid amide (NOF Corporation, Alflo E-10) was used as a raw material instead of calcium stearate.

(Example 5)
A molding composition and a molded body were produced in the same manner as in Example 1, except that stearyl alcohol (NAA-45, NOF Corporation) was used as a raw material instead of calcium stearate.

(Example 6)
A molding composition and a molded body were produced in the same manner as in Example 1, except that stearyl stearate (NOF Corporation, Unistar M-9676) was used as a raw material instead of calcium stearate.

(Example 7)
A molding composition and a molded body were produced in the same manner as in Example 1, except that stearic acid (NAA-180, NOF Corporation) was used as a raw material instead of calcium stearate.

(Example 8)
A molding composition and a molded body were produced in the same manner as in Example 1, except that the blending amount of hardwood-derived dissolving pulp was changed to 40 parts by mass, and the blending amount of polybutylene succinate resin was changed to 60 parts by mass.

(Comparative example 1)
A molding composition and a molded body were produced in the same manner as in Example 1, except that paraffin wax (Nippon Seirin Co., Ltd., LUVAX-1266) was used as a raw material instead of calcium stearate.

(Comparative example 2)
A molding composition and a molded body were produced in the same manner as in Example 1 except that calcium stearate was not added as a raw material.

(Comparative example 3)
A molding composition and a molded article were produced in the same manner as in Example 1 except that carbodi-modified isocyanate was not added as a raw material.

(Comparative example 4)
A molding composition and a molded body were produced in the same manner as in Example 1, except that maleic anhydride (Nippon Shokubai Co., Ltd.) was used as a raw material instead of calcium stearate.

(Comparative example 5)
A molding composition and a molded article were produced in the same manner as in Example 1 except that calcium stearate and carbodi-modified isocyanate were not added as raw materials.

(Reference example 1)
Using an injection molding machine, polybutylene succinate resin (Mitsubishi Chemical Corporation, BioPBS FZ71PM) was molded into the shape of a multipurpose test piece (A1) described in JIS K 7139. During injection molding, the cylinder temperature was uniformly set at 165°C, and the mold temperature was set at 30°C.

(Reference example 2)
A molded body was produced in the same manner as in Reference Example 1, except that the polybutylene succinate resin was changed to polylactic acid resin (Nature works, ingeo 3251D), the cylinder temperature was set to 180°C, and the mold temperature was set to 30°C. did.

(measurement)
<Melting point of resin>
The melting point of the resin was calculated from the crystal melting endothermic peak temperature by the heating 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 was measured according to JIS K 7210 at 190° C. and under a load of 10 kg. The MFR of the resins of Reference Examples 1 and 2 was measured at 190° C. and under a load of 2.16 kg.

<Moldability>
The molding compositions obtained in Examples and Comparative Examples were molded into a plate shape of 200 mm x 200 mm and 1 mm thick using a heat press machine and an SUS frame. The molded plate was heated in a toaster oven to a temperature of 20 to 40° C. above the melting point of the matrix resin, and then press-molded using a container-shaped mold measuring 80 mm x 80 mm and 30 mm in height. The molded containers were visually observed and moldability was evaluated based on the following criteria.
◎: No molding defects were observed, and there was no collapse of the thin wall portion.
○: Minute molding defects are observed in only a few parts, or the product collapses when strong force is applied to the thin wall part.
Δ: Minute molding defects are observed at multiple locations, or thin portions collapse under slight force.
×: Molding defects are observed over a wide range, and the thin wall portion collapses with slight force.

<Bending modulus, bending stress, bending strain>
The bending modulus, bending stress, and bending strain of the molded bodies obtained in Examples and Comparative Examples were measured according to JIS K 7171.

<Tensile strength>
The tensile strength of the molded bodies obtained in Examples and Comparative Examples was measured according to JIS K 7161.

Compared to the comparative example, in the example, a molded article with good moldability and excellent tensile properties was obtained. In addition, the molded bodies of the examples are also superior in biodegradability compared to the reference examples.

Claims (6)

A molding composition obtained by kneading pulp fibers, a biodegradable resin, a hydrolysis inhibitor, and a lubricant,
The biodegradable resin contains polybutylene succinate as a main component,
When the content of the pulp fiber is P and the content of the biodegradable resin is Q, P:Q = 10:90 to 60:40,
The lubricant is an aliphatic compound having 12 or more carbon atoms, and the aliphatic compound has at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amide group, and an ester bond,
A molding composition, wherein the molding composition has a melt flow rate of 9.0 to 20.0 g/10 min as measured under 190° C. and 10 kg load according to JIS K 7210 . The molding composition according to claim 1, wherein the content of the hydrolysis inhibitor is 0.1 to 5.0% by mass based on the total mass of the molding composition. The molding composition according to claim 1, wherein the content of the lubricant is 0.1 to 5.0% by mass based on the total mass of the molding composition. The molding composition according to any one of claims 1 to 3, wherein the hydrolysis inhibitor is at least one selected from the group consisting of a carbodiimide compound, an isocyanate compound, an oxazoline compound, and an epoxy compound. The molding composition according to any one of claims 1 to 4, wherein the biodegradable resin has a melting point of 160° C. or lower. A molded article obtained by molding the molding composition according to any one of claims 1 to 5 .