Flame-retardant resin composition and method for producing the same, flame-retardant resin molded product and flame-retardant resin housing

Abstract

To provide a flame-retardant resin composition with improved flame resistance and impact resistance, a manufacturing method therefor, a flame-retardant resin molded product, and a flame-retardant resin housing.SOLUTION: A flame-retardant resin composition of the present invention comprises a resin and a polysaccharide, wherein a sugar backbone in the polysaccharide has at least a basic functional group or a salt of the basic functional group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a flame-retardant resin composition, a method for producing the same, a flame-retardant resin molded product, and a flame-retardant resin housing. More specifically, the present invention relates to a flame-retardant resin composition having improved flame retardancy and impact resistance, etc.

Background Art

[0002] In recent years, reduction of environmental load has been demanded, and biomass resins that substitute petroleum raw materials with biomass raw materials have attracted attention.However, since electrical and electronic devices potentially have a risk of ignition due to circuit short-circuit, deterioration, etc., in order to use biomass resins as materials for parts and housings in electrical and electronic devices, it is necessary to impart flame retardancy from the viewpoint of safety such as fire prevention.

[0003] Regarding biomass resins, use in electrical and electronic devices, which has been increasing in recent years, has been studied. However, since electrical and electronic devices potentially have a risk of ignition due to circuit short-circuit, deterioration, etc., in order to use biomass resins as materials for parts and housings in electrical and electronic devices, it is necessary to impart flame retardancy from the viewpoint of safety such as fire prevention.

[0004] Examples of flame retardants used to impart flame retardancy include phosphorus-based flame retardants. However, many phosphorus-based flame retardants are made from fossil resources. When an appropriate amount of a phosphorus-based flame retardant is added to impart sufficient flame retardancy, the biomass degree of the entire resin will be greatly reduced. Therefore, from the viewpoint of achieving both the biomass degree and flame retardancy of the entire resin, a technique of using natural polysaccharides as flame retardants has attracted attention.

[0005] Patent Document 1 discloses technology relating to flame retardants containing sugar compounds. In particular, the polysaccharides contained in the sugar compounds are compounds whose basic skeleton is a cyclic structure having a large number of hydroxyl groups. During combustion, as a result of dehydration condensation accompanied by heating, water vapor is generated, which causes cooling due to a large amount of endothermic heat, dilution of combustion gases, and blocking of oxygen. In addition, the dehydrated polysaccharides are carbonized, forming a heat-insulating film (hereinafter also referred to as "char" or "carbonized layer"), thus providing a high flame retardant effect.

[0006] However, when adding polysaccharides to resins to impart flame retardancy, depending on the compatibility between the resin and the polysaccharides, it was difficult to uniformly disperse the polysaccharides within the resin, making it challenging to uniformly impart flame retardancy to the entire resin. Furthermore, the heat generated when adding and mixing polysaccharides with the resin could cause dehydration condensation of the polysaccharides, leading to problems such as a decrease in flame retardancy.

[0007] Patent Document 2 discloses a flame-retardant resin composition containing a phosphorus-containing polysaccharide, which is formed by adding a phosphate ester to the side chain of a natural polysaccharide, as a flame retardant, possessing impact resistance, moldability, and flame retardancy. However, since the flame retardancy of the phosphorus-containing polysaccharide is thought to be more due to phosphorus than to the polysaccharide itself, the phosphorus-containing polysaccharide, with its relatively low phosphorus concentration in the flame retardant, has lower flame retardancy than conventional phosphorus-based flame retardants that do not contain polysaccharides. Therefore, further improvement in flame retardancy was required for the use of the phosphorus-containing polysaccharide as a flame retardant.

[0008] Furthermore, Patent Document 3 discloses a technology relating to a flame-retardant biodegradable resin composition in which a biodegradable flame retardant having at least a hydroxyl group and a carboxyl group in the molecule is the main component. Examples of such biodegradable flame retardants include acids selected from the group consisting of tartaric acid, citric acid, gluconic acid, lactic acid, malic acid, and gallic acid, ester derivatives, or metal salts. However, these example compounds have relatively low decomposition temperatures, and in molded articles obtained by melting the biodegradable resin composition with heat and injecting it into a mold, the example compounds may decompose, resulting in a problem where sufficient flame retardancy cannot be obtained. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2006-77215 [Patent Document 2] Japanese Patent Publication No. 2010-31230 [Patent Document 3] Japanese Patent Publication No. 2003-213149 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] This invention has been made in view of the above-mentioned problems and circumstances, and its objective is to provide a flame-retardant resin composition with improved flame retardancy and impact resistance, a method for producing the same, a flame-retardant resin molded article, and a flame-retardant resin housing. [Means for solving the problem]

[0011] In order to solve the above problems, the inventors investigated the causes of the above problems and, as a result, found that in a flame-retardant resin composition containing a resin and a polysaccharide, the flame retardancy and impact resistance are improved if the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group, leading to the present invention. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0012] 1. A flame-retardant resin composition containing resin and polysaccharides, The sugar skeleton contained in the aforementioned polysaccharide has at least a basic functional group or a salt of a basic functional group. death, The average primary particle size of the polysaccharide dispersed in particulate form is within the range of 30.00 to 300.00 μm. A flame-retardant resin composition characterized by the following.

[0013] 2. The basic functional group is an amino group or a substituted amino group. The flame-retardant resin composition according to paragraph 1, characterized by the above.

[0014] 3. The sugar skeletons having the amino group or substituted amino group are glucosamine skeletons or N-acetylglucosamine skeletons, respectively. The flame-retardant resin composition according to claim 2, characterized in that.

[0015] 4. The polysaccharide is chitosan or chitin. The flame-retardant resin composition according to claim 3, characterized in that.

[0016] 5. The resin is a thermoplastic resin. The flame-retardant resin composition according to claim 1 or 2, characterized in that.

[0017] 6. The thermoplastic resin is an amorphous resin. The flame-retardant resin composition according to claim 5, characterized in that.

[0018] 7. The thermoplastic resin contains at least one of ABS resin, polystyrene, polymethyl methacrylate or polycarbonate. The flame-retardant resin composition according to claim 5, characterized in that.

[0020] 8 . The content of the polysaccharide is in the range of 5 to 40% by mass based on the total mass of the flame-retardant resin composition. The flame-retardant resin composition according to claim 1 or 2, characterized in that.

[0021] 9 [[ID=​​​​​​​​​​​​​The process includes a step of melting and kneading the thermoplastic resin and the polysaccharide, The number of times the aforementioned melting and kneading is performed is two or more. A method for producing a flame-retardant resin composition characterized by the above.

[0023] 1 1 Formed using the flame-retardant resin composition described in paragraph 1 or 2. A flame-retardant resin molded product characterized by the following.

[0024] 1 2 1st 1 Includes flame-retardant resin molded products as described in the section. A flame-retardant resin housing characterized by the following features. [Effects of the Invention]

[0025] The above-described means of the present invention make it possible to provide a flame-retardant resin composition with improved flame retardancy and impact resistance, a method for producing the same, a flame-retardant resin molded article, and a flame-retardant resin housing.

[0026] Although the mechanism of action or mechanism of the present invention is not yet clear, it is speculated as follows.

[0027] One method for imparting flame retardancy to resins is to generate water vapor from within the resin when it is ignited, thereby lowering its temperature and stopping combustion. Specifically, as mentioned above, it is thought that by including polysaccharides in the resin, the dehydration condensation reaction of the polysaccharides proceeds, generating water vapor and lowering the temperature.

[0028] In the present invention, in a resin composition containing a resin and a polysaccharide, it is believed that the presence of a basic functional group or a salt of a basic functional group in the sugar skeleton of the polysaccharide promotes the dehydration condensation reaction that occurs when the resin composition is heated. Simultaneously with the generation of water vapor, the carbonization of the resin surface is promoted, and it is believed that flame retardancy is improved compared to neutral polysaccharides that do not have a basic functional group or a salt of a basic functional group, such as cellulose.

[0029] Furthermore, in this invention, polysaccharides are not completely miscible with resins. By dispersing polysaccharides as fine particles in the resin composition, a stable dispersion state can be maintained (dispersion stabilization), resulting in a resin composition with uniform properties without unevenness, which is thought to improve impact resistance. [Brief explanation of the drawing]

[0030] [Figure 1] Schematic perspective view of a large copier 10 housed in a flame-retardant resin enclosure of the present invention. [Modes for carrying out the invention]

[0031] The flame-retardant resin composition of the present invention is a flame-retardant resin composition containing a resin and a polysaccharide, characterized in that the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group. This feature is a technical feature common to or corresponding to the following embodiments.

[0032] In embodiments of the present invention, from the viewpoint of exhibiting the effects of the present invention, it is preferable that the basic functional group is an amino group or a substituted amino group.

[0033] In embodiments of the present invention, from the viewpoint of appearance and impact resistance, it is preferable that the sugar skeleton having the amino group or substituted amino group is a glucosamine skeleton or an N-acetylglucosamine skeleton, respectively.

[0034] In embodiments of the present invention, from the viewpoint of appearance and impact resistance, the polysaccharide is preferably chitosan or chitin.

[0035] In embodiments of the present invention, from the viewpoint of ease of handling, the resin is preferably a thermoplastic resin, and from the viewpoint of impact resistance, the thermoplastic resin is preferably an amorphous resin.

[0036] In embodiments of the present invention, from the viewpoint of appearance, flame retardancy, and impact resistance, it is preferable that the thermoplastic resin contains at least ABS resin, polystyrene, polymethyl methacrylate, or polycarbonate.

[0037] In embodiments of the present invention, from the viewpoint of appearance, flame retardancy, and impact resistance, it is preferable that the average primary particle size of the polysaccharide dispersed in particulate form is within the range of 0.10 to 300.00 μm.

[0038] In embodiments of the present invention, from the viewpoint of appearance and flame retardancy, it is preferable that the content of the polysaccharide is in the range of 5 to 40% by mass relative to the total mass of the flame-retardant resin composition.

[0039] The method for producing the flame-retardant resin composition of the present invention is a method for producing the flame-retardant resin composition of the present invention, characterized by comprising the steps of: dry grinding the polysaccharide; and melt kneading the thermoplastic resin and the polysaccharide.

[0040] The method for producing the flame-retardant resin composition of the present invention is a method for producing the flame-retardant resin composition of the present invention, comprising a step of melt-kneading the thermoplastic resin and the polysaccharide, characterized in that the number of melt-kneading steps is two or more.

[0041] The flame-retardant resin molded article of the present invention is characterized by being formed using the flame-retardant resin composition of the present invention, and the flame-retardant resin housing of the present invention is characterized by including the flame-retardant resin molded article of the present invention.

[0042] The present invention, its components, and embodiments and models for carrying out the present invention will be described in detail below. In this application, "~" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0043] <<Overview of Flame-Retardant Resin Compositions>> The flame-retardant resin composition of the present invention is a flame-retardant resin composition containing a resin and a polysaccharide, characterized in that the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group. In this invention, "flame-retardant resin composition" refers to a resin composition that has the following "flame-retardant properties".

[0044] "Flame retardancy" is a type of heat resistance, meaning that while the rate of combustion is slow, the material continues to burn to a certain extent. Specifically, this means meeting the acceptance criteria of the UL94 standard set by Underwriters Laboratories (UL) in the United States. More specifically, it means meeting the acceptance criteria of UL94HB in the UL94 test (flammability test for plastic materials for equipment components). In addition, it is preferable to meet the V-2 criterion of UL94V, more preferably the V-1 criterion, and even more preferably the V-0 criterion.

[0045] "Combustion" refers to an oxidation reaction that produces light and heat, and requires three elements: combustible material, an oxygen source, and an ignition source. In the case of resin (a flammable material), once it is ignited (ignition source), the phenomena described in A to C below are repeated, and combustion continues. a) High temperatures cause the resin (flammable material) to melt and decompose, generating a large amount of flammable gas. (i) In a high-temperature environment, flammable gases become radicalized, and chemical reactions with oxygen in the air (oxygen source) are accelerated, resulting in the generation of a considerable amount of light and heat. (c) The generated heat maintains a high temperature, causing the resin to continue to decompose.

[0046] Therefore, combustion can be stopped by lowering the temperature, cutting off the oxygen supply, or removing flammable gases, and flame retardancy can be imparted to a resin by designing it so that such phenomena occur when it is ignited.

[0047] Specifically, examples include generating water vapor from within the resin to lower the temperature (cooling by a large amount of endothermic heat), generating a large amount of non-flammable gas from within the resin to lower the oxygen concentration and cut off the oxygen supply, and carbonizing the surface of the resin to form a barrier layer (corresponding to "char" or "carbonized layer" in this invention) and cut off the oxygen supply.

[0048] In the present invention, it is believed that the above phenomenon can be exhibited and flame retardancy can be imparted by the resin composition containing polysaccharides, and furthermore, by the sugar skeleton contained in said polysaccharides having at least a basic functional group or a salt of a basic functional group.

[0049] The flame-retardant resin composition of the present invention exhibits excellent flame retardancy and impact resistance, and can be used as a housing or component in electronic devices and the like by molding it into an appropriate form and shape. Furthermore, when used as a housing, it is preferable that it has a good appearance.

[0050] <<Composition of Flame-Retardant Resin Composition>> The flame-retardant resin composition of the present invention is a flame-retardant resin composition containing a resin and a polysaccharide, characterized in that the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group. Furthermore, from the viewpoint of reducing environmental impact, the materials used in the flame-retardant resin composition of the present invention are preferably biomass materials, but materials other than biomass materials may also be used.

[0051] [1 Polysaccharide] The flame-retardant resin composition of the present invention contains polysaccharides, and furthermore, the sugar skeleton contained in the polysaccharides has at least a basic functional group or a salt of a basic functional group. The flame-retardant resin composition of the present invention can be imparted with flame retardancy by containing the polysaccharide.

[0052] In this invention, "polysaccharides" refers to substances formed by the dehydration condensation of numerous monosaccharides via glycosidic bonds, and is a general term for such substances. The types of monosaccharides that make up the polysaccharides may be one type or two or more types.

[0053] The degree of polymerization of the polysaccharide is preferably in the range of 50 to 20000, more preferably in the range of 200 to 1500, and even more preferably in the range of 200 to 1100.

[0054] The molecular weight of the polysaccharide is preferably in the range of 10,000 to 250,000, and more preferably in the range of 20,000 to 80,000, based on the weight-average molecular weight of polystyrene as determined by gel permeation chromatography (GPC).

[0055] Furthermore, "monosaccharide" refers to a sugar that cannot be further hydrolyzed, and is a general term for such sugars. Structurally, it is a chain-type polyhydroxy compound having an aldehyde group or a ketone group, and usually exists in a cyclic form that is hemiacetalized within the molecule. The monosaccharide is preferably a pentose or a hexose, and more preferably a hexose. In this invention, "sugar skeleton" refers to the skeletal structure of a monosaccharide.

[0056] For example, if there is only one type of monosaccharide (A) that forms the constituent unit of a polysaccharide, the sugar skeleton corresponds to the skeletal structure of monosaccharide A. In the present invention, the sugar skeleton is characterized by having at least a basic functional group or a salt of a basic functional group, and in this case, the skeletal structure of monosaccharide A has at least a basic functional group or a salt of a basic functional group.

[0057] When a polysaccharide is composed of two types of monosaccharides (A and B), the sugar skeleton corresponds to the skeletal structures of monosaccharides A and B. In this case, the skeletal structure of monosaccharide A or monosaccharide B contains at least a basic functional group or a salt of a basic functional group.

[0058] Similarly, when there are three or more types of monosaccharides that make up a polysaccharide, the sugar skeleton corresponds to the skeletal structure of each monosaccharide, and each monosaccharide's skeletal structure has at least a basic functional group or a salt of a basic functional group. Furthermore, polysaccharides do not necessarily have to be structures that contain repeating units.

[0059] In the present invention, "the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group" means that the skeletal structure of the monosaccharide contained in the polysaccharide has at least one basic functional group other than a hydroxyl group, and such basic functional group may form a salt. Hereinafter, "basic functional group or salt of a basic functional group" will be collectively referred to as "basic functional group, etc." In the present invention, the hydroxyl group is not included in basic functional groups. Polysaccharides may have acidic functional groups in addition to basic functional groups, etc., to the extent that they do not hinder the effects of the present invention, and furthermore, the acidic functional groups may form salts. Also, from the viewpoint of the expression of the effects of the present invention, it is preferable that the total number of basic functional groups and salts of basic functional groups in the polysaccharide as a whole is greater than the total number of acidic functional groups and salts of acidic functional groups.

[0060] In the present invention, from the viewpoint of preferring the use of biomass materials, it is preferable to use natural polysaccharides. However, the polysaccharides according to the present invention are not limited to those of natural origin.

[0061] Furthermore, the polysaccharide may be a modified version of a natural polysaccharide. Specifically, a polysaccharide that does not have basic functional groups may be modified by introducing basic functional groups to obtain the polysaccharide according to the present invention, or a derivative may be used as needed.

[0062] Examples of polysaccharide derivatives include compounds in which atoms other than basic functional groups are replaced with different atoms or substituents, such as compounds in which hydrogen atoms in polysaccharides are replaced with substituents such as halogen groups or hydrocarbon groups. Furthermore, examples of cross-linked polysaccharides, such as ester derivatives and ether derivatives, obtained by reacting a hydroxyl group in a polysaccharide with a compound having a functional group that is reactive with a hydroxyl group, are also mentioned later.

[0063] Examples of basic functional groups include amino groups (primary amino groups), substituted amino groups (secondary and tertiary amino groups), amide groups, pyridyl groups, pyridine groups, pyrrolidone groups, imidazole groups, and imine groups, among which amino groups or substituted amino groups (primary, secondary, or tertiary amino groups) are preferred.

[0064] Examples of salts of basic functional groups include quaternary ammonium salts, which include salts with chloride ions, bromide ions, alkyl sulfate ions having 1 or 2 carbon atoms, fatty acid ions having 1 to 12 carbon atoms, and benzenesulfonate ions substituted with 1 to 3 alkyl groups having 1 to 3 carbon atoms.

[0065] In particular, a salt with a divalent or higher anion is preferred. By being a salt with a divalent or higher anion, a cross-linked structure is formed within or between molecules, resulting in a rigid structure. Therefore, heat resistance is dramatically improved, and deformation of the flame-retardant resin composition can be prevented during melt mixing and molding, resulting in excellent strength and appearance.

[0066] Examples of monosaccharides having basic functional groups include glucosamine, galactosamine, mannosamine, and their derivatives, while examples of monosaccharides having salts of basic functional groups include salts of these.

[0067] Examples of derivatives include N-substituted compounds or salts of inorganic salts such as sulfuric acid or organic acids such as acetic acid. Among these, N-substituted compounds of organic acids are preferred, and N-acyl substituted compounds are more preferred.

[0068] Examples of N-acyl substituted compounds include N-formyl substituted compounds, N-acetyl substituted compounds, N-propionyl substituted compounds, N-butyryl substituted compounds, N-isobutyryl substituted compounds, N-valeryl substituted compounds, N-isovaleryl substituted compounds, and N-pivaloyl substituted compounds. Among these, N-acetyl substituted compounds are preferred, and examples of N-acetyl substituted compounds include N-acetylglucosamine, N-acetylgalactosamine, and N-acetylmannosamine.

[0069] Monosaccharides having basic functional groups may also have functional groups other than basic functional groups, and may have acidic functional groups or salts of acidic functional groups (hereinafter also referred to as "acidic functional groups, etc."). Examples of monosaccharides having both basic functional groups, etc. and acidic functional groups, etc. include muramic acid, N-acetylglucosamine-4-sulfate, N-acetylgalactosamine-4-sulfate, neuraminic acid, and N-acetylneuraminic acid.

[0070] When there are two or more types of monosaccharides that make up a polysaccharide, at least one of them falls under the above-mentioned monosaccharides, but the other monosaccharides are not particularly limited and may fall under the above-mentioned monosaccharides or not.

[0071] Other monosaccharides not included in the above list include, for example, ribose, arabinose, xylose, lyxose, xylulose, ribulose, deoxyribose, glucose, mannose, galactose, fructose, sorbose, tagatose, fucose, fuculose, and rhamnose.

[0072] Furthermore, other monosaccharides may have acidic functional groups, such as carboxyl groups and sulfoxy groups. Examples of monosaccharides having a carboxyl group include uronic acid, such as glucuronic acid, iduronic acid, mannuronic acid, and galacturonic acid. Examples of monosaccharides having a sulfoxy group include galactose-3-sulfate.

[0073] Examples of polysaccharides in which the sugar skeleton is composed of a single monosaccharide include chitosan, which contains glucosamine, and chitin, which contains N-acetylglucosamine. However, natural chitin contains not only N-acetylglucosamine but also glucosamine, with a composition ratio of approximately 9:1 between N-acetylglucosamine and glucosamine.

[0074] Furthermore, examples of polysaccharides in which the sugar skeleton is composed of two types of monosaccharides include hyaluronic acid, chondroitin, chondroitin 4-sulfate, chondroitin 6-sulfate, heparin, heparan sulfate, dermatan sulfate, and keratan sulfate.

[0075] Cross-linked polysaccharides may be used as derivatives of polysaccharides. In the present invention, "crosslinked polysaccharide" refers to a compound having a structure in which hydroxyl groups in the sugar chains of two or more polysaccharide molecules are crosslinked. Crosslinked polysaccharides can be obtained, for example, by crosslinking hydroxyl groups between at least different polysaccharide molecules using a crosslinking agent. However, only when crosslinking occurs between different molecules, two hydroxyl groups within the same molecule may also be crosslinked using a crosslinking agent.

[0076] The crosslinked polysaccharide used in the present invention is a crosslinked product of the above-mentioned polysaccharide, and any of the above-mentioned polysaccharides can be used as the polysaccharide constituting the crosslinked polysaccharide.

[0077] The crosslinking agent is preferably a compound having a hydroxyl group and two or more functional groups that are reactive with hydroxyl groups. Examples of functional groups that are reactive with hydroxyl groups include epoxy groups, chloro groups, silyl groups, isocyanate groups, and acid anhydrides. Examples of crosslinking agents include epichlorohydrin, hexamethylene diisocyanate, and tetraethyl silicate, with epichlorohydrin being the most preferred.

[0078] Crosslinking of polysaccharides using epichlorohydrin can be carried out, for example, by the reactions shown in the following formulas (I-1) and (I-2). In each formula, "*" indicates the linkage site with the skeletal structure formed by dehydration condensation of monosaccharides via glycosidic bonds.

[0079] Formula (I-1) is carried out under alkaline conditions, where the epoxy ring of epichlorohydrin opens and reacts with the OH group of the polysaccharide molecule to obtain intermediate (P). Furthermore, according to formula (I-2), the terminal chloro group derived from epichlorohydrin in intermediate (P) reacts with the OH group of another polysaccharide molecule, and the two polysaccharide molecules are cross-linked by a linking group (-CH2-CH(OH)-CH2-).

[0080] [ka]

[0081] The degree of crosslinking in crosslinked polysaccharides can be adjusted by the amount of crosslinking agent added to the polysaccharide. Preferably, the degree of crosslinking in the polysaccharide is adjusted so that the weight-average molecular weight of the resulting crosslinked polysaccharide falls within a preferred range of the weight-average molecular weight of the polysaccharide mentioned above.

[0082] Whether a resin composition contains polysaccharides and whether the sugar skeleton contained in the polysaccharides has a basic functional group or a salt of a basic functional group can be determined by finely grinding the resin composition, washing and extracting it with a solvent, separating only the polysaccharides, hydrolyzing them to monosaccharides, and identifying the molecular structure of the monosaccharides by high-performance chromatography.

[0083] In the flame-retardant resin composition of the present invention, polysaccharides are thought to be dispersed in a particulate state, and it is believed that the dispersion state of the polysaccharides can be stably maintained by adjusting the particle size within a specific range. Furthermore, it is believed that the properties of the flame-retardant resin composition will be uniformly expressed as a result of the stable dispersion state of the polysaccharides. Specifically, it is believed that flame-retardant resin molded products can be given uniform flame retardancy, impact resistance, and appearance without unevenness.

[0084] Regarding appearance, if defects are found, it is necessary to modify the mold and change the molding conditions (cooling time, etc.), so it is preferable to have a superior appearance from the standpoint of production efficiency.

[0085] The average primary particle size of the polysaccharide particles is preferably in the range of 0.10 to 300.00 μm, more preferably in the range of 0.10 to 80.00 μm, and even more preferably in the range of 0.10 to 30.00 μm.

[0086] The average primary particle size of polysaccharide particles can be measured by the following method. A scanning electron microscope (SEM) (manufactured by JEOL Ltd.) is used to capture a 1000x magnified image (SEM image) of the flame-retardant resin composition, which is then scanned and imported into a computer. The SEM image is then binarized using software Ver. 1.3.2 with the automated image processing and analysis system "Luzex® AP" (manufactured by Nireco Corporation). The diameters of 300 randomly selected polysaccharide particles are then calculated as the horizontal Ferret diameter, and the average value of these diameters is taken as the average primary particle diameter. The "horizontal Ferret diameter" refers to the length of the side parallel to the x-axis of the circumscribing rectangle when the image of the polysaccharide particles is binarized.

[0087] The average primary particle size of polysaccharides can be adjusted to within the above range by using the method for producing the flame-retardant resin composition of the present invention, as described later. In particular, natural polysaccharides often have relatively large particle sizes, but by using this production method, even natural polysaccharides can have their particle size made relatively small.

[0088] Although the method for producing the flame-retardant resin composition of the present invention, described later, uses a melt-kneading method, if the resin is a resin other than a thermoplastic resin, the average primary particle size of the polysaccharide can be adjusted to the above range by using a known method of uniformly mixing each component after performing a step of dry-grinding the polysaccharide (pretreatment).

[0089] In addition to flame retardancy, from the viewpoint of impact resistance and appearance, the polysaccharide content is preferably in the range of 5 to 40% by mass, and more preferably in the range of 20 to 30% by mass, relative to the total mass of the flame-retardant resin composition.

[0090] [2 resins] The flame-retardant resin composition of the present invention contains a resin. The type of resin is not particularly limited and includes thermoplastic resins, thermosetting resins, photocurable resins, and thermo- and photocurable resins. Among these, thermoplastic resins are preferred from the viewpoint of ease of handling.

[0091] From the viewpoint of reducing environmental impact, the resin according to the present invention is preferably a biomass resin, but the present invention can also be applied to resins other than biomass resins. Furthermore, a combination of biomass resin and a resin other than a biomass resin may be used.

[0092] The resin content is preferably in the range of 30 to 95% by mass, more preferably in the range of 40 to 90% by mass, and even more preferably in the range of 50 to 80% by mass, based on the total mass of the flame-retardant resin composition.

[0093] [2.1 Thermoplastic resin] The resin according to the present invention is preferably a thermoplastic resin from the viewpoint of ease of handling. The type of thermoplastic resin is not particularly limited, but from the viewpoint of suppressing the decomposition of polysaccharides and having excellent impact resistance and appearance in addition to flame retardancy, it is preferable that the softening point of the thermoplastic resin be 200°C or lower.

[0094] Furthermore, the thermoplastic resin may be either a crystalline resin or an amorphous resin, but from the viewpoint of impact resistance, an amorphous resin is preferable.

[0095] In this invention, "amorphous resin" refers to a resin that does not exhibit a clear endothermic peak in differential scanning calorimetry (DSC). In other words, it refers to a resin that does not have a melting point (a clear endothermic peak in the DSC curve measured using a differential scanning calorimetry (DSC) device) and has a relatively high glass transition temperature (Tg). On the other hand, "crystalline resin" refers to a resin that exhibits a clear endothermic peak in DSC, rather than a stepwise endothermic change.

[0096] Here, a "clear endothermic peak" specifically refers to a peak in DSC measurement where, when measured at a heating rate of 10°C / min, the full width at half maximum of the endothermic peak is within 15°C. For DSC measurement, for example, a differential scanning calorimeter ("Diamond DSC," manufactured by PerkinElmer) can be used. The melting points of indium and zinc can be used for temperature correction of the detector section of this device, and the heat of fusion of indium can be used for heat quantity correction.

[0097] If a resin is a crystalline resin, it has a crystallization temperature. In crystalline resins, the crystallization rate is fastest at a certain temperature during the cooling process; this temperature is called the "crystallization temperature." Therefore, the presence or absence of a crystallization temperature can be used to determine whether a resin is crystalline or amorphous.

[0098] The crystallization temperature can be measured by the following method. Using a differential scanning calorimeter (DSC), either "DSC Pyris1" (manufactured by PerkinElmer Japan Co., Ltd.) or "DSC7020" (manufactured by Hitachi High-Tech Science Co., Ltd.), the sample (approximately 5 mg) is heated under a nitrogen atmosphere (20 mL / min) to the target temperature set for each resin, held at that temperature for 3 minutes, then cooled to 30°C at 10°C / min, held at 30°C for 1 minute, and then heated again to the target temperature at 10°C / min. The melting point (Tm) can then be calculated from the peak of the crystal melting peak during the heating process, and the crystallization temperature (Tc) can be calculated from the peak of the crystallization peak during the cooling process. If multiple crystal melting peaks are observed, the higher-temperature peak is used as the melting point (Tm).

[0099] Crystalline resins are prone to shrinkage during the cooling process after melting and molding due to the formation of crystalline structures. On the other hand, amorphous resins are less susceptible to shrinkage and can maintain the dispersion of polysaccharides in the flame-retardant resin composition, thus offering superior impact resistance.

[0100] Examples of thermoplastic resins include polystyrene resins, polymethyl methacrylate, polycarbonate, aromatic polyesters, polyphenylene sulfide, polyolefin resins, polyamide-imide, polyetheretherketone, polyethersulfone, polyimide, polyvinyl chloride, polyamide, polyacetal, polylactic acid, polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, 1,2-polybutadiene-based thermoplastic elastomers, ethylene-vinyl acetate copolymer-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, and chlorinated polyethylene-based thermoplastic elastomers.

[0101] From the perspective of reducing environmental impact, thermoplastic biomass resins may be used as thermoplastic resins. Examples of thermoplastic biomass resins include aliphatic polyesters, polyamino acids, polyvinyl alcohol, polyalkylene glycols, and copolymers containing these. Alternatively, thermoplastic biomass resins may be combined with resins other than thermoplastic biomass resins to create a thermoplastic resin that combines the advantages of both. These thermoplastic resins may be used individually or in combination of two or more types.

[0102] Examples of polystyrene-based resins include polystyrene, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin).

[0103] Aromatic polyesters include aromatic polyesters having a structure in which an aromatic dicarboxylic acid or its ester derivative component is linked to a diol component such as an aliphatic diol or alicyclic diol by an esterification reaction. Specifically, examples include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4′-dicarboxylate, as well as copolymer polyesters such as polyethylene isophthalate / terephthalate, polybutylene terephthalate / isophthalate, and polybutylene terephthalate / decanedicarboxylate.

[0104] Examples of aliphatic polyesters include polyoxy acids, which are copolymers of oxy acids, and polycondensates of aliphatic diols and aliphatic dicarboxylic acids. Examples of polyoxy acids include poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), random copolymers of L-lactic acid and D-lactic acid, stereocomplexes of L-lactic acid and D-lactic acid, polycaprolactone, polyhydroxybutyric acid, and polyhydroxyvaleric acid. Examples of polycondensates of aliphatic diols and aliphatic dicarboxylic acids include polyethylene succinate, polybutylene succinate (PBS), and polybutylene adipate.

[0105] From the viewpoint of impact resistance, the thermoplastic resin is preferably an amorphous resin, and in particular, ABS resin, polystyrene, polymethyl methacrylate, or polycarbonate. Two or more types of thermoplastic resins may be used in combination, and it is preferable to use at least one of these resins.

[0106] Examples of commercially available thermoplastic resins include "Toyolac (registered trademark)" (ABS resin, manufactured by Toray Industries, Inc.), "Suntac (registered trademark)" (ABS resin, manufactured by Nippon A&L Co., Ltd.), "Toyo Styrofoam (registered trademark)" (polystyrene, manufactured by Toyo Styrene Co., Ltd.), "Acrypet (registered trademark)" (polymethyl methacrylate, manufactured by Mitsubishi Chemical Corporation), "Taflon (registered trademark)" (polycarbonate, manufactured by Idemitsu Kosan Co., Ltd.), "Panlite (registered trademark)" (polycarbonate, manufactured by Teijin Chemicals Limited), "Prime Polypro (registered trademark)" (polypropylene, manufactured by Prime Polymer Co., Ltd.), "Duranex (registered trademark)" (polybutylene terephthalate, manufactured by Polyplastics Co., Ltd.), "Clapet (registered trademark)" (polyethylene terephthalate, manufactured by Kuraray Co., Ltd.), "Alamin" (polyamide, manufactured by Toray Industries, Inc.), "Leicia (registered trademark)" (polylactic acid, manufactured by Mitsui Chemicals, Inc.), and "Terramac (registered trademark)" (polylactic acid, manufactured by Unitika Ltd.).

[0107] [2.1.1 Polystyrene resins] The thermoplastic resin according to the present invention is preferably a polystyrene-based resin from the viewpoint of impact resistance, and among these, ABS resin or polystyrene is preferred.

[0108] In the present invention, "polystyrene resin" refers to a polymer containing at least a styrene monomer as a monomer component. Here, "styrene monomer" refers to a monomer having a styrene skeleton in its structure.

[0109] The styrene monomer is not particularly limited as long as it is a monomer having a styrene skeleton in its structure. Examples include styrene, nuclear alkyl-substituted styrene (o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 4-ethylstyrene, p-tert-butylstyrene, etc.), α-alkyl-substituted styrene (α-methylstyrene, etc.), and among these, styrene is preferred.

[0110] Polystyrene resins may be homopolymers of styrene monomers or copolymers of styrene monomers with other monomer components. Examples of monomer components copolymerizable with styrene monomers include unsaturated carboxylic acid alkyl ester monomers such as alkyl methacrylate monomers (methyl methacrylate, cyclohexyl methacrylate, methylphenyl methacrylate, isopropyl methacrylate, etc.) and alkyl acrylate monomers (methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, etc.).

[0111] Other examples include unsaturated carboxylic acid monomers (methacrylic acid, acrylic acid, itaconic acid, maleic acid, fumaric acid, cinnamic acid, etc.), unsaturated dicarboxylic acid anhydride monomers (maleic anhydride, etc.), unsaturated nitrile monomers (acrylonitrile, methacrylonitrile, etc.), and conjugated diene monomers (1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc.). Furthermore, the styrene monomer may be copolymerized with one other monomer component, or with two or more other monomer components.

[0112] The copolymerization ratio of other monomer components is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total mass of the styrene monomer.

[0113] In this invention, "ABS resin" refers to an acrylonitrile-butadiene-styrene copolymer. Furthermore, "polystyrene" refers to a homopolymer of the above-mentioned styrene monomers.

[0114] From the viewpoint of heat resistance, the polystyrene-based resin is preferably acrylonitrile-butadiene-styrene copolymer (ABS resin), polystyrene, acrylonitrile-styrene copolymer (AS resin), styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, etc.

[0115] In acrylonitrile-butadiene-styrene copolymer (ABS resin), from the viewpoint of impact resistance and heat resistance, the proportion of acrylonitrile monomer in the copolymer is preferably in the range of 1 to 40% by mass, more preferably in the range of 1 to 30% by mass, and even more preferably in the range of 1 to 25% by mass, based on the total mass of the ABS resin.

[0116] In styrene-methacrylic acid copolymers, from the viewpoint of heat resistance, it is preferable that the proportion of methacrylic acid monomer in the copolymer is 0.1% by mass or more relative to the total mass of the styrene-methacrylic acid copolymer. Furthermore, if transparency is to be imparted, it is preferable that it be 50% by mass or less. If both heat resistance and transparency are to be achieved, it is preferable that it be in the range of 0.1 to 40% by mass, and more preferably in the range of 0.1 to 30% by mass.

[0117] In a styrene-maleic anhydride copolymer, from the viewpoint of heat resistance, it is preferable that the proportion of maleic anhydride monomer in the copolymer is 0.1% by mass or more relative to the total mass of the styrene-maleic anhydride copolymer. Furthermore, if transparency is to be imparted, it is preferable that it be 50% by mass or less, and if both heat resistance and transparency are to be achieved, it is more preferable that it be in the range of 0.1 to 40% by mass, and even more preferable that it be in the range of 0.1 to 30% by mass.

[0118] Examples of commercially available polystyrene resins include "Toyolac (registered trademark)" (ABS resin, manufactured by Toray Industries, Inc.), "Suntac (registered trademark)" (ABS resin, manufactured by Nippon A&L Co., Ltd.), "Toyo Styrofoam (registered trademark)" (polystyrene, manufactured by Toyo Styrene Co., Ltd.), "Clearlen (registered trademark)" (styrene-butadiene copolymer, manufactured by Denka Co., Ltd.), "Asaflex (registered trademark)" (styrene-butadiene copolymer, manufactured by Asahi Kasei Chemicals Corporation), "Styrolux (registered trademark)" (styrene-butadiene copolymer, manufactured by BASF Ltd.), and "PSJ (registered trademark)-Polystyrene" (polystyrene, manufactured by PS Japan Co., Ltd.).

[0119] The polystyrene resin content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, based on the total mass of the thermoplastic resin. Furthermore, in the flame-retardant resin composition of the present invention, it is particularly preferable that the thermoplastic resin consists solely of polystyrene resin.

[0120] [2.1.2 Polymethyl methacrylate] From the viewpoint of impact resistance, the thermoplastic resin according to the present invention is preferably polymethyl methacrylate.

[0121] Polymethyl methacrylate may be a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate with other monomer components. Examples of monomer components copolymerizable with methyl methacrylate include alkyl(meth)acrylates such as methyl acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, amyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, cyclohexyl(meth)acrylate, dodecyl(meth)acrylate, octadecyl(meth)acrylate, phenyl(meth)acrylate, and benzyl(meth)acrylate. In this specification, (meth)acrylate refers to both acrylate and methacrylate. Furthermore, methyl methacrylate may be copolymerized with one other monomer component, or with two or more other monomer components.

[0122] In polymethyl methacrylate, from the viewpoint of impact resistance and heat resistance, the proportion of methyl methacrylate in the copolymer is preferably in the range of 50 to 99% by mass, more preferably in the range of 60 to 95% by mass, and even more preferably in the range of 70 to 95% by mass, relative to the total mass of polymethyl methacrylate.

[0123] Examples of commercially available polymethyl methacrylate products include "Acrypet®" (manufactured by Mitsubishi Chemical Corporation).

[0124] The polymethyl methacrylate content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, based on the total mass of the thermoplastic resin. Furthermore, in the flame-retardant resin composition of the present invention, the thermoplastic resin may consist solely of polymethyl methacrylate.

[0125] [2.1.3 Polycarbonate] From the viewpoint of impact resistance, the thermoplastic resin according to the present invention is preferably polycarbonate.

[0126] Polycarbonate is a compound in which the bonding sites between monomers are composed of carbonate groups, and has a structure represented by the following general formula (1). General formula (1) -(-OROC(=O)-)- However, in the formula, R represents a hydrocarbon group.

[0127] Polycarbonates are obtained by the reaction of a divalent hydroxy compound with a carbonate precursor such as phosgene. Depending on the structure of the divalent hydroxy compound, aromatic polycarbonates, aliphatic polycarbonates, alicyclic polycarbonates, etc., can be obtained. In this invention, aromatic polycarbonates are more preferable from the viewpoint of impact resistance.

[0128] Examples of divalent aromatic hydroxy compounds include bis(hydroxyaryl)alkanes such as 2,2′-bis(4-hydroxyphenyl)propane [bisphenol A], 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane [bisphenol B], 2,2-bis(4-hydroxyphenyl)octane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(3-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(3-phenyl-4-hydroxyphenyl)propane, 2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane [bisphenol AP], and bis(4-hydroxyphenyl)diphenylmethane [bisphenol BP].

[0129] Other examples include bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane [bisphenol Z], and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane [bisphenol TMC]; bisphenols containing a cardo structure such as 9,9-bis(4-hydroxyphenyl)fluorene and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene; dihydroxydiaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; and dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide.

[0130] Furthermore, examples include dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide, dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone, and others such as hydroquinone, resorcinol, and 4,4'-dihydroxydiphenyl.

[0131] These can be used individually or in combination of two or more. In particular, bis(4-hydroxyphenyl)alkanes are preferred, and bisphenol A is especially preferred.

[0132] Alternatively, a polycarbonate having a branched structure may be obtained by using a trivalent or higher aromatic hydroxy compound in combination with the above-mentioned divalent aromatic hydroxy compound. Examples of aromatic hydroxy compounds with a valency of 3 or higher include phloroglucins and phloroglucides, as well as trisphenols such as 4,6-dimethyl-2,4,6-tris(4-hydroxyphenyl)heptene, 2,4,6-trimethyl-2,4,6-tris(4-hydroxyphenyl)heptane, 1,3,5-tris(4-hydroxyphenyl)benzene, 1,1,1-tris(4-hydroxyphenyl)ethane, 1,1,1-tris(3,5-dimethyl-4-hydroxyphenyl)ethane, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol, and 4-{4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene}-α,α-dimethylbenzylphenol.

[0133] Other examples include tetra(4-hydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)ketone, 1,4-bis(4,4-dihydroxytriphenylmethyl)benzene, and trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, and their acid chlorides. In particular, 1,1,1-tris(4-hydroxyphenyl)ethane or 1,1,1-tris(3,5-dimethyl-4-hydroxyphenyl)ethane is preferred, and 1,1,1-tris(4-hydroxyphenyl)ethane is more preferred.

[0134] Examples of carbonate precursors include phosgene, diaryl carbonates (diphenyl carbonate, dityl carbonate, etc.), dialkyl carbonates (dimethyl carbonate, diethyl carbonate, etc.), and dihaloformates of divalent phenols, among which phosgene is preferred. These can be used individually or in combination of two or more.

[0135] Examples of commercially available polycarbonate products include "Toughlon®" (manufactured by Idemitsu Kosan Co., Ltd.), "Panlite®" (manufactured by Teijin Chemicals Limited), "Yupilon®" (manufactured by Mitsubishi Engineering Plastics Corporation), and "Novarex®" (manufactured by Mitsubishi Engineering Plastics Corporation).

[0136] The polycarbonate content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, based on the total mass of the thermoplastic resin. Furthermore, in the flame-retardant resin composition of the present invention, the thermoplastic resin may consist only of polycarbonate.

[0137] [3 Other Additives] The flame-retardant resin composition of the present invention may contain other additives, depending on the purpose, to the extent that they do not impair the effects of the present invention.

[0138] Examples of additives include antioxidants, fillers, and nucleating agents. Furthermore, in the present invention, the above-mentioned polysaccharides may be used in combination with commonly used flame retardants. Examples of flame retardants include phosphorus-based flame retardants (including red phosphorus), bromine-based flame retardants, chlorine-based flame retardants, antimony-based flame retardants, boron-based flame retardants, nitrogen-based flame retardants, metal hydroxide-based flame retardants, and silicone-based flame retardants.

[0139] The additive content is preferably in the range of 0 to 30% by mass, and more preferably in the range of 0 to 20% by mass, relative to the total mass of the flame-retardant resin composition.

[0140] ≪Method for producing flame-retardant resin compositions≫ The present invention provides a method for producing a flame-retardant resin composition, comprising the steps of dry grinding the polysaccharide and melt-kneading the thermoplastic resin and the polysaccharide.

[0141] The present invention provides a method for producing a flame-retardant resin composition, comprising the step of melt-kneading the thermoplastic resin and the polysaccharide, characterized in that the melt-kneading is performed two or more times.

[0142] The method for producing the flame-retardant resin composition of the present invention is not particularly limited, but when the resin is a thermoplastic resin, a melt-kneading method is preferred, and known melt-kneading methods can be used. When the resin is a resin other than a thermoplastic resin, known methods for uniformly mixing each component can be used.

[0143] The following describes a method for producing the flame-retardant resin composition of the present invention by a melt-kneading method. By using this production method, the average primary particle size of the polysaccharides contained in the flame-retardant resin composition can be adjusted to the aforementioned preferred range. In particular, while natural polysaccharides often have relatively large particle sizes, this production method allows for the reduction of particle size even in natural polysaccharides.

[0144] The manufacturing method preferably includes the following steps. However, the pretreatment step may or may not be included.

[0145] 1) Dry grinding process of polysaccharides (pretreatment) By pre-grinding polysaccharides dry to reduce their particle size before mixing them with other materials, the number of melt-mixing steps can be reduced.

[0146] The method of dry grinding is not particularly limited, and suitable grinders include, for example, mortars, ball mills, pot mills, grinders, cutter mills, homogenizers, multi-bead shockers, pin mills, jet mills, hybridizers, extruders, and muscoloiders. The grinding time, processing pressure, etc., should preferably be adjusted as appropriate according to the type of polysaccharide and particle size.

[0147] In flame-retardant resin compositions, dry grinding is preferred, particularly using a ball mill, pot mill, grinder, or multi-bead shocker, from the viewpoint of excellent dispersibility.

[0148] 2) A process of melting and kneading thermoplastic resin and polysaccharides. As for melt-kneading methods, for example, thermoplastic resins, polysaccharides, etc., are pre-mixed using various mixers such as tumblers and high-speed mixers known as Henschel mixers, and then melt-kneaded using kneading equipment such as a Banbarri mixer, roll mixer, plastograph, single-screw extruder, twin-screw extruder, or kneader.

[0149] In particular, from the viewpoint of production efficiency, it is preferable to use an extruder, and more preferably to use a twin-screw extruder. Using an extruder, the material is melted and kneaded, the kneaded material is extruded into a strand shape, and then the kneaded material can be processed into shapes such as pellets or flakes.

[0150] It is preferable to thoroughly dry each material before pre-mixing. The drying temperature is not particularly limited, but is preferably in the range of 60 to 120°C, and the drying time is not particularly limited, but is preferably in the range of 2 to 6 hours. Furthermore, drying under reduced pressure is preferable from the viewpoint of promoting faster drying. The above drying may be performed after pre-mixing.

[0151] The melt-mixing temperature is not particularly limited and is preferably selected appropriately depending on the type of resin used, and is preferably in the range of 150 to 280°C. Here, the melt-mixing temperature corresponds to, for example, the cylinder temperature in a mixing device such as a twin-screw extruder. Furthermore, "cylinder temperature" refers to the highest temperature in the cylinder of a mixing device when multiple temperature settings are available. The mixing pressure is not particularly limited, but is preferably in the range of 1 to 20 MPa.

[0152] The discharge rate from the mixing device is not particularly limited, but from the viewpoint of ensuring sufficient melt mixing, it is preferably in the range of 10 to 100 kg / hr, and more preferably in the range of 20 to 70 kg / hr.

[0153] In the above method, the kneaded mixture, after being melted and kneaded by the kneading apparatus, is preferably subjected to a cooling treatment after being extruded from the kneading apparatus. The method of cooling is not particularly limited and includes, for example, immersing the mixture in water in the range of 0 to 60°C for water cooling, cooling with gas in the range of -40 to 60°C, or contacting it with metal in the range of -40 to 60°C.

[0154] The form and shape of the flame-retardant resin composition of the present invention are not particularly limited, and may be in solid form such as powder, granules, tablets, pellets, flakes, or fibers, or in liquid form.

[0155] Furthermore, by performing melt-kneading multiple times, the average primary particle size of the polysaccharides contained in the flame-retardant resin composition can be made smaller. When performing melt-kneading multiple times, the kneaded material is cooled and then melt-kneaded again in a kneading device. It is preferable to adjust the number of melt-kneading times appropriately according to the type and particle size of the polysaccharides.

[0156] Flame-retardant resin molded products The flame-retardant resin molded article of the present invention is characterized by being formed using the flame-retardant resin composition described above. The flame-retardant resin molded article of the present invention can be formed using the aforementioned flame-retardant resin composition to improve its flame retardancy and impact resistance.

[0157] When the resin is a thermoplastic resin, the flame-retardant resin molded article of the present invention is obtained by melting the aforementioned flame-retardant resin composition in various molding machines and molding it. The molding method can be appropriately selected depending on the form and application of the molded article, and examples include injection molding, extrusion molding, compression molding, blow molding, calendering, and inflation molding. Furthermore, sheet-like or film-like molded articles obtained by extrusion molding, calendering, etc., may be subjected to secondary molding such as vacuum forming or pressure forming.

[0158] Furthermore, if the resin is a curable resin other than a thermoplastic resin, a molded product can be obtained by curing the aforementioned flame-retardant resin composition. Conventional known curing methods can be used.

[0159] Flame-retardant resin molded products are not particularly limited and include, for example, parts in the fields of home appliances and automobiles (electrical and electronic components, electrical components, exterior parts, interior parts, etc.), various packaging materials, household goods, office supplies, piping, agricultural materials, etc.

[0160] Flame-retardant resin casing The flame-retardant resin housing of the present invention is characterized by including the aforementioned flame-retardant resin molded product. The flame-retardant resin composition of the present invention can improve flame retardancy and impact resistance, and furthermore, has an excellent appearance, so it is preferable to mold it into an appropriate shape and form and use it as a housing. Furthermore, the flame-retardant resin housing of the present invention may consist solely of the aforementioned flame-retardant resin molded product, or it may also include a portion of the aforementioned flame-retardant resin molded product.

[0161] The articles housed in the flame-retardant resin housing of the present invention are not particularly limited, but it is preferable to house electronic devices and the like. In addition, the flame-retardant resin housing of the present invention can be applied to housings that are generally preferably made of flame-retardant resins.

[0162] In this invention, "electronic equipment" refers to electrical products that utilize electronic engineering technology. Electronic equipment is not particularly limited and includes, for example, computers, scanners, copiers, printers, facsimile machines, office automation equipment such as MFPs (Multi-Function Peripherals) that combine these functions, and digital printing systems for commercial printing.

[0163] Because the flame-retardant resin housing of the present invention has excellent flame retardancy and impact resistance, even if the internal electronic equipment is damaged and ignites due to an external impact, the fire is less likely to spread, thereby reducing the risk of fire.

[0164] An example of the flame-retardant resin housing of the present invention is shown. Figure 1 is a schematic perspective view of a large copier 10 housed in the flame-retardant resin housing of the present invention. The flame-retardant resin housing includes flame-retardant resin molded products as exterior parts G1 to G9. [Examples]

[0165] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, the units "parts" or "%" are used, and unless otherwise specified, they represent "parts by mass" or "mass%". Furthermore, in the following examples, the operations were carried out at room temperature (25°C) unless otherwise specified.

[0166] [Preparation of flame-retardant resin compositions] The following resins and polysaccharides were prepared as constituent materials for the flame-retardant resin composition.

[0167] (resin) ABS1 (ABS resin): "Toyolac (registered trademark) 700-314", manufactured by Toray Industries, Inc. ABS2 (ABS resin): "Suntac (registered trademark) AT-05", manufactured by Japan A&L Co., Ltd. PS (Polystyrene): "Toyo Styrofoam (registered trademark) HI H450 K9-020", manufactured by Toyo Styrofoam Co., Ltd. PP (Polypropylene): "Prime Polypropylene (Registered Trademark) J715M", manufactured by Prime Polymer Co., Ltd. PC (Polycarbonate resin): "Toughlon (registered trademark) A1900", manufactured by Idemitsu Kosan Co., Ltd. PMMA (Polymethyl Methacrylate): "Acrypet (Registered Trademark) VRS40 0001", manufactured by Mitsubishi Chemical Corporation. Furthermore, PP (polypropylene) is a crystalline resin, while the other resins are amorphous resins.

[0168] (polysaccharide) Chitin: Manufactured by Tokyo Chemical Industry Co., Ltd. Chitosan: Chitosan (5-20 mPa·s, 0.5% / 0.5% acetic acid solution / 20℃), manufactured by Tokyo Chemical Industry Co., Ltd. Cellulose: Cellulose, powder, 38 μm (400 mesh) pass-through, manufactured by Fujifilm Wako Pure Chemical Corporation. A4 (Sodium Chondroitin Sulfate): Manufactured by Tokyo Chemical Industry Co., Ltd.

[0169] (Pretreatment of polysaccharides) In flame-retardant resin compositions 1-3, 5-9, 11-22, and 24, a pretreatment was performed in which polysaccharides were dry-ground using a ball mill. For dry grinding, 50 parts by mass of particulate polysaccharides were mixed with 300 parts by mass of alumina balls (10 mm in diameter) in a 180 mm diameter pot, and the mixture was ground using a ball mill (tabletop pot mill stand "PM-002", manufactured by AS ONE Corporation). Rotation speed: 100 rpm Time: Pre-processing time [hr] as listed in Table I

[0170] (Preparation of flame-retardant resin composition) As a pre-drying step before mixing, the resin and polysaccharides were dried separately at 80°C for 4 hours. Then, they were weighed according to the component ratios [mass%] shown in Table I and dry-blended. Next, the mixture obtained by dry blending was supplied at a rate of 10 kg per hour from the raw material supply port (hopper) of the twin-screw extruder "KTX-30" (manufactured by Kobe Steel, Ltd.), and melt-mixing was performed under the conditions of cylinder temperature and screw rotation speed of 200 rpm as described in Table I. After mixing, the molten resin was cooled in a 30°C water bath and then pelletized using a pelletizer to obtain a flame-retardant resin composition.

[0171] In addition, for those in Table I where the number of melt-kneading cycles was two or more (two or three times), the pelletized flame-retardant resin composition was again supplied from the raw material supply port of the twin-screw extruder, and melt-kneading was performed one or two more times under the above conditions.

[0172] The crystallization temperature of the final flame-retardant resin composition was measured using the following method. Using a differential scanning calorimeter (DSC), either "DSC Pyris1" (manufactured by PerkinElmer Japan Co., Ltd.) or "DSC7020" (manufactured by Hitachi High-Tech Science Co., Ltd.), the sample (approximately 5 mg) was heated under a nitrogen atmosphere (20 mL / min) to the target temperature set for each resin (cylinder temperature listed in Table I), held at that temperature for 3 minutes, then cooled to 30°C at 10°C / min and held at 30°C for 1 minute, then heated back up to the target temperature at 10°C / min. The crystallization temperature (Tc) was calculated from the peak of the crystallization peak during the cooling process.

[0173] For flame-retardant resin compositions 11 and 12, the crystallization temperature was measured in a region lower than the cylinder setting temperature listed in Table I, but the crystallization temperature was not measured for the other flame-retardant resin compositions.

[0174] Furthermore, the average primary particle size of polysaccharides in the flame-retardant resin composition was measured by the following method. A scanning electron microscope (SEM) (manufactured by JEOL Ltd.) was used to capture 1000x magnified images of the flame-retardant resin composition, which were then scanned and imported into a computer. The SEM images were then binarized using the automated image processing and analysis system "Luzex® AP" (manufactured by Nireco Corporation) with software Ver. 1.3.2. The diameters of 300 randomly selected polysaccharide particles were then calculated as the horizontal Ferret diameters, and the average value of these diameters was defined as the average primary particle diameter. The "horizontal Ferret diameter" refers to the length of the side parallel to the x-axis of the circumscribing rectangle obtained when the polysaccharide particle image is binarized.

[0175] <Rating> The following evaluations were performed on each of the flame-retardant resin compositions obtained above.

[0176] (Rating 1: Appearance of exterior parts) Each of the pelletized flame-retardant resin compositions obtained above was dried at 80°C for 5 hours in a hot air circulation dryer. Then, using an injection molding machine "J1300E-C5" (manufactured by Japan Steel Works Ltd.), a simulated molded product representing the exterior part G8 of a large copier shown in Figure 1 was molded at the cylinder setting temperature and mold temperature of 50°C as described in Table I, and a sample was taken from the center of the simulated molded product. The obtained samples were visually inspected for appearance defects. If any defects were found, the mold was modified and the molding conditions (cooling time, etc.) were changed. The results were then evaluated according to the following criteria to see if the appearance defects improved. A score of △ or higher indicated no practical problems and was considered acceptable.

[0177] ◎: Molded products without appearance defects can be obtained, and mold modifications are unnecessary. ○: By making only mold modifications, molded products without appearance defects can be obtained. △: By modifying the mold and changing the molding conditions, molded products without surface defects can be obtained. ×: Even after modifying the mold and changing the molding conditions, the appearance defect (severe warping) does not improve.

[0178] (Rating 2: Flame retardant) Each of the pelletized flame-retardant resin compositions obtained above was dried at 80°C for 4 hours, and then molded using an injection molding machine "J55ELII" (manufactured by Japan Steel Works Ltd.) at the cylinder temperature and mold temperature of 50°C as shown in Table I to obtain rectangular test pieces measuring 125 mm in length, 13 mm in width, and 1.6 mm in thickness.

[0179] Next, the obtained test specimens were conditioned for 48 hours in a constant temperature chamber at 23°C and 50% humidity, and then subjected to flame retardancy testing in accordance with the UL94 test (flammability test for plastic materials for equipment components) established by Underwriters Laboratories (UL) in the United States. The test was conducted by first performing the UL94V test, and for specimens that did not meet the V-2 criteria, the UL94HB test was performed further, and the specimens were evaluated according to the following criteria. Specimens with a score of △ or higher were considered to be acceptable and had no practical problems.

[0180] ◎: Meets the V-0 standard in UL94V testing. ○: In the UL94V test, it corresponds to V-1 or V-2. △: In the UL94V test, it does not meet the V-2 criteria, but in the UL94HB test, it meets the criteria. ×: In the UL94V test, it did not meet the V-2 acceptance criteria, and in the UL94HB test, it also did not meet the acceptance criteria. (Out of specification)

[0181] (Rating 3: Impact resistance (impact strength)) Each of the pelletized flame-retardant resin compositions obtained above was dried at 80°C for 4 hours, and then molded using an injection molding machine "J55ELII" (manufactured by Japan Steel Works Ltd.) at the cylinder temperature and mold temperature of 50°C as shown in Table I to obtain rectangular test pieces measuring 80 mm in length, 10 mm in width, and 4.0 mm in thickness. After discarding 300 shots, 100 consecutive shots were used as test specimens. The Izod impact strength of the 100 test specimens obtained was measured in accordance with JIS K7110:1999 and evaluated according to the following criteria. A score of ○ or higher was considered acceptable, indicating no practical problems.

[0182] ◎: 10kJ / m2 That's all. ○: 7kJ / m 2 More than 10kJ / m 2 It is less than. △: 4kJ / m 2 More than 7kJ / m 2 It is less than. ×: 4kJ / m 2 It is less than.

[0183] The composition of each flame-retardant resin composition obtained above and their evaluation results are shown in Table I. Note that "-" in the pretreatment time column in the table indicates that no pretreatment was performed.

[0184] [Table 1]

[0185] A comparison of flame-retardant resin compositions 1-22 (the present invention) and 23 and 24 (comparative examples) shows that the effects of the present invention are achieved when the sugar skeleton contained in the polysaccharide has at least a basic functional group or a salt of a basic functional group. Furthermore, it can be seen from flame-retardant resin compositions 1 to 22 that the effects of the present invention are achieved when the basic functional group is an amino group or a substituted amino group.

[0186] A comparison of flame-retardant resin compositions 1 and 6 with 13 reveals that the appearance and impact resistance are further improved when the sugar skeleton having an amino group or substituted amino group is a glucosamine skeleton or an N-acetylglucosamine skeleton, respectively, and when the polysaccharide is chitosan or chitin.

[0187] From flame-retardant resin compositions 1 to 22, it can be seen that the resin being a thermoplastic resin makes it easy to handle and allows the effects of the present invention to be realized. A comparison of flame-retardant resin compositions 8 and 12 shows that the appearance and impact resistance are further improved when the thermoplastic resin is an amorphous resin.

[0188] A comparison of flame-retardant resin compositions 1-5, 14, and 15 with 11 shows that the appearance, flame retardancy, and impact resistance are further improved when the thermoplastic resin contains at least ABS resin, polystyrene, polymethyl methacrylate, or polycarbonate.

[0189] A comparison of flame-retardant resin compositions 1-3, 17, and 18 with 10 and 16 reveals that when the average primary particle size of the polysaccharides is within the range of 0.1-300 μm, the appearance, flame retardancy, and impact resistance are further improved.

[0190] A comparison of flame-retardant resin compositions 1, 20, and 22 with 19 and 21 reveals that the appearance and flame retardancy are improved when the polysaccharide content is within the range of 5 to 40% by mass relative to the total mass of the flame-retardant resin composition.

[0191] Furthermore, it is understood that the flame retardancy and impact resistance are improved by having a step of dry grinding polysaccharides and a step of melt-kneading a thermoplastic resin with the polysaccharides in the method for producing the flame-retardant resin composition, or by having a step of melt-kneading a thermoplastic resin with polysaccharides and performing the melt-kneading two or more times. [Explanation of Symbols]

[0192] 10 Large-format photocopiers G1~G9 Exterior Parts

Claims

1. A flame-retardant resin composition containing a resin and polysaccharides, The sugar skeleton contained in the aforementioned polysaccharide has at least a basic functional group or a salt of a basic functional group, The average primary particle size of the polysaccharide dispersed in particulate form is within the range of 30.00 to 300.00 μm. A flame-retardant resin composition characterized by the following.

2. The basic functional group is an amino group or a substituted amino group. The flame-retardant resin composition according to claim 1.

3. The sugar skeleton having the amino group or substituted amino group is, respectively, a glucosamine skeleton or an N-acetylglucosamine skeleton. The flame-retardant resin composition according to claim 2.

4. The polysaccharide is chitosan or chitin. The flame-retardant resin composition according to claim 3.

5. The resin is a thermoplastic resin. The flame-retardant resin composition according to claim 1 or 2.

6. The thermoplastic resin is an amorphous resin. The flame-retardant resin composition according to claim 5.

7. The thermoplastic resin contains at least ABS resin, polystyrene, polymethyl methacrylate, or polycarbonate. The flame-retardant resin composition according to claim 5.

8. The content of the polysaccharide is within the range of 5 to 40% by mass relative to the total mass of the flame-retardant resin composition. The flame-retardant resin composition according to claim 1 or 2.

9. A method for producing the flame-retardant resin composition described in claim 5, A step of dry grinding the aforementioned polysaccharide, and The process includes melt-kneading the thermoplastic resin and the polysaccharide. A method for producing a flame-retardant resin composition characterized by the above.

10. A method for producing the flame-retardant resin composition described in claim 5, The process includes a step of melting and kneading the thermoplastic resin and the polysaccharide, The number of times the aforementioned melt kneading is performed is two or more. A method for producing a flame-retardant resin composition characterized by the above.

11. Formed using the flame-retardant resin composition according to claim 1 or claim 2 A flame-retardant resin molded product characterized by the following.

12. Includes the flame-retardant resin molded article described in claim 11. A flame-retardant resin housing characterized by the following features.

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