Flame-retardant resin compositions, flame-retardant resin molded articles, flame-retardant resin housings, and electronic equipment.

Abstract

To provide an excellent flame-retardant resin composition, flame-retardant resin molding, flame-retardant resin housing, and electronic apparatus.SOLUTION: A flame-retardant resin composition contains acidic polysaccharides, and a flame retardant.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to flame-retardant resin compositions, flame-retardant resin molded articles, flame-retardant resin housings, and electronic devices. More specifically, it relates to superior flame-retardant resin compositions, etc. [Background technology]

[0002] In recent years, with the increasing demand for reducing environmental impact, biomass resins, which replace petroleum-based raw materials with biodegradable biomass raw materials, have attracted attention. The use of biomass resins is expected to reduce energy consumption during manufacturing and carbon dioxide emissions during final incineration compared to petroleum-based resins (resins synthesized from petroleum). However, when using biomass resins in electronic devices, flame retardancy is required for safety reasons.

[0003] One known method for imparting flame retardancy is to add polysaccharides to the resin. Polysaccharides are compounds whose basic skeleton is a cyclic structure containing a large amount of hydroxyl groups. During combustion, dehydration condensation occurs as a result of heating, generating water vapor. This leads to cooling due to a large amount of endothermic heat, dilution of combustion gases, and blocking of oxygen. In addition, the carbonization of the dehydrated polysaccharides forms an insulating film (hereinafter also referred to as "char" or "carbonized layer"), resulting in a high flame retardant effect.

[0004] However, in methods that involve adding polysaccharides to resin, depending on the compatibility between the resin and the polysaccharides, it can be 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 can cause dehydration condensation of the polysaccharides, leading to problems such as a decrease in flame retardancy.

[0005] To address these problems, Patent Document 1 discloses a technology relating to a resin composition containing polysaccharides, a flame retardant additive containing a phosphorus-containing compound, and a hydrolysis inhibitor that suppresses the hydrolysis of polysaccharides. This technology achieves both flame retardancy and storage properties by using polysaccharides, flame retardant additives, and hydrolysis inhibitors in combination.

[0006] Furthermore, Patent Document 2 discloses a technology relating to a flame-retardant resin composition containing a phosphorus-containing polysaccharide obtained by adding a phosphate ester to the side chain of a natural polysaccharide. In this technology, by using a phosphorus-containing polysaccharide, the material has low reliance on petroleum, high plant-based content, and low environmental impact, while also possessing impact resistance, moldability, and flame retardancy. However, the demand for flame retardancy was constantly increasing, and there was still room for further improvement in all of these technologies. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2005-162872 [Patent Document 2] Japanese Patent Publication No. 2010-31230 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] This invention has been made in view of the above-mentioned problems and circumstances, and its objective is to provide an excellent flame-retardant resin composition, a flame-retardant resin molded article, a flame-retardant resin housing, and an electronic device. [Means for solving the problem]

[0009] In order to solve the above problems, the inventors investigated the causes of the above problems and, as a result, discovered that a flame-retardant resin composition containing an acidic polysaccharide and a flame retardant exhibits excellent flame retardancy, leading to the present invention. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0010] 1. A flame-retardant resin composition containing an acidic polysaccharide, a flame retardant, and a thermoplastic resin, where the content of the acidic polysaccharide with respect to the total mass of the flame-retardant resin composition is within the range of 3 to 50% by mass, the content of the flame retardant is within the range of 0.5 to 25% by mass, the content of the thermoplastic resin is within the range of 30 to 95% by mass, the acidic polysaccharide is a polysaccharide having an acidic functional group, and a derivative of the polysaccharide having an acidic functional group in which a site other than the acidic functional group is modified Body one or more selected from salt and includes the salt contained in the acidic polysaccharide is a salt of divalent or higher valence A flame-retardant resin composition characterized by this.

[0011] 2. The flame retardant is a phosphorus compound The flame-retardant resin composition according to claim 1, characterized by this.

[0013] 3 . The total number of the acidic functional group and its salt per monosaccharide unit in the acidic polysaccharide is within the range of 0.20 to 1.50 The flame-retardant resin composition according to claim 1 item or paragraph 2 described.

[0015] 4 . The total number of the acidic functional group and its salt per monosaccharide unit in the acidic polysaccharide is within the range of 0.60 to 1.20 The flame-retardant resin composition according to any one of claims 1 to 3 described.

[0016] 5 . The content of the acidic polysaccharide with respect to the total mass of the flame-retardant resin composition is within the range of 5 to 40% by mass The flame-retardant resin composition according to any one of claims 1 to 4 described.

[0017] 6 The content of the flame retardant relative to the total mass of the flame-retardant resin composition is 2 It is within the range of ~20% by mass. The first to the second paragraphs characterized by... 5 A flame-retardant resin composition as described in any one of the items up to item [number].

[0018] 7 The acidic functional group is a carboxyl group or a sulfo group. The characteristic of the first 1 From item to the 6 A flame-retardant resin composition as described in any one of the items up to item [number].

[0019] 8. The acidic polysaccharides are at least ,a Luginic acid salt include A flame-retardant resin composition according to any one of the first to seventh paragraphs, characterized by the above.

[0020] 9 The alginate is calcium alginate. The characteristic of the first 8 The flame-retardant resin composition described in the section.

[0021] 1 0 The above Flame retardant However, it is a phosphate ester. The characteristic of the first 1 From item to the 9 A flame-retardant resin composition as described in any one of the items up to item [number].

[0023] 1 1 The softening point of the thermoplastic resin is 200°C or lower. The characteristic of the first 1 term Any one of the items from item 10 to item 10 The flame-retardant resin composition described above.

[0024] 1 2 The thermoplastic resin is a polystyrene-based resin. The characteristic of the first From paragraph 1 11 term any one of the following items The flame-retardant resin composition described above.

[0025] 1 3 Articles 1 to 1 2 Formed using the flame-retardant resin composition described in any one of the items up to item [number]. A flame-retardant resin molded product characterized by the following.

[0026] 1 4 1st 3 Includes flame-retardant resin molded products as described in the section. A flame-retardant resin housing characterized by the following features.

[0027] 1 5 1st 3 It is equipped with a flame-retardant resin molded product as described in the section. An electronic device characterized by the following features. [Effects of the Invention]

[0028] The above-described means of the present invention make it possible to provide excellent flame-retardant resin compositions, flame-retardant resin molded articles, flame-retardant resin housings, and electronic devices.

[0029] Although the mechanism of action or mechanism of the present invention is not yet clear, it is speculated as follows.

[0030] One method for imparting flame retardancy to resins involves generating water vapor from within the resin when it is ignited, thereby lowering its temperature and stopping combustion. Specifically, as mentioned above, it is believed that by incorporating polysaccharides into the resin, the dehydration condensation reaction of the polysaccharides proceeds, generating water vapor and lowering the temperature. However, while flame retardancy can be achieved with the polysaccharides specifically mentioned in references 1 and 2, the effect is not considered sufficient, and further improvements are needed.

[0031] Through repeated investigations, the inventors discovered that using acidic polysaccharides, which have an acidic portion within the molecule, improves flame retardancy. Although not entirely clear, many of these acidic polysaccharides have acidic functional groups, so protons (H + It is thought that the hydroxyl groups in the polysaccharides are easily detached, and that the dehydration condensation reaction with the hydroxyl groups in the polysaccharides is promoted. As a result, water vapor is generated, which can lower the temperature of the resin, and in addition, the dehydrated polysaccharides carbonize to form a carbonized layer, which can further cut off the supply of oxygen, thus improving flame retardancy.

[0032] Furthermore, through repeated investigations, the inventors discovered that by further incorporating a flame retardant into the resin, the flame retardancy is dramatically improved through a synergistic effect with the acidic polysaccharides, and depending on the type of flame retardant, the strength and appearance can also be improved. [Brief explanation of the drawing]

[0033] [Figure 1] Schematic perspective view of a large-format copier as an example of application of the flame-retardant resin molded product of the present invention. [Modes for carrying out the invention]

[0034] The flame-retardant resin composition of the present invention is characterized by containing an acidic polysaccharide and a flame retardant. This feature is a technical feature common to or corresponding to the embodiments described below.

[0035] In embodiments of the present invention, it is preferable that the flame retardant is a phosphorus compound, in addition to having excellent strength and appearance, in addition to flame retardancy.

[0036] From the viewpoint of excellent flame retardancy, it is preferable that the acidic polysaccharide includes one or more selected from polysaccharides having an acidic functional group, derivatives of polysaccharides having an acidic functional group in which the parts other than the acidic functional group have been modified, and salts thereof.

[0037] From the viewpoint of excellent flame retardancy, it is preferable that the total number of acidic functional groups and their salts per monosaccharide unit in the acidic polysaccharide is within the range of 0.20 to 1.50.

[0038] In addition to flame retardancy, it is preferable that the salt contained in the acidic polysaccharide is a divalent or higher salt, from the viewpoint of superior strength and appearance.

[0039] From the viewpoint of excellent flame retardancy, it is preferable that the total number of acidic functional groups and their salts per monosaccharide unit in the acidic polysaccharide is within the range of 0.60 to 1.20.

[0040] In addition to flame retardancy, it is preferable that the content of the acidic polysaccharide relative to the total mass of the flame-retardant resin composition is within the range of 5 to 40% by mass, from the viewpoint of having excellent strength and appearance.

[0041] In addition to flame retardancy, it is preferable that the content of the flame retardant relative to the total mass of the flame-retardant resin composition is within the range of 1 to 20% by mass, from the viewpoint of having excellent strength and appearance.

[0042] From the viewpoint of excellent flame retardancy, it is preferable that the acidic functional group is a carboxyl group or a sulfo group.

[0043] From the viewpoint of excellent flame retardancy, it is preferable that the acidic polysaccharide contains at least alginic acid, alginate, carrageenan, pectin, xanthan gum, or gellan gum.

[0044] Furthermore, in addition to flame retardancy, it is preferable that the alginate be calcium alginate, from the viewpoint of superior strength and appearance.

[0045] In addition to flame retardancy, it is preferable that the phosphorus compound be a phosphate ester, as this provides excellent strength and appearance.

[0046] From the viewpoint of ease of handling, the flame-retardant resin composition preferably contains a thermoplastic resin, and from the viewpoint of having excellent strength and appearance in addition to flame retardancy, it is more preferable that the softening point of the thermoplastic resin be 200°C or lower, and in particular, it is preferable that the thermoplastic resin is a polystyrene-based resin.

[0047] The flame-retardant resin molded article of the present invention is formed using the flame-retardant resin composition of the present invention. Furthermore, the flame-retardant resin molded article of the present invention is contained within the flame-retardant resin housing of the present invention and is provided in the electronic device of the present invention.

[0048] 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.

[0049] <<Overview of Flame-Retardant Resin Compositions>> The flame-retardant resin composition of the present invention is characterized by containing an acidic polysaccharide and a flame retardant. In this invention, "flame-retardant resin composition" refers to a resin composition that has the following "flame-retardant properties".

[0050] "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.

[0051] "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.

[0052] 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.

[0053] 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.

[0054] In this invention, it is believed that the resin composition can exhibit the above phenomenon and impart flame retardancy by containing acidic polysaccharides. Furthermore, it is believed that the flame retardancy can be improved by further including a flame retardant in the resin composition.

[0055] Resin compositions can be molded into appropriate forms and shapes and used as housings and components in electronic devices, but when used as housings in particular, superior strength and appearance are required in addition to flame retardancy.

[0056] Regarding strength, the effect can be enhanced by using a resin with high strength after curing. However, from the standpoint of flame retardancy, the resin also needs to have excellent compatibility with acidic polysaccharides and flame retardants. Furthermore, regarding appearance, it is thought that color unevenness occurs during molding due to differences in the physical properties of each material used in the resin composition, particularly its properties with respect to temperature. Therefore, it is considered necessary to use a combination of materials that is less prone to color unevenness.

[0057] From this perspective, it is believed that by selecting appropriate materials, mixing them under appropriate conditions (such as mixing ratios), and, if necessary, then molding them, it is possible to impart not only flame retardancy but also superior strength and appearance.

[0058] <<Composition of Flame-Retardant Resin Composition>> The flame-retardant resin composition of the present invention is characterized by containing an acidic polysaccharide and a flame retardant. The following describes each component constituting the flame-retardant resin composition. 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.

[0059] [1 Acidic polysaccharide] The flame-retardant resin composition of the present invention contains acidic polysaccharides. The flame-retardant resin composition of the present invention can be imparted with flame retardancy by containing acidic polysaccharides.

[0060] In this invention, "acidic polysaccharides" refers to polysaccharides that have a portion in their molecule that functions as an acid.

[0061] Polysaccharides are substances formed by the dehydration condensation of numerous monosaccharide molecules via glycosidic bonds, and the term is a general term for such substances. Polysaccharides consist of one or more types of monosaccharides.

[0062] The term "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.

[0063] 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.

[0064] 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).

[0065] Furthermore, "functioning as an acid" means functioning as an acceptor that receives electron pairs involved in bonding (Lewis definition). This function involves protons (H + This also includes the function of being a provider of (Brønsted's definition).

[0066] In particular, from the viewpoint of excellent flame retardancy, the acidic polysaccharide is preferably a polysaccharide having an acidic functional group, a derivative of a polysaccharide having an acidic functional group in which the parts other than the acidic functional group have been modified, or a salt thereof. One of these may be used alone, or two or more may be used in combination.

[0067] Examples of derivatives of polysaccharides having acidic functional groups in which parts other than the acidic functional group have been modified include compounds in which atoms in parts other than the acidic functional group of a polysaccharide having an acidic functional group are replaced with different atoms or substituents, and compounds obtained by bonding the sugar chain of a polysaccharide having an acidic functional group with other compounds or other molecules of the polysaccharide having an acidic functional group via functional groups other than the acidic functional group, such as hydroxyl groups that are originally present in the polysaccharide's sugar chain. Specifically, these include cross-linked polysaccharides, which will be described later.

[0068] Examples of acidic functional groups found in acidic polysaccharides include carboxyl groups (-COOH), sulfo groups (-SO3H), thiocarboxyl groups (-CSOH), sulfino groups (-SO2H), sulfeno groups (-SOH), phospho groups (-OP(=O)(OH)2), phosphono groups (-P(=O)(OH)2), and vorono groups (-B(OH)2). Among these, carboxyl groups or sulfo groups are preferred from the viewpoint of flame retardancy. The acidic functional group may also be an acidic functional group having a sulfo group, for example, an acidic functional group in which the sulfo group is bonded to an oxygen atom (-O-SO3H).

[0069] Examples of acidic functional group salts include salts with alkali metals such as Li, Na, and K, salts with alkaline earth metals such as Mg, Ca, Sr, and Ba, and alkylammonium ("R4N") + Represented as "-", each R is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. However, at least one of the four Rs is an alkyl group.) Examples include salts.

[0070] In particular, a divalent or higher salt is preferred. Being a divalent or higher salt allows for the formation of crosslinked structures within or between molecules, resulting in a rigid structure. Therefore, heat resistance is dramatically improved, and deformation of the resin composition can be prevented during melt mixing and molding, resulting in superior strength and appearance.

[0071] Furthermore, from the viewpoint of having even better flame retardancy, the total number of acidic functional groups and their salts per monosaccharide unit in the acidic polysaccharide (hereinafter also simply referred to as the "number of acidic functional groups") is preferably in the range of 0.20 to 1.50, more preferably in the range of 0.60 to 1.20, and even more preferably in the range of 0.60 to 1.00. A number of acidic functional groups of 0.20 or higher facilitates dehydration condensation reactions, thereby improving flame retardancy. Furthermore, a number of acidic functional groups of 1.50 or lower further suppresses the decrease in dispersibility of acidic polysaccharides in the resin composition, making it easier to uniformly form char on the surface of the resin composition and further improving flame retardancy.

[0072] Acidic polysaccharides may be used individually or in combination of two or more. When using two or more acidic polysaccharides in combination, it is preferable that the total number of acidic functional groups of the acidic polysaccharides as a whole be within the above range. However, it is not necessary for the number of acidic functional groups of each individual acidic polysaccharide to be within the above range. Individual acidic polysaccharides should be selected so that the total number of acidic functional groups of the resulting acidic polysaccharide as a whole is within the above range.

[0073] In other words, when an acidic polysaccharide consists of a combination of two or more acidic polysaccharides, the individual acidic polysaccharides being combined do not necessarily need to have an acidic functional group number in the range of 0.20 to 1.50. Instead, the individual acidic polysaccharides should be selected so that the total acidic functional group number of the resulting acidic polysaccharide is in the range of 0.20 to 1.50.

[0074] The number of acidic functional groups can be adjusted by appropriately introducing or separating acidic functional groups or their salts (hereinafter collectively referred to as "acidic functional groups, etc.").

[0075] From the viewpoint of reducing environmental impact, it is preferable that the acidic polysaccharides used are naturally occurring acidic polysaccharides. Alternatively, the number of acidic functional groups may be adjusted to a suitable level by appropriately introducing or separating acidic functional groups from naturally occurring polysaccharides.

[0076] Examples of derivatives of acidic polysaccharides include compounds obtained by replacing atoms other than the acidic functional groups, such as hydrogen atoms, in naturally occurring acidic polysaccharides or naturally occurring polysaccharides into which acidic functional groups have been introduced, with substituents such as halogen atoms or hydrocarbon groups.

[0077] Furthermore, examples include ester derivatives, ether derivatives, etc., obtained by reacting the hydroxyl group originally present in the sugar chain of the acidic polysaccharide with a compound having a functional group that is reactive with the hydroxyl group. Similarly, if the acidic polysaccharide has a functional group other than a hydroxyl group, it may be reacted with another compound using that functional group to obtain a derivative. The derivative may also be a crosslinked polysaccharide as described later.

[0078] Examples of acidic polysaccharides include pectin, alginic acid, propylene glycol alginate, carboxymethylcellulose, xanthan gum, gum arabic, karaya gum, plantain, xylan, arabic acid, tragacanthic acid, khava gum, linseedic acid, cerulonic acid, lichenin uronic acid, gellan gum, ramzan gum, gellan gum, carrageenan, glycosaminoglycans (e.g., hyaluronic acid, chondroitin-4 sulfate, chondroitin-6 sulfate, dermatan sulfate, keratin sulfate, and heparin) and their salts. Among these, alginic acid, alginates, carrageenan, pectin, xanthan gum, or gellan gum are preferred, and calcium alginate is more preferred.

[0079] The number of acidic functional groups can be determined by calculation from the molecular structure formula or by measurement and calculation using neutralization titration. The following describes the molecular structures of alginic acid and carrageenan, and the method for calculating the number of acidic functional groups from these molecular structures.

[0080] For example, the molecular structure of alginic acid is shown by the following formula (A). As shown in formula (A), the acidic functional group of alginic acid is the carboxyl group (-COOH). From the molecular structure in formula (A), the number of acidic functional groups of alginic acid can be said to be 1.00.

[0081] [ka]

[0082] Furthermore, there are three types of carrageenan, for example: κ-carrageenan, whose molecular structure is represented by formula (C1) below; ι-carrageenan, whose molecular structure is represented by formula (C2) below; and λ-carrageenan, whose molecular structure is represented by formula (C3) below. As shown in formulas (C1) to (C3), the acidic functional group of carrageenan is a sulfo group, or more specifically, an acidic functional group (-O-SO3H) in which a sulfo group is bonded to an oxygen atom. In formulas (C1) to (C3), the acidic functional group is in an ionized state (-OSO3H). - ) is described there.

[0083] From the molecular structure in formula (C1), the number of acidic functional groups of κ-carrageenan can be 0.50, and from the molecular structure in formula (C2), the number of acidic functional groups of ι-carrageenan can be 1.00. In formula (C3), typically, R is H (30%) or SO3 - (70%), and from the molecular structure in formula (C3), the number of acidic functional groups of λ-carrageenan can be 1.35.

[0084]

Chemical formula

[0085] Also, when the acidic polysaccharide consists of a combination of two or more acidic polysaccharides, the number of acidic functional groups can be determined using the following formulas (1) and (2) based on the number of acidic functional groups per monosaccharide unit and the molar ratio in each acidic polysaccharide. Formula (1): Number of acidic functional groups = A1×R1 + A2×R2 + B3×R3 + … Formula (2): R n = B n / (B1 + B2 + B3 + …)

[0086] However, for each symbol, it is as follows. A n : Number of acidic functional groups per monosaccharide unit in each acidic polysaccharide B n : Number of moles per monosaccharide unit in each acidic polysaccharide (calculated by dividing the content mass of each acidic polysaccharide by the molecular weight of the monosaccharide) R n : Molar ratio per monosaccharide unit in each acidic polysaccharide

[0087] Also, the number of acidic functional groups can be determined by the following method. When determining the number of acidic functional groups for the acidic polysaccharide contained in the flame-retardant resin composition, first, extract the acidic polysaccharide from the flame-retardant resin composition by an appropriate method. For the extracted acidic polysaccharide, identify the molecular structure by thermogravimetric analysis, infrared spectroscopy (IR), etc.

[0088] [Method for measuring the number of acidic functional groups] The number of acidic functional groups per monosaccharide unit in acidic polysaccharides can be measured, for example, by neutralization titration. In neutralization titration, approximately 1 g of extracted acidic polysaccharide is accurately weighed and prepared as a slurry, which is then treated with a strongly acidic ion exchange resin. Next, a 0.1 mol / L sodium hydroxide aqueous solution is added, and the change in pH is observed to obtain a titration curve. The number of moles of sodium hydroxide required from the start of titration to the inflection point of the titration curve is equal to the number of moles of acid in the acidic polysaccharide used in the titration. The number of acidic functional groups per monosaccharide unit can be calculated from the obtained number of moles of acid and molecular structure.

[0089] Furthermore, in carboxymethylcellulose, the number of acidic functional groups can be calculated by measuring the degree of substitution of carboxymethyl groups. Carboxymethylcellulose is an acidic polysaccharide obtained by introducing carboxymethyl groups into cellulose. Furthermore, the number of acidic functional groups in carboxymethylcellulose can be adjusted to a suitable range by controlling the manufacturing conditions.

[0090] Carboxymethylcellulose can be produced by known manufacturing methods, specifically by a method described in Japanese Patent Publication No. 2000-34301, which includes the steps of reacting cellulose and alkali at a temperature range of 20 to 50°C to produce alkali cellulose, and reacting alkali cellulose with monochloroacetic acid to produce carboxymethylcellulose.

[0091] Alternatively, carboxymethylcellulose can also be produced by another method, for example, according to the method described in Japanese Patent Publication No. 2012-12553, which involves mixing cellulose, an alkaline agent, and monohaloacetic acid or a salt thereof, and then heating and reacting them in the range of 40 to 90°C.

[0092] In either method, the number of acidic functional groups in the resulting carboxymethylcellulose can be adjusted by adjusting the amount of monochloroacetic acid or monohaloacetic acid added to the cellulose.

[0093] The structural formula of carboxymethylcellulose can be represented, for example, by the following general formula (CMC). In formula (CMC), each R independently represents either H or CH2COOH. For example, by adjusting the ratio of R in formula (CMC) so that 0.2 to 1.5 are CH2COOH when averaged within the molecule, carboxymethylcellulose with superior flame retardancy can be obtained.

[0094] [ka]

[0095] Examples of acidic polysaccharides obtained by introducing acidic functional groups into cellulose include, in addition to carboxymethylcellulose, carboxyalkyl (for example, with a carbon number in the range of 2 to 3) cellulose, sulfoethylcellulose, and hydroxypropyl methylcellulose acetate succinate. Furthermore, in the present invention, acidic polysaccharides obtained by introducing acidic functional groups into polysaccharides other than cellulose that do not have acidic functional groups, such as starch, agarose, and guar gum, can also be used.

[0096] [Method for measuring the degree of substitution of a carboxymethyl group] In carboxymethylcellulose, the number of acidic functional groups can be calculated by measuring the degree of substitution of carboxymethyl groups. The method is shown below. Note that the number of acidic functional groups in other acidic polysaccharides can also be calculated using the method described below.

[0097] The degree of substitution of the carboxymethyl group can be calculated by measuring the amount of base, such as sodium hydroxide, required to neutralize the carboxymethylcellulose in the sample. If the carboxymethyl ether group is in the form of a salt, it should be converted to carboxymethylcellulose beforehand.

[0098] (Conversion to carboxymethylcellulose) Accurately weigh approximately 2.0 g of the sample and place it in a 300 mL stoppered Erlenmeyer flask. Add 100 mL of methanol nitric acid (a solution of 100 mL of special grade concentrated nitric acid added to 1000 mL of methanol) and shake at room temperature for 3 hours to convert the carboxymethylcellulose salt to carboxymethylcellulose.

[0099] (Measurement of the degree of substitution of carboxymethylcellulose) Approximately 1.5 g of oven-dried carboxymethylcellulose is accurately weighed and placed in a 300 mL stoppered Erlenmeyer flask. The carboxymethylcellulose is then moistened with 15 mL of 80% methanol. Subsequently, 100 mL of 0.1 N sodium hydroxide (NaOH) solution is added, and the mixture is shaken at room temperature for 3 hours. The excess NaOH is then back-titrated with 0.1 N sulfuric acid (H2SO4) using phenolphthalein as an indicator.

[0100] The degree of substitution of carboxymethylcellulose is calculated using the following equations (i) and (ii). Equation (i): A = (100 × f1 - a × f2) / Mass of sample (g) Formula (ii): Degree of substitution = (162×A) / (10000-58×A)

[0101] However, the meanings of each symbol and number are as follows: A: Amount of 0.1N sodium hydroxide solution (mL) required to neutralize 1g of sample (completely dried carboxymethylcellulose) a: Titration volume of 0.1N sulfuric acid (mL) f1: Factor of 0.1N sodium hydroxide solution f2: Factor of 0.1N sulfuric acid Amount of 100:0.1N sodium hydroxide solution to use (mL) 162: Anhydrous glucose (C6H 10 Molecular weight of O5) 58: Difference in molecular weight between CH2COOH (molecular weight 59) and H (molecular weight 1)

[0102] As acidic polysaccharides, cross-linked polysaccharides, which are derivatives of the above-mentioned acidic polysaccharides, can also be used.

[0103] In the present invention, "crosslinked polysaccharide" refers to a compound having a structure in which the hydroxyl groups in the sugar chains of two or more polysaccharide molecules are crosslinked. Crosslinked polysaccharides can be obtained, for example, by crosslinking the hydroxyl groups between at least different polysaccharide molecules using a crosslinking agent. In addition, as long as the crosslinking occurs between different molecules, it may also include a structure in which two hydroxyl groups are linked within the same molecule via a crosslinking agent. The types of polysaccharide molecules to be crosslinked may be the same or different.

[0104] The crosslinked polysaccharides used in the present invention are crosslinked acidic polysaccharides, and the aforementioned acidic polysaccharides can be used without particular limitation as the acidic polysaccharides constituting the crosslinked polysaccharides. The acidic polysaccharide used in the production (synthesis) of the crosslinked polysaccharides is preferably at least one selected from alginic acid, alginate, carrageenan, pectin, xanthan gum, and gellan gum. These may be used individually or in combination of two or more.

[0105] Examples of crosslinking agents used to obtain crosslinked polysaccharides from acidic polysaccharides include compounds having two or more functional groups that react with hydroxyl groups. Examples of functional 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 preferred.

[0106] Crosslinking of acidic 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 bonding site with the sugar backbone of the acidic polysaccharide.

[0107] Equation (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 equation (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-).

[0108] As previously described, the reactions shown in formulas (I-1) and (I-2) were explained as intermolecular reactions. However, the reactions shown in formulas (I-1) and (I-2) may also occur in parallel within a single molecule. Furthermore, the final reactant may contain a molecular terminus (-CH2-CH(OH)-CH2-Cl) similar to that of the intermediate (P).

[0109] [ka]

[0110] The degree of crosslinking in the crosslinked polysaccharide can be adjusted by the amount of crosslinking agent added to the acidic polysaccharide. Preferably, the weight-average molecular weight of the resulting crosslinked polysaccharide is within the same range as the weight-average molecular weight of the aforementioned acidic polysaccharide.

[0111] Theoretically, the number of acidic functional groups in the resulting cross-linked polysaccharide is the same as the number of acidic functional groups in the acidic polysaccharide used as a raw material. However, acidic functional groups may react during manufacturing (synthesis), and usually, the number of acidic functional groups in the resulting cross-linked polysaccharide is smaller than that of the acidic polysaccharide used as a raw material. Therefore, in this invention, when synthesizing and using cross-linked polysaccharides, it is preferable to measure and calculate the number of acidic functional groups in the resulting cross-linked polysaccharide by neutralization titration.

[0112] In addition to flame retardancy, the content of acidic polysaccharides 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, from the viewpoint of excellent strength and appearance.

[0113] [2 Flame retardants] The flame-retardant resin composition of the present invention contains a flame retardant. The flame-retardant resin composition of the present invention can be further improved in terms of flame retardancy by containing a flame retardant.

[0114] In this invention, "flame retardant" refers to a substance that can impart flame retardancy to a resin when incorporated into it. In other words, it refers to a substance that can impart flame retardancy to a resin even when incorporated into the resin alone, without being used in combination with the aforementioned acidic polysaccharides (meeting the acceptance criteria for UL94HB in the UL94 test).

[0115] In this invention, by using the aforementioned acidic polysaccharides in combination with the flame retardant, flame retardancy is dramatically improved, and depending on the type of flame retardant, even better strength and appearance can be imparted. In this invention, the flame retardant can be a compound that is commonly used as a flame retardant.

[0116] Examples of flame retardants include phosphorus compounds, red phosphorus, bromine compounds, chlorine compounds, antimony compounds, boron compounds, nitrogen compounds, metal hydroxides, silicone compounds, and polysaccharides that do not fall under the category of acidic polysaccharides according to the present invention. These may be used individually or in combination of two or more. In particular, phosphorus compounds are preferred because, in addition to being flame-retardant, they also offer superior strength and appearance.

[0117] In addition to flame retardancy, from the viewpoint of having excellent strength and appearance, the content of the flame retardant is preferably in the range of 1 to 20% by mass, more preferably in the range of 2 to 16% by mass, and even more preferably in the range of 3 to 12% by mass, based on the total mass of the flame retardant resin composition.

[0118] [2.1 Phosphorus Compounds] In addition to flame retardancy, a phosphorus compound is preferable as the flame retardant from the viewpoint of superior strength and appearance. Furthermore, it is easier to handle compared to red phosphorus.

[0119] The mechanism of action or manifestation when phosphorus compounds are used as flame retardants is not yet clear, but it is speculated as follows. During combustion, the phosphorus contained in the phosphorus compound combines with oxygen and water in the air to produce phosphoric acid, which then mixes with the carbonized polysaccharides to form char. Furthermore, because phosphoric acid combines with water during its production, the dehydration condensation reaction in the acidic polysaccharides is promoted. In addition, since both phosphoric acid and acidic polysaccharides readily form hydrogen bonds and have a high affinity for each other, they are relatively close together in the resin composition, and it is thought that a synergistic effect between phosphoric acid and acidic polysaccharides can be easily obtained.

[0120] Examples of phosphorus compounds include phosphate esters and phosphate salts. Examples of phosphate esters include aromatic phosphate esters such as triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(t-butylated phenyl) phosphate, tris(i-propylated phenyl) phosphate, and 2-ethylhexyl diphenyl phosphate; aromatic condensed phosphate esters such as 1,3-phenylene bis(diphenyl phosphate), 1,3-phenylene bis(dixylenyl) phosphate, resorcinol bis(diphenyl) phosphate, and bisphenol A bis(diphenyl phosphate); halogenated phosphate esters such as tris(dichloropropyl) phosphate, tris(β-chloropropyl) phosphate, and tris(chloroethyl) phosphate; and halogenated condensed phosphate esters such as 2,2-bis(chloromethyl)trimethylene bis(bis(2-chloroethyl) phosphate) and polyoxyalkylene bisdichloroalkyl phosphate.

[0121] Examples of phosphates include monophosphates such as ammonium salts like ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; sodium salts such as monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium phosphite, disodium phosphite, and sodium hypophosphite; potassium salts such as monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium phosphite, dipotassium phosphite, and potassium hypophosphite; lithium salts such as monolithium phosphate, dilithium phosphate, trilithium phosphate, monolithium phosphite, dilithium phosphite, and lithium hypophosphite; barium salts such as barium dihydrogen phosphate, barium hydrogen phosphate, tribarium phosphate, and barium hypophosphite; magnesium salts such as magnesium monohydrogen phosphate, magnesium hydrogen phosphate, trimagnesium phosphate, and magnesium hypophosphite; calcium salts such as calcium dihydrogen phosphate, calcium hydrogen phosphate, tricalcium phosphate, and calcium hypophosphite; zinc salts such as zinc phosphate, zinc phosphite, and zinc hypophosphite; and aluminum salts such as monoaluminum phosphate, dialuminum phosphate, trialuminum phosphate, aluminum phosphite, and aluminum hypophosphite.

[0122] The phosphate is preferably high molecular weight, and more preferably polyphosphate. Examples of polyphosphates include ammonium polyphosphate, piperazine polyphosphate, melamine polyphosphate, ammonium polyphosphate amide, and aluminum polyphosphate.

[0123] The phosphorus compound content is preferably in the range of 1 to 20% by mass, more preferably in the range of 1 to 15% by mass, and even more preferably in the range of 3 to 15% by mass, based on the total mass of the flame-retardant resin composition.

[0124] [2.2 Red Phosphorus] Red phosphorus may be in its pure form, or it may be coated or mixed with resin, metal hydroxide, metal oxide, or the like.

[0125] The resin used to coat or mix with red phosphorus is not particularly limited, but examples include thermosetting resins such as phenolic resins, epoxy resins, unsaturated polyester resins, melamine resins, urea resins, aniline resins, and silicone resins.

[0126] From the viewpoint of flame retardancy, it is preferable that the red phosphorus is coated or mixed with a metal hydroxide, and the metal oxide can be the same as the metal oxide used as a flame retardant described later.

[0127] [2.3 Bromine Compounds] The bromine compound is not particularly limited as long as it contains bromine in its molecular structure and is solid at room temperature and pressure, but examples include aromatic compounds containing brominated aromatic rings. Other compounds besides aromatic compounds containing brominated aromatic rings, such as hexabromocyclododecane, may also be used.

[0128] Examples of brominated aromatic ring-containing aromatic compounds include brominated compound monomers such as hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylenebis(pentabromophenyl), ethylenebis(tetrabromophthalimide), and tetrabromobisphenol A.

[0129] Furthermore, the brominated aromatic ring-containing aromatic compound may also be a brominated compound polymer. Specifically, examples include polycarbonate oligomers produced using brominated bisphenol A as a raw material, brominated polycarbonates such as copolymers of this polycarbonate oligomer and bisphenol A, and diexo compounds produced by the reaction of brominated bisphenol A with epichlorohydrin.

[0130] Furthermore, examples include brominated epoxy compounds such as monoepoxy compounds obtained by the reaction of brominated phenols with epichlorohydrin, poly(brominated benzyl acrylate), brominated phenol condensates of brominated polyphenylene ether, brominated bisphenol A, and cyanur chloride, brominated polystyrene such as brominated (polystyrene), poly(brominated styrene), and crosslinked brominated polystyrene, and crosslinked or non-crosslinked brominated poly(methylstyrene).

[0131] [2.4 Chlorine Compounds] Examples of chlorine compounds include polychlorinated naphthalene and chlorendic acid.

[0132] [2.5 Antimony Compounds] Examples of antimony compounds include antimony oxide, antimony salts, and pyroantimony salts. Examples of antimony oxides include antimony trioxide and antimony pentoxide. Examples of antimonate salts include sodium antimonate and potassium antimonate. Examples of pyroantimonate salts include sodium pyroantimonate and potassium pyroantimonate.

[0133] [2.6 Boron Compounds] Examples of boron compounds include borax, boron oxide, boric acid, and borate salts.

[0134] Examples of boron oxides include diboron trioxide, boron trioxide, diboron dioxide, tetraboron trioxide, and tetraboron pentoxide. Examples of borates include alkali metals, alkaline earth metals, elements from groups 4, 12, and 13 of the periodic table, and ammonium. Specifically, examples include alkali metal borates such as lithium borate, sodium borate, potassium borate, and cesium borate; alkaline earth metal borates such as magnesium borate, calcium borate, and barium borate; and others such as zirconium borate, zinc borate, aluminum borate, and ammonium borate.

[0135] [2.7 Nitrogen Compounds] Examples of nitrogen compounds include aliphatic amine compounds, aromatic amine compounds, nitrogen-containing heterocyclic compounds, cyanide compounds, aliphatic amide compounds, aromatic amide compounds, urea, and thiourea.

[0136] Examples of aliphatic amine compounds include ethylamine, butylamine, diethylamine, ethylenediamine, butylenediamine, triethylenetetramine, 1,2-diaminocyclohexane, and 1,2-diaminocyclooctane.

[0137] Examples of aromatic amine compounds include aniline and phenylenediamine. Examples of nitrogen-containing heterocyclic compounds include uric acid, adenine, guanine, 2,6-diaminopurine, 2,4,6-triaminopyridine, and triazine compounds.

[0138] Triazine compounds are compounds having a triazine skeleton, and examples include triazine, melamine, benzoguanamine, methylguanamine, cyanuric acid, melamine cyanurate, melamine isocyanurate, trimethyltriazine, triphenyltriazine, amelin, amelido, thiocyanuric acid, diaminomercaptotriazine, diaminomethyltriazine, diaminophenyltriazine, diaminoisopropoxytriazine, and melamine polyphosphate. Among these, melamine cyanurate, melamine isocyanurate, and melamine polyphosphate are preferred.

[0139] Examples of cyanide compounds include dicyandiamide. Examples of aliphatic amide compounds and aromatic amide compounds include N,N-dimethylacetamide and N,N-diphenylacetamide.

[0140] [2.8 Metal hydroxides] Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, iron hydroxide, nickel hydroxide, zirconium hydroxide, titanium hydroxide, zinc hydroxide, copper hydroxide, vanadium hydroxide, and tin hydroxide.

[0141] The metal hydroxide is preferably in the form of particles. The shape of the particles is not particularly limited and can be spherical, spindle-shaped, plate-shaped, flake-shaped, needle-shaped, fibrous, etc. The average primary particle diameter of the metal hydroxide particles is preferably in the range of 10 nm to 100 μm, and more preferably in the range of 10 to 100 nm. The average primary particle diameter of the metal hydroxide particles is, for example, the volume-based median diameter (D50), which can be measured, for example, by laser diffraction / scattering using a laser detector such as the LA-960S2 (manufactured by HORIBA).

[0142] Metal hydroxide particles may be surface-modified with a surface modifier as needed. Suitable surface modifiers include alkylsilazane compounds such as hexamethyldisilazane (HMDS), alkylalkoxysilane compounds such as dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, and butyltrimethoxysilane, chlorosilane compounds such as dimethyldichlorosilane and trimethylchlorosilane, silicone oils, silicone varnishes, and various fatty acids. These surface modifiers may be used individually or in combination of two or more.

[0143] The content of metal hydroxide is preferably in the range of 5 to 20% by mass, and more preferably in the range of 5 to 10% by mass, relative to the total mass of the flame-retardant resin composition. By being within this range, it is possible to achieve both flame retardancy and strength and appearance in the resulting molded article.

[0144] [2.9 Silicone Compounds] Examples of silicone compounds include silicone compounds having a (poly)organosiloxane structure. In particular, silicone compounds having a modified (poly)organosiloxane structure with substituents such as epoxy groups, hydroxyl groups, carboxyl groups, amino groups, and ether groups at the molecular ends or main chain are preferred.

[0145] Furthermore, the silicone compound may be silica particles coated with a modified (poly)organosiloxane. The volume-average particle diameter of the silica particles coated with the modified (poly)organosiloxane is preferably in the range of 5 to 250 μm, and the bulk density is preferably in the range of 0.1 to 0.7.

[0146] As silica particles coated with modified (poly)organosiloxane, commercially available products can be used. Examples of commercially available products include "Si Powder DC4-7051", "7081", "7105", and "DC1-9641" (all manufactured by Toray Dow Corning Silicone Co., Ltd.).

[0147] [3 Resin] 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.

[0148] 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.

[0149] 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. In this invention, "resin content" refers to the mass of the flame-retardant resin composition excluding the content of acidic polysaccharides, flame retardants, and other optional additives.

[0150] [3.1 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 it is preferable that the softening point of the thermoplastic resin be 200°C or lower, from the viewpoint of suppressing the decomposition of acidic polysaccharides and having excellent strength and appearance in addition to flame retardancy.

[0151] Examples of thermoplastic resins include polystyrene resins, polycarbonate resins, aromatic polyester resins, polyphenylene sulfite resins, polyolefin resins, polyamide-imide resins, polyetheretherketone resins, polyethersulfone resins, polyimide resins, polyvinyl chloride resins, polyamide resins, polyacetal resins, acrylic resins, 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.

[0152] Furthermore, a thermoplastic biomass resin may be used as the thermoplastic resin. Examples of thermoplastic biomass resins include aliphatic polyesters, polyamino acids, polyvinyl alcohol, polyalkylene glycols, and copolymers containing these. Thermoplastic resins may be used individually or in combination of two or more types.

[0153] Examples of polystyrene-based resins include polystyrene resin, syndiotactic polystyrene resin, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin).

[0154] Aromatic polyester resins 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 ester 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.

[0155] 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.

[0156] From the viewpoint of reducing environmental impact, it is preferable to use thermoplastic biomass resin. Alternatively, thermoplastic biomass resin may be combined with other resins to create a thermoplastic resin that combines the advantages of both.

[0157] From the viewpoint of strength and ease of handling, the thermoplastic resin is preferably a resin having an aromatic ring, such as polystyrene resin, polycarbonate resin, or aromatic polyester resin.

[0158] Examples of commercially available thermoplastic resins include "Panlite®" (polycarbonate resin, manufactured by Teijin Chemicals), "Duranex®" (polybutylene terephthalate, manufactured by Polyplastics Co., Ltd.), "Clapet®" (polyethylene terephthalate, manufactured by Kuraray Co., Ltd.), "Alamin" (polyamide resin, manufactured by Toray Industries, Inc.), "Leicia®" (polylactic acid resin, manufactured by Mitsui Chemicals, Inc.), and "Terramac®" (polylactic acid resin, manufactured by Unitika Corporation).

[0159] [3.1.1 Polystyrene resins] The thermoplastic resin according to the present invention is preferably a polystyrene-based resin from the viewpoint of strength and ease of handling. Furthermore, when using phosphorus compounds as flame retardants, the fact that the thermoplastic resin according to the present invention is a polystyrene-based resin can suppress the bleeding (leaching) of phosphorus compounds.

[0160] 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.

[0161] 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 styrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, and p-tert-butylstyrene; and aromatic vinyl compound monomers such as α-methylstyrene and α-methyl-p-methylstyrene. Among these, styrene is preferred.

[0162] Polystyrene resins may be homopolymers of styrene monomers or copolymers of styrene monomers with other monomer components. Monomer components copolymerizable with styrene monomers include unsaturated carboxylic acid alkyl ester monomers such as alkyl methacrylate monomers like methyl methacrylate, cyclohexyl methacrylate, methylphenyl methacrylate, and isopropyl methacrylate; alkyl acrylate monomers like methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate; methacrylic acid, acrylic acid, itaconic acid, maleic acid, fumaric acid, Examples include unsaturated carboxylic acid monomers such as cinnamic acid; unsaturated dicarboxylic acid anhydride monomers such as maleic anhydride, itaconic acid, ethyl maleic acid, methylitaconic acid, and chlormaleic acid; unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; and conjugated diene monomers such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Two or more of these monomer components may be copolymerized. The copolymerization ratio of such 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.

[0163] From the viewpoint of heat resistance and other factors, the polystyrene-based resin is preferably polystyrene resin, syndiotactic polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, etc.

[0164] In acrylonitrile-butadiene-styrene copolymers (ABS resins), from the viewpoint of mechanical strength and heat resistance, the copolymerization ratio of acrylonitrile 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.

[0165] In styrene-methacrylic acid copolymers, from the viewpoint of heat resistance, it is preferable that the copolymerization ratio of methacrylic acid 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 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.

[0166] In a styrene-maleic anhydride copolymer, from the viewpoint of heat resistance, it is preferable that the copolymerization ratio of methacrylic acid 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. 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.

[0167] Commercially available polystyrene resins include "Clearlen®" (manufactured by Denki Kagaku Kogyo Co., Ltd.), "Asaflex®" (manufactured by Asahi Kasei Chemicals Corporation), "Styrolux®" (manufactured by BASF Corporation), and "PSJ®-Polystyrene" (manufactured by PS Japan Co., Ltd.).

[0168] 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.

[0169] [3.2 Thermosetting resin] A thermosetting resin may be used as the resin according to the present invention. While there are no particular restrictions on the type of thermosetting resin, it is preferable that the curing point of the thermosetting resin be 200°C or lower, from the viewpoint of suppressing the decomposition of acidic polysaccharides and having excellent strength and appearance in addition to flame retardancy.

[0170] The thermosetting resin can be any resin that has one or more functional groups in one molecule that can be used in crosslinking reactions by heating, such as hydroxyl groups, phenolic hydroxyl groups, methoxymethyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazine groups, aziridine groups, thiol groups, isocyanate groups, blocked isocyanate groups, blocked carboxyl groups, silanol groups, etc.

[0171] Examples include acrylic resins, maleic acid resins, polybutadiene resins, polyester resins, polyurethane resins, epoxy resins, oxetane resins, phenoxy resins, polyimide resins, polyamide resins, phenolic resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluororesins.

[0172] Furthermore, the thermosetting resin in the present invention may, in addition to the above-mentioned resin, optionally contain a compound referred to as a "curing agent," such as a resin or low-molecular-weight compound that reacts with the above-mentioned functional group to form chemical crosslinks.

[0173] Examples of commercially available acrylic resins include "Acrydic®" (hydroxyl group or carboxyl group-containing acrylic resin, manufactured by DIC Corporation) and "8UA" (hydroxyl group-containing urethane graft acrylic resin, manufactured by Taisei Fine Chemical Co., Ltd.).

[0174] Commercially available maleic acid resins include "Marquid®" (maleic acid resin, manufactured by Arakawa Chemical Co., Ltd.), "Alastor®" (styrene-maleic acid resin, manufactured by Arakawa Chemical Co., Ltd.), and "Isoban®" (isobutylene-maleic anhydride block copolymer, manufactured by Kuraray Co., Ltd.).

[0175] Examples of commercially available polydiene resins include "Poly bd(registered trademark)" (hydroxyl-terminated polybutadiene, manufactured by Idemitsu Kosan Co., Ltd.), "Poly ip(registered trademark)" (hydroxyl-terminated polyisoprene, manufactured by Idemitsu Kosan Co., Ltd.), "Epol(registered trademark)" (hydroxyl-terminated hydrogenated polyisoprene, manufactured by Idemitsu Kosan Co., Ltd.), and "NISSO-PB" (polybutadiene resin, manufactured by Nippon Soda Co., Ltd.).

[0176] Commercially available polyester resins include "Elitel®" (hydroxyl-terminated or carboxyl-terminated polyester, manufactured by Unitika Ltd.), "Byron®" (hydroxyl-terminated or carboxyl-terminated amorphous polyester, manufactured by Toyobo Co., Ltd.), and "Nichigo Polyester®" (manufactured by Nippon Synthetic Chemical Co., Ltd.).

[0177] Examples of commercially available polyurethane resins include "Byron® UR" (hydroxyl group-terminated or carboxyl group-containing polyester urethane, manufactured by Toyobo Co., Ltd.). Commercially available epoxy resins include "Epotote (registered trademark)" (manufactured by Toto Kasei Co., Ltd.), "jER (registered trademark)" (manufactured by Mitsubishi Chemical Corporation), and "Epiclon" (manufactured by DIC Corporation).

[0178] Commercially available oxetane resins include "Aron Oxetane (registered trademark)" (manufactured by Toagosei Co., Ltd.) and "Ethanacol (registered trademark)" (manufactured by Ube Industries, Ltd.). Commercially available phenoxy resins include "jER(registered trademark) 1256," "4275," and "4250" (all manufactured by Mitsubishi Chemical Corporation), and "PKHH" and "PKHB" (both manufactured by InChem).

[0179] Examples of commercially available polyimide resins include "UNIDIC (registered trademark) V-8000" (carboxyl group-containing branched polyimide resin, manufactured by DIC Corporation). Commercially available polyamide resins include "Newmid" (manufactured by Harima Chemicals, Inc.) and "Tresin (registered trademark)" (manufactured by Nagase ChemteX Corporation).

[0180] Commercially available phenolic resins include "Hariphenol" (rosin-modified phenolic resin, manufactured by Harima Chemicals Co., Ltd.), "Fudolight (registered trademark)" (manufactured by Fudo Co., Ltd.), "Nikanol (registered trademark)" (xylene resin, manufactured by Fudo Co., Ltd.), "Marukalinker (registered trademark)" (poly-p-vinylphenol resin, manufactured by Maruzen Petrochemical Co., Ltd.), and "Phenolite (registered trademark)" (novolac-type phenolic resin, manufactured by DIC Corporation).

[0181] Commercially available alkyd resins include "Beckozol (registered trademark)" (manufactured by DIC Corporation) and "Haliftal" (manufactured by Harima Chemicals Co., Ltd.). Commercially available amino resins include "Beckamine®" (manufactured by DIC Corporation), "Cymel" (manufactured by Mitsui Cytec Co., Ltd.), and "Melan®" (manufactured by Hitachi Chemical Co., Ltd.).

[0182] Examples of commercially available polylactic acid resins include "Byroecol (registered trademark) BE" (hydroxyl group-containing polylactic acid resin, manufactured by Toyobo Co., Ltd.). Commercially available oxazoline resins include "Epocross (registered trademark)" (manufactured by Nippon Shokubai Co., Ltd.) and "1,3-PBO" (manufactured by Mikuni Pharmaceutical Co., Ltd.).

[0183] Commercially available benzoxazine resins include "Pd" and "Fa" (both manufactured by Shikoku Chemicals Co., Ltd.). Commercially available silicone resins include "KR" and "ES" (both manufactured by Shin-Etsu Silicone Co., Ltd.), "Cylaprene®" (manufactured by Chisso Corporation), and "Zemlac®" (manufactured by Kaneka Corporation).

[0184] Examples of commercially available fluororesins include "Lumiflon®" (manufactured by Asahi Glass Co., Ltd.) and "Fluonate®" (hydroxyl group-containing fluororesin, manufactured by DIC Corporation).

[0185] [3.3 Photocurable resin] A photocurable resin may be used as the resin according to the present invention. The photocurable resin is not particularly limited as long as it has one or more functional groups in a single molecule that can be used for crosslinking reactions by light irradiation, such as (meth)acryloyl groups, epoxy groups, vinyl groups, oxetanyl groups, etc., and also includes compounds and oligomers that are low molecular weight compounds, so-called "monomers" or "monomers".

[0186] Examples include acrylic (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate, polycarbonate (meth)acrylate, diepoxide resin, and alicyclic epoxy resin.

[0187] Examples of commercially available acrylic (meth)acrylate products include "8KX" (manufactured by Taisei Fine Chemical Co., Ltd.).

[0188] Commercially available urethane (meth)acrylate products include "Shiko (registered trademark)" (manufactured by Nippon Synthetic Chemical Co., Ltd.), "Beamset (registered trademark) 500" (manufactured by Arakawa Chemical Co., Ltd.), "Unidic (registered trademark) V-4000" (manufactured by DIC Corporation), "EBECRYL (registered trademark)" (manufactured by Daicel-Scytec Corporation), and "Art Resin (registered trademark)" (manufactured by Negami Kogyo Co., Ltd.).

[0189] Commercially available polyester (meth)acrylate products include "Beamset® 700" (manufactured by Arakawa Chemical Co., Ltd.) and "EBECRYL®" (manufactured by Daicel-Scytec Co., Ltd.). Examples of commercially available polyether (meth)acrylates include "EBECRYL® 80," "81," and "83" (all manufactured by Daicel-Scytec Corporation).

[0190] Commercially available epoxy (meth)acrylate products include "KAYARAD® ZAR" and "ZFR" (both manufactured by Nippon Kayaku Co., Ltd.), "DIC Lite®" (manufactured by DIC Corporation), and "Lipoxy®" (manufactured by Showa Polymer Co., Ltd.). Examples of commercially available polycarbonate (meth)acrylate products include "PCD-DM" and "PCD-DA" (both manufactured by Ube Industries, Ltd.).

[0191] Examples of commercially available diepoxide resins include "UVACURE®" (manufactured by Daicel-Scytec Corporation). Examples of commercially available alicyclic epoxy resins include "Celoxide (registered trademark) 2021P" (manufactured by Daicel-Scytec Corporation).

[0192] [3.4 Heat / light curing resin] As the resin according to the present invention, a thermo- and photo-curable resin may be used. The thermo- and photo-curable resin is not particularly limited as long as it has both functional groups that can be used for crosslinking reactions by light irradiation and functional groups that can be used for crosslinking reactions by heating.

[0193] Examples of commercially available thermo- and photo-curable resins include "Cychromer® P" (manufactured by Daicel Cytec Co., Ltd.), "DIC Lite®" (manufactured by DIC Corporation), "Lipoxy® PR" and "SPC" (both manufactured by Showa Polymer Co., Ltd.), and "KAYARAD® ZFR1122" (manufactured by Nippon Kayaku Co., Ltd.).

[0194] Furthermore, the functional groups that can be used in the crosslinking reaction by light irradiation and the functional groups that can be used in the crosslinking reaction by heating may be the same. The above resin may be used alone or in combination of two or more types.

[0195] [4 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.

[0196] Examples of additives include antioxidants, fillers, and nucleating agents. The content of the additive 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.

[0197] ≪Method for producing flame-retardant resin compositions≫ 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. The following describes a method for producing the flame-retardant resin composition of the present invention using a melt-kneading method.

[0198] As for melt-kneading methods, for example, one method involves pre-mixing acidic polysaccharides, flame retardants, resins, etc., using various mixers such as tumblers and high-speed mixers known as Henschel mixers, and then melt-kneading them using kneading equipment such as a Banbarri mixer, roll mixer, plastograph, single-screw extruder, twin-screw extruder, or kneader.

[0199] In particular, from the viewpoint of production efficiency, it is preferable to use an extruder, and more preferable 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.

[0200] 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.

[0201] The melt-mixing temperature is not particularly limited, but it is preferable to select it appropriately depending on the type of resin used, and specifically, it is preferable to be 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, if there are multiple temperature settings in the cylinder of the mixing device, the cylinder temperature refers to the temperature of the cylinder with the highest temperature. The mixing pressure is not particularly limited, but it is preferable to be in the range of 1 to 20 MPa.

[0202] 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.

[0203] The kneaded material, melted and kneaded in the kneading apparatus using the method described above, 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 kneaded material 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.

[0204] 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.

[0205] 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 articles of the present invention can be imparted with flame retardancy by being formed using the aforementioned flame-retardant resin composition. Furthermore, when a phosphorus compound is used as the flame retardant, it is possible to achieve both flame retardancy and strength and appearance.

[0206] 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 molding.

[0207] 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.

[0208] 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.

[0209] Flame-retardant resin housings and electronic equipment The flame-retardant resin housing of the present invention is characterized by including the aforementioned flame-retardant resin molded product. Furthermore, the electronic device of the present invention is characterized by comprising the aforementioned flame-retardant resin molded product. In other words, the aforementioned flame-retardant resin molded product may be used in electronic devices, either as a housing for the electronic device or as a component. In this invention, "electronic equipment" refers to electrical products that utilize the technology of electronic engineering.

[0210] 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.

[0211] Furthermore, when phosphorus compounds are used as flame retardants, it is possible to create flame-retardant resin housings that offer not only flame retardancy but also superior strength and appearance.

[0212] Electronic devices are not particularly limited and include, 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.

[0213] Figure 1 shows a specific example of an electronic device of the present invention. Figure 1 is a schematic perspective view of a large copier 10 whose exterior parts are made of the flame-retardant resin molded product of the present invention. As shown in Figure 1, the large copier 10 is enclosed by exterior parts G1 to G9. The flame-retardant resin molded product of the present invention can be used for such exterior parts. [Examples]

[0214] 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.

[0215] [Preparation of resin composition] The following resins, polysaccharides, and flame retardants were used as constituent materials for the resin compositions in the examples.

[0216] (resin) The following commercially available resins were used. The softening point of the mixed resin was 200°C or higher, while the softening points of the other resins were below 200°C. 1. Polystyrene resin Polystyrene resin (PS): "H9152" (product name, manufactured by PS Japan Co., Ltd.) Acrylonitrile-butadiene-styrene copolymer (ABS): "Toyolac® 700-314" (product name, manufactured by Toray Industries, Inc.) 2. Other thermoplastic resins Polylactic acid resin (PLA): "Teramac® TE-8303" (product name, manufactured by Unitika Corporation) Mixed resin (PC / ABS): "Multilon (registered trademark) T-3750" (product name, manufactured by Teijin Corporation)

[0217] (polysaccharide) The following commercially available products and those obtained in the synthesis examples were used as polysaccharides. Polysaccharides A1 to A12 correspond to the acidic polysaccharides used in this invention. A1: Calcium alginate: "Snow Algin SAW-80" (product name, manufactured by Kimika Co., Ltd.) A2: Carrageenan: "Carrageenan WG-108" (product name, manufactured by Sansho Co., Ltd.) A3: Xanthan gum: "Xanthan gum" (product name, manufactured by Tokyo Chemical Industry Co., Ltd.) A4: Sodium alginate: "Kimika Algin I-3G" (product name, manufactured by Kimika Corporation) A5: Carboxymethylcellulose: "Aqualon(registered trademark) CMC-7LF" (product name, manufactured by ASHland) A10: Pectin: "Pectin, derived from citrus fruits" (product name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) A11: Gellan gum: "Gellan gum" (product name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) C1: Cellulose: "Cellulose, powder, 38μm passable" (product name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0218] (A6: Synthesis of carboxymethylcellulose) The following ingredients were placed in a 5L flask and stirred at room temperature. Isopropyl alcohol 2500 parts by mass Water 180 parts by mass Powdered cellulose (cellulose, powder, 38μm passable (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), polysaccharide C1) 100 parts by mass

[0219] A solution containing the following components was added to this mixture and stirred at 35°C for 1 hour. Sodium hydroxide 21.6 parts by mass 25 parts by mass of water

[0220] Subsequently, a mixture of the following components was added dropwise, and the mixture was stirred and reacted at 65°C for 2 hours. Monochloroacetic acid 11.6 parts by mass Isopropyl alcohol 15 parts by mass

[0221] After the resulting reaction solution was cooled to room temperature, it was removed, and the following components were added and the mixture was stirred to neutralize the excess sodium hydroxide. 1000 parts by mass of 70% methanol aqueous solution Acetic acid 0.1 parts by mass

[0222] Subsequently, the following components were added and stirred, then the slurry was filtered, washed with acetone, and dried to obtain 103 parts by mass of carboxymethylcellulose as polysaccharide A6. 3000 parts by mass of 70% methanol aqueous solution When the number of acidic functional groups of the obtained polysaccharide A6 was confirmed using the above-described method for measuring the degree of substitution of carboxymethyl groups, it was 0.20.

[0223] (A7: Synthesis of Carboxymethyl Cellulose) The following components were placed in a 5 L flask and stirred at room temperature. Isopropyl alcohol: 2500 parts by mass Water: 180 parts by mass Powdered cellulose (cellulose, powder, passing through 38 μm sieve (manufactured by Fujifilm Wako Pure Chemical Corporation), polysaccharide C1) 100 parts by mass

[0224] A solution prepared by dissolving the following components was added thereto, and the mixture was stirred at 35 °C for 1 hour. Sodium hydroxide: 56.1 parts by mass Water: 60 parts by mass

[0225] Thereafter, a mixture prepared by mixing the following components was added dropwise, and the mixture was stirred and reacted at 65 °C for 2 hours. Monochloroacetic acid: 63.4 parts by mass Isopropyl alcohol: 45 parts by mass

[0226] After the obtained reaction solution was cooled to room temperature, it was taken out, the following components were added and stirred to neutralize the excess sodium hydroxide. 70% by mass aqueous methanol solution: 1000 parts by mass Acetic acid: 3.7 parts by mass

[0227] Thereafter, the following components were added, and after stirring, the slurry was filtered, washed with acetone, and dried to obtain 123 parts by mass of carboxymethyl cellulose as polysaccharide A7. 70% by mass aqueous methanol solution: 3000 parts by mass When the number of acidic functional groups of the obtained polysaccharide A7 was confirmed using the above-described method for measuring the degree of substitution of carboxymethyl groups, it was 0.61.

[0228] (A8: Synthesis of Carboxymethyl Cellulose) The following ingredients were placed in a 5L flask and stirred at room temperature. Isopropyl alcohol 2500 parts by mass Water 180 parts by mass Powdered cellulose (cellulose, powder, 38μm passable (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), polysaccharide C1) 100 parts by mass

[0229] A solution containing the following components was added to this mixture and stirred at 35°C for 1 hour. Sodium hydroxide 160 parts by mass 150 parts by mass of water

[0230] Subsequently, a mixture of the following components was added dropwise, and the mixture was stirred and reacted at 65°C for 2 hours. Monochloroacetic acid 180 parts by mass Isopropyl alcohol 130 parts by mass

[0231] After the resulting reaction solution was cooled to room temperature, it was removed, and the following components were added and the mixture was stirred to neutralize the excess sodium hydroxide. 1000 parts by mass of 70% methanol aqueous solution Acetic acid 8.2 parts by mass

[0232] Subsequently, the following components were added and stirred, then the slurry was filtered, washed with acetone, and dried to obtain 152 parts by mass of carboxymethylcellulose as polysaccharide A8. 3000 parts by mass of 70% methanol aqueous solution The number of acidic functional groups in the obtained polysaccharide A8 was confirmed to be 1.70 using the aforementioned method for measuring the degree of substitution of carboxymethyl groups.

[0233] (A9: Preparation of magnesium alginate) Sodium alginate (A4) was dissolved in water to prepare a 10% by mass aqueous solution of sodium alginate. A 10% by mass aqueous solution of magnesium chloride was added dropwise to this solution, and the precipitated magnesium alginate was filtered and dried.

[0234] (Preparation of Calcium Alginate and Cellulose Mixture) Calcium alginate (A1) and cellulose (C1) were mixed at a molar ratio of 3:1 per monosaccharide unit. When the number of acidic functional groups of the obtained polysaccharide A12 was confirmed, it was 0.75.

[0235] (Flame Retardant) The following commercially available products were used as flame retardants. Aromatic condensed phosphate ester (condensed phosphate ester): "PX - 200" (product name, manufactured by Daihachi Chemical Industry Co., Ltd.) Triphenyl phosphate (phosphate ester): "TPP" (product name, manufactured by Daihachi Chemical Industry Co., Ltd.) Ammonium polyphosphate: "Taien K" (product name, manufactured by Taiping Chemical Industry Co., Ltd.)

[0236] The composition of each resin composition is shown in Table I. Note that "-" indicates not contained.

[0237]

Table 1

[0238] (Preparation of Resin Composition) As pre - drying before kneading, the resin and the polysaccharide were each dried at 80°C for 4 hours. Then, they were weighed according to the component ratio (mass%) shown in Table I and dry - blended. Next, the mixture obtained by dry - blending was supplied at 10 kg per hour from the raw material supply port (hopper) of a twin - screw extrusion kneader "KTX - 30" (manufactured by Kobe Steel, Ltd.), and melt - kneading was carried out under the conditions of a cylinder temperature of 200°C (only 240°C for resin composition 28), and a screw rotation speed of 200 rpm. The molten resin after kneading was cooled in a water bath at 30°C and then pelletized by a pelletizer to obtain a resin composition.

[0239] ≪Evaluation≫ (Evaluation 1: Appearance) Each of the obtained pelletized resin compositions 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 a cylinder temperature of 200°C (240°C for resin composition 28 only) and a mold temperature of 80°C, and a sample was taken from the center. The obtained samples were visually inspected for appearance and evaluated according to the following criteria.

[0240] ◎: No cosmetic defects. ○: There is some color unevenness, but it can be used as an exterior part. △: There are color inconsistencies, but it can be used as an interior part or for parts in inconspicuous areas. ×: The color is uneven and it cannot be used. A score of △ or higher indicates no practical problems and is considered a passing grade.

[0241] (Rating 2: Flame retardant) The obtained pelletized resin compositions were dried at 80°C for 4 hours, and then molded using an injection molding machine "J55ELII" (manufactured by Japan Steel Works Ltd.) at a cylinder temperature of 200°C (240°C for resin composition 28 only) and a mold temperature of 50°C to obtain rectangular test pieces measuring 125 mm in length, 13 mm in width, and 1.6 mm in thickness.

[0242] 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 (combustion test for plastic materials for equipment components) established by Underwriters Laboratories (UL) in the United States. The UL94V test method was used to confirm the hierarchy of flame retardancy, and the specimens were evaluated according to the following criteria.

[0243] ◎: V-0 〇:V-1 △:V-2 ×: Nonstandard Furthermore, items with a △ or higher meet the UL94HB acceptance criteria, pose no practical problems, and are therefore considered to have passed.

[0244] (Rating 3: Strength) The obtained pelletized resin compositions were dried at 80°C for 4 hours, and then molded using an injection molding machine "J55ELII" (manufactured by Japan Steel Works Ltd.) at a cylinder temperature of 200°C (240°C for resin composition 28 only) and a mold temperature of 50°C to obtain test pieces measuring 80 mm in length, 10 mm in width, and 4.0 mm in height.

[0245] The molding process involved discarding 300 shots and then molding 100 consecutive shots. The flexural strength variation XTS(%) of the 100 resulting test specimens was calculated using the following formula and evaluated according to the following criteria.

[0246] XTS(%)=(TR max -TR min ) / (TR av ) × 100 Note that in the above formula, TR max This represents the maximum bending strength (MPa) of 100 test specimens, TR min This represents the minimum bending strength (MPa) of 100 test specimens, TR av This represents the average bending strength (MPa) of 100 test specimens. The bending strength of the test specimens is measured according to JIS-K7171.

[0247] ◎:TR av The pressure is 20 MPa or higher, and the XTS is less than 0.5%. 〇:TR av The pressure is 20 MPa or higher, and the XTS is 0.5% or higher and less than 5%. △:TR av The pressure is 20 MPa or higher, and the XTS is 5% or more but less than 15%. ×:TR av The pressure is less than 20 MPa, or the XTS is 15% or more.

[0248] The evaluation results are shown in Table II.

[0249] [Table 1]

[0250] The evaluation results show that the resin composition of the present invention exhibits excellent flame retardancy due to the inclusion of acidic polysaccharides and a flame retardant. Furthermore, while the reference example containing only acidic polysaccharides (resin composition 100) exhibits sufficient flame retardancy for practical purposes, resin compositions 1 and 26, which also contain flame retardants, show superior appearance in addition to flame retardancy.

[0251] A comparison of resin compositions 1-8 and 101 reveals that the resin composition of the present invention exhibits excellent flame retardancy due to its inclusion of acidic polysaccharides. From a comparison of resin compositions 1-3, 5-8, 24, 25, 29 and 101, and in particular from a comparison of resin compositions 5-8, it can be seen that the acidic polysaccharide according to the present invention exhibits excellent flame retardancy when the number of acidic functional groups is in the range of 0.20 to 1.50, more preferably in the range of 0.60 to 1.20.

[0252] A comparison of resin compositions 1, 4, and 23 reveals that the salt contained in the acidic polysaccharide according to the present invention, being a divalent or higher salt, exhibits superior strength and appearance in addition to flame retardancy. Furthermore, among alginates, calcium alginate is found to exhibit superior strength and appearance. A comparison of resin compositions 1, 9-12, 19, and 20 shows that when the acidic polysaccharide content according to the present invention is within the range of 5-40% by mass, it exhibits excellent strength and appearance in addition to flame retardancy. A comparison of resin compositions 1, 13, 16, 21, and 22 shows that when the flame retardant content according to the present invention is within the range of 1 to 20% by mass, it exhibits excellent strength and appearance in addition to flame retardancy.

[0253] A comparison of resin compositions 1, 26, and 27 shows that the phosphorus compound according to the present invention exhibits excellent flame retardancy because it is a phosphate ester. A comparison of resin compositions 1 and 28 reveals that a thermoplastic resin with a softening point of 200°C or lower offers superior strength and appearance in addition to flame retardancy. [Explanation of Symbols]

[0254] 10 Large-format photocopiers G1~G9 Exterior Parts

Claims

1. A flame-retardant resin composition containing an acidic polysaccharide, a flame retardant, and a thermoplastic resin, The content of the acidic polysaccharide relative to the total mass of the flame-retardant resin composition is in the range of 3 to 50% by mass. The content of the aforementioned flame retardant is within the range of 0.5 to 25% by mass. The content of the thermoplastic resin is in the range of 30 to 95% by mass. The acidic polysaccharide comprises one or more salts selected from polysaccharides having an acidic functional group and derivatives of the acidic functional group having an acidic functional group in which the parts other than the acidic functional group have been modified. The salt contained in the aforementioned acidic polysaccharide is a divalent or greater salt. A flame-retardant resin composition characterized by the following.

2. The flame retardant is a phosphorus compound. The flame-retardant resin composition according to claim 1.

3. The total number of acidic functional groups and their salts per monosaccharide unit in the aforementioned acidic polysaccharide is within the range of 0.20 to 1.

50. The flame-retardant resin composition according to claim 1 or 2.

4. The total number of acidic functional groups and their salts per monosaccharide unit in the aforementioned acidic polysaccharide is within the range of 0.60 to 1.

20. A flame-retardant resin composition according to any one of claims 1 to 3.

5. The content of the acidic polysaccharide relative to the total mass of the flame-retardant resin composition is in the range of 5 to 40% by mass. A flame-retardant resin composition according to any one of claims 1 to 4.

6. The amount of the flame retardant relative to the total mass of the flame-retardant resin composition is within the range of 2 to 20% by mass. A flame-retardant resin composition according to any one of claims 1 to 5.

7. The acidic functional group is a carboxyl group or a sulfo group. A flame-retardant resin composition according to any one of claims 1 to 6.

8. The acidic polysaccharide comprises at least an alginate. The flame-retardant resin composition according to any one of claims 1 to 7.

9. The alginate is calcium alginate. The flame-retardant resin composition according to claim 8.

10. The flame retardant is a phosphate ester. A flame-retardant resin composition according to any one of claims 1 to 9.

11. The softening point of the thermoplastic resin is 200°C or lower. A flame-retardant resin composition according to any one of claims 1 to 10.

12. The thermoplastic resin is a polystyrene-based resin. The flame-retardant resin composition according to any one of claims 1 to 11.

13. Formed using the flame-retardant resin composition according to any one of claims 1 to 12 A flame-retardant resin molded product characterized by the following.

14. Includes the flame-retardant resin molded article described in claim 13. A flame-retardant resin housing characterized by the following features.

15. A flame-retardant resin molded article as described in claim 13. An electronic device characterized by the following features.

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