Flame-retardant resin composition and flame-retardant resin housing

Abstract

To provide a flame-retardant resin composition capable of producing a molded product having reduced environmental load and excellent flame retardancy and color tone and to provide a flame-retardant resin housing produced using the flame-retardant resin composition.SOLUTION: There is provided a flame retardant resin composition comprising a thermoplastic resin and a polysaccharide, wherein the polysaccharide includes one or more alginic acids selected from alginic acid, a derivative of alginic acid and a salt thereof and the M / G ratio, which represents the molar ratio of mannuronic acid units and guluronic acid units, which are the repeating constitutional units of the alginic acid skeleton in the alginic acids, is 1.2 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a flame-retardant resin composition and a flame-retardant resin housing. More specifically, the present invention relates to a flame-retardant resin composition that reduces environmental impact and enables the production of molded articles with excellent flame retardancy and colorability, and to a flame-retardant resin housing manufactured using the flame-retardant resin composition. [Background technology]

[0002] In recent years, with the growing demand for reducing environmental impact, biomass resins, which replace petroleum 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).

[0003] Generally, resin products are manufactured by adding various additives to resin according to their intended purpose. The use of biomass raw materials with low environmental impact is also expected for such additives. For example, polysaccharides are known to be incorporated into resin compositions as flame retardants to reduce environmental impact (see, for example, Patent Document 1). Polysaccharides are compounds with a cyclic structure containing a large amount of hydroxyl groups as their basic framework. During combustion, they generate water vapor as a result of dehydration condensation accompanied by heating, resulting in flame retardancy through cooling due to a large amount of endothermic heat, dilution of combustion gases, and blocking of oxygen. Furthermore, it is expected that the carbonization of dehydrated polysaccharides forms a heat-insulating film (char (carbonized layer)), thereby exhibiting flame retardancy.

[0004] However, resin compositions containing polysaccharides tend to discolor easily due to heating during the molding process to obtain molded products, and this thermal discoloration impairs the colorability of the molded products, which is a problem. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-77215 [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention has been made in view of the above-mentioned problems and circumstances, and its objective is to provide a flame-retardant resin composition that reduces environmental impact and enables the production of molded articles with excellent flame retardancy and colorability, and a flame-retardant resin housing manufactured using the flame-retardant resin composition. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors of the present invention, in the process of investigating the causes of the above problems, discovered that by incorporating alginic acid compounds, which consist of one or more selected from alginic acid, alginic acid derivatives, and salts thereof, and in which the molar ratio of mannuronic acid units and guluronic acid units, which are the constituent units, within a specific range, into a resin composition, a flame-retardant resin composition can be obtained that reduces environmental impact and enables the production of molded articles with excellent flame retardancy and colorability, leading to the present invention. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0008] 1. A flame-retardant resin composition containing a thermoplastic resin and a polysaccharide, The aforementioned polysaccharides include alginic acid derivatives, which consist of one or more selected from alginic acid, alginic acid derivatives, and salts thereof. The M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units, which are the repeating structural units of the alginic acid skeleton in the aforementioned alginic acids, is 1.2 or less. the law of nature, The content of the alginic acid derivatives relative to the total amount of the flame-retardant resin composition is within the range of 5 to 40% by mass. A flame-retardant resin composition characterized by [having the following properties].

[0009] 2. The flame-retardant resin composition according to paragraph 1, characterized in that the alginic acids include calcium alginate.

[0010] 3. The flame-retardant resin composition according to claim 1 or 2, wherein the M / G ratio is 0.6 or less.

[0012] 4 . Further, a phosphorus-based flame retardant is contained in the range of 1 to 20% by mass based on the total amount of the flame-retardant resin composition, and the flame-retardant resin composition according to any one of claims 1 to 3 any one of the above items.

[0013] 5 . A flame-retardant resin housing produced using the flame-retardant resin composition, wherein the flame-retardant resin composition is the flame-retardant resin composition according to any one of claims 1 to 4 any one of the above items, and the flame-retardant resin housing is characterized thereby. [Effect of the Invention]

[0014] By the above means of the present invention, it is possible to provide a flame-retardant resin composition capable of manufacturing a molded product with a reduced environmental load and excellent flame retardancy and color tone, and a flame-retardant resin housing manufactured using the flame-retardant resin composition. Regarding the mechanism or action mechanism for the manifestation of the effects of the present invention, the following speculation is made.

[0015] As described above, hydrocarbons rich in oxygen atoms in the molecule such as polysaccharides are converted into carbon by extracting oxygen and hydrogen by dehydration reaction during combustion, and a carbonized layer is formed. The carbonized layer is difficult to burn, acts as a heat-insulating layer to suppress the decomposition of new resin, and also inhibits the diffusion of the decomposition products of the resin generated inside the carbonized layer, that is, flammable gases to the outside. For this reason, it is known that the flame retardancy that stops the combustion reaction is manifested.

[0016] The inventors have found that when using polysaccharides having acidic functional groups in the molecule among polysaccharides, the above dehydration reaction can be promoted. Among typical polysaccharides, cellulose does not have acidic functional groups, but there are also many polysaccharides having acidic functional groups such as carboxy groups, and these acidic functional groups assist in the formation of a carbonized layer. Since these acidic polysaccharides have acidic functional groups directly bonded to the main chain, the distance between the acidic functional groups and the main chain is short and the carbonization promoting effect is strong.

[0017] However, the ease of carbonization is likely to lead to easy discoloration to brown or the like by heat, and the surface is likely to be browned mainly due to the heat of melting during kneading and molding, the frictional heat with the wall surface, or the increase in the compression temperature due to pressurization. As a result, it becomes difficult for the molded product to have other than a dark color like black, and the adjustable color range is narrow, that is, the color adjustability is not sufficient.

[0018] In response to the above problems, the inventors have found that alginic acid, which is one of the acidic polysaccharides, has mannuronic acid and guluronic acid, which are stereoisomers, as constituent units, and by increasing the ratio of guluronic acid units, in other words, decreasing the ratio of mannuronic acid units, thermal discoloration is suppressed.

[0019] In alginic acid, the part where guluronic acid units are linked is considered to be more likely to have a dense molecular structure and be more likely to crosslink compared to the part where mannuronic acid units are linked or the part where mannuronic acid units and guluronic acid units are randomly bonded, resulting in an improvement in thermal stability. Therefore, it is considered that an increase in the ratio of guluronic acid units increases the part where guluronic acid units are linked, resulting in an improvement in thermal stability. As a result, it is considered that a flame-retardant resin composition capable of producing a molded product with reduced environmental load and excellent flame retardancy and color adjustability can be obtained.

Mode for Carrying Out the Invention

[0020] The flame-retardant resin composition of the present invention is a flame-retardant resin composition containing a thermoplastic resin and a polysaccharide, wherein the polysaccharide comprises alginic acid compounds consisting of one or more selected from alginic acid, derivatives of alginic acid, and salts thereof, and the M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units, which are repeating structural units of the alginic acid skeleton in the alginic acid compounds, is 1.2 or less. This feature is a technical feature common to each of the embodiments described below.

[0021] In embodiments of the present invention, from the viewpoint of exhibiting the effects of the present invention, it is preferable that the alginic acids include calcium alginate. In alginic acid, it is known that the portion in which guluronic acid units are linked forms a structure called an egg box structure when it becomes a divalent salt. This egg box structure is a dense intermolecular crosslinking structure centered on ions, and it is thought that an increase in such crosslinking leads to improved thermal stability. In particular, calcium alginate is said to readily form the above intermolecular crosslinking structure, and can effectively suppress discoloration during molding.

[0022] In embodiments of the present invention, from the viewpoint of achieving the effects of the present invention, it is preferable that the M / G ratio is 0.6 or less.

[0023] In embodiments of the present invention, from the viewpoint of achieving the effects of the present invention, it is preferable that the content of the alginic acid derivatives relative to the total amount of the flame-retardant resin composition is in the range of 5 to 40% by mass.

[0024] In embodiments of the present invention, from the viewpoint of achieving the effects of the present invention, it is preferable that the flame-retardant resin composition further contains a phosphorus-based flame retardant in an amount of 1 to 20% by mass relative to the total amount of the flame-retardant resin composition. Phosphorus-based flame retardants, which are a type of general flame retardant, are thought to assist in the formation of a carbonized layer by converting phosphorus into phosphoric acid during combustion, and by promoting the dehydration reaction of this phosphoric acid. In other words, phosphorus-based flame retardants have the effect of promoting carbonization, similar to the acidic functional groups of acidic polysaccharides, and thus can work together to promote flame retardancy. In addition, since both phosphoric acid and polysaccharides can form hydrogen bonds, the intermolecular distances tend to be close, making it easier to obtain a more flame-retardant effect.

[0025] The flame-retardant resin housing of the present invention is a flame-retardant resin housing made using a flame-retardant resin composition, characterized in that the flame-retardant resin composition is the flame-retardant resin composition of the present invention.

[0026] 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.

[0027] [Flame-retardant resin composition] The flame-retardant resin composition of the present invention is a flame-retardant resin composition containing a thermoplastic resin and a polysaccharide, wherein the polysaccharide comprises alginic acid compounds consisting of one or more selected from alginic acid, derivatives of alginic acid, and salts thereof, and the M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units, which are repeating structural units of the alginic acid skeleton in the alginic acid compounds, is 1.2 or less.

[0028] Hereinafter, alginic acid compounds consisting of one or more selected from alginic acid, alginic acid derivatives, and salts thereof, in which the M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units that are repeating structural units of the alginic acid skeleton, is 1.2 or less, will also be referred to as "alginic acid compounds (A)".

[0029] The flame-retardant resin composition of the present invention contains a thermoplastic resin and alginic acid(A). In the flame-retardant resin composition of the present invention, alginic acid(A) functions as a flame retardant. In addition to the thermoplastic resin and alginic acid(A), the flame-retardant resin composition of the present invention may also contain other flame retardants, such as phosphorus-based flame retardants. Furthermore, the flame-retardant resin composition of the present invention may optionally contain various additives that are generally found in flame-retardant resin compositions. The components of the flame-retardant resin composition of the present invention will be described below.

[0030] (thermoplastic resin) The thermoplastic resin contained in the flame-retardant resin composition of the present invention can be any known thermoplastic resin without particular limitation. Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polycarbonate resins, aromatic polyester resins, polyphenylene sulfite 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.

[0031] Furthermore, the thermoplastic resin contained in the flame-retardant resin composition of the present invention can be a thermoplastic resin that is generally treated as a biodegradable resin. Examples of biodegradable thermoplastic resins include aliphatic polyesters, polyamino acids, polyvinyl alcohol, polyalkylene glycols, and copolymers containing these. The thermoplastic resin may be one of the above resins used alone or two or more used in combination.

[0032] The above-mentioned polystyrene resins include polystyrene resin, syndiotactic polystyrene resin, acrylonitrile-styrene resin (AS resin), acrylonitrile-butadiene-styrene resin (ABS resin), and the like.

[0033] 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.

[0034] Examples of aliphatic polyesters, which are biodegradable thermoplastic resins, include polyoxy acids, which are (co)polymers 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.

[0035] Using biodegradable thermoplastic resins as thermoplastic resins is preferable from the viewpoint of reducing environmental impact. Furthermore, by combining biodegradable thermoplastic resins with non-biodegradable thermoplastic resins, a thermoplastic resin that combines the advantages of both can be obtained.

[0036] The thermoplastic resin content in the flame-retardant resin composition of the present invention is the amount obtained by subtracting the content of alginic acid (A) and other various additives optionally included in the flame-retardant resin composition.

[0037] (Alginic acid derivatives (A)) Alginic acid compounds (A) are alginic acid compounds consisting of one or more selected from alginic acid, derivatives of alginic acid, and salts thereof, wherein the M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units that are repeating structural units of the alginic acid skeleton, is 1.2 or less.

[0038] Alginic acid is known as an intercellular polysaccharide found in the thallus of seaweed (brown algae), and is typically considered a naturally occurring compound obtained by industrial extraction and purification from the thallus. Alginic acid is a type of polysaccharide whose structure is represented by the following formula (1), consisting of repeating mannuronic acid units and guluronic acid units. In formula (1), the units enclosed in parentheses on the left are guluronic acid units, and the units enclosed in parentheses on the right are mannuronic acid units. Both guluronic acid and mannuronic acid are types of uronic acid. Guluronic acid and mannuronic acid are stereoisomers of each other, with guluronic acid being the L-form and mannuronic acid being the D-form.

[0039] [ka]

[0040] Here, in formula (1), G represents the number of moles of guluronic acid units in the alginate skeleton, and M represents the number of moles of mannuronic acid units in the alginate skeleton. Note that formula (1) is a formula that shows the molar composition of each constituent unit in the compound, and does not show a structure in which a block of G moles of guluronic acid units and a block of M moles of mannuronic acid units are bonded together. In other words, formula (1) does not specify the bonding order of guluronic acid units and mannuronic acid units in the compound. The molar ratio (M / G ratio) of mannuronic acid units to guluronic acid units in the alginic acid shown in formula (1) is denoted as M / G. As for alginic acid, alginic acid in which the M / G ratio in formula (1) is 1.2 or less can be used in the present invention as alginic acid (A).

[0041] Examples of alginic acid derivatives include compounds in which the hydrogen atom in formula (1) above is replaced with a substituent such as a halogen atom or a hydrocarbon group. Also, examples include ester derivatives and ether derivatives obtained by reacting the alginic acid shown in formula (1) with a compound having a functional group that is reactive with the hydroxyl group (-OH) or carboxyl group (-COOH) of this alginic acid. As for alginic acid derivatives, alginic acid derivatives in formula (1) with an M / G ratio of 1.2 or less can be used in the present invention as alginic acid derivatives (A).

[0042] Examples of salts of alginic acid or derivatives of alginic acid include compounds in which the carboxyl group (-COOH) of alginic acid or its derivatives of formula (1) has been replaced with a salt. Specifically, these include salts with alkali metals such as Li, Na, and K, salts with alkaline earth metals such as Mg, Ca, Sr, and Ba, and alkyl(ammonium) salts (for example, R4N + -(R is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, provided that at least one of R is an alkyl group.)) salts are examples. As salts of alginic acid or its derivatives, salts of alginic acid or its derivatives in formula (1) in which M / G is 1.2 or less can be used in the present invention as alginic acid(A).

[0043] The molecular weight of alginates (A) 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).

[0044] In this specification, the terms "guluronic acid unit" and "mannuronic acid unit" include not only the guluronic acid unit and mannuronic acid unit shown in formula (1), but also units containing the guluronic acid skeleton and units containing the mannuronic acid skeleton in derivatives in which hydrogen atoms of each unit are substituted or substituents are introduced via hydroxyl or carboxyl groups. The same applies to salts of alginic acid or derivatives of alginic acid.

[0045] As described above, the order in which guluronic acid units and mannuronic acid units are bonded in formula (1) is not particularly limited. Glucuronic acid units and mannuronic acid units may be bonded randomly, blocks of guluronic acid units and blocks of mannuronic acid units may be bonded, or a combination thereof may be present. The alginic acid shown in formula (1) typically consists of blocks in which guluronic acid and mannuronic acid are bonded randomly (hereinafter also referred to as "MG blocks"), and combinations of blocks of guluronic acid units (hereinafter also referred to as "GG blocks") and blocks of mannuronic acid units (hereinafter also referred to as "MM blocks").

[0046] The M / G ratio of alginates can be measured using the method described, for example, in "On the Raw Material Properties of Unutilized Brown Algae" (Research Report of Hokkaido Prefectural Fisheries Experiment Station, No. 57, 15-22 (2000), Akiko Miyazaki et al.).

[0047] Specifically, taking alginic acid as an example, alginic acid is partially hydrolyzed under predetermined conditions and then subjected to a first centrifugation. The supernatant 1 obtained from the first centrifugation contains MG blocks. By measuring the uronic acid content (total content of guluronic acid and mannuronic acid) in supernatant 1, the MG block content (hereinafter referred to as "MG") can be determined.

[0048] Next, precipitate 1 obtained from the first centrifugation is suspended in distilled water, neutralized to form a solution, treated with acid at a pH of approximately 2.9, and then subjected to a second centrifugation. The supernatant 2 obtained from the second centrifugation contains a portion of the MM block and the GG block. The content of the MM block and a portion of the GG block in supernatant 2 (hereinafter referred to as "MM+GG1") is measured as the uronic acid content. The MM block content (hereinafter referred to as "MM") is measured by measuring the uronic acid content in the filtrate obtained by filtering supernatant 2.

[0049] Furthermore, the precipitate 2 obtained from the second centrifugation is suspended in distilled water, neutralized to form a solution, and the uronic acid content in this solution is measured to determine the content of the remaining GG block (hereinafter referred to as "GG2"). From the uronic acid content measured above, the M / G (M / G ratio) is obtained using the following formula (2).

[0050]

number

[0051] The M / G ratio of alginic acid derivatives and salts of alginic acid or its derivatives can also be measured using the same method as described above. Furthermore, the M / G ratio of alginic acid derivatives and salts of alginic acid or its derivatives obtained from alginic acid with a known M / G ratio as a raw material does not change from the M / G ratio of the raw material alginic acid, so the M / G ratio of the raw material alginic acid can be used as is.

[0052] The M / G ratio of the alginic acid compounds according to the present invention is 1.2 or less, preferably 1.0 or less, more preferably 0.6 or less, and even more preferably 0.4 or less. The lower limit of the M / G ratio is 0. An M / G ratio of 0 means that all the constituent units of the alginic acid compounds are composed of guluronic acid units. As described above, the portion where guluronic acid units are linked together tends to have a denser molecular structure and is more easily crosslinked, so the smaller the M / G ratio, the more pronounced the effects of the present invention become.

[0053] Alginic acid derivatives are typically naturally occurring, and their M / G ratio varies depending on the type of seaweed (brown algae), origin, season, and even the part of the thallus. By carefully selecting appropriate raw seaweed and industrially extracting and purifying it, it is possible to produce alginic acid derivatives with different M / G ratios.

[0054] Since the M / G ratio of alginates is adjusted in this way, considering factors such as availability (including cost) and environmental impact, the lower limit of the M / G ratio is preferably around 0.3, and more preferably around 0.4.

[0055] Furthermore, in alginic acid or its derivatives, the portion where guluronic acid units are linked tends to form a dense intermolecular cross-linking structure centered on an ion, known as an eggbox structure, when it becomes a divalent salt, as described above. Formula (3) below shows a part of the intermolecular cross-linking structure of the portion where guluronic acid units are linked in calcium alginate.

[0056] [ka]

[0057] Equation (3) shows two adjacent molecular chains (molecular chain (I) and molecular chain (II)), each showing a region where four guluronic acid units are linked together. In molecular chains (I) and (II), the guluronic acid units are bent and linked together, and COO is located on both sides of the molecular chain (for convenience, one side is distinguished as the "upper side" and the other as the "lower side" based on their visual position in equation (3)). - In equation (3), the COO on the lower side of molecular chain (I) - and the COO on the upper side of molecular chain (II) - Ca 2+ The molecular chain (I) and molecular chain (II) are cross-linked by forming a salt via this linkage.

[0058] Also, although not shown in equation (3), the COO on the upper side of molecular chain (I) - and the COO on the underside of molecular chain (II) - These are Ca 2+through the COO of another molecular chain - forms a salt and crosslinks with it. The intermolecular crosslinked structure thus formed is said to particularly improve thermal stability and effectively suppress coloring during molding.

[0059] Note that the alginic acids (A) may be surface-modified with a surface modifier as long as the effects of the present invention are not impaired. Examples of the surface modifier include carboxylic acids, amino acids or monovalent metal salts of amino acid derivatives, sulfate esters, or monovalent salts of sulfonic acids.

[0060] The alginic acids (A) may be used alone or in combination of two or more. In the flame-retardant resin composition of the present invention, the content of the alginic acids (A) is preferably in the range of 5 to 40% by mass, more preferably in the range of 20 to 30% by mass, based on the total amount of the flame-retardant resin composition. If the content of the alginic acids (A) in the flame-retardant resin composition is within the above range, it is easy to achieve both the expression of flame retardancy and the maintenance of color tone in the obtained molded product. Further, if the content is below the above upper limit, it is easy to suppress the decrease in the strength of the molded product due to the inclusion of the alginic acids (A).

[0061] (Phosphorus-based flame retardant) The flame-retardant resin composition of the present invention preferably contains a phosphorus-based flame retardant as a flame retardant other than the alginic acids (A) in addition to the alginic acids (A). As described above, the phosphorus-based flame retardant has an effect of assisting the formation of the carbonized layer of the alginic acids (A) and can further form hydrogen bonds to shorten the intermolecular distance. Therefore, the combination of the two can further promote flame retardation.

[0062] The content of the phosphorus-based flame retardant is preferably in the range of 1 to 20% by mass, more preferably in the range of 2 to 15% by mass, still more preferably in the range of 3 to 10% by mass, based on the total amount of the flame-retardant resin composition of the present invention.

[0063] If the content of phosphorus-based flame retardants is within the above range, a sufficient amount of alginic acid (A) can be ensured, and flame retardancy can be promoted in the resulting molded product without impairing the effects of alginic acid (A). Furthermore, if the content is below the above upper limit, it is easier to suppress the reduction in strength of the molded product due to the inclusion of phosphorus-based flame retardants.

[0064] Furthermore, depending on the type of thermoplastic resin it is combined with, phosphorus-based flame retardants tend to separate during melting, and the separated material may bleed out and remain on the surface of the molded product, leading to a deterioration in appearance. If the content of phosphorus-based flame retardants relative to the total amount of the flame retardant resin composition is 20% by mass or less, the deterioration in appearance caused by the bleed-out of phosphorus-based flame retardants can be suppressed.

[0065] Examples of phosphorus-based flame retardants include phosphinic acid, phosphonic acid, salts with metals such as phosphoric acid and ammonium, and ester compounds of phosphinic acid, phosphonic acid, and phosphoric acid. Among these, phosphorus ester compounds (described in detail later) are preferred as phosphorus-based flame retardants from the viewpoint of flame retardant effect.

[0066] Specifically, the above-mentioned salts include phosphinate metal salts, particularly aluminum phosphinate and zinc phosphinate; phosphonate metal salts, particularly aluminum phosphonate, calcium phosphonate, and zinc phosphonate; and hydrates of equivalent phosphonate metal salts, ammonium phosphate, and ammonium polyphosphate.

[0067] Examples of phosphinic acid ester compounds include dimethylphosphinic acid, methylethylphosphinic acid, methylpropylphosphinic acid, diethylphosphinic acid, dioctylphosphinic acid, phenylphosphinic acid, diethylphenylphosphinic acid, diphenylphosphinic acid, and bis(4-methoxyphenyl)phosphinic acid.

[0068] Examples of phosphonic acid ester compounds include methylphosphonic acid, dimethyl methylphosphonic acid, diethyl methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid, 2-methyl-propylphosphonic acid, t-butylphosphonic acid, 2,3-dimethylbutylphosphonic acid, octylphosphonic acid, phenylphosphonic acid, and dioctylphenylphosphonate.

[0069] In addition, as phosphorus-based flame retardants other than those mentioned above, derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO), polyphosphonates (e.g., Nofia® HM1100 (manufactured by FRXPolymers (Chelmsford, USA))), zinc bis(diethylphosphinate), aluminum tris(diethylphosphinate), melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine poly(aluminum phosphate), melamine poly(zinc phosphate), methylphosphonate melamine salt, guanylurea phosphate, guanidine phosphate, ethylenediamine phosphate, and phosphazene compounds, such as phenoxyphosphazene oligomers, may be used as phosphorus-based flame retardants.

[0070] Phosphorus-based flame retardants may be used individually or in combination of two or more types.

[0071] [Phosphate ester compounds] The phosphate ester compound may be either an aliphatic phosphate ester compound or an aromatic phosphate ester compound, with aromatic phosphate ester compounds being preferred. Using an aromatic phosphate ester compound as a phosphorus-based flame retardant allows for mixing and molding at lower temperatures and with lower shear, and suppresses the thermal decomposition of alginic acid (A) during mixing and molding, which can cause discoloration and foaming. Furthermore, it is expected that decomposition at high temperatures during ignition will generate phosphoric acid, promoting the carbonization of alginic acid (A) and making it easier to exhibit flame retardant effects.

[0072] Examples of phosphate ester compounds include monomeric phosphate ester compounds obtained by reacting phosphoric acid with aliphatic or aromatic alcohols, and aromatic condensed phosphate ester compounds which are reaction products of phosphorus oxychloride with a divalent phenolic compound and phenol (or alkylphenol).

[0073] Phosphate ester compounds specifically include trimethyl phosphate (TMP), triethyl phosphate (TEP), tributyl phosphate, triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), cresyl diphenyl phosphate (CDP), tris(2,4-di-t-butylphenyl) phosphate, distearyl pentaerythritol diphosphate, bis(2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphate, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphate, resorcinol bis-dixylenyl phosphate, resorcinol bis-diphenyl phosphate, bisphenol A bis-diphenyl phosphate (BADP), bisphenol A bis-dicresyl phosphate, biphenol A bis-diphenyl phosphate, and biphenol A bis-dixylenyl phosphate.

[0074] Furthermore, from the viewpoint of heat resistance and other factors, the phosphate ester compound is preferably a condensed phosphate ester compound of the condensation type. Examples of condensed phosphate ester compounds include aromatic condensed phosphate ester compounds represented by the following chemical formula (P).

[0075] [ka]

[0076] In the above formula (P), R 1 ~R 5 Each of these is independently a hydrogen atom, a C1-C10 alkyl group, a C3-C20 cycloalkyl group, a C6-C20 aryl group, or a C1-C10 alkoxy group, and R 1~R 5 They may be the same or different. There can be multiple (5) Rs. 1 These elements may be identical or different from each other. There may be multiple (4-5) of each R. 2 , R 3 , R 4 and R 5 The same applies to n. n is an integer from 1 to 30, preferably an integer from 1 to 10.

[0077] Examples of the alkyl groups mentioned above include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, amyl group, tert-amyl group, hexyl group, 2-ethylhexyl group, n-octyl group, nonyl group, decyl group, and the like.

[0078] Examples of the above cycloalkyl groups include cyclohexyl groups. Examples of the above aryl groups include phenyl groups, cresyl groups, xylyl groups, 2,6-xylyl groups, 2,4,6-trimethylphenyl groups, butylphenyl groups, and nonylphenyl groups.

[0079] Examples of the alkoxy groups mentioned above include methoxy groups, ethoxy groups, propoxy groups, and butoxy groups.

[0080] Aromatic condensed phosphate ester compounds are reaction products of phosphorus oxychloride, a divalent phenolic compound, and phenol (or alkylphenol), as described above. The aromatic condensed phosphate ester compound represented by formula (P) is a resodium in which the divalent phenolic compound may have substituents. Ru Synol (hereinafter referred to as "Reso") Ru Also called "sinol compounds." These are compounds in the case of ( ). Aromatic condensed phosphate ester compounds are resos Ru The compound may be obtained by using 4,4'-biphenol or bisphenol A (each of which may have substituents) instead of the cinol compound. Specifically, in formula (P), reso RuInstead of the sinol compound residue, aromatic condensed phosphate ester compounds having a 4,4'-biphenol residue or a bisphenol A residue, which may each have substituents, can be used in the present invention.

[0081] Commercial phosphate ester compounds may be used. Examples of commercially available phosphate ester compounds include PX-200 (resorcinol bis-dixylenyl phosphate), CR-733S (resorcinol bis-diphenyl phosphate), and CR-741 (bisphenol A bis(diphenyl phosphate), all manufactured by Daihachi Chemical Industry Co., Ltd. ) These can be used.

[0082] (Other flame retardants) The flame-retardant resin composition of the present invention contains alginic acid (A) as a flame retardant. The flame retardant may optionally contain phosphorus-based flame retardants, and may also contain other flame retardants other than alginic acid (A) and phosphorus-based flame retardants (also simply referred to as "other flame retardants"), as long as the effects of the present invention are not impaired. Examples of other flame retardants include polysaccharides other than alginic acid (A), metal hydroxides, and intomessent flame retardants.

[0083] If the above-mentioned flame retardant contains metal hydroxides as other flame retardants, the content 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 amount of the flame retardant resin composition. If the content of metal hydroxides in the flame retardant resin composition is within the above range, it is easier to achieve a higher level of balance between the development of flame retardancy and the maintenance of strength in the resulting molded article.

[0084] Examples of the above-mentioned metal hydroxides include aluminum hydroxide and magnesium hydroxide, with aluminum hydroxide being particularly preferred.

[0085] The form of the metal hydroxide described above is preferably particles. The particle shape is not particularly limited and can be spherical, spindle-shaped, plate-shaped, flake-shaped, needle-shaped, fibrous, etc. Furthermore, 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). The volume-based median diameter (D50) can be measured, for example, by laser diffraction / scattering using a laser detector such as the LA-960S2 (manufactured by HORIBA).

[0086] The metal hydroxide particles described above 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.

[0087] (Other additives) Other additives that may be optionally included in the flame-retardant resin composition of the present invention include antioxidants, fillers, and nucleating agents. The content of other additives in the flame-retardant resin composition of the present invention is within a range that does not impair the effects of the present invention, and for example, is in the range of 0 to 30% by mass of the total amount of the flame-retardant resin composition, preferably in the range of 0 to 20% by mass. Furthermore, a total of 30% by mass or less is preferred.

[0088] (Manufacturing of flame-retardant resin compositions) The flame-retardant resin composition of the present invention can be obtained by melt-kneading a thermoplastic resin and alginic acid (A), as well as a phosphorus-based flame retardant, other flame retardants, and other additives, which may be optionally contained therein. The method of melt-kneading is not particularly limited, and known melt-kneading methods can be used.

[0089] Specific examples include a method in which each component is pre-mixed using various mixers such as tumblers or high-speed mixers known as Henschel mixers, and then melt-kneaded using kneading equipment such as Banbury mixers, rolls, plastographs, single-screw extruders, twin-screw extruders, and kneaders. Among these, the manufacturing method using an extruder for melt-kneading is more preferable due to its high production efficiency, and the manufacturing method using a twin-screw extruder is even more preferable. After melt-kneading each component using an extruder and extruding the kneaded material into strands, the extruded strands can be processed into pellets, flakes, or other forms.

[0090] It is preferable to thoroughly dry each component before pre-mixing. The drying temperature is not particularly limited, but is preferably 60 to 100°C. The drying time is also not particularly limited, but is preferably 2 to 6 hours. Furthermore, drying under reduced pressure is preferable as it facilitates the drying process. Alternatively, the above drying process may be repeated after pre-mixing.

[0091] The temperature during melt mixing is, for example, 150 to 280°C, and is appropriately selected depending on the type and content of the thermoplastic resin and alginic acid (A) used. The temperature during melt mixing corresponds to, for example, the cylinder temperature in a mixing device such as a twin-screw extruder. Furthermore, if multiple temperature settings are available 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 is preferably 1 to 20 MPa.

[0092] The discharge rate from the mixing device during melt mixing is not particularly limited, but it is preferable to discharge at 10 to 100 kg / hr, and more preferably at 20 to 70 kg / hr, in order to ensure sufficient melt mixing.

[0093] The kneaded mixture, melted and kneaded in the kneading apparatus as described above, is preferably subjected to a cooling treatment after being extruded from the kneading apparatus. The cooling treatment is not particularly limited, and for example, methods such as immersing the mixture in water at 0 to 60°C for water cooling, cooling with gas at -40 to 60°C, or contacting it with metal at -40 to 60°C can be used.

[0094] The flame-retardant resin composition of the present invention can take various forms, such as powder, granules, tablets, pellets, flakes, fibers, and liquid.

[0095] According to the flame-retardant resin composition of the present invention, it is possible to manufacture molded articles that maintain flame retardancy, colorability, and strength while using alginic acid (A), a naturally derived flame retardant with low environmental impact.

[0096] Here, flame retardancy is a type of fire resistance, referring to the property of burning slowly but continuing to burn to a certain extent. There are various standards for evaluating flame resistance, such as JIS and ASTM, but generally, the UL standard is particularly important. The UL standard is a standard established and evaluated by the American company Underwriters Laboratories.

[0097] In a molded article formed from the flame-retardant resin composition of the present invention, when evaluated using a test piece of a predetermined size according to the above UL standards, it is preferable that it be evaluated as passing under UL94HB, more preferably under UL94V-2, and even more preferably under UL94V-0.

[0098] Furthermore, by using the flame-retardant resin composition of the present invention, a molded product can be obtained by the conventional molding method described below, which has sufficient flame retardancy, excellent color matching properties, a good appearance, and excellent mechanical strength such as bending strength.

[0099] (molded product) Molded articles can be produced using the flame-retardant resin composition of the present invention. These molded articles provide flame-retardant products. When manufacturing the molded articles, the flame-retardant resin composition can be melted and molded in various molding machines. 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 and calendering can be subjected to secondary molding such as vacuum forming or pressure forming.

[0100] [Flame-retardant resin housing] The present invention provides a flame-retardant resin housing made from a molded article manufactured using the flame-retardant resin composition described above. The articles housed in the flame-retardant resin housing are not particularly limited. Examples of flame-retardant resin housings include housings for various machines and equipment, and other housings generally made from flame-retardant resins.

[0101] (Application) The applications of molded articles including the housing molded from the flame-retardant resin composition of the present invention are not particularly limited, and include, for example, electrical and electronic components, electrical components, exterior parts, and interior parts in fields such as home appliances and automobiles, as well as various packaging materials, household goods, office supplies, piping, and agricultural materials.

[0102] The present invention provides electronic equipment characterized by using the above-mentioned molded product as a component. While not particularly limited, examples of electronic equipment include computers, scanners, copiers, printers, facsimile machines, compositing machines called MFPs (Multi-Function Peripherals) that combine these functions, and digital printing systems for commercial printing. [Examples]

[0103] 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 refer to "parts by mass" or "mass%".

[0104] [Preparation of flame-retardant resin compositions] The following thermoplastic resins and flame retardants (alginic acids, phosphorus-based flame retardants, etc.) were prepared as constituent materials for the flame-retardant resin compositions in the examples.

[0105] (thermoplastic resin) As the thermoplastic resin, we prepared ABS resin; Toyorac 700-314 (product name, manufactured by Toray Industries, Inc.).

[0106] (Phosphorus-based flame retardant) As a phosphorus-based flame retardant, we prepared a phosphate ester compound; PX-200 (product name, manufactured by Daihachi Chemical Industry Co., Ltd.).

[0107] (Alginic acid derivatives) As alginic acids, we used commercially available products shown in Table I or alginic acids A1-A4 and alginic acid Cf1 obtained in the following synthesis examples. Alginic acids A1-A4 are applicable to the flame-retardant resin composition of the present invention, while alginic acid Cf1 is an alginic acid for comparative examples that is not suitable for the flame-retardant resin composition of the present invention. Flavicafine N is calcium alginate surface-modified with a metal carboxylate salt.

[0108] [Table 1]

[0109] (Synthesis Example 1; Production of Alginic Acid A3) One part by mass of sodium alginate (IL-6G (Kimika Co., Ltd., M / G ratio = 0.6)) was gradually added to 100 parts by mass of vigorously stirred water and dissolved. This aqueous solution was then added dropwise to 100 parts by mass of 1% aqueous solution of calcium chloride that was vigorously stirred. After stirring for 20 minutes, the mixture was filtered, washed with water and ethanol, spread on a tray, and dried at 50-60°C until a constant weight was confirmed to obtain alginates A3 shown in Table I.

[0110] (Synthesis Example 2; Preparation of Alginic Acid Cf1) Except for using IL-6M (manufactured by Kimika, M / G ratio = 2.2) instead of IL-6G (manufactured by Kimika, M / G ratio = 0.6) as sodium alginate, the same procedure as in Synthesis Example 1 was followed to obtain the alginic acid derivatives Cf1 shown in Table I.

[0111] (Preparation of flame-retardant resin composition) As a pre-drying step before mixing, the thermoplastic resin and flame retardant (alginic acid derivatives, phosphorus-based flame retardant, etc.) were dried separately at 80°C for 4 hours. Then, the components were weighed according to the ratios (mass%) shown in Table II and dry-blended.

[0112] Next, the mixture obtained by dry blending was supplied at a rate of 10 kg per hour from the raw material supply port (hopper) of a twin-screw extruder (HAAKE twin-screw extruder manufactured by Thermo Scientific). Melt mixing was performed under the conditions of a cylinder temperature of 180°C and a screw rotation speed of 400 rpm. After mixing, the molten resin was cooled in a 30°C water bath and then pelletized in a pelletizer to obtain flame-retardant resin compositions 1 to 9. Flame-retardant resin compositions 1 to 8 correspond to the flame-retardant resin compositions of the present invention, and flame-retardant resin composition 9 is a comparative example.

[0113] <Rating> The flame-retardant resin compositions 1 to 9 obtained above were evaluated using the following evaluations 1 to 3. The results, along with the compositions of the flame-retardant resin compositions, are shown in Table II.

[0114] (Rating 1: Toning ability) Each of the obtained pelletized flame-retardant resin compositions 1 to 9 was dried at 80°C for 4 hours, and then molded using an injection molding machine (Rambaldi, Babyplast) with a cylinder temperature of 180°C 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. The appearance of the obtained test pieces was observed visually, and the colorability was evaluated according to the following criteria. A score of △ or higher was considered to be acceptable for practical use.

[0115] ◎: Close to white, and allows for a very wide range of coloring options. ○: It is cream-colored and can be colored in a wide range of ways. △: It is light brown and may be usable for dark colors other than black. ×: It is dark brown and difficult to use for anything other than black.

[0116] (Rating 2: Flame retardant) The test specimens obtained above 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 adopted, and flame retardancy was evaluated based on the following evaluation criteria.

[0117] ◎:V-0 (passed) ○:V-1 (passed) △:V-2 (passed) ×: Not conforming to specifications (does not meet V-2 standards = fails)

[0118] (Rating 3: Bending strength) Each of the obtained pelletized flame-retardant resin compositions 1 to 9 was dried at 80°C for 4 hours, and then molded using an injection molding machine (Rambaldi, Babyplast) with a cylinder temperature of 180°C and a mold temperature of 50°C to obtain test specimens measuring 80 mm in length, 10 mm in width, and 4.0 mm in height.

[0119] The molding process involved discarding 10 shots, followed by 10 consecutive shots. The bending strength variation XTS(%) of the 10 resulting molded parts was calculated using the following formula and evaluated according to the following criteria. A value of △ or higher was considered acceptable for practical use.

[0120] XTS(%)=(TRmax-TRmin) / (TRav)×100 In the above formula, TRmax represents the maximum bending strength (MPa) of 100 molded parts, TRmin represents the minimum bending strength (MPa) of 100 molded parts, and TRav represents the average bending strength (MPa) of 100 molded parts. Here, the bending strength of the molded parts is measured according to JIS K7171.

[0121] ◎: TRav is 20 MPa or higher, and XTS is less than 0.5%. ○: TRav is 20 MPa or higher, and XTS is 0.5% or more but less than 5% △: TRav is 20 MPa or higher, and XTS is 5% or more but less than 15% ×: TRav is less than 20 MPa, or XTS is 15% or more.

[0122] [Table 2]

[0123] Table II shows that the flame-retardant resin composition of the present invention results in molded articles with reduced environmental impact and excellent flame retardancy and colorability. Furthermore, it is evident that strength is maintained.

Claims

1. A flame-retardant resin composition containing a thermoplastic resin and a polysaccharide, The aforementioned polysaccharides include alginic acid derivatives, which consist of one or more selected from alginic acid, alginic acid derivatives, and salts thereof. The M / G ratio, which represents the molar ratio of mannuronic acid units to guluronic acid units, which are the repeating structural units of the alginic acid skeleton in the aforementioned alginic acids, is 1.2 or less. A flame-retardant resin composition characterized in that the content of alginic acids relative to the total amount of the flame-retardant resin composition is in the range of 5 to 40% by mass.

2. The flame-retardant resin composition according to claim 1, characterized in that the aforementioned alginic acids include calcium alginate.

3. The flame-retardant resin composition according to claim 1 or claim 2, characterized in that the M / G ratio is 0.6 or less.

4. Furthermore, the flame-retardant resin composition according to any one of claims 1 to 3 is characterized by containing a phosphorus-based flame retardant in an amount of 1 to 20% by mass relative to the total amount of the flame-retardant resin composition.

5. A flame-retardant resin housing made using a flame-retardant resin composition, A flame-retardant resin housing characterized in that the flame-retardant resin composition is the flame-retardant resin composition described in any one of claims 1 to 4.

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