TW202602964A - Flame retardants for fibers containing phosphorus-containing polymers and flame-retardant fiber products - Google Patents

Abstract

The object of the present invention is to provide a phosphorus-based flame retardant that has excellent initial flame retardancy as well as high durability after washing. The present invention relates to a phosphorus-containing (meth)acrylic polymer that contains one or more specific phosphorus-based compounds as the (meth)acrylic monomer (A), and a flame retardant for fibers that contains the same.

Description

Flame retardants for fibers containing phosphorus polymers and flame-retardant fiber products

This invention relates to a flame retardant for fibers comprising a novel phosphorus-containing polymer and flame-retardant fiber products.

Background Art When flame retardancy is required for fiber products, it is also required that the desired flame retardant effect be maintained even after repeated washing of the fiber products (wash durability).

Currently, halogen compounds such as hexabromocyclododecane and tris(2,3-dibromopropyl)triisocyanate are known as flame retardants that can meet the requirements of flame retardancy and washability. Specifically, there are methods such as adding the aforementioned flame retardant during the melt spinning of raw yarn, and methods of bringing the aforementioned flame retardant into contact during processing after fiberization. In these methods, heat is applied after the flame retardant is applied to efficiently fix the flame retardant component, thereby applying a flame retardant process in a manner that maintains washability.

However, considering the need to address the global environmental issues of recent years, there is a strong desire to exercise self-restraint in the use of halogen compounds, which easily produce toxic gases when burned. In view of this situation, various phosphorus-based flame retardants, such as phosphate ester compounds (Patents 1-2), phosphonate compounds, and hypophosphonate compounds (Patents 2-7), have been proposed as halogen-free flame retardant components used in both the raw silk manufacturing stage and the post-processing stage in fiber weaving.

These low-molecular-weight phosphorus compounds can impart flame retardancy to fibers, for example, by adding them in appropriate amounts during the manufacturing stage of raw silk (e.g., during melt spinning) or by adding them in appropriate amounts to the dyeing solution of fiber fabrics for exhaustion processing in the same bath, but they have the following disadvantages.

First, phosphate compounds are mostly liquid, oily, or viscous fluids, and have insufficient affinity for fibers. Therefore, they tend to act as plasticizers in fibers and induce the exudation of dyes and flame retardants.

Secondly, in the case of dyeing and exhaustion treatment of polyester fibers, these phosphorus-containing compounds generally have very low fixation rates (exhaustion rates) on the fibers. Although there are methods to treat fibers with high temperatures to improve the fixation rate of flame retardants, it is unlikely that any substance can be fixed to a level that can be expected to improve wash durability. As another method to fix flame retardants, although coating with synthetic resins such as pastes can be carried out at the same time as the flame retardant adheres to the fibers to prevent peeling, this will cause changes in appearance and hardening of texture, which will significantly hinder the original characteristics of the fiber products. Furthermore, heat treatment for adhesion can lead to seepage problems, as well as processing/working environment issues such as white fumes and smoke generated due to sublimation or thermal decomposition of the flame retardant at high temperatures. (Preferred Art Documents, Patent Documents)

[Patent Document 1] Japanese Patent Application Publication No. 2000-328445 [Patent Document 2] International Publication No. WO2007-032277 [Patent Document 3] Japanese Patent Application Publication No. 56-16798 [Patent Document 4] Japanese Patent Application Publication No. 56-9178 [Patent Document 5] Japanese Patent Application Publication No. 2002-275473 [Patent Document 6] Japanese Patent Application Publication No. 2006-83491 [Patent Document 7] Japanese Patent Application Publication No. 2005-9041

Summary of the Invention Problem to be Solved by the Invention As such, among phosphorus-based flame retardants for fibers, there is a strong desire to develop a flame retardant that allows the flame retardant to be homogeneously adhered to the fiber surface through post-processing, and that the flame retardant itself has strong adhesion to the fiber and can penetrate and fix the fiber through melt softening, thus achieving both early flame retardancy and washability. However, such a phosphorus-based flame retardant has not yet been developed.

Therefore, the main objective of this invention is to provide a phosphorus-based flame retardant that, in addition to its early flame retardancy, also exhibits excellent washability and durability. This is a means to solve the problem.

In order to achieve the aforementioned objectives, the inventors conducted repeated and dedicated research and discovered that phosphorus-containing polymers with specific chemical structures can achieve the aforementioned objectives, thereby leading to the completion of this invention.

That is, this invention relates to flame retardants for fibers and flame-retardant fiber products comprising the following phosphorus-containing polymer. 1. A phosphorus-containing (meth)acrylic polymer comprising one or more phosphorus compounds represented by the following general formula (I) as (meth)acrylic monomers (A): [Chemical Formula 1] [In the formula, _R1 represents a hydrogen atom or a methyl group. _L1 and _L2 may be the same or different, representing an oxygen atom or an imine (NH) group. _R2 represents an hydrocarbon group that can be substituted by a substituent containing at least one of nitrogen, oxygen, phosphorus, and sulfur atoms.] 2. The phosphorus-containing (meth)acrylic polymer as described in claim 1, having a weight-average molecular weight Mw (but Mw represents the relative weight-average molecular weight relative to standard polystyrene when measured by differential refractometer according to gel osmosis chromatography) of 1000 to 20000. 3. A flame retardant for fibers, comprising the phosphorus-containing (meth)acrylic polymer as described in claim 1 above. 4. The flame retardant for fibers as described in claim 3 above, further comprising an aqueous medium, and being in a liquid state. 5. The flame retardant for fibers as described in item 3 above is used to perform flame retardant processing on fiber products through post-processing. 6. A flame-retardant fiber product comprising synthetic fibers and the flame retardant for fibers as described in item 3 above. 7. The flame-retardant fiber product as described in item 6 above, wherein the synthetic fibers include polyester fibers. Invention Effects

According to the present invention, a phosphorus-based flame retardant with excellent washability in addition to its early flame retardancy can be provided. That is, in particular, a flame retardant for fibers can be provided that can effectively inhibit or prevent the reduction of flame retardant properties caused by washing.

The fiber flame retardant of this invention provides high flame retardancy for fiber products, while also achieving excellent wash durability (especially water wash durability). As a result, good flame retardancy can be maintained for a relatively long period of time.

The flame retardant of this invention makes it relatively easy to perform flame retardant processing on non-flame retardant fiber products through post-processing. In the prior art, although post-processing fiber products with low-molecular-weight flame retardants can temporarily impart flame retardancy, the flame retardant performance will decrease after washing due to the detachment of the flame retardant. In contrast, the fiber flame retardant of this invention can easily impart high flame retardancy to fiber products, and the polymer itself has flame retardancy, adhesion, and softness, thus obtaining flame retardant fiber products that combine high flame retardancy and wash durability.

Forms for Implementing the Invention 1. Phosphorus-Containing Polymer The phosphorus-containing polymer of the present invention (the polymer of the present invention) is characterized in that it comprises one or more phosphorus compounds represented by the following general formula (I) as (meth)acrylate monomers (A): [Chemical Formula 2] [In the formula, _R1 represents a hydrogen atom or a methyl group. _L1 and _L2 may be the same or different, representing an oxygen atom or an imine (NH) group. _R2 represents an hydrocarbon group that can be substituted by a substituent containing at least one of the following: nitrogen, oxygen, phosphorus, and sulfur atoms.]

Furthermore, unless otherwise specified in this specification, "(meth)acrylic monomers" refers to monomers containing an acrylonitrile group and substances containing a methacrylic group. Also, "(meth)acrylic compounds" refers to compounds containing an acrylonitrile group and substances containing a methacrylic group.

The polymer of the present invention comprises the aforementioned phosphorus-based compound as the (meth)acrylate monomer (A). That is, the polymer of the present invention, in addition to the polymer comprising the aforementioned (meth)acrylate monomer (A), also comprises polymers comprising the aforementioned (meth)acrylate monomer (A) and other monomers. Among the aforementioned polymers comprising the (meth)acrylate monomer (A), it further comprises a) one polymer of the aforementioned (meth)acrylate monomer (A), and b) two or more polymers of the aforementioned (meth)acrylate monomer (A).

In general formula (I), _R1 represents a hydrogen atom or a methyl group. _L1 and _L2 may be the same or different, representing an oxygen atom or an imine (NH) group. Therefore, it also includes the cases where _L1 and _L2 are both oxygen atoms, both are imine groups, _L1 is an oxygen atom and _L2 is an imine group, and _L1 is an imine group and _L2 is an oxygen atom. Furthermore, _R2 represents an alkyl group (alkylene group) that can be substituted by a substituent containing at least one of a nitrogen atom, an oxygen atom, a phosphorus atom, and a sulfur atom. Therefore, ^R2 can also be an unsubstituted alkylene group. As for the aforementioned substituents, anything that can be used within the scope that does not impede the effects of the present invention is acceptable, such as phenoxy ( _{C6H5 -} O-). The number of carbon atoms in the hydrocarbon group is not limited, but is generally preferred to be 2 to 12 (including the number of carbon atoms in the substituents). Furthermore, the hydrocarbon group can be any of the following: linear, branched, or cyclic, but is particularly preferred to be linear. Also, the hydrocarbon group can be either saturated or unsaturated.

The phosphorus compounds that become the aforementioned (meth)acrylic acid monomer (A) include, in addition to the case where one phosphorus compound is represented by the aforementioned general formula (I), two or more phosphorus compounds represented by the aforementioned general formula (I).

In the polymer of the present invention, the content of (meth)acrylic acid monomer (A) is not particularly limited, but is usually set to about 50-100% by weight, and particularly preferably 70-100% by weight. Therefore, the polymer of the present invention may also contain 100% by weight of (meth)acrylic acid monomer (A), in which case it may be either a homopolymer composed of one type of (meth)acrylic acid monomer (A) or a copolymer composed of two or more types of (meth)acrylic acid monomer (A). The copolymer may also be any of a cross-linked copolymer, a random copolymer, a segment copolymer, or a graft copolymer.

Furthermore, in the polymer of the present invention, other monomers (A') may be included to the extent that they do not impair the effects of the present invention, provided that the content of (meth)acrylic monomer (A) is less than 100% by weight. As other monomers (A'), phosphorus-free (meth)acrylic compounds may be suitably used from the viewpoint of improving adhesion to the substrate or dispersion/compatibility with water or organic solvents.

Specific examples of phosphorus-free (meth)acrylate compounds include: 2-hydroxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, neopentyltetra(meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, etc., and polyethylene glycol (meth)acrylate having ethylene oxide as a repeating unit, etc., at least one of which is not limited to these.

The ratio of other monomers (A’) in the polymer of this invention can be set as the remainder of the content of (meth)acrylic monomers (A) in the polymer of this invention, for example, it can be set to about 0 to 30% by weight, but is not limited to this.

The weight-average molecular weight of the polymers of this invention is typically between 1,000 and 20,000, and is particularly desirable to be between 1,000 and 10,000. This weight-average molecular weight represents the molecular weight of polystyrene converted using gel osmosis chromatography (GPC). When the weight-average molecular weight is less than 1,000, it is considered to be almost identical to low-molecular-weight compounds, thus failing to achieve sufficient washability. Furthermore, if the molecular weight is greater than 20,000, the dispersibility/miscibility with water or organic solvents is drastically reduced, potentially leading to difficulties in handling.

2. Manufacturing method of phosphorus-containing polymers, etc. (1) Manufacturing method of phosphorus compounds The manufacturing method of the phosphorus compounds of the present invention is not particularly limited, but the method shown below may be suitably adopted, for example. That is, by the method of manufacturing the phosphorus compounds represented by the aforementioned general formula (I), i.e., the manufacturing method including the following steps, the phosphorus compounds of the present invention can be suitably obtained: (a) reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with trihalomethane triisocyanate to obtain the compound represented by the following general formula (II) (step 1): [Chemical Formula 3] [In the formula: X represents a halogen atom.], and (b) the step of reacting the compound represented by the aforementioned general formula (II) with a (meth)acrylic acid compound having a hydroxyl and/or amino group in the presence of an organic amine (step 2).

Step 1 In Step 1, 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide is reacted with trihalomethane triisocyanate to obtain the compound represented by the aforementioned general formula (II).

The trihalomethane triisocyanate used in step (a) is a compound represented by general formula (V): [Chemical Formula 4] [In the formula: ^X1 , ^X2 , and ^X3 are the same or different, representing halogen atoms.] Trihalogenated triisocyanates may also be one or more types.

As halogen atoms represented by ^X1 , ^X2 , and ^X3 , there are no particular restrictions; for example, chlorine atoms, bromine atoms, etc. can be listed.

From the perspectives of operability and economy, trihalomethanes are preferred as trihalomethanes, compounds in the general formula (V) where ^X1 , ^X2 , and ^X3 are all chlorine atoms. Trichloroisocyanurates are known compounds used as disinfectants/bactericides for swimming pools, and commercially available products are also available. Examples of commercially available products include "STARTRICHLON PG (90% available chlorine in granules)" from Nankai Chemical Co., Ltd., and "Neochlor 90W (90% available chlorine in granules)" from Shikoku Chemical Co., Ltd.

The amount of trihalomethane used is not limited, but from the perspective of yield and ease of synthesis, it is usually set to about 0.1 to 1 mol relative to 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and preferably 0.2 to 0.6 mol, and even more preferably 0.3 to 0.4 mol.

The aforementioned reaction can be carried out in the presence of an organic solvent as needed. That is, a liquid-liquid reaction can be appropriately employed. The organic solvent is not limited to any particular type; hydrocarbon solvents such as benzene, toluene, xylene, and n-hexane; ether solvents such as tetrahydrofuran and dialkylene; and ester solvents such as ethyl acetate and butyl acetate, or any other general aprotic organic solvent, can be used. One or more of these solvents can be used. Among these, a hydrocarbon solvent is preferred in this invention.

The reaction temperature in step 1 is not particularly limited, but from the perspective of reaction yield and purity, it is better to set it below 50°C, and even better to set it between 0 and 40°C, especially after all the trihalomethane isocyanate has been added) between 0 and 20°C.

As a preferred embodiment of the invention, for example, a step of intermittently adding trihalomethane triisocyanate to a feed solution containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and an organic solvent can be adopted. In this way, by adjusting the amount of trihalomethane triisocyanate added each time, the liquid temperature can be easily controlled within the aforementioned range.

The reaction time mentioned above is not particularly limited; for example, it can be set to about 10 minutes to 8 hours, and it is particularly preferable to set it to 30 minutes to 4 hours.

This process, through step 1, yields a compound represented by general formula (II): [Chemical Formula 5] [In the formula: X represents a halogen atom.]

The halogen atom represented by X is determined by the halogen atom in the trihalomethane triisocyanate used in step 1. For example, in the case of using trichlorotriisocyanate, X in the compound obtained in step 1 will become a chlorine atom.

The progress of the reaction in step 1 can be tracked using the usual methods of chromatography. Furthermore, the structure of the reaction products can be identified by methods such as elemental analysis, MS (ESI-MS) analysis, IR analysis, ^1H -NMR, and ^13C -NMR.

After the reaction in step 1 is completed, the solvent can be removed by distillation, and the reaction products can be separated and purified by conventional methods such as chromatography or recrystallization. In this invention, separation and purification can also be omitted, and the reaction products in step 1 can be used as is in step 2.

Step 2: In step 2, the compound represented by the aforementioned general formula (II) is reacted with a (meth)acrylic acid compound having a hydroxyl and/or amino group in the presence of an organic amine. This reaction esterifies the halogen group X of the aforementioned general formula (II), introducing an acrylonitrile or methacrylonitrile.

The aforementioned (meth)acrylic acid compounds are any substances having a hydroxyl group and/or an amino group, such as at least one of the following: 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxyphenyl acrylate, 4-hydroxyphenyl methacrylate, N-(hydroxymethyl)acrylamide, N-(hydroxymethyl)methacrylamide, N-(hydroxyethyl)acrylamide, N-(hydroxyethyl)methacrylamide, N-(4-hydroxyphenyl)acrylamide and N-(4-hydroxyphenyl)methacrylamide, but are not limited to these.

The amount of (meth)acrylic acid compounds containing hydroxyl and/or amino groups used is not limited, but from the viewpoint of yield and ease of synthesis, it is usually set to about 0.5 to 1.5 mol relative to 1 mol of the compound represented by the aforementioned general formula (II), particularly preferably to 0.8 to 1.2 mol, and even more preferably to 1.0 to 1.1 mol.

The aforementioned reaction can be carried out in the presence of an organic solvent, as needed. That is, a liquid-liquid reaction can be appropriately employed. The organic solvent is not limited; hydrocarbon solvents such as benzene, toluene, xylene, and n-hexane; ether solvents such as tetrahydrofuran and dialkylene; ester solvents such as ethyl acetate and butyl acetate, and other general aprotic organic solvents can be used. One or more of these solvents can be used.

Furthermore, the organic amine used in step 2 is not particularly limited, and examples include at least one tertiary amine selected from the following: trimethylamine (TMA), triethylamine (TEA), tripropylamine (TPA), tributylamine (TBA), pyridine, N,N-dimethylaniline, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene, and 4-dimethylaminopyridine. Among these, trialkylamines such as TMA, TEA, TPA, and TBA are preferred, and triethylamine is more preferred from the viewpoints of ease of use and cost.

Depending on the need, various additives may also be added in step 2. For example, polymerization inhibitors such as dibutylhydroxytoluene may be added.

The reaction temperature in step 2 is not particularly limited, but from the perspective of reaction yield and purity, it is better to set it below 50°C, and ideally it is set between 0 and 40°C.

The reaction time in the aforementioned reaction can be set to, for example, 10 minutes to about 8 hours, but is not limited to this.

The progress of the reaction in step 2 can be tracked using the usual methods of chromatography. Furthermore, the structure of the reaction products can be identified by methods such as elemental analysis, MS (ESI-MS) analysis, IR analysis, ^1H -NMR, and ^13C -NMR.

After the reaction in step 2 is complete, the solvent can be removed by distillation, and the purification reaction products can be separated and purified by conventional methods such as chromatography or recrystallization. This process can be repeated to obtain the specified phosphorus compounds.

(2) Method for manufacturing phosphorus-containing polymer The phosphorus-containing polymer of the present invention can be suitably manufactured by a method comprising the following steps: feeding one or more raw materials comprising a phosphorus compound represented by the aforementioned general formula (I) into a polymerization reaction.

As mentioned above, any of the following can be used as raw materials: including raw materials of one phosphorus compound represented by (a) the aforementioned general formula (I); including raw materials of two or more phosphorus compounds represented by (b) the aforementioned general formula (I); including raw materials of one phosphorus compound represented by (c) the aforementioned general formula (I) and a phosphorus-free (meth)acrylic acid compound; including raw materials of two or more phosphorus compounds represented by (d) the aforementioned general formula (I) and a phosphorus-free (meth)acrylic acid compound, etc.

During the polymerization reaction, various polymerization methods can be used, such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, precipitation polymerization, etc. However, from the perspective of precise molecular weight control below 20,000, solution polymerization is preferred.

In the case of solution polymerization, polymerization can be carried out using generally known methods. For example, raw materials containing phosphorus compounds and chain transfer agents as needed can be placed in an organic solvent, and in the presence of a polymerization initiator, inert gases such as nitrogen and argon are used for polymerization, while the solution is heated and stirred to obtain a phosphorus-containing polymer.

The reaction conditions can be set appropriately depending on the reaction solvent used, but phosphorus-containing polymers can usually be obtained by continuously stirring at a temperature of about 40~120°C for about 1~48 hours.

As a chain transfer agent, well-known or commercially available chain transfer agents can be used. Examples of such chain transfer agents include: thioglycolic acid, 2-caprylic acid, 3-caprylic acid, thiomalic acid, and other caprylic carboxylic acids; caprylic esters such as methyl caprylate, methyl 3-caprylate, 2-ethylhexyl 3-caprylate, n-octyl 3-caprylate, methoxybutyl 3-caprylate, stearate 3-caprylate, trimethylolpropane (3-caprylate), neopentyl tetroxide (3-caprylate), dinepentyl tetroxide (3-caprylate); ethyl mercaptan, ... Alkyl thiols such as tributylthiol, n-dodecylthiol, and 1,2-dithioethane; thioethanol, 4-thio-1-butanol, and α-thioglycerol; aromatic thiols such as benzylthiol, m-toluenethiol, p-toluenethiol, and 2-naphthylthiol; disulfides such as 2-hydroxyethyl disulfide and tetraethylthiuram disulfide; dithiocarbamates such as benzyl diethyl dithiocarbamate; and monomer dimers such as α-methylstyrene dimer, but not limited to these. These can be used alone or in combination of two or more. In this invention, it is particularly desirable to use thiocarboxylic acids as chain transfer agents.

The amount of chain transfer agent added during polymerization is not particularly limited, but it is preferably set to about 0.01 to 0.5 equivalents relative to phosphorus-containing (meth)acrylic acid monomer (general formula I), and even more preferably to 0.05 to 0.3 equivalents.

As a polymerization initiator, a well-known or commercially available polymerization initiator can be used, including peroxide-based, azo-based, and redox-based polymerization initiators. More specifically, examples include at least one of the following: 2,2’-azobis(isobutyronitrile), 2,2’-azobis(2,4-dimethylvaleronitrile), 2,2’-azobis(2-methylbutyronitrile), dimethyl 2,2’-azobis(2-methylpropionic acid), 4,4’-azobis(4-cyanocyclooxalic acid), benzoyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, and diisopropylphenyl peroxide.

There is no limit to the amount of polymerization initiator used, but it is generally appropriate to use it in the range of 0.01 to 5 parts by weight relative to 100 parts by weight of phosphorus-containing (meth)acrylic acid monomer.

When the aforementioned monomer components are polymerized by solution polymerization, the solvent used for polymerization is not particularly limited as long as it is inactive in the polymerization reaction. At least one of water and organic solvents can be used as the solvent. Examples of organic solvents include: monools such as methanol, ethanol, isopropanol, and n-butanol; diols such as ethylene glycol and propylene glycol; cyclic ethers such as tetrahydrofuran, dialkylene, and 4-methyltetrahydropiperanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, 3-methoxybutanol, etc. Glycol monoethers; glycol monoethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, etc.; glycol monomethyl ether acetate, glycol monoethyl ether acetate, glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, etc. Esters of glycol monomethyl ether acetates, propylene glycol monoethyl ether acetates, propylene glycol monobutyl ether acetates, dipropylene glycol monomethyl ether acetates, dipropylene glycol monoethyl ether acetates, dipropylene glycol monobutyl ether acetates, 3-methoxybutyl acetates, etc.; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, methyl 3-methoxypropionate, etc. Alkyl esters such as esters, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl acetoacetate, and ethyl acetoacetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, cyclohexane, and octane; amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and phosphorus-containing hydrocarbons such as chloroform and dichloroethane. These can be used alone or in combination of two or more.

The amount of organic solvent used is not particularly restricted, but it can generally be used in the range of 100 to 5000 parts by weight relative to 100 parts by weight of phosphorus-containing (meth)acrylic acid monomer.

3. Flame Retardant for Fibers This invention contains a flame retardant for fibers comprising the polymer of the invention (the flame retardant of the invention). The flame retardant of the invention can be suitably used to impart flame retardancy to fibers (particularly synthetic fibers, preferably polyester fibers). More specifically, the flame retardant of the invention can be suitably used to perform flame retardant processing on fiber products through post-processing.

The flame retardant of this invention may also include secondary components as needed, to the extent that it does not impair the effectiveness of the invention. For example, as a component other than the polymer of this invention, a halogen-free flame retardant component (hereinafter also referred to as "secondary flame retardant component") may be appropriately used.

As the aforementioned second flame-retardant component, it may be appropriately blended with, to the extent that it does not impair the flame-retardant function of the polymer of the present invention, compounds such as phosphorus-containing compounds, nitrogen-containing compounds, sulfur-containing compounds, silicon-containing compounds, and inorganic metal compounds. In the present invention, these second flame-retardant components may be used alone or in combination of two or more. Furthermore, these second flame-retardant components may also be well-known or commercially available substances.

Examples of the aforementioned phosphorus-containing compounds include: a) amine salts or metal salts of non-condensed or condensed phosphoric acids such as red phosphorus, phosphoric acid, and phosphorous acid; b) inorganic phosphorus-containing compounds such as boron phosphate; and c) phosphorus-containing compounds such as orthophosphate esters or their condensates, phosphoamine phosphates, phosphonates, and hypophosphonates.

Examples of the aforementioned nitrogen-containing compounds include: a) triazine or triazole compounds or their salts [metal salts, (poly)phosphates, sulfates], b) urea compounds, (poly)phosphamides, hindered amines (HALS, especially NOR-type HALS, etc.).

Examples of sulfur-containing compounds mentioned above include: a) organic sulfonic acids [alkyl sulfonic acids, aromatic sulfonic acids] or their metal salts; b) sulfonated polymers; c) organic sulfonamides or their salts [ammonium salts, metal salts], etc.

Examples of the aforementioned silicone-containing compounds include: a) resins containing (poly)siloxanes, b) elastomers containing (poly)siloxanes, c) silicone compounds such as oils containing (poly)siloxanes, and d) zeolites.

As for the aforementioned inorganic metal compounds, compounds other than those mentioned above can be listed, such as: a) metal salts of inorganic acids such as antimonates and borates; b) metal oxides such as antimony trioxide and antimony pentoxide; c) metal hydroxides such as aluminum hydroxide and magnesium hydroxide; d) metal sulfides, etc.

The content of the second flame retardant component is not particularly limited, but it may be set, for example, in the range of polymer/second flame retardant component (weight ratio) of 100/1 to 100/50, and particularly in the range of 100/1 to 100/10.

The properties and state of the flame retardant of this invention are not particularly limited and can be appropriately changed according to the form/purpose, application, and target user. Furthermore, it can be in the same form as well-known or commercially available flame retardants (or flame retardant processing agents). Therefore, it can be suitably adopted in forms such as solutions, dispersions, latexes, and aerosols. That is, the polymer of this invention can be dissolved or dispersed in water, organic solvents, etc., depending on the type and shape of the fiber product, for example. The concentration (solid fraction) of the polymer of this invention during dissolution or dispersion can typically be suitably prepared in the range of approximately 1 to 50% by weight, but is not limited to this.

In the case of a solution formed by dissolving the polymer of the present invention in an organic solvent, the polymer of the present invention can be dissolved simply by stirring in the organic solvent. Furthermore, in the case of dispersions or latexes made using aqueous media, it is desirable to add dispersants, emulsifiers, etc., as needed to improve dispersibility/emulsification. As a dispersant or emulsifier, there are no particular limitations on any substance that can improve dispersibility/emulsification, and various dispersants or emulsifiers can be used.

At this time, the aqueous medium can be 1) water alone or 2) a mixed solvent containing water and organic solvent.

As organic solvents, examples include polar organic solvents that are highly soluble in water, such as methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, propylene glycol, dipropylene glycol, tripropylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monotert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether. Also included are petroleum-based solvents that can emulsify with water, such as toluene, xylene, and mineral turpentine. These solvents can be used alone or in mixtures of two or more.

When using mixed solvents, the content of organic solvent is not particularly limited. It can be set appropriately by considering the type of organic solvent, the degree of dispersion or emulsification, etc., but it is usually set to 1 to 50% by weight, and preferably in the range of 3 to 30% by weight.

Furthermore, the aforementioned dispersant or emulsifier is not limited, and well-known or commercially available surfactants may be used. In particular, in this invention, at least one of anionic surfactants and nonionic surfactants is suitable.

Examples of anionic surfactants include at least one of the following: higher alcohol sulfate salts, polyoxyethylene alkylphenyl sulfate salts, sulfur-oxidized fatty acid ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, higher alcohol phosphate salts, and polyoxyethylene stilbene phenolic ether sulfates.

As nonionic surfactants, examples include at least one of the following: polyoxyalkyl natural oil alkyl ethers, polyoxyalkyl higher alcohol alkyl ethers, polyoxyalkyl alkyl phenyl ethers, and polyol fatty acid esters.

There is no particular limitation on the amount of surfactant added. For example, the type of surfactant, the degree of dispersion or emulsification, etc. can be considered to set it appropriately. However, when the dispersion medium (emulsification medium) is an aqueous medium, it is usually set to about 0.1 to 30% by weight, and preferably about 0.3 to 20% by weight.

Furthermore, dispersing stabilizers or emulsifying stabilizers may be used as needed. Examples of dispersing stabilizers include at least one of the following: polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, succinate, starch paste, etc. Examples of emulsifying stabilizers include at least one of the following: triglycerides of castor oil (polyoxyethylene-cured castor oil, etc.), rapeseed oil, etc.; esters such as phosphate esters and phthalates; and higher alcohols, etc.

The amount of these stabilizers added is not particularly limited and can be appropriately set by considering factors such as the type of stabilizer and the degree of dispersion or emulsification. However, when the dispersion medium (emulsifying medium) is an aqueous medium, the total amount of the dispersion stabilizer or emulsifying stabilizer is usually set to about 0.1 to 10% by weight, preferably about 0.3 to 3% by weight.

Other additives can be used, such as those currently used in well-known or commercially available flame-retardant processing agents. Examples include: pastes, colorants, softeners, light stabilizers, antioxidants, UV absorbers, penetrants, humectants, deodorizing agents, antistatic agents, and stain inhibitors. The amount added can be appropriately set according to the type of flame-retardant processing.

The flame retardant of the present invention preferably comprises at least one of the aforementioned surfactants (anionic surfactants and nonionic surfactants) and two of the dispersant or emulsion stabilizers. For example, as a suitable component of the flame retardant of the present invention, when the dispersion medium (emulsion medium) is an aqueous medium, the polymer of the present invention is set at about 1 to 50% by weight, preferably about 5 to 50% by weight; the surfactant is set at about 0.1 to 30% by weight, preferably about 0.3 to 20% by weight; and the dispersant or emulsion stabilizer is set at about 0.1 to 10% by weight, preferably about 0.3 to 3% by weight. Therefore, the composition can also be, for example, approximately 20-54% by weight of the polymer of this invention, approximately 5-20% by weight of surfactant, approximately 1-3% by weight of dispersant or emulsifying stabilizer, and approximately 40-60% by weight of aqueous medium.

The flame retardant of this invention can be appropriately prepared by micronization, for example, after mixing the specified components, using an emulsifying device such as a homogenizer, high-pressure homogenizer, or ultrasonic homogenizer, or a dispersing device such as a ball mill or bead mill.

The microparticle conditions are not particularly limited, but in the obtained dispersion or latex, it is acceptable to set the average particle size of the dispersed microparticles (including microparticles of the polymer of the present invention) to be less than 10 μm. It is usually preferred to set it to about 0.05~5 μm, and even more preferably to set it to 0.1~5 μm.

4. Flame-retardant fiber products This invention includes flame-retardant fiber products comprising fibers and the flame retardant of the invention. More specifically, it includes flame-retardant fiber products formed by spreading the flame retardant of the invention onto fibers.

The type of fiber is not particularly limited; at least one of natural fibers, chemical fibers, inorganic fibers, and composite fibers thereof may be used. Specifically, examples of natural fibers include cotton, linen, silk, and wool. Examples of chemical fibers include rayon, acetate, polyester, nylon, acrylic, polyurethane, polypropylene, and cellulose. Examples of inorganic fibers include glass fiber, carbon fiber, and metal fiber. Furthermore, blends of these fibers may also be used appropriately.

In this invention, from the viewpoint of the adhesion and processability of the flame-retardant component, synthetic fibers are preferred, and more particularly preferred are polyester fibers. Polyester fibers are not limited to any one of the following: polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PET) fibers, polymethylene terephthalate (PTA) fibers, and polylactic acid (PLA) fibers.

In addition to monofilaments (short or long fibers), fibers can also be in the form of fabrics or non-woven fabrics. Therefore, the flame retardant of this invention can also be applied to pre-made fabrics or non-woven fabrics or products using such fibers (clothing, furniture, vehicle parts, daily necessities, etc.).

The method for flame-retardant processing of fibers using the flame retardant of this invention is not limited; for example, it can be carried out by fixing the flame retardant of this invention onto the fibers. Therefore, the method for manufacturing flame-retardant fiber products of this invention includes the step of bringing the flame retardant of this invention into contact with the fibers.

The manufacturing method (especially the fixation method) of the flame-retardant fiber product of this invention can be any method that allows the flame retardant of this invention to come into contact with the fiber (especially as long as the flame retardant of this invention can be applied to the surface of the fiber). Therefore, for example, impregnation, coating, spraying, brushing, etc., can be used to adhere about 1 to 50% by weight of the flame retardant of this invention, equivalent to the solid portion per unit area of the fabric, to at least one side of the entire surface of the fabric, and, if necessary, perform a hardening treatment to allow it to penetrate into the interior by heat treatment.

More specifically, it can be implemented by a method comprising the following steps: a) drying the fibers at a temperature below 120°C after the flame retardant of the present invention has come into contact with them; and b) heat-treating the fibers containing the flame retardant of the present invention at a temperature of approximately 140 to 180°C.

The method of bringing the flame retardant of this invention into contact with fibers is not particularly limited. As mentioned above, examples include: impregnating fibers with the flame retardant of this invention, spraying or applying the flame retardant of this invention to fibers, etc. The contact time is not particularly limited and can be appropriately set according to the type of fiber used and the degree of flame retardancy.

The drying method is not particularly limited; natural drying or heated drying can be used. When using heated drying, the ideal drying temperature is around 60-120°C. The ideal drying time is around 10 seconds to 30 minutes.

Alternatively, depending on the need, the fibers can be heat-treated (thermo-curing treatment) at approximately 140-180°C (preferably 140-160°C) after drying. This treatment allows the polymer of the present invention to be more firmly bonded to the interior and surface of the fibers. The treatment method is not particularly limited; it can be implemented by, for example, heating a roller transporting the fibers (fabric) to the aforementioned temperature, or by passing it through an ambient gas furnace set to the aforementioned temperature. The treatment time can be appropriately set according to factors such as the heat treatment temperature and the degree of bonding of the flame retardant of the present invention, but it is typically set to approximately 30 seconds to 5 minutes, preferably approximately 1 to 2 minutes.

The polymer of the present invention (phosphorus-containing polymer microparticles or microparticles of a second flame-retardant component added simultaneously) contained in the flame retardant of the present invention, when its average particle size is sufficiently small to 0.01~10μm, can easily diffuse/adhere to the entire tissue of the fiber surface through thermosetting treatment, thereby producing high-quality flame-retardant fiber products. Therefore, it is preferable that the average particle size of the aforementioned microparticles is set within the aforementioned range, and more preferably 0.05~5μm.

The flame-retardant fiber products of this invention are particularly characterized by the fact that the flame retardant contained in the polymer of this invention (which uses a phosphorus-containing compound represented by general formula (I) as a monomer) as a flame-retardant component is fixed in the product, and due to its inherently highly flame-retardant properties, it can prevent the fiber from burning. Furthermore, since the polymer of this invention does not easily detach from washing like low-molecular-weight compounds, it has high washing durability and can effectively suppress the reduction of flame retardancy caused by washing, such as water washing and dry cleaning. In particular, it exhibits excellent effects when washing with polar solvents such as water and alcohol.

Furthermore, the flame-retardant fiber products of this invention differ from flame-retardant fiber products made from fabrics or textiles made from flame-retardant fibers. They can be appropriately endowed with flame retardancy through post-processing as needed for all general-purpose non-flame-retardant fiber products, thus without significantly compromising the original properties of the fiber products. This invention is suitable for both small-batch and large-batch production. Example

The present invention is illustrated in more detail by the following embodiments and comparative examples. However, the present invention is not limited to these embodiments. Furthermore, the "%" in the embodiments refers to "weight %".

<1. Synthesis of the Compound> After synthesizing a phosphorus-containing (meth)acrylic acid monomer using the following synthesis example, a chain transfer agent was added to control the molecular weight and polymerize it, thereby synthesizing a phosphorus-containing (meth)acrylic acid polymer. Furthermore, the synthesized compound was identified and its molecular weight was measured by the following methods. (1) Tracking of the reaction: The reaction was monitored by a gas chromatography system (GC-2010: manufactured by Shimadzu Corporation) equipped with a flame ionization detector (FID). (2) Measurement of molecular weight: The weight average molecular weight was measured by a gel permeation chromatography system (GPC Alliance System: manufactured by Waters Corporation) equipped with a differential refractive index (RID) detector, which was converted from polystyrene values. Furthermore, in the aforementioned GPC, the product name "Styragel (registered trademark) HR1 (column length: 4.6×300mm): manufactured by Waters Corporation" was used as the column. (3) Identification of chemical structure: ^1H -NMR, ^13C -NMR and IR were obtained from the hydrogen nuclear magnetic resonance ( ^1H -NMR) spectrum and carbon nuclear magnetic resonance ( ^13C -NMR) spectrum of a 600MHz superconducting nuclear magnetic resonance analyzer (JNM-ECA600: manufactured by Nippon Electronics Co., Ltd.), and from the infrared absorption (IR) spectrum of a Fourier transform infrared spectrophotometer (IRAffinity-1S: manufactured by Shimadzu Corporation).

Synthesis Example 1 <Synthesis of (meth)acrylic acid monomer (1)> 500 g of 9,10-dihydro-9-oxa-10-phosphenanthroline-10-oxide [Sanko Chemicals] and 2229 g of toluene [Ando Parachemie Chemicals] were placed in a four-necked flask equipped with a dropping funnel with a side tube and a thermometer, and stirred and cooled to below 20°C under a nitrogen atmosphere. 179 g of trichloroisocyanuric acid [Fujifilm and Hikari Chemicals] was added in 6 portions to carry out chlorination. The addition of trichloroisocyanuric acid was appropriately carried out with the reaction temperature usually below 40°C. After addition, the mixture was further stirred at below 20°C for 2 hours. Add 7.5 mL of anisole [Tokyo Chemical Industry Co., Ltd.] and stop the reaction. Then, under an air atmosphere prepared by dehydration from a nitrogen atmosphere, add 0.25 g of dibutylhydroxytoluene [Honshu Chemical Industry Co., Ltd.] (a polymerization inhibitor for acrylonitrile) and 412 g of triethylamine [Kishida Chemical Co., Ltd.]. Next, add 274 g of 2-hydroxyethyl acrylate [Tokyo Chemical Industry Co., Ltd.] dropwise at a rate that keeps the reaction temperature below 40°C using a dropping funnel with a side tube, and stir for 6 hours. After stopping the reaction with water, wash with water, saturated sodium bicarbonate solution, saturated ammonium chloride solution, and saturated brine. After the reaction solution was concentrated by depressurization in an evaporator, recrystallization was carried out using a toluene-hexane mixed solvent, thereby obtaining 531 g of a white powder (70% yield). Measurements by ^1H -NMR and ^13C -NMR confirmed that the obtained compound was a phosphorus-containing acrylic acid monomer of formula (1) below. [Formula 6] ¹ H-NMR (600MHz, CDCl ₃ ; internal standard TMSδppm) 7.93-8.00(m,3H),7.73(br t,J＝7.8Hz,1H),7.52(br td,J＝4.8,7.8Hz,1H),7.38(br t,J＝7.8Hz,1H),7,27(br t,J＝8.4Hz,1H),7.22(brd,J＝8.4Hz,1H),6.34(dd,J＝1.2,17.4Hz,1H),6.01(dd,J＝1 0.2,17.4Hz,1H),5.80(dd,J＝1.2,10.2Hz,1H),4.38-4.41(m,2H),4.29-4.30(m,2H) ¹³ C-NMR (151MHz, _CDCl3 ; internal standard TMS δppm) 165.8, 149.9, 137.2, 133.8, 131.6, 130.7, 130.3, 128.4, 127.9, 125.3, 124.9, 124.2, 122.6, 121.3, 120.3, 64.2, 63.2 <Synthesis of phosphorus-containing (meth)acrylic acid polymer (2)> 100g of phosphorus-containing acrylic acid monomer (1), 6.43g of hydroxypropionic acid, and 1.15g of 2,2'-azobis(isobutyronitrile) [Fujifilm and Kohsen Pharmaceutical Co., Ltd.] synthesized in (1) above. 1.39 L of ethyl acetate [Lin Chun Pharmaceutical Co., Ltd.] was added to a four-necked flask equipped with a thermometer, nitrogen inlet tube, and Deutsche condenser. The reaction temperature was set to 65°C under a nitrogen atmosphere, and the mixture was allowed to mature for 16 hours. After confirming the disappearance of the phosphorus-containing acrylic monomer by GC, the solvent was removed by reduced pressure distillation and dissolved in chloroform. Reprecipitation was then carried out with hexane/ethyl acetate = 1:1 (w/w) to obtain 105.4 g (98% yield) of a white solid polymer represented by the following formula (2). The weight average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 2200 (converted from polystyrene). [Formula 7]

Synthesis Example 2: 10.0 g of phosphorus-containing acrylic acid monomer [compound (1)] synthesized in Synthesis Example 1, 161 mg of hydroxypropionic acid, 100 mg of 2,2'-azobis(isobutyronitrile), and 100 g of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 13 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 9.44 g (92% yield) of a white solid polymer represented by formula (2). After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 6000 (converted from polystyrene).

Synthesis Example 3: 10.0 g of phosphorus-containing acrylic acid monomer [compound (1)] synthesized in Synthesis Example 1, 107 mg of hydroxypropionic acid, 100 mg of 2,2'-azobis(isobutyronitrile), and 100 g of ethyl acetate were mixed. The reaction temperature was set at 65 °C under a nitrogen atmosphere and allowed to mature for 13 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 9.13 g (89% yield) of a white solid polymer represented by formula (2). After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 14000 (converted from polystyrene).

Synthesis Example 4 <Synthesis of (Meth)acrylic Acid Monomer (3)> Except for the synthesis of the phosphorus-containing acrylic acid monomer obtained in Synthesis Example 1 [Compound (1)], in which 2-hydroxyethyl acrylate was replaced with 301g of 2-hydroxyethyl methacrylate [Light Ester HO-250(N): Kyoei Kagaku (Stock) Ltd.], and the recrystallization treatment was replaced with rapid column chromatography, the reaction was carried out in the same manner to obtain 700g of a colorless liquid (yield 88%) of the compound. The results of ^1H -NMR and ^13C -NMR measurements confirmed that the obtained compound was the phosphorus-containing methacrylic acid monomer of the following formula (3). [Chemical Formula 8] ^¹H -NMR (600MHz, _CDCl₃ ; internal standard TMS δppm): 7.91-7.98 (m, 3H), 7.71 (t, J = 7.8 Hz, 1H), 7.50 (td, J = 4.8, 7.8 Hz, 1H), 7.37 (br t, J = 7.8 Hz, 1H), 7.26 (br t, J = 6.6 Hz, 1H), 7.21 (br d, J = 8.4 Hz, 1H), 6.00 (s, 1H), 5.51 (br s, 1H), 4.37-4.41 (m, 2H), 4.27-4.29 (m, 2H), 1.84 (br s, 3H) ^¹³C -NMR (151MHz, _CDCl₃ ; internal standard TMS δppm) 149.8,137.0,135.6,133.6,130.6,130.2,128.3,126.3,125.2,124.8,124.1,122.4,121.3,120.1,64.1,63.2,18.2 <Synthesis of phosphorus-containing (meth)acrylic acid polymer (4)> 10.0 g of the previously synthesized phosphorus-containing methacrylic acid monomer [compound (3)], 617 mg of 3-methylpropionic acid, 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate were mixed. The reaction temperature was set at 65 °C under a nitrogen atmosphere and allowed to mature for 14 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by redeposition with hexane/ethyl acetate at a ratio of 1:1 (w/w) to obtain 10.1 g (94% yield) of a white solid polymer (4). The weight-average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 2200 (converted from polystyrene). [Formula 9]

Synthesis Example 5 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (5)> 10.0 g of phosphorus-containing acrylic acid monomer [compound (1)] synthesized in Synthesis Example 1, 1.23 g of n-dodecyl mercaptan [Tokyo Chemical Industry Co., Ltd.], 100 mg of 2,2'-azobis(isobutyronitrile) and 100 g of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 13 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 8.61 g (76% yield) of white solid polymer (5). After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 2300 (converted from polystyrene). [Formula 10]

Synthesis Example 6 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (6)> 10.0 g of phosphorus-containing acrylic acid monomer [compound (1)] synthesized in Synthesis Example 1, 473 mg of 2-methylethanol [Tokyo Chemical Industry Co., Ltd.], 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 17 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 9.83 g (93% yield) of white solid polymer (6). After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 1700 (converted from polystyrene). [Formula 11]

Synthesis Example 7 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (7)> 10.0 g of phosphorus-containing acrylic acid monomer [compound (1)] synthesized in Synthesis Example 1, 655 mg of α-thioglycerol [Tokyo Chemical Industry Co., Ltd.], 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 14 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 10.3 g (96% yield) of white solid polymer (7). The weight average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 1800 (converted from polystyrene). [Formula 12]

Synthesis Example 8 <Synthesis of (meth)acrylic acid monomer (8)> Except for the synthesis of the phosphorus-containing acrylic acid monomer obtained in Synthesis Example 1 [compound (1)], in which 2-hydroxyethyl acrylate was replaced with 513g of 2-hydroxy-3-phenoxypropyl acrylate [Tokyo Chemical Industry Co., Ltd.], and recrystallization was replaced with rapid column chromatography, the reaction was carried out in the same manner to obtain 645g of a colorless liquid (64% yield). The results of ^1H -NMR and ^13C -NMR confirmed that the obtained compound was the phosphorus-containing acrylic acid monomer of the following formula (8). [Formula 13] ^¹H -NMR (600MHz, _CDCl₃ ; internal standard TMS δppm) 7.90-7.97 (m, 3H), 7.69-7.73 (m, 1H), 7.46-7.52 (m, 1H), 7.16-7.37 (m, 5H), 6.93-6.98 (m, 1H), 6.82 (dd, J = 1.2, 9.0 Hz, 1.33H), 6.77 (d, J = 8.4) Hz, 0.67H), 6.33-6.43 (m, 1H), 5.99-6.08 (m, 1H), 5.81-5.86 (m, 1H), 5.18-5.33 (m, 1H), 4.43-4.50 (m, 1.33H), 4.34-4.38 (m, 0.67H), 4.15 (t, J = 4.8 Hz, 1.33H), 3.98-4.00 (m, 0.67H) ¹³ C-NMR (151MHz, _CDCl3 ; internal standard TMS δppm) 165.5,165.2,158.0,149.8,137.0,133.6,132.0,131.7,130.5,130.3,129.5,128.3,127.7,125.2,124.7,124.0,122.6,122.3,121.4,120.2,144.6,73.3,70.3,67.0,64.9,64.1,63.6 <Synthesis of phosphorus-containing (meth)acrylic acid polymer (9)> 10.0 g of the aforementioned synthesized phosphorus-containing acrylic acid monomer compound [compound (8)], 471 mg of 3-methylpropionic acid, 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate. The reaction was carried out at 65°C under a nitrogen atmosphere for 15 hours. The solvent was removed by reduced pressure distillation and dissolved in ethyl acetate, followed by redeposition with hexane to obtain 9.51 g (90% yield) of a white solid polymer (9). The weight-average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 2500 (converted from polystyrene). [Formula 14]

Synthesis Example 9 <Synthesis of (meth)acrylic acid monomer (10)> Except that in the synthesis of acrylic acid monomer [compound (1)] in Synthesis Example 1, 333g of 2-hydroxyethyl acrylate was replaced with 4-hydroxybutyl acrylate [Tokyo Kasei Corporation], and the recrystallization treatment was replaced with rapid column chromatography, the reaction was carried out in the same manner to obtain 620g of a colorless liquid (75% yield). The results of ^1H -NMR and ^13C -NMR measurements confirmed that the obtained compound was a phosphorus-containing acrylic acid monomer of the following formula (10). [Formula 15] ¹ H-NMR (600MHz, CDCl ₃ ; internal standard TMSδppm) 7.93-7.99(m,3H),7.73(t,J＝8.4 Hz,1H),7.52(br td,J＝4.8,7.8Hz,1H),7.39(br t,J＝7.8 Hz,1H),7.27(br t,J＝7.8 Hz,1H),7.24(dd,J＝1.2,8.4 Hz,1H),6.36(dd,J＝1.2,17.4 Hz,1H),6.07(dd,J＝10.2,17.4 Hz,1H),5.80(br d,J＝10.2 Hz,1H),4.19(dt,J=6.0,6.6 Hz, 2H), 4.06 (t, J = 6.6 Hz, 2H), 1.69-1.73 (m, 2H), 1.58-1.63 (m, 2H) ¹³ C-NMR (151 MHz, _CDCl3 ; internal standard TMS δppm) 166.1, 149.9, 137.0, 133.5, 130.7, 130.5, 130.1, 128.4, 128.3, 125.3, 124.8, 124.1, 122.7, 121.6, 120.1, 66.1, 63.7, 27.0, 24.7 <Synthesis of phosphorus-containing (meth)acrylic acid polymer (11)> Mixed with the aforementioned synthesized 10.0 The reaction mixture consisted of 592 mg of a phosphorus-containing acrylic monomer [compound (10)], 592 mg of 3-methylpropionic acid, 100 mg of 2,2'-azobis(isobutyronitrile), and 100 mL of ethyl acetate. The reaction was carried out at 65 °C under a nitrogen atmosphere for 14 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate at a ratio of 1:1 (w/w) to obtain 9.30 g (87% yield) of a pale yellow solid polymer (11). The weight-average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 2000 (converted from polystyrene). [Formula 16]

Synthesis Example 10 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (12)> 10.0 g of phosphorus-containing acrylic acid monomer [compound (10)] synthesized in Synthesis Example 9, 816 mg of 2-ethyl-1-hexanethiol [Tokyo Chemical Industry Co., Ltd.], 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 14 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, and then redetermined with hexane/ethyl acetate = 1:1 (w/w) to obtain 8.86 g (yield 81%) of polymer (12) as a yellow viscous liquid. After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 1900 (converted from polystyrene). [Chemical Formula 17]

Synthesis Example 11 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (13)> 10.0 g of phosphorus-containing acrylic acid monomer [compound (10)] synthesized in Synthesis Example 9, 1.14 g of 2-ethylhexyl thioglycolate [Tokyo Chemical Industry Co., Ltd.], 100 mg of 2,2'-azobis(isobutyronitrile) and 100 mL of ethyl acetate were mixed. The reaction temperature was set at 65°C under a nitrogen atmosphere and allowed to mature for 14 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, and then redetermined with hexane/ethyl acetate = 1:1 (w/w) to obtain 10.6 g (95% yield) of polymer (13) as a yellow viscous liquid. After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 2300 (converted from polystyrene). [Chemical Formula 18]

Synthesis Example 12 <Synthesis of Phosphorus-Containing (Meth)acrylic Acid Polymer (14)> 10.0 g of the phosphorus-containing acrylic monomer [compound (1)] synthesized in Synthesis Example 1 was mixed with 100 mg of 2,2'-azobis(isobutyronitrile) and 100 g of ethyl acetate without the addition of hydroxypropionic acid. The reaction was carried out at 65°C under a nitrogen atmosphere for 13 hours. The solvent was removed by depressurized distillation and dissolved in chloroform, followed by reprecipitation with hexane/ethyl acetate = 1:1 (w/w) to obtain 10.0 g (100% yield) of a white solid polymer (14). The weight average molecular weight (Mw) of the obtained phosphorus-containing polymer was measured to be 16000 (converted from polystyrene). [Formula 19]

Synthesis Example 13: 10.0 g of the phosphorus-containing acrylic monomer [compound (1)] synthesized in Synthesis Example 1 was mixed with 100 mg of 2,2'-azobis(isobutyronitrile) and 180 g of chloroform without the addition of hydroxypropionic acid. The reaction temperature was set at 60 °C under a nitrogen atmosphere and allowed to mature for 13 hours. After concentrating the reaction solution, it was reprecipitated with hexane/ethyl acetate = 1:1 (w/w) to obtain 7.0 g (70% yield) of a white solid polymer represented by formula (14). After measuring the GPC of the obtained phosphorus-containing polymer, the weight average molecular weight (Mw) was 18000 (converted from polystyrene).

<2. Preparation of flame retardants for fibers> Flame retardants were prepared using the phosphorus-containing polymers obtained in the above-mentioned synthesis examples as follows.

Example 1: 35 parts by weight of the phosphorus-containing polymer (2) [Mw2200] obtained by Synthesis Example 1, 7 parts by weight of polyoxyethylene styrene phenolic ether sulfate, and 3 parts by weight of polyoxyethylene hardened castor oil were placed in a container equipped with a stirrer and heated to 80°C. After mixing, 55 parts by weight of water were added little by little while stirring to emulsify the mixture. The mixture was cooled in a water bath until it reached room temperature while stirring continuously. Finally, the mixture was filtered through a gauze to obtain 100 parts by weight of a uniform milky white liquid flame retardant.

Example 2: The phosphorus-containing polymer (2) [Mw6000] obtained in Synthesis Example 2 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 3: The phosphorus-containing polymer (2) [Mw14000] obtained in Synthesis Example 3 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 4 The phosphorus-containing polymer (4) [Mw2200] obtained in Synthesis Example 4 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 5: The phosphorus-containing polymer (5) [Mw2300] obtained in Synthesis Example 5 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 6: The phosphorus-containing polymer (6) [Mw1700] obtained in Synthesis Example 6 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 7: The phosphorus-containing polymer (7) [Mw1800] obtained in Synthesis Example 7 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

In Example 8, the phosphorus-containing polymer (9) [Mw2500] obtained in Synthesis Example 8 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 9 The phosphorus-containing polymer (11) [Mw2000] obtained in Synthesis Example 9 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 10: The phosphorus-containing polymer (12) [Mw1900] obtained in Synthesis Example 10 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

In Example 11, the phosphorus-containing polymer (13) [Mw2300] obtained in Synthesis Example 11 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Example 12 uses the phosphorus-containing polymer (14) [Mw16000] obtained in Synthesis Example 12 instead of Synthesis Example 1, and emulsifies and disperses it in the same way as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

In Example 13, the phosphorus-containing polymer (14) [Mw18000] obtained in Synthesis Example 13 was used instead of Synthesis Example 1, and it was emulsified and dispersed in the same manner as in Example 1 to obtain a flame retardant that is a uniform milky white liquid.

Comparative Example 1 uses a 60% (w/w) aqueous solution of guanidine phosphate [Marumi Oil Chemical Co., Ltd. "Nonnen 984"], which is a phosphate-based flame retardant, to replace the phosphorus-containing polymer obtained in the synthesis example to make a flame retardant.

Comparative Example 2 uses a 55% (w/w) aqueous solution of condensed phosphate carbamate [Marumi Oil Chemical Co., Ltd. "Nonnen W2-50"], which is a phosphate-based flame retardant, to replace the phosphorus-containing polymer obtained in the synthesis example to make a flame retardant.

Comparative Example 3 uses an 80% (w/w) aqueous solution of a mixture of bis[(5-ethyl-2-methyl-2-sideoxy-1,3,2λ(5)-dioxophosphazenecyclohexane-5-yl)methyl]=methylphosphonate and (5-ethyl-2-methyl-2-sideoxy-1,3,2λ(5)-dioxophosphazenecyclohexane-5-yl)methyl=methyl=methylphosphonate [Maru-bishi Oil Chemical Co., Ltd. "Nonnen R031-5"] instead of the phosphorus-containing polymer obtained in the synthesis example to make a flame retardant processing agent.

Comparative Example 4 uses an aromatic phosphonate, namely 9,10-dihydro-9-oxa-10-phenoxy-10-phosphaphenanthrene-10-oxide [Maru-bishi Oil Chemical Co., Ltd. "Nonnen 73"], which is a low-molecular-weight phosphorus flame retardant, instead of the phosphorus-containing polymer obtained in the synthesis example, and wet disperses it according to the following method to obtain a uniform white dispersion liquid flame retardant processing agent. After preparing a homogeneous mixture of 40 parts by weight of 9,10-dihydro-9-oxa-10-phenoxy-10-phosphenanthroline-10-oxide, 5 parts by weight of polyoxyethylene styrene phenolic ether, 2 parts by weight of carboxymethyl cellulose (10% aqueous solution), and 53 parts by weight of water, this mixture was placed in an agate basin (crushed with 2mm diameter zirconium oxide beads) and dispersed using a planetary ball mill [made by Fritsch] at a revolution speed of 400 rpm for 2 hours to prepare a homogeneous white dispersion liquid flame retardant.

Comparative Example 5 In Synthetic Examples 12 and 13, the phosphorus-containing acrylic monomer [compound (1)] was dissolved in ethyl acetate or chloroform, and a phosphorus-containing polymer (14) with a weight average molecular weight of 16,000 to 18,000 was obtained by solution polymerization without the use of a chain transfer agent. However, in order to synthesize a polymer with a larger molecular weight, emulsion polymerization was performed. 60.0 g of the phosphorus-containing acrylic monomer [compound (1)] obtained in Synthetic Example 1 was mixed with 150 mg of sodium bicarbonate and 3.00 g of sodium dodecyl sulfate, and dissolved in 550 g of water. Nitrogen substitution was carried out over 15 minutes and the solution was heated to 80°C. 50.0 g of a 1.20% (w/w) ammonium persulfate aqueous solution was dripped over 30 minutes and allowed to mature at 80°C for 3 hours while stirring. After cooling to room temperature, the polymer was filtered through a sieve (#100) to obtain a yellowish-white emulsion (8.3% solids, 60.2 nm particle size). This polymer is insoluble in common organic solvents such as tetrahydrofuran and N,N-dimethylformaldehyde, and its molecular weight could not be measured by GPC. After measuring the residual monomer by GC, the monomer conversion rate was approximately 100%, and the IR spectra of the obtained polymer (Fig. 1) and the polymer obtained in Synthesis Example 12 (Fig. 2) were approximately the same. Therefore, a polymer represented by chemical formula (14) with a weight average molecular weight at least greater than that of Synthesis Example 13 (Mw > approximately 20,000) was obtained. The yellowish-white emulsion formed by Synthesis Example 1 was replaced by the phosphorus-containing polymer (14) [Mw > 20,000] obtained as described above.

<3. Manufacturing and Evaluation of Flame-Retardant Finished Products> Test Example 1: As follows, flame-retardant finishing agents obtained in each embodiment and comparative example were used to process fibers to produce flame-retardant finished products (flame-retardant fabric samples), and the evaluation of these samples was carried out. The flame-retardant performance test results of the flame-retardant fabric samples treated with each flame-retardant finishing agent are shown in Table 1. In Table 1, the adhesion amount (flame-retardant qualified adhesion amount) in the early stage of flame-retardant processing, where the residual flame time, afterglow time, and charred area of each flame-retardant are all marked as "○", is recorded as "%o.w.f (on the weight of fiber): percentage of flame retardant adhesion amount on the weight of fabric)". Furthermore, the same tests were also conducted on untreated flame-retardant fabrics made of polyester fibers that were supplied for flame-retardant processing.

(1) Flame-retardant processing of fiber products (preparation of test samples) Flame-retardant processing agents prepared according to the various embodiments and comparative examples were used to process polyester fibers. The polyester fabric used was a plain-woven combed fabric of 100% polyester with a basis weight of 164 g/ ^m² . Flame-retardant processing solutions were prepared by diluting each flame-retardant processing agent with a general-purpose organic solvent such as water and acetone while adjusting the concentration. After impregnating the aforementioned polyester fabric, a padding treatment (100% tensile strength) was performed, and the fabric was pre-dried at 80°C for 10 minutes. Then, the padding-treated fabric was hardened at 150°C for 1 minute to obtain the flame-retardant processed fabric. Furthermore, the amount of flame retardant adhering to the polyester fabric is determined by the increase in the dry weight of the processed fabric relative to the dry weight of the unprocessed fabric. Moreover, these flame-retardant processed fabrics are separated into early-stage flame-retardant processed fabrics and post-washed flame-retardant processed fabrics, and combustion tests are conducted separately. The washing process involves five repeated washes based on the method outlined in Fire Department Notice No. 2 of June 28, 2003, "Standards for Washability of Flame Retardant Performance."

(2) Evaluation of the flame-retardant properties of flame-retardant fiber products (Japanese Industrial Standard JIS L 1091 A-1 method) A combustion test was conducted on the aforementioned flame-retardant fabric according to the JIS L 1091 A-1 method (45° micro-burner method). A combustion test was also conducted on the fabric that had been washed five times. (2-1) Flame Residue Time When evaluating the flame-retardant fabric, the flame residue time specified in JIS L-1091 A-1 was measured a total of four times using flame contact measurements on the surface or inside of each fabric in both the longitudinal and transverse directions. Furthermore, the evaluation criteria for flame residue time are as follows. ○: The afterglow time after 3 seconds of ignition is less than 3 seconds 4 times ×: Other than this (2-2) The afterglow time is the same as the afterglow time, and the afterglow time is also measured a total of 4 times. Furthermore, the evaluation criteria for afterglow time are as follows. ○: The afterglow time after 3 seconds of ignition is less than 5 seconds 4 times ×: Other than this (2-3) The charred area is the same as the afterglow time, and the charred area is also measured a total of 4 times. Furthermore, the evaluation criteria for charred area are as follows. ○: The charred area after 3 seconds of ignition is less than 30 cm ^{2 4} times ×: Other than this (2-4) Texture: The texture of the flame-retardant fabric is confirmed by touch. Furthermore, the evaluation criteria for texture are as follows: ○: Has the same softness as unprocessed fabric △: Has a slightly firmer feel compared to unprocessed fabric ×: Has a noticeably stiffer feel compared to unprocessed fabric

[Table 1]

As can be clearly seen from the results in Table 1, compared to untreated polyester fibers which are completely non-flame-retardant, flame-retardant treatment of phosphorus-containing (meth)acrylic polymers with a weight average molecular weight (Mw) of about 20,000 or less imparts flame retardancy in the early stage in all Examples 1 to 13 and Comparative Examples 1 to 4, thus possessing flame retardancy that is not a problem for flame-retardant fiber products. In contrast, the phosphorus-containing (meth)acrylic polymer of Comparative Example 5, with a weight-average molecular weight (Mw) greater than 20,000, exhibits low flame retardancy. Furthermore, it fails to achieve the acceptable adhesion amount in the flame retardancy performance test (45° micro-burner method) specified in JIS L 1091, where all flame time, afterglow time, and charred area are zero. This suggests that the flame retardancy of the phosphorus-containing (meth)acrylic polymer is strongly influenced by its molecular weight. It is evident that flame-retardant fibers processed with the flame-retardant processing agent composed of the phosphorus-containing (meth)acrylic polymer of this invention do not show a significant reduction in flame retardancy even after washing, maintaining a relatively high level of flame retardancy as flame-retardant fiber products (Examples 1-13).

Test Example 2: A flame-retardant fabric manufactured using the flame retardants of Examples 1, 2, 11, Comparative Examples 1, 4, and 5, and produced in the same manner as "(1) Flame-retardant processing of fiber products (preparation of test samples)" in Test Example 1, was subjected to a burning test according to the Japanese Industrial Standard JIS L 1091 A-4 method (vertical method). The results are shown in Table 2. Table 2 records the percentage of flame retardant adhesion to the fabric weight as "%o.w.f (on the weight of fiber): the percentage of flame retardant adhesion to the fabric weight," indicating the char length, average char length, and adhesion amount where all flame droplets ignite and yarn ignition are marked as "○" in the early stages of flame retardant processing (flame retardant acceptable adhesion amount). Furthermore, tests were also conducted on unprocessed flame-retardant fabrics made of the same polyester fibers supplied to the flame-retardant processing unit.

(1) Carbonization Length: When evaluating flame-retardant processed fabrics, the carbonization length specified in JIS L-1091 A-4 is measured three times. The evaluation criteria for carbonization length are as follows: ○: Carbonization length less than 25.4 cm after 3 seconds of ignition. ×: Other than this. (2) Ignition of Flame Droplet Ignition Yarn: Similar to carbonization length, the presence or absence of ignition in flame droplet ignition yarn is also measured three times. The evaluation criteria for the presence or absence of ignition in flame droplet ignition yarn are as follows: ○: No yarn ignition in all three measurements. ×: Other than this. (3) Average Carbonization Length: The average of the three carbonization lengths obtained from the aforementioned (3) measurement is calculated. The evaluation criteria for average carbonization length are as follows. ○: Those with an average carbonization length of less than 17.8cm ×: Other than this

[Table 2]

As can be clearly seen from the results in Table 2, the phosphorus-containing (meth)acrylic polymer of the present invention with a weight average molecular weight (Mw) of less than 20,000 has very high flame retardancy. Even in the vertical method, it still shows the same tendency as the 45° micro-burner method, and it continues to maintain high flame retardancy even after washing with water.

In contrast, it can be seen that when using the low molecular weight phosphate-based flame retardant of the comparative examples, as a result of washing with water causing the flame retardant components to fall off, a significant reduction in flame retardancy is observed (Comparative Examples 1 and 2 in Tables 1 and 2, and Comparative Example 2 in Table 1).

Furthermore, low-molecular-weight phosphonate flame retardants tend to exhibit uneven adhesion due to variations in the amount of adhesion on the surface of polyester fibers (which are fabrics) and through internal penetration into the amorphous regions of the polyester (Comparative Example 3 in Table 1, and Comparative Example 4 in Tables 1 and 2). In contrast, the phosphorus-containing (meth)acrylic acid polymer of the present invention causes relatively strong penetration/adhesion on the surface of the fiber structure, thus no fabric-specific differences are observed, and stable adhesion is maintained (Examples 1-13 in Table 1).

Regarding texture, for the same structure of phosphorus-containing (meth)acrylic polymers, it was observed that the larger the molecular weight, the worse the texture tends to be (Examples 12 and 13 in Table 1, Comparative Example 5). However, it can be seen that if chain-like aliphatic hydrocarbons are included in the intramolecular structure, the texture will be improved (Examples 5 and Examples 9-11 in Table 1).

without

[Figure 1] Figure 1 shows the IR chromatogram of the phosphorus-containing polymer (Synthesis Example 12). [Figure 2] Figure 2 shows the IR chromatogram of the phosphorus-containing polymer (Comparative Example 5).

Claims (7)

A phosphorus-containing (meth)acrylic polymer comprising one or more phosphorus compounds represented by the following general formula (I) as (meth)acrylic monomers (A): [Chemical Formula 20] [In the formula, _R1 represents a hydrogen atom or a methyl group; _L1 and _L2 are the same or different, representing an oxygen atom or an imine (NH) group; _R2 represents an hydrocarbon group that can be substituted by a substituent containing at least one of nitrogen, oxygen, phosphorus and sulfur atoms]. For example, the phosphorus-containing (meth)acrylic acid polymer in Request 1 has a weight-average molecular weight Mw (but Mw represents the relative weight-average molecular weight with standard polystyrene as the reference when measured by differential refractometer according to gel osmosis chromatography) of 1000~20000. A flame retardant for fibers comprising a phosphorus-containing (meth)acrylic polymer as claimed in claim 1. For example, the flame retardant for fibers in claim 3 further includes an aqueous medium and is in liquid form. For example, the flame retardant for fibers in claim 3 is used to perform flame retardant processing on fiber products through post-processing. A flame-retardant fiber product comprising synthetic fibers and a flame retardant for fibers as described in claim 3. For example, flame-retardant fiber products in claim 6, wherein synthetic fibers include polyester fibers.