Flame-retarding agent for polyester-based synthetic fiber structure, flame-retardant polyester-based synthetic fiber structure, vehicle interior material, and flame-retarding method for polyester-based synthetic fiber structure

Abstract

To provide: a flame-retarding agent for polyester-based synthetic fiber structures which contains no halogen or phosphorus elements and exhibits suppressed ring stains; a flame-retardant polyester-based synthetic fiber structure; a vehicle interior material; and a flame-retarding method for polyester-based synthetic fiber structures.SOLUTION: A flame-retarding agent for a polyester-based synthetic fiber structure includes at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidium salts of malic acid, and guanidium salts of citric acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a flame retardant finishing agent for polyester synthetic fiber structures, a flame retardant polyester synthetic fiber structure, a vehicle interior material, and a method for flame retarding a polyester synthetic fiber structure.

Background Art

[0002] For the flame retardant treatment of fiber structures, a flame retardant and a processing method suitable for the fiber material are used. Conventionally, for polyester synthetic fiber structures, water-soluble salts such as guanidine phosphate and carbamate phosphate have been used as flame retardants, and flame retardant processing has been performed by the padding method (for example, Patent Document 1).

[0003] Also, it is known to flame retard polyester synthetic fiber structures using halogen compounds by the exhaustion method or the padding method (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when water-soluble salts are used as flame retardants, when the flame-retarded polyester synthetic fiber structure absorbs and desorbs moisture, crystals may precipitate on the surface of the fiber structure, or when water adheres to the surface of the fiber structure, bleeding, also referred to as bleeding, may occur.

[0006] Conventionally, halogen-based, phosphorus-based, and inorganic substances have been used as flame retardants. However, from the perspective of environmental impact, it is preferable that the flame retardant does not contain halogen compounds or has a low usage amount. In addition, industrially available phosphorus is obtained from phosphate ore, but since the countries producing phosphate ore are limited, there are issues such as unstable phosphorus supply due to resource regulations in producing countries and soaring prices.

[0007] In view of such problems, the present disclosure aims to provide a flame retardant processing agent for polyester-based synthetic fiber structures that does not contain halogen and phosphorus elements and has suppressed flammability, a flame-retardant polyester-based synthetic fiber structure, a vehicle interior material, and a method for flame-retardant processing of polyester-based synthetic fiber structures.

Means for Solving the Problems

[0008] The flame retardant processing agent for polyester-based synthetic fiber structures according to an embodiment of the present disclosure contains at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidinium salts of malic acid, and guanidinium salts of citric acid.

Effects of the Invention

[0009] According to an embodiment of the present disclosure, there are provided a flame retardant processing agent for polyester-based synthetic fiber structures that does not contain halogen and phosphorus elements and has suppressed flammability, a flame-retardant polyester-based synthetic fiber structure, a vehicle interior material, and a method for flame-retardant processing of polyester-based synthetic fiber structures.

Modes for Carrying Out the Invention

[0010] The flame retardant finishing agent of the present disclosure can be used for the flame retardant finishing of various fiber structures, and is particularly preferably used for the flame retardant finishing of polyester-based synthetic fiber structures. In the present disclosure, the polyester-based synthetic fiber structure refers to fibers containing at least polyester fibers, and fabrics such as yarns, cotton, knitted fabrics, and non-woven fabrics containing such fibers. Preferably, the polyester-based synthetic fiber structure is a fabric such as polyester fiber, yarn made of polyester fiber, cotton, knitted fabric, or non-woven fabric. Furthermore, fabrics such as knitted fabrics and non-woven fabrics may be single-layered, may be a laminate of two or more layers, or may be a composite made of yarns, cotton, knitted fabrics, non-woven fabrics, etc. The knitted fabric may be a polyester jersey knit or a polyester tricot knit.

[0011] The above polyester fibers are made of polymers such as, for example, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene terephthalate / isophthalate, polyethylene terephthalate / 5-sulfoisophthalate, polyethylene terephthalate / polyoxybenzoyl, polybutylene terephthalate / isophthalate, poly(D-lactic acid), poly(L-lactic acid), copolymer of D-lactic acid and L-lactic acid, copolymer of D-lactic acid and aliphatic hydroxycarboxylic acid, copolymer of L-lactic acid and aliphatic hydroxycarboxylic acid, polycaprolactone such as poly-ε-caprolactone (PCL), poly(malic acid), polyhydroxybutyric acid, polyhydroxyvaleric acid, polyaliphatic hydroxycarboxylic acid such as β-hydroxybutyric acid (3HB)-3-hydroxyvaleric acid (3HV) random copolymer, polyethylene succinate (PES), polybutylene succinate (PBS), polybutylene adipate, polyester of glycol and aliphatic dicarboxylic acid such as polybutylene succinate-adipate copolymer.

[0012] In addition, the above polymer may be a copolymer with a functional compound such as a flame retardant. Also, a functional compound such as an antibacterial agent may be blended during the polymerization of the polymer or during the yarn production.

[0013] The flame-retardant polyester-based synthetic fiber structure flame-retardantly processed with the flame-retardant processing agent of the present disclosure is suitably used for, for example, seat covers, sheet covers, curtains, wallpapers, ceiling cloths, carpets, satin curtains, construction curing sheets, tents, canvas, and the like. In particular, the flame-retardant polyester-based synthetic fiber structure of the present disclosure is suitably used for vehicle interior materials such as seat covers, sheet covers, ceiling materials, door trim materials, and vehicle interior curtains.

[0014] (First Embodiment) The flame-retardant processing agent for the polyester-based synthetic fiber structure of the present embodiment includes a flame retardant. The flame retardant contains at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidinium salts of malic acid, and guanidinium salts of citric acid as a main component of the flame retardant. The flame retardant may contain both ammonium salts and guanidinium salts, or may contain both salts of malic acid and salts of citric acid. The main component means a component contained in a proportion exceeding 50% by weight. When the flame-retardant processing agent further contains a flame retardant aid, it means a component contained in a proportion exceeding 50% by weight with respect to the total of the flame retardant and the flame retardant aid.

[0015] Malic acid and citric acid are hydroxycarboxylic acids and polyvalent carboxylic acids. Specifically, malic acid is a divalent carboxylic acid, and citric acid is a trivalent carboxylic acid. In the ammonium salt of malic acid and the guanidinium salt of malic acid, at least one of the two carboxy groups of malic acid is neutralized to form a carboxylate group, which pairs with an ammonium ion or a guanidinium ion as a counter ion. Similarly, in the ammonium salt of citric acid and the guanidinium salt of citric acid, at least one of the three carboxy groups of citric acid is neutralized to form a carboxylate group, which pairs with an ammonium ion or a guanidinium ion as a counter ion.

[0016] That is, the flame retardant contains ammonium ions and / or guanidium ions in an amount of 1 mol or more per 1 mol of malic acid as the cation of the salt by neutralization. Similarly, the flame retardant contains ammonium ions and / or guanidium ions in an amount of 1 mol or more per 1 mol of citric acid.

[0017] The flame retardant may contain ammonium ions and / or guanidium ions in an amount exceeding 2 mol per 1 mol of malic acid. Similarly, the flame retardant may contain ammonium ions and / or guanidium ions in an amount exceeding 3 mol per 1 mol of citric acid. However, when the flame retardant processing agent exhibits alkalinity due to excessive ammonium ions and / or guanidium ions exceeding the neutralization point, the polyester synthetic fiber structure may be damaged by the flame retardant processing agent.

[0018] From the above, it is preferable that the flame retardant contains ammonium ions and / or guanidium ions in an amount of 1 mol or more and 2 mol or less per 1 mol of malic acid. Also, it is preferable that the flame retardant contains ammonium ions and / or guanidium ions in an amount of 1 mol or more and 3 mol or less per 1 mol of citric acid.

[0019] Among the carboxy groups of malic acid and citric acid in the flame retardant, the carboxy groups that do not form ammonium salts or guanidium salts may not be neutralized, but it is preferable that they do not form sodium salts or potassium salts. As will be described later, the ammonium salts or guanidium salts of malic acid and citric acid have high flame retardant performance, while the sodium salts or potassium salts of malic acid and citric acid have low flame retardant performance.

[0020] As described above, the flame retardant may contain both the salt of malic acid and the salt of citric acid. In this case, since malic acid and citric acid are polyvalent carboxylic acids, from the viewpoint of facilitating the control of the pH of the flame retardant processing agent during production and suppressing the variation in the properties of the flame retardant processing agent, it is preferable that there is one type of cation. Specifically, the flame retardant may contain the ammonium salt of malic acid and the ammonium salt of citric acid. Alternatively, the flame retardant may contain the guanidium salt of malic acid and the guanidium salt of citric acid.

[0021] When the flame retardant contains the guanidium salt of malic acid and the guanidium salt of citric acid, it is preferable that the guanidium salt of malic acid and the guanidium salt of citric acid are contained in the flame retardant at a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid. Thereby, the texture of the flame-retardant polyester-based synthetic fiber structure is excellent.

[0022] In the flame retardant, it is preferable that the guanidium ion is contained at a ratio of 0.4 mol or more and 1.1 mol or less per 1 mol of the total number of carboxy groups of malic acid and citric acid. When the ratio of the carboxy group to the guanidium ion is within the above-described range, the pH of the flame retardant processing agent becomes a value within a predetermined range as described later, and bleeding is suppressed. Since the above-described flame retardant does not contain halogen and phosphorus elements, it is excellent from the viewpoints of environmental load and raw material procurement. Further, as will be described in detail in the following examples, since malic acid and citric acid are ammonium salts or guanidium salts, they exhibit excellent flame retardancy and suppress smoke generation during flame retardant processing. Furthermore, although the flame retardant is a water-soluble salt, bleeding and the like are suppressed, and the properties of the polyester-based synthetic fiber structure after flame retardant processing are also good.

[0023] The flame retardant processing agent for the polyester-based synthetic fiber structure of the present embodiment further includes a solvent, and the flame retardant is dissolved in a solvent containing at least water. The pH of the flame retardant processing agent is preferably 3 or more and 9 or less, and more preferably 4.5 or more and 7 or less.

[0024] In particular, when the flame retardant contains the guanidium salt of malic acid and the guanidium salt of citric acid, the pH of the flame retardant processing agent is preferably 4 or more and 9 or less. The acid dissociation constants of malic acid and citric acid are as shown in Table 1, and the first acid dissociation constant pKa1 of malic acid is larger than the first acid dissociation constant pKa1 of citric acid.

[0025]

Table 1

[0026] Therefore, when the ratio of guanidium ions in the flame retardant is less than 0.4 mol (less than 5:2) per 1 mol of the total number of carboxy groups of malic acid and carboxy groups of citric acid, the flame retardant processing agent may contain malic acid molecules in which both of the two carboxy groups are not neutralized. As a result, the pH of the flame retardant processing agent tends to be less than 4.

[0027] On the other hand, when the ratio of guanidium ions in the flame retardant is more than 1.1 mol per 1 mol of the total number of carboxy groups of malic acid and carboxy groups of citric acid, guanidium ions are in excess over the carboxy groups in the flame retardant, and the excess guanidium ions do not neutralize with the carboxy groups and exhibit alkalinity. For this reason, the pH of the flame retardant processing agent becomes larger than 7, for example, larger than 9.

[0028] As will be described below, when the flame retardant contains the guanidium salt of malic acid and the guanidium salt of citric acid, the occurrence of sticking is suppressed by the pH of the flame retardant processing agent being 4 or more and 9 or less. In particular, the occurrence of sticking by an aqueous calcium chloride solution can be effectively suppressed. Further, when the flame retardant contains the guanidium salt of malic acid and the guanidium salt of citric acid, the texture is superior compared to the case of containing only one of the salts.

[0029] In the flame retardant treating agent, the solvent may further contain an organic solvent. For example, as the organic solvent, alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene, xylene, and alkylnaphthalene, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and ethyl cellosolve, amides such as dimethylformamide, sulfoxides such as dimethyl sulfoxide, and halogenated hydrocarbons such as methylene chloride and chloroform can be mentioned.

[0030] In particular, organic solvents such as alcohols such as methanol, ethers such as acetone and ethyl cellosolve, amides such as dimethylformamide, and sulfoxides such as dimethyl sulfoxide can be preferably used. These organic solvents can be used alone or in combination of two or more.

[0031] The flame retardant treating agent for the polyester synthetic fiber structure of the present embodiment may contain other conventionally known flame retardants. Further, the flame retardant treating agent may contain a flame retardant aid for enhancing the flame retardancy of the flame retardant treating agent, an ultraviolet absorber for enhancing the light fastness, an antioxidant, and the like.

[0032] Furthermore, the flame retardant treating agent may contain, for example, a softening agent, an antistatic agent, a water and oil repellent, a hard finishing agent, a hand modifier, and the like. Since the flame retardant is a water-soluble salt, the flame retardant treating agent may not contain a surfactant or a dispersant.

[0033] The flame retardant treating agent for the polyester synthetic fiber structure of the present embodiment can be obtained, for example, by dissolving a flame retardant in the above-described solvent. Commercially available products can be used as the raw materials. Specifically, for example, at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidinium salts of malic acid, and guanidinium salts of citric acid containing ammonium ions and guanidinium ions in the above-described ratios is prepared or prepared in advance and dissolved in a solvent containing water, whereby a flame retardant treating agent can be produced.

[0034] Alternatively, malic acid and / or citric acid are dissolved in a solvent containing water, and aqueous ammonia containing ammonium ions in the above-described ratio is added to these acids to partially or completely neutralize the malic acid and / or citric acid, whereby a flame retardant processing agent can be obtained. Further, malic acid and / or citric acid are dissolved in a solvent containing water, and guanidine carbonate containing guanidinium ions in the above-described ratio is added to these acids to partially or completely neutralize the malic acid and / or citric acid. Most of the carbonic acid generated by the neutralization decomposes to produce water and carbon dioxide. The solvent may be heated to discharge carbon dioxide as a gas outside the solvent and promote the decomposition. Thereby, a flame retardant processing agent can be obtained.

[0035] The alkaline substances used for neutralizing malic acid and citric acid are not limited to aqueous ammonia and guanidine carbonate, and other substances containing ammonium ions or guanidinium ions and showing alkalinity may be used.

[0036] According to the flame retardant processing agent for the polyester-based synthetic fiber structure of the present embodiment, since the flame retardant does not contain halogen and phosphorus elements, it is excellent from the viewpoints of environmental regulations and raw material procurement. In the polyester-based synthetic fiber structure treated with the flame retardant processing agent of the present embodiment, the occurrence of attachment, chalk marks, deterioration of texture and rubbing fastness, etc. are suppressed, and it is possible to obtain a flame retardant polyester-based synthetic fiber structure with excellent finish.

[0037] (Second Embodiment) Embodiments of a flame retardant polyester-based synthetic fiber structure, a vehicle interior material, and a method for flame-retardant processing of a polyester-based synthetic fiber structure will be described. The flame retardant polyester-based synthetic fiber structure of the present embodiment includes a polyester-based synthetic fiber structure and a flame retardant supported on the polyester-based synthetic fiber structure. Further, the vehicle interior material of the present embodiment includes this flame retardant polyester-based synthetic fiber structure.

[0038] As described above, the types and characteristics of polyester synthetic fibers and fiber structures that are the objects of flame retardant processing are as described above. Also, the uses of polyester synthetic fiber structures are as described above.

[0039] As described in the first embodiment, the flame retardant contains at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidinium salts of malic acid, and guanidinium salts of citric acid.

[0040] The adhesion amount of the flame retardant to the polyester synthetic fiber structure is preferably 0.2% by weight (% owf) or more and less than 10% by weight (% owf) with respect to the polyester synthetic fiber structure, and more preferably in the range of 0.5 to 7% by weight. When the adhesion amount is less than 0.2% by weight, it may not be possible to impart sufficient flame retardancy to the polyester synthetic fiber structure. From the viewpoint of flame retardancy, a larger adhesion amount is preferable. However, if the adhesion amount becomes too large, the feel of the polyester synthetic fiber structure after flame retardant processing becomes rough, etc., and the texture deteriorates. In order to achieve a better feel, the adhesion amount is preferably 7% by weight or less.

[0041] The flame retardant polyester synthetic fiber structure of this embodiment is obtained by subjecting the polyester synthetic fiber structure to flame retardant processing by post-processing using the flame retardant processing agent of the first embodiment to impart flame retardancy.

[0042] For example, the flame retardant processing agent of the first embodiment is diluted with water to prepare a processing liquid. The processing liquid preferably contains the flame retardant in the range of 30 to 70% by weight. If the flame retardant processing agent has been prepared in advance so that the concentration of the flame retardant is within this range, the flame retardant processing agent can be used as the processing liquid as it is.

[0043] There is no limitation on the post-processing method, and various processing methods can be used. For example, after attaching a flame retardant agent to the polyester synthetic fiber structure, heat treatment is carried out at a temperature of 130°C to 170°C for 1 to 5 minutes to dry it, and the flame retardant is supported and fixed on the polyester synthetic fiber structure. For example, as post-processing, methods such as padding, spraying, and coating can be used. Since the flame retardant is dissolved in the solvent, there is no concern about separation or sedimentation of the processing liquid.

[0044] In the padding method, for example, a polyester fiber fabric is immersed in a flame retardant agent or a diluted processing liquid thereof, and then the fabric is wrung by a roller (mangle) to attach the flame retardant. In the spraying method, a flame retardant agent or a diluted processing liquid thereof is sprayed onto the fabric in a mist form to attach it to the fabric. In the coating method, the flame retardant agent is thickened and uniformly applied to the back surface of the fabric to attach it to the fabric.

[0045] In the flame retardant processing method of the polyester synthetic fiber structure of this embodiment, treatment using other functional processing agents may be performed by mixing with the flame retardant agent, or before or after the flame retardant processing with the flame retardant agent. Examples of other functional processing agents include, for example, hardening agents, softening agents, antistatic agents, water and oil repellents, hand modifiers, SR agents, and the like.

[0046] According to this embodiment, as described in the first embodiment, it does not contain halogen and phosphorus elements, and the occurrence of chalk marks and edge marks is suppressed. Further, since the flame retardant is a water-soluble salt, the flame retardant processing agent may not contain a surfactant for dispersing the flame retardant. Therefore, even if the polyester synthetic fiber structure is a dyed fabric, a decrease in the physical properties of the polyester synthetic fiber structure, such as bleed-out of disperse dyes due to surfactants, a decrease in rubbing fastness, and discoloration over time, is suppressed. Furthermore, since no smoke is generated during the flame retardant processing and the polyester synthetic fiber structure does not need to be washed after the flame retardant processing, the workability during the flame retardant processing is excellent, and the processing cost and environmental load can be reduced.

[0047] (Example) In order to confirm the effects and the like of the first embodiment and the second embodiment, flame retardant processing agents were prepared at various compounding ratios, and the polyester-based synthetic fiber structure was subjected to flame retardant processing using the prepared flame retardant processing agents, and the properties of the obtained flame retardant polyester-based synthetic fiber structure were evaluated. [Examples 1 to 11, Comparative Examples 1 to 11] (1) Preparation of flame retardant processing agent According to the procedures shown in Examples 1 to 11, flame retardant processing agents A to K were prepared. Also, according to the procedures shown in Comparative Examples 1 to 11, flame retardant processing agents L to V were prepared.

[0048] The pH of the flame retardant processing agent was measured using a glass electrode pH meter.

[0049] The non-volatile content refers to the non-volatile content remaining after evaporating and drying the flame retardant processing agent at 105°C for 60 minutes, unless otherwise specified. In the examples and comparative examples, since the flame retardant processing agent does not contain additives other than the flame retardant, the non-volatile content indicates the proportion of the flame retardant in the flame retardant processing agent.

[0050] Also, hereinafter, unless otherwise specified, "%" means "wt%". <Example 1> Manufacture of flame retardant processing agent A 10 parts by weight of malic acid was dissolved in 5.8 parts by weight of water, and 5.1 parts by weight of aqueous ammonia (25%) was gradually added and neutralized to obtain a flame retardant processing agent A composed of an ammonium malate salt aqueous solution. COOH:NH3 = 2:1 pH = 4.1 Non-volatile content: 57.6% <Example 2> Manufacture of flame retardant processing agent B 10 parts by weight of malic acid was dissolved in 3 parts by weight of water, and 10.2 parts by weight of aqueous ammonia (25%) was gradually added and neutralized to obtain a flame retardant processing agent B composed of an ammonium malate salt aqueous solution. COOH:NH3 = 2:2 pH = 5.5 Non-volatile content: 56.7% <Example 3> Manufacture of Flame Retardant Agent C 10 parts by weight of malic acid was dissolved in 12 parts by weight of water, 6.7 parts by weight of guanidine carbonate was gradually added, neutralized, and carbon dioxide gas was removed to obtain Flame Retardant Agent C consisting of an aqueous solution of guanidine malate salt. COOH:Gu = 2:1 pH = 4.0 Non-volatile content: 54.1% <Example 4> Manufacture of Flame Retardant Agent D 10 parts by weight of malic acid was dissolved in 14 parts by weight of water, 13.4 parts by weight of guanidine carbonate was gradually added, neutralized, and carbon dioxide gas was removed to obtain Flame Retardant Agent D consisting of an aqueous solution of guanidine malate salt. COOH:Gu = 2:2 pH = 6.5 Non-volatile content: 58.0% <Example 5> Manufacture of Flame Retardant Agent E 10 parts by weight of citric acid was dissolved in 14 parts by weight of water, 3.5 parts by weight of aqueous ammonia (25%) was gradually added, and neutralized to obtain Flame Retardant Agent E consisting of an aqueous solution of ammonium citrate salt. COOH:NH3 = 3:1 pH = 3.4 Non-volatile content: 43.1% <Example 6> Manufacture of Flame Retardant Agent F 10 parts by weight of citric acid was dissolved in 13 parts by weight of water, 7 parts by weight of aqueous ammonia (25%) was gradually added, and neutralized to obtain Flame Retardant Agent F consisting of an aqueous solution of ammonium citrate salt. COOH:NH3 = 3:2 pH = 4.8 Non-volatile content: 43.5% <Example 7> Manufacture of Flame Retardant Agent G 10 parts by weight of citric acid was dissolved in 12 parts by weight of water, 10.6 parts by weight of aqueous ammonia (25%) was gradually added, and neutralized to obtain Flame Retardant Agent G consisting of an aqueous solution of ammonium citrate salt. COOH:NH3 = 3:3 pH = 8.7 Non-volatile content: 39.7% <Example 8> Manufacture of Flame Retardant Agent H 10 parts by weight of citric acid was dissolved in 8 parts by weight of water, and 4.7 parts by weight of guanidine carbonate was gradually added. After neutralization and removal of carbon dioxide gas, a flame retardant agent H composed of an aqueous solution of guanidine citrate salt was obtained. COOH:Gu = 3:1 pH = 3.3 Non-volatile content: 63.8% <Example 9> Manufacture of Flame Retardant Agent I 10 parts by weight of citric acid was dissolved in 11 parts by weight of water, and 9.8 parts by weight of guanidine carbonate was gradually added. After neutralization and removal of carbon dioxide gas, a flame retardant agent I composed of an aqueous solution of guanidine citrate salt was obtained. COOH:Gu = 3:2 pH = 5.0 Non-volatile content: 62.4% <Example 10> Manufacture of Flame Retardant Agent J 10 parts by weight of citric acid was dissolved in 13 parts by weight of water, and 14.1 parts by weight of guanidine carbonate was gradually added. After neutralization and removal of carbon dioxide gas, a flame retardant agent J composed of an aqueous solution of guanidine citrate salt was obtained. COOH:Gu = 3:3 pH = 9.1 Non-volatile content: 60.6% <Example 11> Manufacture of Flame Retardant Agent K 50 parts by weight of flame retardant agent D and 50 parts by weight of flame retardant agent J were mixed to obtain flame retardant agent K. COOH:Gu = 2:2, COOH:Gu = 3:3 pH = 6.6 Non-volatile content: 59.4% <Reference Example 1> Manufacture of Flame Retardant Agent L 10 parts by weight of malic acid was dissolved in 10 parts by weight of water to obtain a flame retardant agent L composed of an aqueous solution of malic acid. pH = 1.0 Non-volatile content: 49.8% <Reference Example 2> Manufacture of Flame Retardant Agent M 10 parts by weight of citric acid was dissolved in 10 parts by weight of water to obtain a flame retardant agent M composed of an aqueous solution of citric acid. pH = 0.9 Non-volatile content: 48.7% <Reference Example 3> Production of Flame Retardant Agent N 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, 3 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant agent N composed of an aqueous solution of sodium malate salt. COOH:Na = 2:1 pH = 4.3 Non-volatile content: 57.6% <Reference Example 4> Production of Flame Retardant Agent O 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, 6 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant agent O composed of an aqueous solution of sodium malate salt. COOH:Na = 2:2 pH = 13.7 Non-volatile content: 62.8% <Reference Example 5> Production of Flame Retardant Agent P 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, 2 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant agent P composed of an aqueous solution of sodium citrate salt. COOH:Na = 3:1 pH = 3.6 Non-volatile content: 30.8% <Reference Example 6> Production of Flame Retardant Agent Q 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, 4.2 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant agent Q composed of an aqueous solution of sodium citrate salt. COOH:Na = 3:2 pH = 5.0 Non-volatile content: 35.7% <Reference Example 7> Production of Flame Retardant Agent R 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, 6.2 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant agent R composed of an aqueous solution of sodium citrate salt. COOH:Na = 3:3 pH = 8.1 Non-volatile content: 41.0% <Reference Example 8> Manufacture of Flame Retardant Processing Agent S 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, 4.2 parts by weight of potassium hydroxide was added and neutralized to obtain a flame retardant processing agent S composed of an aqueous solution of potassium malate salt. COOH:K = 2:1 pH = 4.8 Non-volatile content: 59.6% <Reference Example 9> Manufacture of Flame Retardant Processing Agent T 47 parts by weight of guanidine phosphate was dissolved in 53 parts by weight of water to obtain a flame retardant processing agent T. Phosphoric acid:Gu = 1:1 to 1:2 pH = 5.0 Non-volatile content: 47.0% <Reference Example 10> Manufacture of Flame Retardant Processing Agent U 40 parts by weight of anilinodiphenyl phosphate (hereinafter referred to as ADPP), 1.5 parts by weight of ammonium salt of sulfuric acid ester of tristyrenated phenol ethylene oxide 10 mol adduct, and 0.05 parts by weight of silicone-based defoaming agent were mixed in 35 parts by weight of water. This mixture was charged into a mill filled with glass beads having a diameter of 0.8 mm and pulverized for 4 hours to disperse the above ADPP as fine particles having an average particle diameter of 0.548 μm. When the obtained dispersion was dried at a temperature of 105 ° C for 40 minutes, the amount of water was adjusted so that the non-volatile content became 41.6% to obtain a flame retardant processing agent U. <Reference Example 11> Manufacture of Flame Retardant Processing Agent V 40 parts by weight of crystalline powder of tetrakis(2,6-dimethylphenyl)-m-phenylene phosphate (alias resorcinol bis-dixylyl phosphate. Hereinafter referred to as RDXP), 1.5 parts by weight of ammonium salt of sulfuric acid ester of tristyrenated phenol ethylene oxide 10 mol adduct, and 0.05 parts by weight of silicone-based defoaming agent were mixed in 35 parts by weight of water. This mixture was pulverized at 3000 rpm for 1 hour with a homogenizer to obtain a treatment liquid in which the above RDXP had an average particle diameter of 50 μm or less. Next, this treatment liquid was charged into a mill filled with glass beads having a diameter of 0.8 mm and pulverized for 3 hours to disperse the above RDX as fine particles with an average particle diameter of 1.140 μm. When the obtained dispersion was dried at a temperature of 105 °C for 40 minutes, the amount of water was adjusted so that the non-volatile content became 41.6%, and a flame retardant processing agent V according to the reference example was obtained. (2) Preparation of Flame Retardant Polyester Synthetic Fiber Structure Two types of fabrics were prepared as the polyester synthetic fiber structure. First, a polyester jersey knitted fabric (areal weight: 280 g / m 2 ) knitted weftwise using black raw polyester fibers containing 1.5% by weight of carbon black was scoured and pre-set by a conventional method to obtain a polyester fiber fabric for vehicle interior materials. Hereinafter, this fabric is referred to as fabric a.

[0051] In addition, a polyester tricot knitted fabric (areal weight: 250 g / m 2 ) knitted warpwise using regular polyester fibers was subjected to a bath dyeing treatment at 130 °C for 30 minutes with 4% owf of disperse dye Dianix Black AM-SLR (manufactured by DyStar), then subjected to reduction washing by a conventional method and dried to obtain a polyester fiber fabric for vehicle interior materials. Hereinafter, this fabric is referred to as fabric b.

[0052] Using the flame retardant processing agents A to V prepared in Examples 1 to 11 and Reference Examples 1 to 11 respectively, a processing liquid diluted to an arbitrary concentration was prepared. After attaching a flame retardant to fabric a by the padding method using the processing agent, it was dried at 150 °C for 3 minutes to obtain a polyester fiber fabric for a flame retardant vehicle interior material. Similarly, using the processing agents containing the flame retardant processing agents A to V respectively, after attaching a flame retardant to fabric b by the padding method, it was dried at 150 °C for 3 minutes to obtain a polyester fiber fabric for a flame retardant vehicle interior material.

[0053] Regarding the flame retardant processing agent J of Example 10, a plurality of fabric a were subjected to flame retardant processing by changing the adhesion amount of the flame retardant. In addition, fabric a and fabric b without undergoing flame retardant processing were also prepared. (3) Evaluation The flame retardancy performance test, attached evaluation, chalk mark evaluation, texture evaluation, and rubbing fastness test of the produced polyester fiber fabric for flame-retardant vehicle interior materials were carried out.

[0054] <Flame retardancy performance test> In accordance with the United States Federal Motor Vehicle Safety Standard No. 302 (FMVSS 302), the horizontal combustion tests of fabric a and fabric b were carried out. When the combustion rate was less than 101 mm / min, it was determined to have good flame retardancy performance. The specific evaluation criteria are as follows. This criterion is based on the flame retardancy performance required for vehicle interior materials by the safety standards of road transport vehicles in Japan. In Tables 7 to 10 shown below, the combustion rate and evaluation are indicated by the corresponding symbols shown in Table 2.

[0055]

Table 2

[0056] <Attached> Fabric a was placed on the urethane foam, 5 mL of pure water and boiling water were respectively dropped on the surface, and the surface of the sample was visually observed after 24 hours. Those without attached in both pure water and boiling water were evaluated as having no attached in the comprehensive evaluation. In Tables 7 to 10 shown below, the observation results and evaluation are indicated by the corresponding symbols shown in Table 3.

[0057]

Table 3

[0058] <Chalk mark> The surface of fabric a was gently rubbed with a fingernail, and the degree of whitening due to the scratch was visually observed. In Tables 7 to 10 shown below, the observation results and evaluation are indicated by the corresponding symbols shown in Table 4.

[0059]

Table 4

[0060] <Texture Using fabric a, based on Method A (45° cantilever method) described in 8.21.1 of 8.21 (Stiffness and softness) in JIS L 1096:2010 "Test methods for fabrics and knitted fabrics", a test piece of 2 cm × 15 cm was prepared in the warp direction, placed on a horizontal table with a 45° inclination, and the scale was read and evaluated when the center point of one end of the test piece contacted the inclined surface by sliding the test piece. When the measured value was 50 mm or less, the texture was evaluated as good, and when the measured value exceeded 50 mm, the texture was evaluated as not good. In Tables 7 to 10 shown below, the evaluation is indicated by the corresponding symbols shown in Table 5.

[0061]

Table 5

[0062] <Colorfastness to rubbing Fabric b was tested by the method for testing colorfastness to rubbing in JIS L 0849, using the rubbing tester type II (Gakushin type) described in 7.1.2 of JIS L 0849, and the grade was determined with a staining gray scale for contamination (JIS L 0805). Grade 5 has the best colorfastness to rubbing, and when it was 3 or higher in both the dry test and the wet test, it was judged that the colorfastness to rubbing was good. In Tables 7 to 10 shown below, the evaluation is indicated by the corresponding symbols shown in Table 6.

[0063]

Table 6

[0064] (4) Results and discussion Tables 7 to 10 show the test and evaluation results for Fabric a and Fabric b. In the column of COOH ratio, the ratio of cations to malic acid or citric acid in the flame retardant finishing agents of each example and reference example is shown as a ratio based on the number of carboxyl groups. That is, for the flame retardant finishing agent containing malic acid, it is shown as the ratio of cations to 2 carboxyl groups (or moles) of (COOH), and for the flame retardant finishing agent containing citric acid, it is shown as the ratio of cations to 3 carboxyl groups (or moles) of (COOH). NH3 represents ammonia, Gu represents guanidine, Na represents sodium, and K represents potassium.

[0065]

Table 7

[0066]

Table 8

[0067]

Table 9

[0068]

Table 10

[0069] As shown in these tables, by using the flame retardant finishing agent of the first embodiment, it can be seen that the flame retardant performance required for vehicle interior materials is satisfied, and a flame retardant polyester-based synthetic fiber structure excellent in attachment, chalk mark, and rubbing fastness can be obtained. Specifically, sufficient flame retardant performance can be obtained by neutralizing at least one carboxyl group of malic acid and citric acid to form an ammonium salt or a guanidinium salt. Further, as the flame retardant, a guanidinium salt of malic acid, an ammonium salt of malic acid, a guanidinium salt of citric acid, and an ammonium salt of citric acid may be used alone, or the above-described effects can be obtained by mixing two kinds of acids as in the flame retardant finishing agent K of Example 11.

[0070] As shown in Example 10 of Table 8, when the adhesion amount of the flame retardant is 0.2% by weight or more, sufficient flame retardant performance can be obtained, and when it is 0.5% by weight or more, the flame-retardant polyester-based synthetic fiber structure exhibits self-extinguishing properties. However, when the adhesion amount of the flame retardant reaches 10% by weight, the texture of the flame-retardant polyester-based synthetic fiber structure deteriorates. Therefore, it can be understood that the adhesion amount of the flame retardant is preferably 0.2% by weight or more and less than 10% by weight.

[0071] As shown in Reference Example 1 and Reference Example 2 of Table 9, malic acid and citric acid function as flame retardants even when not neutralized, and sufficient flame retardant performance can be obtained. However, when the flame retardant processing agent L containing malic acid was used, smoke was generated during processing. This is presumably because the boiling point of non-neutralized malic acid is as low as 167°C, and a part of malic acid volatilizes under the drying condition of 150°C. In addition, when the flame retardant processing agent M containing citric acid was used, the rubbing fastness of the obtained flame-retardant polyester-based synthetic fiber structure was not sufficient.

[0072] As shown in Reference Examples 3 to 8 of Table 9 and Table 10, when using the flame retardant processing agents N to S containing sodium salt of malic acid, potassium salt of malic acid and sodium salt of citric acid, sufficient flame retardant performance could not be obtained.

[0073] The flame retardant processing agent T of Reference Example 9 contains guanidine phosphate as a flame retardant and has sufficient performance in terms of flame retardant performance, adhesion, chalk mark, and rubbing fastness, but it contains phosphorus element. In other words, the flame retardant processing agent of this embodiment does not contain phosphorus element, but can satisfy various finishing characteristics of polyester-based synthetic fiber structures such as flame retardancy and adhesion equivalent to or better than those of conventional phosphorus-based flame retardant processing agents.

[0074] The flame retardant finishing agent U shown in Reference Example 10 contains a phosphoric acid ester amide as a flame retardant, and the flame retardant finishing agent V shown in Reference Example 11 contains a phosphoric acid ester as a flame retardant. When these organic phosphorus-based flame retardants were used, sufficient performance could not be obtained in terms of chalk marks and rubbing fastness. [Examples 12 to 29] Flame retardant finishing agents with different addition ratios of guanidinium malate and guanidinium citrate were prepared. The prepared flame retardant finishing agents were used to perform flame retardant finishing on a polyester-based synthetic fiber structure, and the properties of the obtained flame retardant polyester-based synthetic fiber structure were evaluated. (1) Preparation of flame retardant finishing agent Raw materials were weighed at the ratios shown in Tables 14 and 15, and flame retardant finishing agents from Example 12 to Example 29 were prepared. Specifically, 0 to 10 parts by weight of citric acid was weighed with respect to 1 part by weight of malic acid, and malic acid and citric acid were dissolved in 1 to 15 parts by weight of water to obtain an aqueous solution. 0.28 to 15.4 parts by weight of guanidinium carbonate was weighed and gradually dissolved in the aqueous solution, and carbon dioxide gas was removed to prepare flame retardant finishing agents from Example 12 to Example 29. The pH of the flame retardant finishing agent was measured using a glass electrode pH meter. (2) Preparation of flame retardant polyester-based synthetic fiber structure Three types of fabrics were prepared as the polyester-based synthetic fiber structure. Fabrics a and b used in Examples 1 to 11 and Reference Examples 1 to 11 were prepared. Also, as the polyester-based synthetic fiber structure, white polyester double pique (areal weight 230 g / m 2 ) was prepared. This fabric is referred to as fabric c.

[0075] Flame retardant finishing agents diluted to an arbitrary concentration were prepared using the flame retardant finishing agents from Example 12 to Example 29. After attaching the flame retardant to fabrics a, b, and c by the padding method using the processing liquid, it was dried at 150 °C for 3 minutes to obtain a flame retardant polyester-based synthetic fiber structure. The amount of the flame retardant attached to the flame retardant polyester-based synthetic fiber structure of each example was measured. (3) Evaluation Flame retardant performance tests, calcium chloride pickup tests, and handle tests were performed on the prepared flame retardant polyester-based synthetic fiber structures. <Flame Retardancy Test> In accordance with the United States Federal Motor Vehicle Safety Standard No. 302 (FMVSS 302), a horizontal combustion test of the fabric a was conducted. When the combustion speed is less than 101 mm / min (slow burning property), it was determined that it has good flame retardancy. In Tables 14 and 15 shown below, the evaluation is indicated by the corresponding symbols shown in Table 11.

[0076]

Table 11

[0077] <With Calcium Chloride> The fabric b was placed on the urethane foam, and a 3% aqueous solution of calcium chloride was dropped on the surface. After 24 hours, the surface of the sample was visually observed. Whether or not attachment was seen was used as the evaluation criterion. In Tables 14 and 15 shown below, the evaluation is indicated by the corresponding symbols shown in Table 12.

[0078]

Table 12

[0079] <Texture> Using the fabric c, based on Method A (45° Cantilever Method) described in 8.21 (Stiffness and Softness), 8.21.1 of JIS L 1096:2010 "Test Methods for Fabrics and Knitted Fabrics", a test piece of 2 cm × 15 cm in the warp direction was prepared, placed on a horizontal table with a 45° inclination, and the scale was read when the central point of one end of the test piece came into contact with the inclined surface by sliding the test piece for evaluation. When the measured value is 50 mm or less, it was evaluated that the texture is good, and when the measured value exceeds 50 mm, it was evaluated that the texture is not good. In Tables 14 and 15 shown below, the evaluation is indicated by the corresponding symbols shown in Table 13.

[0080]

Table 13

[0081] (4) Results and Discussion Tables 14 and 15 show the results of the tests and evaluations conducted on Fabric a, Fabric b, and Fabric c. In the flame retardant agents of Examples 12 to 29, the flame retardants exist as the guanidium salts of malic acid and the guanidium salts of citric acid, but the addition ratios shown in Tables 14 and 15 indicate the weight ratios of malic acid, citric acid, and guanidine carbonate added as raw materials. The flame retardant agents of each example contain the guanidium salts of malic acid and the guanidium salts of citric acid at the addition ratios shown in Tables 14 and 15 in terms of malic acid and citric acid conversion.

[0082] The column of COOH ratio shows the ratio of the total number of two carboxy groups of malic acid and three carboxy groups of citric acid in the flame retardant agent of each example to the number of guanidium ions of the added guanidine carbonate, with the carboxy group as the reference (1).

[0083] [Table 14]

[0084] [Table 15]

[0085] As shown in Example 12 and Example 29, even when the flame retardant of the flame retardant agent contains only the guanidium salt of malic acid or the guanidium salt of citric acid, or as shown in Examples 13 to 28, when it contains both the guanidium salt of malic acid and the guanidium salt of citric acid, the polyester-based synthetic fiber structure can have sufficient flame retardant performance.

[0086] However, in order to obtain a good texture through flame-retardant processing, it can be seen that it is preferable for the flame retardant of the flame-retardant processing agent to contain both guanidine malate and guanidine citrate. More specifically, as shown in Examples 14 to 27, it is preferable that the flame retardant contains the guanidine salt of malic acid and the guanidine salt of citric acid in a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid.

[0087] Note that in the texture test, the adhesion amount of the flame retardant is set in the range of about 10% by weight to about 31% by weight so that differences in texture are likely to occur. As shown in Examples 17 to 19, even if the addition ratios of guanidine malate and guanidine citrate are within the above-mentioned range, if the adhesion amount exceeds 31% by weight, the texture deteriorates.

[0088] As shown in Examples 16 to 21, Example 23, Example 24, and Examples 26 to 29, when the pH of the flame-retardant processing agent is 4.0 or more and 9.0 or less, the adhesion of calcium chloride is suppressed. It is considered that this range of pH can be achieved when the ratio of the carboxy group to the guanidinium ion is generally from 1:0.5 to 1:1.1. As shown in Example 25, when the pH of the flame-retardant processing agent is less than 4.0, in addition to the adhesion of calcium chloride occurring, the flame-retardant performance may be insufficient. From these results, when the flame-retardant processing agent contains both the guanidine salt of malic acid and the guanidine salt of citric acid as the flame retardant, the flame retardant contains the guanidine salt of malic acid and the guanidine salt of citric acid in a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid, and when the pH of the flame-retardant processing agent is 4.0 or more and 9.0 or less, it can be seen that a flame-retardant polyester-based synthetic fiber structure excellent in flame retardancy and texture can be obtained.

[0089] Note that the attached test using an aqueous calcium chloride solution is a more severe test than the attached test using water or boiling water because calcium ions easily form salts with acid components. Therefore, if the weight ratio of the guanidinium salt of malic acid and the guanidinium salt of citric acid and the pH of the flame retardant processing agent are within the ranges described above, it is considered that the obtained flame retardant polyester-based synthetic fiber structure can effectively suppress attachment by water and boiling water. Furthermore, when the flame retardant processing agent contains both the guanidinium salt of malic acid and the guanidinium salt of citric acid in the weight ratio described above and the pH of the flame retardant processing agent is within the range described above, it is considered that a more excellent effect of suppressing attachment can be imparted to the flame retardant polyester-based synthetic fiber structure compared to a flame retardant processing agent containing only one of the guanidinium salt of malic acid and the guanidinium salt of citric acid.

[0090] As described above, from the results of Examples 1 to 29, Reference Examples 1 to 11, and the blank sample, the flame retardant processing agent of the present embodiment does not contain halogen and phosphorus elements and can impart sufficient flame retardant performance to the polyester-based synthetic fiber structure. In addition, although it contains a water-soluble salt as a flame retardant, a flame retardant polyester-based synthetic fiber structure with suppressed attachment, good texture, and excellent chalk marks and rubbing fastness can be obtained.

[0091] The flame retardant processing agent, flame retardant polyester-based synthetic fiber structure, vehicle interior material, and flame retardant processing method of the polyester-based synthetic fiber structure of the present disclosure can also be described as follows.

[0092] The flame retardant processing agent for a polyester-based synthetic fiber structure according to the first configuration includes a flame retardant containing at least one selected from the group consisting of an ammonium salt of malic acid, an ammonium salt of citric acid, a guanidinium salt of malic acid, and a guanidinium salt of citric acid.

[0093] The flame retardant finishing agent for the polyester synthetic fiber structure according to the second configuration may contain at least one selected from the group consisting of the ammonium salt of malic acid and the guanidium salt of malic acid in the first configuration.

[0094] The flame retardant finishing agent for the polyester synthetic fiber structure according to the third configuration may contain ammonium ions and / or guanidium ions of 1 mol or more per mol of malic acid as the flame retardant in the second configuration.

[0095] The flame retardant finishing agent for the polyester synthetic fiber structure according to the fourth configuration may contain at least one selected from the group consisting of the ammonium salt of citric acid and the guanidium salt of citric acid as the flame retardant in the first configuration.

[0096] The flame retardant finishing agent for the polyester synthetic fiber structure according to the fifth configuration may contain ammonium ions and / or guanidium ions of 1 mol or more per mol of citric acid as the flame retardant in the fourth configuration.

[0097] The flame retardant finishing agent for the polyester synthetic fiber structure according to the sixth configuration may contain the ammonium salt of malic acid and the ammonium salt of citric acid as the flame retardant in the first configuration.

[0098] The flame retardant finishing agent for the polyester synthetic fiber structure according to the seventh configuration further includes a solvent in the first configuration, and the solvent may contain water.

[0099] The flame retardant finishing agent for the polyester synthetic fiber structure according to the eighth configuration includes a flame retardant containing the guanidium salt of malic acid and the guanidium salt of citric acid.

[0100] The flame retardant processing agent for the polyester synthetic fiber structure according to the ninth configuration may contain the guanidium salt of malic acid and the guanidium salt of citric acid in a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid in the eighth configuration.

[0101] The flame retardant processing agent for the polyester synthetic fiber structure according to the tenth configuration further includes a solvent in the eighth configuration, and the solvent may contain water.

[0102] The pH of the flame retardant processing agent for the polyester synthetic fiber structure according to the eleventh configuration may be 4.0 or more and 9.0 or less in the tenth configuration.

[0103] The polyester synthetic fiber structure according to the twelfth configuration includes a polyester synthetic fiber structure and the flame retardant contained in the flame retardant processing agent for the polyester synthetic fiber structure according to any one of the first to eleventh configurations, and the flame retardant supported on the polyester synthetic fiber structure.

[0104] The polyester synthetic fiber structure according to the thirteenth configuration may be a polyester jersey fabric or a polyester tricot fabric in the twelfth configuration.

[0105] The vehicle interior material according to the fourteenth configuration includes the flame retardant polyester synthetic fiber structure described in the twelfth configuration.

[0106] The flame retardant processing method for the polyester synthetic fiber structure according to the fifteenth configuration uses the flame retardant processing agent for the polyester synthetic fiber structure according to any one of the first to eleventh configurations to support the flame retardant on the polyester synthetic fiber structure.

[0107] The flame retardant processing method for the polyester synthetic fiber structure according to the sixteenth configuration may apply the flame retardant to the polyester synthetic fiber structure at a ratio of 0.2% by weight or more and less than 10% by weight in the fifteenth configuration.

[0108] In the method for flame-retardant processing of a polyester synthetic fiber structure according to the 17th configuration, in the 16th configuration, after applying the flame retardant to the polyester synthetic fiber structure, the polyester synthetic fiber structure may be heat-treated at a temperature of 130°C or higher and 170°C or lower.

Industrial Applicability

[0109] The flame-retardant processing agent for a polyester synthetic fiber structure, the flame-retardant polyester synthetic fiber structure, and the method for flame-retardant processing of a polyester synthetic fiber structure of the present disclosure are suitably used for polyester synthetic fiber structures for various applications.

Claims

1. A flame retardant processing agent for a polyester synthetic fiber structure, comprising at least one selected from the group consisting of ammonium salts of malic acid, ammonium salts of citric acid, guanidinium salts of malic acid, and guanidinium salts of citric acid.

2. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 1, wherein the flame retardant comprises at least one selected from the group consisting of ammonium salts of malic acid and guanidinium salts of malic acid.

3. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 2, wherein the flame retardant contains 1 mol or more of ammonium ions and / or guanidinium ions per mol of malic acid.

4. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 1, wherein the flame retardant comprises at least one selected from the group consisting of ammonium salts of citric acid and guanidinium salts of citric acid.

5. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 4, wherein the flame retardant contains 1 mol or more of ammonium ions and / or guanidinium ions per mol of citric acid.

6. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 1, wherein the flame retardant comprises ammonium salts of malic acid and ammonium salts of citric acid.

7. Further comprising a solvent, The flame retardant processing agent for a polyester synthetic fiber structure according to claim 1, wherein the solvent contains water.

8. A flame retardant processing agent for a polyester synthetic fiber structure, comprising a flame retardant containing guanidinium salts of malic acid and guanidinium salts of citric acid.

9. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 8, wherein the flame retardant contains guanidinium salts of malic acid and guanidinium salts of citric acid in a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid.

10. Further comprising a solvent, The flame retardant processing agent for a polyester synthetic fiber structure according to claim 8, wherein the solvent contains water.

11. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 10, wherein the pH of the flame retardant processing agent is 4.0 or more and 9.0 or less.

12. A flame-retardant polyester-based synthetic fiber structure comprising a polyester-based synthetic fiber structure and the flame retardant contained in the flame-retardant treating agent for the polyester-based synthetic fiber structure according to any one of claims 1 to 11, wherein the flame retardant is supported on the polyester-based synthetic fiber structure.

13. The flame-retardant polyester-based synthetic fiber structure according to claim 12, wherein the polyester-based synthetic fiber structure is a polyester jersey knitted fabric or a polyester tricot knitted fabric.

14. An interior material for a vehicle, comprising the flame-retardant polyester-based synthetic fiber structure according to claim 12.

15. A method for flame-retardant treatment of a polyester-based synthetic fiber structure, wherein the flame retardant is supported on the polyester-based synthetic fiber structure by using the flame-retardant treating agent for the polyester-based synthetic fiber structure according to any one of claims 1 to 11.

16. The method for flame-retardant treatment of a polyester-based synthetic fiber structure according to claim 15, wherein the flame retardant is applied to the polyester-based synthetic fiber structure at a ratio of 0.2% by weight or more and less than 10% by weight.

17. The method for flame-retardant treatment of a polyester-based synthetic fiber structure according to claim 16, wherein after the flame retardant is applied to the polyester-based synthetic fiber structure, the polyester-based synthetic fiber structure is heat-treated at a temperature of 130°C or higher and 170°C or lower.

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