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

This 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.

Description

Flame retardant agent for polyester synthetic fiber structures, flame retardant polyester synthetic fiber structures, vehicle interior materials, and flame retardant processing method for polyester synthetic fiber structures

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

[0002] Flame retardant treatment of textile structures is carried out using flame retardants and processing methods suited to the textile material. For polyester synthetic textile structures, flame retardant processing has traditionally been carried out using water-soluble salts such as guanidine phosphate and carbamate phosphate as flame retardants and by the padding method (see, for example, Patent Document 1).

[0003] It is also known to flame-retard polyester synthetic fiber structures using halogen compounds by exhaustion or padding (see, for example, Patent Document 2).

[0004] JP 2002-38374 A JP 53-8840 A

[0005] However, when water-soluble salts are used as flame retardants, the flame-retardant polyester synthetic fiber structure may absorb and release moisture, causing crystalline deposits on the surface of the fiber structure, or may cause ring stains, also known as edge stains, when water adheres to the surface of the fiber structure.

[0006] Conventionally, halogen-based, phosphorus-based, and inorganic substances have been used as flame retardants. However, from the viewpoint of environmental impact, it is preferable that flame retardants do not contain halogen compounds or that they be used in small amounts. Furthermore, industrially usable phosphorus is obtained from phosphate rock, but because the number of countries that produce phosphate rock is limited, there are issues such as a lack of a stable supply of phosphorus and rising prices due to resource restrictions in producing countries.

[0007] In view of these problems, the present disclosure aims to provide a flame retardant for polyester synthetic fiber structures that does not contain halogens or phosphorus and that suppresses fringing, a flame-retardant polyester synthetic fiber structure, a vehicle interior material, and a method for flame-retarding a polyester synthetic fiber structure.

[0008] A flame retardant for a polyester-based synthetic fiber structure according to one embodiment of the present disclosure comprises 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.

[0009] According to one embodiment of the present disclosure, there are provided a flame retardant for polyester-based synthetic fiber structures that is free of halogens and phosphorus elements and has reduced fringing, a flame-retardant polyester-based synthetic fiber structure, a vehicle interior material, and a method for flame retarding a polyester-based synthetic fiber structure.

[0010] The flame retardant of the present disclosure can be used for flame retarding various fiber structures, and is particularly suitable for flame retarding polyester synthetic fiber structures. In this disclosure, polyester synthetic fiber structures refer to fibers containing at least polyester fibers, and fabrics containing such fibers, such as yarn, cotton, knitted or woven fabric, and nonwoven fabric. Preferably, the polyester synthetic fiber structures are polyester fibers, yarn, cotton, or fabrics such as knitted or woven fabric and nonwoven fabric made of polyester fibers. Furthermore, the knitted or woven fabric and nonwoven fabric may be a single layer, a laminate of two or more layers, or a composite made of yarn, cotton, knitted or woven fabric, and nonwoven fabric. The knitted or woven fabric may be a polyester jersey knit or a polyester tricot knit.

[0011] Examples of the polyester fiber include 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), copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and aliphatic hydroxycarboxylic acid, and L-lactic acid. copolymers of acids and aliphatic hydroxycarboxylic acids; polycaprolactones such as poly-ε-caprolactone (PCL); polyaliphatic hydroxycarboxylic acids such as polymalic acid, polyhydroxycarboxylic butyric acid, polyhydroxyvaleric acid, and β-hydroxybutyric acid (3HB)-3-hydroxyvaleric acid (3HV) random copolymers; and polyesters of glycols and aliphatic dicarboxylic acids such as polyethylene succinate (PES), polybutylene succinate (PBS), polybutylene adipate, and polybutylene succinate-adipate copolymers.

[0012] The polymer may be a copolymer with a functional compound such as a flame retardant, or may be blended with a functional compound such as an antibacterial agent during polymerization of the polymer or during spinning.

[0013] Flame-retardant polyester synthetic fiber structures that have been flame-retarded with the flame retardant of the present disclosure are suitable for use in, for example, seats, seat covers, curtains, wallpaper, ceiling cloth, carpets, drop curtains, architectural protection sheets, tents, canvas, etc. In particular, the flame-retardant polyester synthetic fiber structures of the present disclosure are suitable for use in, for example, vehicle interior materials such as seats, seat covers, ceiling materials, door trim materials, and vehicle interior curtains.

[0014] (First embodiment) The flame retardant for polyester-based synthetic fiber structures of this embodiment comprises 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 the main component of the flame retardant. The flame retardant may contain both an ammonium salt and a guanidinium salt, or may contain both a salt of malic acid and a salt of citric acid. The term "main component" refers to a component contained in a proportion exceeding 50% by weight. When the flame retardant further contains a flame retardant auxiliary, the main component refers to a component contained in a proportion exceeding 50% by weight of the total of the flame retardant and the flame retardant auxiliary.

[0015] Malic acid and citric acid are hydroxycarboxylic acids and polycarboxylic acids. Specifically, malic acid is a dicarboxylic acid, and citric acid is a tricarboxylic 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 is paired 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 is paired with an ammonium ion or a guanidinium ion as a counter ion.

[0016] That is, the flame retardant contains, as cations of the salts formed by neutralization, one or more moles of ammonium ions and / or guanidinium ions per mole of malic acid.Similarly, the flame retardant contains one or more moles of ammonium ions and / or guanidinium ions per mole of citric acid.

[0017] The flame retardant may contain more than 2 moles of ammonium ions and / or guanidinium ions per mole of malic acid. Similarly, the flame retardant may contain more than 3 moles of ammonium ions and / or guanidinium ions per mole of citric acid. However, if the flame retardant exhibits alkaline properties due to excess ammonium ions and / or guanidinium ions exceeding the neutralization point, polyester synthetic fiber structures may be damaged by the flame retardant.

[0018] For these reasons, the flame retardant preferably contains 1 to 2 moles of ammonium ions and / or guanidium ions per mole of malic acid, and preferably contains 1 to 3 moles of ammonium ions and / or guanidium ions per mole of citric acid.

[0019] Of the carboxy groups of malic acid and citric acid in the flame retardant, those that are not in the form of ammonium salts or guanidium salts do not need to be neutralized, but it is preferable that they are not in the form of sodium salts or potassium salts. This is because, as will be described later, ammonium salts or guanidium salts of malic acid and citric acid have high flame retardancy, while sodium salts or potassium salts of malic acid and citric acid have low flame retardancy.

[0020] As described above, the flame retardant may contain both a salt of malic acid and a salt of citric acid. In this case, since malic acid and citric acid are polycarboxylic acids, it is preferable to use a single type of cation, from the viewpoint of facilitating control of the pH of the flame retardant during production and suppressing variation in the properties of the flame retardant. Specifically, the flame retardant may contain an ammonium salt of malic acid and an ammonium salt of citric acid. Alternatively, the flame retardant may contain a guanidinium salt of malic acid and a guanidinium salt of citric acid.

[0021] When the flame retardant contains a guanidinium salt of malic acid and a guanidinium salt of citric acid, the guanidinium salt of malic acid and the guanidinium salt of citric acid are preferably contained in the flame retardant in a weight ratio of 1:0.1 to 1:9, calculated as malic acid and citric acid, which results in excellent texture of the flame-retarded polyester synthetic fiber structure.

[0022] The flame retardant preferably contains guanidium ions in a ratio of 0.4 to 1.1 moles per mole of the total number of carboxy groups in malic acid and citric acid. By ensuring that the ratio of carboxy groups to guanidium ions is within the above-mentioned range, the pH of the flame retardant agent is maintained within a predetermined range, as described below, and smearing is suppressed. Because the flame retardant does not contain halogens or phosphorus, it is excellent in terms of environmental impact and raw material procurement. Furthermore, as described in detail in the following examples, the malic acid and citric acid are converted into ammonium salts or guanidium salts, which provides excellent flame retardancy and suppresses smoke generation during flame retardant processing. Furthermore, although the flame retardant is a water-soluble salt, smearing and other issues are suppressed, and the properties of the polyester synthetic fiber structure after flame retardant processing are also good.

[0023] The flame retardant for the polyester synthetic fiber structure of this embodiment further comprises a solvent, and the flame retardant is dissolved in a solvent containing at least water. The pH of the flame retardant 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 a guanidinium salt of malic acid and a guanidinium salt of citric acid, the pH of the flame retardant 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 pKa of malic acid is １ is the first acid dissociation constant pKa of citric acid １ is greater than.

[0025]

[0026] Therefore, if the ratio of guanidinium ions in the flame retardant is less than 0.4 moles per mole of the combined number of carboxy groups in malic acid and citric acid (less than 5:2), the flame retardant may contain malic acid molecules in which both carboxy groups are not neutralized, which makes it easier for the pH of the flame retardant to be less than 4.

[0027] On the other hand, when the proportion of guanidinium ions in the flame retardant is more than 1.1 moles per mole of the total number of carboxy groups in malic acid and citric acid, the guanidinium ions are in excess of the carboxy groups in the flame retardant, and the excess guanidinium ions do not neutralize with the carboxy groups, resulting in an alkaline property, and the pH of the flame retardant becomes greater than 7, for example, greater than 9.

[0028] As will be explained below, when the flame retardant contains a guanidinium salt of malic acid and a guanidinium salt of citric acid, the pH of the flame retardant is 4 or more and 9 or less, thereby suppressing smearing. In particular, smearing caused by an aqueous calcium chloride solution can be effectively suppressed. Furthermore, when the flame retardant contains a guanidinium salt of malic acid and a guanidinium salt of citric acid, the texture is superior to when only one of the salts is contained.

[0029] In the flame retardant, the solvent may further contain an organic solvent, for example, 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.

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

[0031] The flame retardant for the polyester synthetic fiber structure of this embodiment may contain other conventionally known flame retardants, such as a flame retardant assistant to enhance the flame retardancy of the flame retardant, an ultraviolet absorber to enhance lightfastness, or an antioxidant.

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

[0033] The flame retardant for polyester synthetic fiber structures of this embodiment can be obtained, for example, by dissolving a flame retardant in the solvent described above. Commercially available raw materials can be used. Specifically, the flame retardant can be produced by preparing or preparing in advance at least one compound selected from the group consisting of ammonium salt of malic acid, ammonium salt of citric acid, guanidinium salt of malic acid, and guanidinium salt of citric acid, each containing ammonium ions and guanidinium ions in the ratio described above, and dissolving the compound in a solvent containing water.

[0034] Alternatively, a flame retardant can be obtained by dissolving malic acid and / or citric acid in a solvent containing water, adding ammonia water containing ammonium ions in the ratios described above to the acids, and partially or completely neutralizing the malic acid and / or citric acid. Alternatively, a flame retardant can be obtained by dissolving malic acid and / or citric acid in a solvent containing water, and adding guanidine carbonate containing guanidinium ions in the ratios described above to the acids, and partially or completely neutralizing the malic acid and / or citric acid. Most of the carbonic acid produced by neutralization decomposes, producing water and carbon dioxide. The solvent may be heated to expel the carbon dioxide as a gas and promote decomposition. This allows the flame retardant to be obtained.

[0035] The alkaline substance used to neutralize malic acid and citric acid is not limited to ammonia water and guanidine carbonate, but other substances that contain ammonium ions or guanidium ions and exhibit alkaline properties may also be used.

[0036] The flame retardant for polyester synthetic fiber structures of this embodiment does not contain halogens or phosphorus, making it advantageous in terms of environmental regulations and raw material procurement. Polyester synthetic fiber structures treated with the flame retardant of this embodiment are able to suppress the occurrence of seam marks and chalk marks, as well as deterioration in texture and abrasion fastness, making it possible to obtain flame-retardant polyester synthetic fiber structures with an excellent finish.

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

[0038] The types and characteristics of polyester-based synthetic fibers and fiber structures to be flame-retardant treated have been described above, as have the uses of polyester-based synthetic fiber structures.

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

[0040] The amount of flame retardant attached to a polyester synthetic fiber structure is preferably 0.2% by weight (% owf) or more but less than 10% by weight (% owf) of the polyester synthetic fiber structure, and more preferably in the range of 0.5 to 7% by weight. If the amount attached 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 perspective of flame retardancy, a higher amount attached is preferable. However, if the amount attached is too high, the polyester synthetic fiber structure after flame retardant processing may become coarse and hard, and the texture may deteriorate. To achieve a better texture, the amount attached is preferably 7% by weight or less.

[0041] The flame-retardant polyester synthetic fiber structure of this embodiment can be obtained by subjecting a polyester synthetic fiber structure to flame retardancy as a post-processing step using the flame retardant agent of the first embodiment.

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

[0043] There are no limitations on the post-processing method, and various processing methods can be used. For example, after the flame retardant is attached to the polyester-based synthetic fiber structure, it is heat-treated at a temperature of 130°C to 170°C for 1 to 5 minutes and dried, so that the flame retardant is supported and fixed to the polyester-based synthetic fiber structure. For example, padding, spraying, coating, etc. can be used as post-processing. Because the flame retardant is dissolved in a solvent, there is no concern about separation or sedimentation of the processing solution.

[0044] In the padding method, for example, a polyester fiber fabric is immersed in a flame retardant or a diluted solution thereof, and then the fabric is squeezed with a roller (mangle) to adhere the flame retardant. In the spraying method, the flame retardant or a diluted solution thereof is sprayed onto the fabric in a mist form to adhere it to the fabric. In the coating method, the flame retardant is thickened and then uniformly applied to the backside of the fabric to adhere it to the fabric.

[0045] In the flame-retardant treatment method for polyester synthetic fiber structures of this embodiment, a treatment with other functional finishing agents may be carried out by mixing with a flame-retardant agent, or before or after the flame-retardant treatment with the flame-retardant agent. Examples of other functional finishing agents include hardening agents, softeners, antistatic agents, water and oil repellents, texture adjusters, and SR agents.

[0046] According to this embodiment, as described in the first embodiment, the flame retardant does not contain halogens or phosphorus, thereby suppressing the occurrence of chalk marks and bleed marks. Furthermore, because the flame retardant is a water-soluble salt, the flame retardant does not need to contain a surfactant to disperse the flame retardant. Therefore, even if the polyester synthetic fiber structure is a dyed fabric, deterioration in the physical properties of the polyester synthetic fiber structure, such as bleed-out of disperse dyes due to surfactants, reduced friction fastness, and discoloration over time, is suppressed. Furthermore, since no smoke is generated during the flame retardant treatment and the polyester synthetic fiber structure does not need to be washed after the flame retardant treatment, the process is easy to work with and reduces processing costs and environmental impact.

[0047] (Examples) In order to confirm the effects of the first and second embodiments, flame retardants were prepared at various blend ratios, and polyester synthetic fiber structures were flame-retarded using the prepared flame retardants. The properties of the resulting flame-retardant polyester synthetic fiber structures were evaluated. [Examples 1 to 11, Reference Examples 1 to 11] (1) Preparation of Flame Retardants Flame retardant K was prepared from flame retardant A according to the procedures shown in Examples 1 to 11. Flame retardant V was prepared from flame retardant L according to the procedures shown in Reference Examples 1 to 11.

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

[0049] Unless otherwise specified, the non-volatile content refers to the non-volatile content remaining after evaporating the flame retardant to dryness for 60 minutes at 105° C. In the Examples and Reference Examples, the flame retardant does not contain any additives other than the flame retardant, so the non-volatile content indicates the proportion of the flame retardant in the flame retardant.

[0050] In the following, "%" means "% by weight" unless otherwise specified. Example 1: Preparation of Flame Retardant A 10 parts by weight of malic acid were dissolved in 5.8 parts by weight of water, and 5.1 parts by weight of ammonia water (25%) were gradually added to neutralize, yielding flame retardant A consisting of an aqueous solution of ammonium malate. COOH:NH3 = 2:1 pH = 4.1 Non-volatile content: 57.6% Example 2: Preparation of Flame Retardant B 10 parts by weight of malic acid were dissolved in 3 parts by weight of water, and 10.2 parts by weight of ammonia water (25%) were gradually added to neutralize, yielding flame retardant B consisting of an aqueous solution of ammonium malate. COOH:NH3 = 2:2 pH = 5.5 Non-volatile content: 56.7% Example 3 Preparation of Flame Retardant C 10 parts by weight of malic acid was dissolved in 12 parts by weight of water, and 6.7 parts by weight of guanidine carbonate was gradually added. The mixture was neutralized and carbon dioxide was removed to obtain Flame Retardant C, an aqueous solution of guanidinium malate. COOH:Gu = 2:1 pH = 4.0 Non-volatile content: 54.1% Example 4 Preparation of Flame Retardant D 10 parts by weight of malic acid was dissolved in 14 parts by weight of water, and 13.4 parts by weight of guanidine carbonate was gradually added. The mixture was neutralized and carbon dioxide was removed to obtain Flame Retardant D, an aqueous solution of guanidinium malate. COOH:Gu = 2:2 pH = 6.5 Non-volatile content: 58.0% Example 5 Preparation of flame retardant E 10 parts by weight of citric acid was dissolved in 14 parts by weight of water, and 3.5 parts by weight of ammonia water (25%) was gradually added to neutralize, yielding flame retardant E, an aqueous solution of ammonium citrate. COOH:NH3 = 3:1 pH = 3.4 Non-volatile content: 43.1% Example 6 Preparation of flame retardant F 10 parts by weight of citric acid was dissolved in 13 parts by weight of water, and 7 parts by weight of ammonia water (25%) was gradually added to neutralize, yielding flame retardant F, an aqueous solution of ammonium citrate. COOH:NH3=3:2 pH=4.8 Non-volatile content: 43.5% Example 7 Production of flame retardant G 10 parts by weight of citric acid were dissolved in 12 parts by weight of water, and 10.6 parts by weight of aqueous ammonia (25%) was gradually added thereto for neutralization, to obtain flame retardant G consisting of an aqueous solution of ammonium citrate.COOH:NH3 = 3:3 pH = 8.7 Non-volatile content: 39.7% Example 8 Preparation of Flame Retardant H 10 parts by weight of citric acid were dissolved in 8 parts by weight of water, and 4.7 parts by weight of guanidine carbonate were gradually added. The mixture was neutralized and carbon dioxide was removed to obtain flame retardant H, which was an aqueous solution of guanidinium citrate. COOH:Gu = 3:1 pH = 3.3 Non-volatile content: 63.8% Example 9 Preparation of Flame Retardant I 10 parts by weight of citric acid were dissolved in 11 parts by weight of water, and 9.8 parts by weight of guanidine carbonate were gradually added. The mixture was neutralized and carbon dioxide was removed to obtain flame retardant I, which was an aqueous solution of guanidinium citrate. COOH:Gu = 3:2 pH = 5.0 Non-volatile content: 62.4% Example 10 Preparation of Flame Retardant 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 slowly added. The mixture was neutralized and carbon dioxide removed to obtain flame retardant J, an aqueous solution of guanidinium citrate. COOH:Gu = 3:3 pH = 9.1 Non-volatile content: 60.6% Example 11 Preparation of Flame Retardant K 50 parts by weight of flame retardant D and 50 parts by weight of flame retardant J were mixed to obtain flame retardant K. COOH:Gu = 2:2, COOH:Gu = 3:3 pH = 6.6 Non-volatile content: 59.4% Reference Example 1 Preparation of Flame Retardant L 10 parts by weight of malic acid was dissolved in 10 parts by weight of water to obtain flame retardant L, an aqueous solution of malic acid. pH = 1.0 Non-volatile content: 49.8% Reference Example 2: Preparation of Flame Retardant M 10 parts by weight of citric acid was dissolved in 10 parts by weight of water to obtain flame retardant M, an aqueous citric acid solution. pH = 0.9 Non-volatile content: 48.7% Reference Example 3: Preparation of Flame Retardant N 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, and 3 parts by weight of sodium hydroxide was added for neutralization to obtain flame retardant N, an aqueous solution of malic acid sodium salt. COOH:Na = 2:1 pH = 4.3 Non-volatile content: 57.6% Reference Example 4: Preparation of Flame Retardant O 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, and 6 parts by weight of sodium hydroxide was added for neutralization to obtain flame retardant O, an aqueous solution of malic acid sodium salt.COOH:Na=2:2 pH=13.7 Non-volatile content: 62.8% Reference Example 5 Preparation of flame retardant P 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, and 2 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant P consisting of an aqueous solution of sodium citrate. COOH:Na=3:1 pH=3.6 Non-volatile content: 30.8% Reference Example 6 Preparation of flame retardant Q 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, and 4.2 parts by weight of sodium hydroxide was added and neutralized to obtain a flame retardant Q consisting of an aqueous solution of sodium citrate. COOH:Na=3:2 pH=5.0 Nonvolatile content: 35.7% Reference Example 7 Preparation of Flame Retardant R: 10 parts by weight of citric acid was dissolved in 30 parts by weight of water, and 6.2 parts by weight of sodium hydroxide was added and neutralized to obtain Flame Retardant R, an aqueous solution of sodium citrate. COOH:Na=3:3 pH=8.1 Nonvolatile content: 41.0% Reference Example 8 Preparation of Flame Retardant S: 10 parts by weight of malic acid was dissolved in 10 parts by weight of water, and 4.2 parts by weight of potassium hydroxide was added and neutralized to obtain Flame Retardant S, an aqueous solution of potassium malate. COOH:K=2:1 pH=4.8 Nonvolatile content: 59.6% Reference Example 9 Preparation of Flame Retardant T: 47 parts by weight of guanidine phosphate was dissolved in 53 parts by weight of water to obtain Flame Retardant T. Phosphoric acid:Gu = 1:1 to 1:2 pH = 5.0 Nonvolatile content: 47.0% <Reference Example 10> Preparation of Flame Retardant U 40 parts by weight of anilinodiphenylphosphate (hereinafter referred to as ADPP), 1.5 parts by weight of the ammonium salt of the sulfate ester of a 10-mol adduct of tristyrenated phenol with ethylene oxide, and 0.05 parts by weight of a silicone antifoaming agent were mixed with 35 parts by weight of water. This mixture was charged into a mill filled with glass beads with a diameter of 0.8 mm and pulverized for 4 hours to disperse the ADPP as fine particles with an average particle size of 0.548 μm. The amount of water was adjusted so that the nonvolatile content of the resulting dispersion was 41.6% when dried at 105°C for 40 minutes, yielding Flame Retardant U. Reference Example 11: Preparation of flame retardant V Tetrakis(2,6-dimethylphenyl)-m-phenylene phosphate (also known as resorcinol bis-dixylenyl phosphate)40 parts by weight of crystalline powder of RDXP (hereinafter referred to as RDXP), 1.5 parts by weight of the ammonium salt of the sulfate ester of a 10-mol adduct of tristyrenated phenol with ethylene oxide, and 0.05 parts by weight of a silicone antifoaming agent were mixed with 35 parts by weight of water. This mixture was pulverized using a homogenizer at 3000 rpm for 1 hour to obtain a treatment solution containing the RDXP with an average particle size of 50 μm or less. Next, this treatment solution was charged into a mill filled with 0.8 mm diameter glass beads and pulverized for 3 hours to disperse the RDXP as fine particles with an average particle size of 1.140 μm. The amount of water was adjusted so that the nonvolatile content of the resulting dispersion was 41.6% when dried at 105°C for 40 minutes, yielding flame retardant V according to Reference Example. (2) Preparation of Flame-Retardant Polyester-Based Synthetic Fiber Structures Two types of fabrics were prepared as polyester-based synthetic fiber structures. First, a polyester jersey knit fabric (basis weight: 280 g / m) was weft-knitted using black dope-dyed polyester fibers containing 1.5% by weight of carbon black. ２ The polyester fiber fabric for vehicle interior materials was obtained by scouring and presetting the polyester fiber fabric in accordance with the conventional method. This fabric will be referred to as Fabric a hereinafter.

[0051] In addition, a polyester tricot knitted fabric (basis weight: 250 g / m) was warp knitted using regular polyester fiber. ２ The polyester fiber fabric for vehicle interior materials was obtained by dyeing the polyester fiber fabric with 4% owf of disperse dye Dianix Black AM-SLR (manufactured by DyStar) at 130°C for 30 minutes, followed by reduction washing and drying in a conventional manner. This fabric will be referred to as Fabric b hereinafter.

[0052] Flame retardant finishing agents A to V prepared in Examples 1 to 11 and Reference Examples 1 to 11 were used to prepare treatment solutions diluted to desired concentrations. The flame retardant was applied to Fabric a by padding, followed by drying at 150°C for 3 minutes to obtain a flame-retardant polyester fiber fabric for vehicle interior materials. Similarly, the flame retardant was applied to Fabric b by padding, followed by drying at 150°C for 3 minutes to obtain a flame-retardant polyester fiber fabric for vehicle interior materials.

[0053] For the flame retardant J of Example 10, a plurality of fabrics a were flame-retarded by varying the amount of flame retardant applied. Fabrics a and b that were not flame-retarded were also prepared. (3) Evaluation The flame-retardant polyester fiber fabrics for vehicle interior materials thus prepared were subjected to a flame-retardant performance test, a crease evaluation, a chalk mark evaluation, a texture evaluation, and a rub fastness test.

[0054] <Flame Retardant Performance Test> Fabric a and fabric b were subjected to horizontal burning tests in accordance with Federal Motor Vehicle Safety Standard No. 302 (FMVSS 302). A burning rate of less than 101 mm / min was determined to have good flame retardant performance. Specific evaluation criteria are as follows. These criteria are based on the flame retardant performance required for vehicle interior materials by the road transport vehicle safety standards in Japan. In Tables 7 to 10 shown below, the burning rates and ratings are indicated by the corresponding symbols shown in Table 2.

[0055]

[0056] <Striping> Fabric a was placed on a urethane foam, and 5 mL of pure water and boiling water were dropped onto the surface. After 24 hours, the surface of the sample was visually observed. Samples that showed no striping in either pure water or boiling water were evaluated as having no striping in the overall evaluation. In Tables 7 to 10 shown below, the observation results and evaluations are indicated by the corresponding symbols shown in Table 3.

[0057]

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

[0059]

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

[0061]

[0062] <Rubbing Fastness> Fabric b was tested according to the JIS L 0849 method for testing color fastness to rubbing, using a Type II rubbing tester (Gakushin type) described in 7.1.2 of JIS L 0849, and the grade was determined using the stain gray scale (JIS L 0805). Grade 5 indicates the best rubbing fastness, and grades 3 or higher in both the dry test and the wet test were considered to have good rubbing fastness. In Tables 7 to 10 shown below, the evaluations are indicated by the corresponding symbols shown in Table 6.

[0063]

[0064] (4) Results and Discussion Tables 7 to 10 show the results of the tests and evaluations performed on Fabric a and Fabric b. The COOH ratio column shows the ratio of cations to malic acid or citric acid in the flame retardant of each Example and Reference Example, expressed as a ratio based on the number of carboxy groups. That is, for flame retardants containing malic acid, the ratio is shown as the ratio of cations to two carboxy groups (COOH) (or moles), and for flame retardants containing citric acid, the ratio is shown as the ratio of cations to three carboxy groups (COOH) (or moles). NH3 represents ammonia, Gu represents guanidine, Na represents sodium, and K represents potassium.

[0065]

[0066]

[0067]

[0068]

[0069] As shown in these tables, the use of the flame retardant of the first embodiment provides a flame-retardant polyester synthetic fiber structure that meets the flame-retardant performance requirements for vehicle interior materials and is excellent in terms of fastness to smearing, chalk marks, and abrasion. Specifically, sufficient flame-retardant performance is achieved by neutralizing at least one carboxyl group of malic acid and citric acid to form an ammonium salt or a guanidinium salt. Furthermore, the guanidinium salt of malic acid, ammonium salt of malic acid, guanidinium salt of citric acid, and ammonium salt of citric acid may be used alone as the flame retardant, or a mixture of two types of acids, as in flame retardant K of Example 11, can also achieve the above-mentioned effects.

[0070] As shown in Example 10 of Table 8, if the amount of flame retardant added is 0.2 wt% or more, sufficient flame retardancy can be obtained, and if it is 0.5 wt% or more, the flame-retardant polyester-based synthetic fiber structure exhibits self-extinguishing properties. However, if the amount of flame retardant added is 10 wt%, the texture of the flame-retardant polyester-based synthetic fiber structure deteriorates. Therefore, it is clear that the amount of flame retardant added is preferably 0.2 wt% or more but less than 10 wt%.

[0071] As shown in Reference Examples 1 and 2 in Table 9, malic acid and citric acid function as flame retardants and provide sufficient flame retardancy even when not neutralized. However, when flame retardant L containing malic acid was used, smoke was generated during processing. This is thought to be due to the low boiling point of unneutralized malic acid (167°C), which is partially evaporated under drying conditions at 150°C. Furthermore, when flame retardant M containing citric acid was used, the resulting flame-retardant polyester synthetic fiber structure had insufficient friction resistance.

[0072] As shown in Reference Examples 3 to 8 in Tables 9 and 10, when flame retardant processing agents N to S containing sodium malic acid, potassium malic acid, and sodium citric acid were used, sufficient flame retardancy was not obtained.

[0073] Flame retardant T of Reference Example 9 contains guanidine phosphate as a flame retardant and has sufficient performance in terms of flame retardancy, blotches, chalk marks, and abrasion fastness, but also contains phosphorus. In other words, the flame retardant of this embodiment does not contain phosphorus, but can satisfy various finished characteristics of polyester synthetic fiber structures, including flame retardancy and blotches, equivalent to or better than conventional phosphorus-based flame retardants.

[0074] Flame retardant U shown in Reference Example 10 contains a phosphate ester amide as a flame retardant, while flame retardant V shown in Reference Example 11 contains a phosphate ester as a flame retardant. When these organophosphorus flame retardants were used, sufficient performance was not achieved in terms of chalk mark and abrasion fastness. [Examples 12 to 29] Flame retardants containing different ratios of guanidinium salt of malic acid and guanidinium salt of citric acid were prepared. Polyester-based synthetic fiber structures were flame-retarded using the prepared flame retardants, and the properties of the resulting flame-retardant polyester-based synthetic fiber structures were evaluated. (1) Preparation of Flame Retardants: The raw materials were weighed in the proportions shown in Tables 14 and 15 to prepare the flame retardants of Examples 12 to 29. Specifically, 0 to 10 parts by weight of citric acid were weighed per 1 part by weight of malic acid, and the 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 guanidine carbonate was weighed out and gradually dissolved in an aqueous solution, and carbon dioxide gas was removed to prepare the flame retardants of Examples 12 to 29. The pH of the flame retardant was measured using a glass electrode pH meter. (2) Preparation of Flame-Retardant Polyester-Based Synthetic Fiber Structures Three types of fabrics were prepared as polyester-based synthetic fiber structures. Fabrics a and b used in Examples 1 to 11 and Reference Examples 1 to 11 were prepared. In addition, white polyester double pique (basis weight 230 g / m) was used as the polyester-based synthetic fiber structure. ２ This fabric is called fabric c.

[0075] Flame retardant finishing agents from Examples 12 to 29 were diluted to various concentrations to prepare flame retardant finishing agents. The flame retardant finishing solution was applied to Fabrics a, b, and c by padding, followed by drying at 150°C for 3 minutes to obtain flame-retardant polyester-based synthetic fiber structures. The amount of flame retardant attached to each flame-retardant polyester-based synthetic fiber structure was measured. (3) Evaluation: The flame-retardant polyester-based synthetic fiber structures were subjected to a flame retardancy test, calcium chloride adhesion test, and texture test. <Flame Retardancy Test> Fabric a was subjected to a horizontal flame test in accordance with Federal Motor Vehicle Safety Standard No. 302 (FMVSS 302). A burning rate of less than 101 mm / min (slow flame) was considered to have good flame retardancy. In Tables 14 and 15 below, the evaluations are indicated by the corresponding symbols shown in Table 11.

[0076]

[0077] <Calcium chloride blemishes> Fabric b was placed on urethane foam, and a 3% aqueous solution of calcium chloride was dropped onto the surface. After 24 hours, the surface of the sample was visually observed. The presence or absence of blemishes was used as the evaluation criterion. In Tables 14 and 15 shown below, the evaluations are indicated by the corresponding symbols shown in Table 12.

[0078]

[0079] <Texture> Using fabric c, a 2 cm x 15 cm test piece was prepared in the warp direction according to Method A (45° cantilever method) described in 8.21 (Bending resistance) 8.21.1 of JIS L 1096:2010 "Testing methods for woven and knitted fabrics," and placed on a horizontal table inclined at 45°. The test piece was slid and the scale was read when the center point of one end of the test piece contacted the inclined surface to evaluate. When the measured value was 50 mm or less, the texture was evaluated as good, and when the measured value was more than 50 mm, the texture was evaluated as not good. In Tables 14 and 15 shown below, the evaluations are indicated by the corresponding symbols shown in Table 13.

[0080]

[0081] (4) Results and Discussion Tables 14 and 15 show the results of tests and evaluations performed on Fabric a, Fabric b, and Fabric c. In the flame retardants of Examples 12 to 29, the flame retardants are present as a guanidinium salt of malic acid and a guanidinium salt of citric acid, and the addition ratios shown in Tables 14 and 15 indicate the weight ratios of malic acid, citric acid, and guanidinium carbonate added as raw materials. The flame retardants of each Example contained the guanidinium salt of malic acid and the guanidinium salt of citric acid at the addition ratios shown in Tables 14 and 15, calculated as malic acid and citric acid.

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

[0083]

[0084]

[0085] As shown in Examples 12 and 29, the polyester synthetic fiber structure can have sufficient flame retardancy whether the flame retardant in the flame retardant processing agent contains only guanidinium malate or guanidinium citrate, or whether it contains both guanidinium malate and guanidinium citrate, as shown in Examples 13 to 28.

[0086] However, in order to obtain a good texture by flame retarding, it is found that the flame retardant preferably contains both guanidinium malate and guanidinium citrate. More specifically, as shown in Examples 14 to 27, it is preferable that the flame retardant contains guanidinium malate and guanidinium citrate in a weight ratio of 1:0.1 to 1:9, calculated as malic acid and citric acid.

[0087] In the texture test, the amount of flame retardant added was set in the range of about 10% by weight to about 31% by weight so that differences in texture could be easily observed. As shown in Examples 17 to 19, even if the addition ratios of guanidinium malonate and guanidinium citrate were within the above-mentioned ranges, the texture deteriorated when the amount added exceeded 31% by weight.

[0088] As shown in Examples 16 to 21, 23, 24, and 26 to 29, calcium chloride adhesion is suppressed by setting the pH of the flame retardant at 4.0 or higher and 9.0 or lower. This pH range is thought to be achievable when the ratio of carboxy groups to guanidinium ions is approximately 1:0.5 to 1:1.1. As shown in Example 25, when the pH of the flame retardant is lower than 4.0, calcium chloride adhesion occurs and the flame retardancy may be insufficient. These results show that when the flame retardant processing agent contains both a guanidinium salt of malic acid and a guanidinium salt of citric acid as flame retardants, if the flame retardant contains the guanidinium salt of malic acid and the guanidinium salt of citric acid in a weight ratio of 1:0.1 to 1:9, calculated as malic acid and citric acid, and if the pH of the flame retardant processing agent is 4.0 or more and 9.0 or less, calcium chloride adhesion is suppressed, and a flame-retardant polyester-based synthetic fiber structure with excellent flame retardancy and texture can be obtained.

[0089] Note that the smearing test using a calcium chloride aqueous solution is more stringent than the smearing test using water or boiling water, because calcium ions readily form salts with acidic components. Therefore, it is believed that if the weight ratio of the guanidinium salt of malic acid to the guanidinium salt of citric acid and the pH of the flame retardant are within the above-mentioned ranges, the resulting flame-retardant polyester-based synthetic fiber structure can effectively suppress smearing caused by water and boiling water. Furthermore, it is believed that a flame retardant containing both the guanidinium salt of malic acid and the guanidinium salt of citric acid in the above-mentioned weight ratio and having a pH within the above-mentioned range can impart a more excellent smearing suppression effect to the flame-retardant polyester-based synthetic fiber structure than a flame retardant containing only one of the guanidinium salt of malic acid and the guanidinium salt of citric acid.

[0090] As described above, the results of Examples 1 to 29, Reference Examples 1 to 11, and the blank sample demonstrate that the flame retardant agent of this embodiment does not contain halogens or phosphorus and can impart sufficient flame retardancy to polyester-based synthetic fiber structures. Furthermore, although it contains a water-soluble salt as a flame retardant, it can provide flame-retardant polyester-based synthetic fiber structures with reduced fading, good texture, and excellent durability against chalk marks and abrasion.

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

[0092] The flame retardant for polyester synthetic fiber structures according to the first aspect comprises a flame retardant containing 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.

[0093] The flame retardant for polyester-based synthetic fiber structures according to the second aspect may be the flame retardant for polyester-based synthetic fiber structures according to the first aspect, wherein the flame retardant contains at least one selected from the group consisting of the ammonium salt of malic acid and the guanidinium salt of malic acid.

[0094] The flame retardant for polyester synthetic fiber structures according to a third aspect is the second aspect, wherein the flame retardant contains 1 mole or more of ammonium ions and / or guanidium ions per mole of malic acid.

[0095] A fourth aspect of the flame retardant for polyester-based synthetic fiber structures is the first aspect of the flame retardant, 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.

[0096] A flame retardant for polyester synthetic fiber structures according to a fifth aspect is the fourth aspect, wherein the flame retardant contains 1 mole or more of ammonium ions and / or guanidium ions per mole of citric acid.

[0097] A sixth aspect of the flame retardant for polyester synthetic fiber structures is the first aspect, wherein the flame retardant contains the ammonium salt of malic acid and the ammonium salt of citric acid.

[0098] The flame retardant for polyester synthetic fiber structures according to a seventh aspect is the first aspect, further comprising a solvent, and the solvent may contain water.

[0099] The flame retardant for polyester synthetic fiber structures according to an eighth aspect includes a flame retardant containing a guanidinium salt of malic acid and a guanidinium salt of citric acid.

[0100] A ninth aspect of the flame retardant for polyester-based synthetic fiber structures is the eighth aspect, wherein the flame retardant contains the guanidinium salt of malic acid and the guanidinium salt of citric acid in a weight ratio of 1:0.1 to 1:9, calculated as malic acid and citric acid.

[0101] The flame retardant for polyester synthetic fiber structures according to a tenth aspect is the eighth aspect, further comprising a solvent, and the solvent may contain water.

[0102] The flame retardant for a polyester synthetic fiber structure according to an eleventh aspect may be the flame retardant for the tenth aspect, wherein the pH of the flame retardant is 4.0 or more and 9.0 or less.

[0103] A polyester-based synthetic fiber structure according to a twelfth configuration comprises a polyester-based synthetic fiber structure and the flame retardant contained in the flame retardant processing agent for the polyester-based synthetic fiber structure described in any one of the first to eleventh configurations, the flame retardant being supported on the polyester-based synthetic fiber structure.

[0104] A polyester-based synthetic fiber structure according to a thirteenth aspect is the twelfth aspect, wherein the polyester-based synthetic fiber structure is a polyester jersey knit fabric or a polyester tricot knit fabric.

[0105] A vehicle interior material according to a fourteenth aspect includes the flame-retardant polyester-based synthetic fiber structure according to the twelfth aspect.

[0106] A method for flame-retarding a polyester-based synthetic fiber structure according to a fifteenth aspect comprises carrying a flame-retardant agent for a polyester-based synthetic fiber structure described in any one of the first to eleventh aspects on the polyester-based synthetic fiber structure.

[0107] The flame retardant processing method for polyester-based synthetic fiber structures according to a sixteenth aspect may be the fifteenth aspect, wherein the flame retardant is applied to the polyester-based synthetic fiber structure in a proportion of 0.2% by weight or more but less than 10% by weight.

[0108] The flame retardant processing method for a polyester-based synthetic fiber structure according to the seventeenth aspect may be the sixteenth aspect, in which 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.

[0109] The flame retardant agent for polyester synthetic fiber structures, the flame retardant polyester synthetic fiber structure, and the flame retardant processing method for polyester synthetic fiber structures of the present disclosure are suitable for use in polyester synthetic fiber structures for a variety of 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 contains at least one selected from the group consisting of the ammonium salt of malic acid and the guanidinium salt 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 contains at least one selected from the group consisting of the ammonium salt of citric acid and the guanidinium salt 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 contains the ammonium salt of malic acid and the ammonium salt of citric acid.

7. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 1, further comprising a solvent, 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 the guanidinium salt of malic acid and the guanidinium salt of citric acid in a weight ratio of 1:0.1 to 1:9 in terms of malic acid and citric acid.

10. The flame retardant processing agent for a polyester synthetic fiber structure according to claim 8, further comprising a solvent, 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 synthetic fiber structure, comprising a polyester synthetic fiber structure and the flame retardant contained in the flame retardant processing agent for a polyester synthetic fiber structure according to any one of claims 1 to 11, wherein the flame retardant is supported on the polyester synthetic fiber structure.

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

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

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

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

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

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