JPH0449845B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing flame-resistant polyester. (Prior art) Generally, polyester, especially polyethylene terephthalate, has excellent mechanical and chemical properties, so it is widely used as a textile for clothing, industrial use, etc.
It is widely used for films for magnetic tapes, photographs, condensers, etc., and for molded products such as bottles. Industrially, this polyethylene terephthalate is obtained by directly esterifying or transesterifying terephthalic acid or dimethyl terephthalate and ethylene glycol to obtain bis(β-bitroxyethyl) terephthalate (including its low polymer), which is then catalyzed. It is produced by polycondensation to form a high polymer at high temperature and high reduced pressure in the presence of polyester. Incidentally, in recent years, there has been an increasing demand for synthetic fibers and various plastic products to be flame resistant from the viewpoint of fire prevention. In particular, since polyethylene terephthalate is used in large quantities in clothing, carpets, curtains, vehicle seats, etc., there is an urgent need to establish countermeasures. Conventionally, various methods have been proposed for imparting flame resistance to polyester, and a method of incorporating a phosphorus compound into polyester is said to be effective.
It has been difficult to impart sufficiently satisfactory flame resistance. As a result of intensive research in order to obtain a polyester with excellent flame resistance, the present inventors discovered that when a phosphorus compound was added to a polyester obtained by copolymerizing an ethylene oxide adduct of bisphenol S, the flame resistance was significantly improved. I proposed it earlier (patent application 1983-
No. 6756). However, in this case, if a phosphonic acid compound having a free OH group, which is a preferable phosphorus compound because it is difficult to gel the polyester, is used as the phosphorus compound and the polycondensation reaction is carried out under high vacuum, the phosphorus compound will form a system. It was found that there was a problem in that it was easily scattered outside. (Object of the invention) The present invention provides a method for producing a flame-resistant polyester containing a bisphenol S compound and a phosphorus compound, in which a phosphonic acid compound having a free OH group is used as the phosphorus compound, and a flame-resistant polyester with a high phosphorus residual rate is used. The object of the present invention is to provide a method for producing polyester with excellent properties. (Structure of the Invention) The present invention achieves the above object and has the following structure. When producing polyester from terephthalic acid or a difunctional carboxylic acid component mainly composed of terephthalic acid and ethylene glycol or a glycol component mainly composed of terephthalic acid, a bisphenol S compound is added at any point until the completion of the polycondensation reaction. At the same time, when the intrinsic viscosity reaches 0.3 or more, a phosphonic acid compound having free OH groups is added in an amount of 0.1 to 2.5% by weight as phosphorus atoms to the generated polyester, and the polycondensation reaction is completed at an ultimate vacuum of 1 mmHg or more. A method for producing flame-resistant polyester. The bisphenol S compound in the present invention is a compound represented by the following general formula. (Here, R ₁ and R ₂ are a hydrogen atom, a lower alkyl group, an aryl group, a β-hydroxyalkyl group, and a β-hydroxyalkyl group.
- Indicates the same or different groups selected from carboxyalkyl groups and alkylcarbonyl groups. ) Specifically, bisphenol S (R ₁ , R ₂ in the previous formula
(compounds both having hydrogen atoms), dimethyl ether of bisphenol S, bisethylene oxide adduct of bisphenol S, diacetate of bisphenol S, etc. are used, but those that are reactive with polyester are preferred; Particularly preferred are bisethylene oxide adducts of bisphenol S and diacetates of bisphenol S. The amount of this compound added is 0.1 as bisphenol S skeleton to the acid component constituting the polyester.
A suitable content is 10 mol%. If the amount added is less than this range, no flame resistance improvement effect will be observed, and if it is added in an amount exceeding this range, the original advantages of polyethylene terephthalate will be impaired, such as worsening of the color tone or a large decrease in the melting point. result. The bisphenol S compound may be added at any time until the polycondensation reaction of polyester is completed, but bis(β-hydroxyethyl) terephthalate and/or its low polymer (hereinafter referred to as (abbreviated as BHET)) is practically appropriate. Further, the phosphonic acid compound in the present invention is a compound represented by the following general formula. (Here, R is an aliphatic or aromatic group, and may have a substituent.) Specific examples of phosphonic acid compounds include methylphosphonic acid, chloromethylphosphonic acid, phenylmethylphosphonic acid, ethylphosphonic acid, -bromoethylphosphonic acid, 2-phenylethylphosphonic acid, propylphosphonic acid, 2-propenylphosphonic acid, butylphosphonic acid, octylphosphonic acid,
Dodecylphosphonic acid, phenylphosphonic acid, 4-
Examples include methylphenylphosphonic acid. The intrinsic viscosity of polyester is
It must be added when it reaches 0.3 or higher, and 0.3
If it is added before the ether bond is added, the melting point of the polyester will be lowered due to the ether bond by-product, the residual rate of phosphorus in the polyester will be low, and irritating phosphorus-containing gas will be generated during spinning and molding, which is not preferable. In addition, phosphonic acid compounds have a phosphorus atom of 0.1
It is necessary to contain up to 2.5% by weight. If the amount of the phosphonic acid compound added is too small, the flame resistance will be insufficient, and if it is too large, the mechanical properties of the polyester will deteriorate, making it unsuitable. In the present invention, the polycondensation reaction after addition of the phosphonic acid compound must be carried out at an ultimate vacuum of 1 mmHg or higher; if the vacuum is stronger than this, the phosphonic acid compound will scatter out of the system along with the ethylene glycol produced by the reaction. As the amount of phosphorus increases, the residual rate of phosphorus decreases significantly. The preferred degree of vacuum is 1-20mm
Hg, especially 1-5 mmHg. The polycondensation reaction is carried out in the presence of a catalyst, and conventionally commonly used metal compounds such as antimony, titanium, germanium, tin, zinc, and cobalt can be used as catalysts, but when sulfur acid compounds are used, Favorable results are obtained. The above-mentioned metal compounds are effective for polycondensation reactions under a high vacuum of less than 1 mmHg, which is usually employed, but they are not sufficient when performing polycondensation reactions at a vacuum of 1 mmHg or more. In contrast, sulfuric acid compounds exhibit sufficient catalytic activity even under relatively low vacuum conditions. The sulfur acid compounds mentioned above include sulfur oxide related compounds which are inorganic compounds, such as sulfoxylic acid,
Dithionite, sulfite, sulfuric acid, peroxysulfuric acid,
Examples include peroxydisulfuric acid, thiosulfuric acid, thionic acid compounds, and organic compounds such as sulfonic acid, sulfinic acid, sulfenic acid, thiosulfonic acid, sulfamic acid, and their esters, ammonium salts, and other derivatives. Specific examples include sulfuric acid, acetyl sulfate, sulfuric esters (e.g. dimethyl sulfate, diethyl sulfate,
ethyl hydrogen sulfate, isopropyl hydrogen sulfate, dodecyl hydrogen sulfate, octadecyl hydrogen sulfate, phenyl hydrogen sulfate), sulfurous acid, sulfite esters (e.g. dimethyl sulfite, diethyl sulfite, di-n-butyl sulfite), aliphatic sulfonic acids and their derivatives (e.g. Methanesulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, ethyl ethanesulfonate, methanesulfonyl chloride, methanedisulfonic acid, 2-hydroxy-1-ethanesulfonic acid,
3-hydroxy-1-propanesulfonic acid, propanesultone, sulfoacetic acid, 2-amino-1-ethanesulfonic acid), aliphatic sulfinic acids and their derivatives (e.g. ethanesulfinic acid, ethanesulfinyl chloride), chlorsulfin ethyl acid,
Chlorosulfonic acid, aromatic sulfonic acids and their derivatives (e.g. benzenesulfonic acid, p-toluenesulfonic acid, 3,4-dimethylbenzenesulfonic acid, p-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, p -chlorobenzenesulfonic acid, m-nitrobenzenesulfonic acid, 4-chloro-3-methyl-5-nitrobenzenesulfonic acid, m-nitrobenzenesulfonic acid, 4-chloro-3-methyl-5-nitrobenzenesulfonic acid,
Hydroxybenzenesulfonic acid, o-formylbenzenesulfonic acid, o-aminobenzenesulfonic acid, methyl benzenesulfonate, benzenesulfonyl chloride, benzenesulfonamide, o-sulfobenzoic acid, o-sulfobenzoic anhydride, 4-
sulfoisophthalic acid, 5-sulfosalicylic acid, naphthalene sulfonic acid, 1,8-naphthalene sultone, 1,8-naphthalene sultam, anthracene sulfonic acid, benzoquinone sulfonic acid, naphthoquinone sulfonic acid, anthraquinone sulfonic acid),
Alicyclic sulfonic acids (e.g. cyclopentanesulfonic acid, cyclohexenesulfonic acid), aralkylsulfonic acids (e.g. phenylmethanesulfonic acid,
α-phenylethanesulfonic acid), heterocyclic sulfonic acids (e.g. pyridine sulfonic acid, thiazole sulfonic acid, imidazole sulfonic acid, furan sulfonic acid, pyrrole sulfonic acid), non-benzene aromatic sulfonic acids (e.g. tropolone sulfonic acid,
azulene sulfonic acid), natural or synthetic polymer sulfonic acids (for example, lignin sulfonic acid, polyvinyl sulfonic acid, polystyrene sulfonic acid, and sulfonated polyacrylic acid). Note that if these sulfuric acid compounds have a free acidic group, they may be in the form of ammonium salts (including alkyl or arylammonium salts), but they may not be in the form of alkali metal salts or alkaline earth metal salts. It has no polycondensation catalyst activity and is unsuitable. The amount of such a sulfuric acid compound added is 1×10 ^-5 to 1× per mole of the acid component constituting the polyester.
Preferably, the amount is 10 ^-2 mol. The present invention is directed to polyethylene terephthalate-based polyester, and the copolymerization components include methyl terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenylsulfone dicarboxylic acid, 5-
Also applicable to polyesters containing small amounts of sodium sulfoisophthalic acid, adipic acid, sebacic acid, p-hydroxyethoxybenzoic acid, propylene glycol, 1,4-cycloxanedimethanol, 1,4-butanediol, neopentyl glycol, etc. be able to. Further, additives such as stabilizers such as hindered phenol compounds, cobalt compounds, fluorescent agents, color improvers such as dyes, and pigments such as titanium dioxide may be present together. Incidentally, the polyester obtained by the method of the present invention is usually used as it is as a flame-resistant polyester, but it is also possible to produce a polyester with a high phosphorus content and dilute it with a polyester that does not contain phosphorus for use. (Example) Next, the present invention will be described with reference to Examples, but the present invention is not limited by these. In the Examples, the intrinsic viscosity [η] of the polyester is a value determined at a temperature of 20° C. using a mixture of equal weights of phenol and tetrachloroethane as a solvent. The content of diethylene glycol units was determined by alcoholysizing the polyester under refluxing methanol for 2 hours.
Ethylene glycol and diethylene glycol were determined by gas chromatography, and the mol% of diethylene glycol relative to the total glycol (DEG
%). The phosphorus content in the polyester was determined by fluorescent X-ray method. The color tone of polyester is adjusted to 150℃± after molding into granules.
Crystallize at 2°C for 1 hour and use a colorimeter to determine L, a,
Evaluation was made by determining the b value. The L value is the lightness (the larger the value, the brighter), the a value is the red-green hue (+ is reddish, - is greenish), and the b value is the yellow-blue hue (+ is yellowish, - is The larger the L value, the closer the a value is to 0, and the smaller the b value, unless it becomes extremely small, the better the color tone of polyester. In addition, flame retardancy is determined by spinning and drawing polyester using a conventional method, making a tube-knitted fabric, rolling 1 g of it into a length of 10 cm, and inserting it into a wire coil with a diameter of 10 mm.
Hold the sample at a 45 degree angle and add it from the bottom using a micro burner (0.64mmφ).If the fire is extinguished by moving away from the fire source, repeat the ignition and calculate the number of ignitions required until all the samples are completely burned. It is expressed as the average number of ignitions (denoted as the number of flame contacts) for each sample. (The fire service law standard is at least 3 times.) Example A slurry of terephthalic acid (TPA) and ethylene glycol (BG) (EG/TPA molar ratio 1.5) is continuously poured into an esterification reaction tank containing BHET. The reaction was carried out at 255° C. and under normal pressure for a residence time of 6 hours to continuously obtain an esterified product with a reaction rate of 96%. 50 kg of this esterified product was transferred to an autoclave, 5 x 10 ^-2 mol of bisethylene oxide adduct of bisphenol S/mol of acid component and the catalyst shown in Table 1 were added, and the pressure was gradually reduced until the final 0.1
Pre-polycondensation was carried out at mmHg and 280°C for 1.5 hours. Sample some of the polyester produced,
[η] was measured and found to be 0.50. The phosphonic acid compound shown in Table 1 was further added to the reaction system which had been returned to normal pressure, and the pressure was gradually reduced again.
Late polycondensation was carried out at 1.5 mmHg and 280°C for the time shown in Table 1, and chips were formed. In addition, as a comparative example, polyester was produced in the same manner as in the example except that the points described in the notes column of Table 1 were changed. The obtained polyester was spun and stretched according to a conventional method. The properties of the polyester and yarn are shown in Table 2.

【table】

【table】

[Table] (Effects of the Invention) As described above, according to the present invention, a polyester having a high phosphorus residual rate, good flame resistance, and good color tone can be easily produced.

Claims (1)

[Scope of Claims] 1. When producing polyester from terephthalic acid or a difunctional carboxylic acid component mainly composed of terephthalic acid and ethylene glycol or a glycol component mainly composed of terephthalic acid, at any point until the completion of the polycondensation reaction, A bisphenol S compound is added, and when the intrinsic viscosity reaches 0.3 or more, a phosphonic acid compound having a free OH group is generated.An amount of 0.1 to 2.5% by weight as phosphorus atoms is added to the polyester, and the ultimate vacuum is added. A method for producing flame-resistant polyester, characterized by completing a polycondensation reaction at a temperature of 1 mmHg or higher. 2. The method for producing a flame-resistant polyester according to claim 1, wherein the polycondensation reaction is carried out in the presence of a sulfur acid compound catalyst.