JP2020083932A - Flame-retardant polyester resin composition and molded article therefrom - Google Patents

Abstract

To provide a flame-retardant polyester resin composition substantially free from halogen, having high flame retardancy, having balance of heat resistance and mechanical characteristics industrially useful, and not thickening after heat hysteresis, and to provide a molded article therefrom.SOLUTION: There is provided a flame-retardant polyester resin composition comprising: based on (A) 100 pts. wt. of an aromatic polyester resin having an intrinsic viscosity of 0.5 to 1.6 dL/g, (B) 0.1 to 40 pts. wt. of a pentaerythritol diphosphonate compound represented by formula (1) satisfying the following conditions (a) to (c), and (C) 0.03 to 10 pts. wt. of an acidic compound. The conditions are; (a) an organic purity is 98% or more, (b) a total content of halogen components is 1000 ppm or less, and (c) a total content of volatile organic substances is 800 ppm or less.SELECTED DRAWING: None

Description

The present invention relates to a flame-retardant polyester resin composition having a high degree of flame retardancy and good physical properties, and a molded product made from the same. More specifically, it relates to a substantially halogen-free flame-retardant polyester resin composition containing a specific phosphorus-based flame retardant and a specific acidic compound, and a molded article made from the same.

Since polyester resins such as polybutylene terephthalate (hereinafter abbreviated as PBT) and polyethylene terephthalate (hereinafter abbreviated as PET) have excellent mechanical properties, heat resistance, chemical resistance, etc., they are used in electrical and electronic fields and machine component fields. It is widely used as a molded product for applications such as the automobile field.

Among them, there are many applications in which flame retardancy is required, and conventionally, a halogen-containing compound and an antimony compound are used as a flame retardant and a flame retardant auxiliary, respectively, to provide a resin having flame retardancy.

However, decomposition products of halogen-containing flame retardants may corrode metals in electrical products, and in recent years, some halogen-containing flame retardants have become problematic in terms of environmental impact. The non-halogenated movement has become popular around the world. As a result, the demand for non-halogen flame retardants has increased, and development of non-halogen flame retardants for each resin has become active. Various non-halogen flame-retardant technologies have been reported for polyester resins, but due to various problems, they have not been put to practical use.

Phosphorus-containing compounds are often used as the non-halogen flame retardant, and phosphoric acid esters such as red phosphorus and triphenylphosphonate (hereinafter abbreviated as TPP) are often used in this field. However, polyester resins such as PBT have a relatively high processing temperature, and it is pointed out that phosphine gas, which is highly toxic with red phosphorus, is generated, and when red phosphorus is used, the composition becomes a brown color peculiar to red phosphorus. There is also a problem that the range of use is limited. On the other hand, low molecular weight TPP has a problem of bleed-out, and since aromatic phosphates represented by TPP generally have a plasticizing effect, there is a problem that the heat resistance of the composition is significantly lowered.

Next, we will introduce literatures that are known about techniques for improving flame-retardant resin compositions using phosphorus-containing compounds as flame retardants. For example, Patent Document 1 discloses a non-halogen flame retardant for a polyester resin, which is obtained by melt-reacting a polyester resin and a phosphorus, nitrogen or boron compound having a functional group capable of reacting with two or more epoxy groups in the molecule. Has been done. Patent Document 2 discloses a flame-retardant polyester resin composition obtained by adding 5 to 50 parts by weight of the non-halogen flame retardant to 100 parts by weight of a polyester resin. However, such a resin composition has not only insufficient flame retardancy, but also poor fluidity and is disadvantageous in terms of cost.

In JP-A-8-208884, a thermoplastic resin such as polystyrene or polyester is substituted with a phosphorus-containing compound (specifically, triphenyl phosphate) such as a phosphoric acid ester or a phosphorous acid ester at the ortho position or the para position. A flame-retardant resin composition obtained by adding a phenol resin together is disclosed. This resin composition has not only the problems of bleed-out and deterioration of heat resistance, but also the drawback that sufficient flame retardancy cannot be obtained.

Further, in Patent Document 3, 99 to 34 parts by weight of a thermoplastic polyester resin having a softening point of 150° C. or higher, such as PET, 1 to 25 parts by weight of red phosphorus coated with a thermosetting resin, and a reinforcing filler 10 to 10 A flame retardant polyester resin composition consisting of 55 parts by weight is disclosed. However, this resin composition has a problem relating to coloring and a problem of generation of phosphine gas during molding, as described above.

Further, Patent Document 4 discloses a flame-retardant polyester fiber composition comprising a fiber-forming linear polyester, an aryl spirophosphate, and a halogen-containing flame retardant containing at least 40% of chlorine atoms or nitrogen atoms. This publication specifically discloses the flame retardancy of a fiber in which an aryl spirophosphate and a halogen-containing compound are used in combination with PET as a flame-retardant component.

Further, Patent Document 5 discloses a flame-retardant fiber composition comprising a specific polyester resin and halogen-containing spiro diphosphate. In this publication, specifically, a polyethylene naphthalate resin is blended with a spiro diphosphate containing a halogen element, and the flame retardancy of the obtained fiber is shown. However, this U.S. patent relates to a fiber, and although the flame retardancy of polyester fiber is improved, it uses a halogen-containing flame retardant, and as described above, the influence on the environment poses a problem.

Further, Patent Document 6 discloses a flame-retardant resin composition comprising a polyester resin, melamine pyrophosphate and an organic cyclic phosphorus compound. In this publication, a high flame retardant effect is obtained by using the above two flame retardants together. This flame-retardant effect is largely due to melamine pyrophosphate, but when this melamine pyrophosphate is used, there is a problem in that it is difficult to put it into practical use because the appearance of the molded product will be poor.

Further, Patent Documents 7 and 8 describe examples of resin compositions and fibers that exhibit flame retardancy by using the flame retardant of the formula (1), but the thermal history of the resin composition There is no description regarding the subsequent viscosity increase.

JP, 7-126498, A JP-A-7-278267 Japanese Patent Publication No. 2-37370 Japanese Patent Laid-Open No. 50-58319 US Pat. No. 3,866,405 US Pat. No. 4,257,931 JP, 2003-160722, A JP, 2017-179654, A

The object of the present invention is to eliminate the above-mentioned conventional problems, substantially free of halogen, has a high degree of flame retardancy, and has a balance of industrially useful heat resistance and mechanical properties, and the like. It is an object of the present invention to provide a flame-retardant polyester resin composition which does not increase in viscosity after heat history and a molded article made from the same.

According to the studies by the present inventors, the above-mentioned object of the present invention is achieved by the following <1> to <9>.

（式中、Ｒ２、Ｒ５は同一または異なっていてもよく、置換基を有しても良いフェニル基、置換基を有しても良いナフチル基、置換基を有しても良いアントリル基または芳香族置換基を有しても良い炭素数１〜４の分岐状もしくは直鎖状のアルキル基である。Ｒ１、Ｒ３、Ｒ４、Ｒ６は同一または異なっていてもよく、水素原子、炭素数１〜４の分岐状もしくは直鎖状のアルキル基、置換基を有しても良いフェニル基、置換基を有しても良いナフチル基または置換基を有しても良いアントリル基である。） <1> For (A) 100 parts by weight of an aromatic polyester resin having an intrinsic viscosity of 0.5 to 1.6 dL/g, (B) the following formulas in which each physical property satisfies the following conditions (A) to (C): A flame-retardant polyester resin composition comprising 0.1 to 40 parts by weight of a pentaerythritol diphosphonate compound represented by (1) and 0.03 to 10 parts by weight of an acidic compound (C).
(A) Organic purity of 98% or more (a) Total halogen content of 1000 ppm or less (c) Total volatile organic content of 800 ppm or less

(In the formula, R2 and R5 may be the same or different, and may have a phenyl group which may have a substituent, a naphthyl group which may have a substituent, an anthryl group which may have a substituent or an aromatic group. It is a branched or linear alkyl group having 1 to 4 carbon atoms which may have a group substituent.R1, R3, R4 and R6 may be the same or different, and are a hydrogen atom and 1 to carbon atoms. 4 is a branched or linear alkyl group, a phenyl group which may have a substituent, a naphthyl group which may have a substituent or an anthryl group which may have a substituent.)

<2> The above-mentioned item 1, wherein the pentaerythritol diphosphonate compound represented by the formula (1) is at least one compound selected from the group consisting of compounds represented by the following formulas (2) to (5). Flame-retardant polyester resin composition of.

（式中Ｒ７は炭素数１〜３０の分岐状もしくは直鎖状のアルキル基を表し、ｎは１または２を表す。）

（式中Ｒ８、Ｒ９は同一もしくは異なり、炭素数１〜３０の分岐状もしくは直鎖状のアルキル基を表す。） <3> The flame-retardant polyester resin composition according to item 1, wherein the acidic compound (C) is a compound represented by the following formula (6) and/or the following formula (7).

(In the formula, R7 represents a branched or linear alkyl group having 1 to 30 carbon atoms, and n represents 1 or 2.)

(In the formula, R8 and R9 are the same or different and each represents a branched or linear alkyl group having 1 to 30 carbon atoms.)

<4> The flame-retardant polyester resin composition according to the above item 1, having a viscosity increase of 200 Pa·s or less evaluated by the following method.
Evaluation method of viscosity increase: A polyester composition dried by a hot air dryer at 120° C. for 12 hours was used as a viscosity measuring device using Rheometer ARES-G2 manufactured by TA Instruments, measurement temperature 300° C., shear rate 1 Hz, upper jig 25 mmφ. Cone plate (0.1 rad), lower jig 25φ parallel plate, GAP 0.50 mm. Increase the difference (calculated by the following formula (II)) between the resin viscosity 1 minute after the start of measurement (measurement value is μ1) and the resin viscosity 30 minutes after the start of measurement (measurement value is μ2) The viscosity was used.
Viscosity increase=|μ2-μ1|...(II)

<5> The aromatic polyester resin of (A) is a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polyethylene naphthalate resin, a polybutylene naphthalate resin, a polycyclohexane dimethyl terephthalate resin, a polytrimethylene terephthalate resin, or a polytrimethylene naphtha resin. The flame-retardant polyester resin composition according to item 1, which is at least one selected from the group consisting of phthalate resins.
<6> A masterbatch comprising the flame-retardant polyester resin composition according to any one of items 1 to 5 above.
<7> A molded product obtained by molding the flame-retardant polyester resin composition according to any one of items 1 to 5 above.
<8> A fiber obtained by spinning the flame-retardant polyester resin composition according to any one of items 1 to 5 above.
<9> A sheet or film obtained by molding the flame-retardant polyester resin composition according to any one of items 1 to 5 above.

According to the present invention, it is substantially halogen-free, has a high degree of flame retardancy, and has a balance of industrially useful heat resistance, mechanical properties, etc., and does not increase in viscosity after heat history. A flammable polyester resin composition and a molded article made thereof can be provided.

Hereinafter, the flame-retardant polyester resin composition of the present invention will be described in more detail.

(Polyester resin)
The polyester resin used for producing the flame-retardant polyester fiber of the present invention is mainly a polyester obtained from an aromatic dicarboxylic acid or its ester-forming derivative and a diol and its ester-forming derivative as a main starting material. is there. Specific examples of the dicarboxylic acid or its ester-forming derivative include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4, 4-diphenyldicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-tetra Dicarboxylic acids such as butylphosphonium sulfoisophthalic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, benzophenone dicarboxylic acid, diphenoxyethane dicarboxylic acid, cyclohexane dicarboxylic acid, decalin dicarboxylic acid, tricyclodecane dicarboxylic acid And ester-forming derivatives thereof. Examples of the ester-forming derivative include dimethyl ester, diethyl ester, dipropyl ester, dibutyl ester, dipentyl ester, dihexyl ester, diphenyl ester, and acid halide of dicarboxylic acid described above. You may use together 1 type(s) or 2 or more types of these compounds. Among these, terephthalic acid, 2,6-naphthalenedicarboxylic acid or their ester-forming derivatives are preferably used, and more preferably terephthalic acid, 2,6-naphthalenedicarboxylic acid or their ester-forming derivatives are obtained. From the viewpoint of heat resistance, it is preferable to use 80 mol% or more of all dicarboxylic acid components in the polyester.

As the diol and its ester-forming derivative, specifically, ethylene glycol, trimethylene glycol, 1,2-propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, octamethylene glycol, decanediol, dodecanediol, tricyclo[5.2.1.02,6]decanedimethanol, polyethylene glycol, polypropylene glycol, 1,4- Examples thereof include bis(β-hydroxyethoxy)benzene, 2,2-bis(p-β-hydroxyethoxyphenyl)propane, and bis(p-β-hydroxyethoxyphenyl)sulfone dihydroxy compound.

As a preferred example of the aromatic polyester resin (A), the main dicarboxylic acid component is at least one dicarboxylic acid selected from terephthalic acid and 2,6-naphthalene dicarboxylic acid, and the main diol component is ethylene glycol, trimethylene glycol, It is a polyester having an ester unit composed of at least one diol selected from tetramethylene glycol and 1,4-cyclohexanedimethanol.

Specific aromatic polyester resins (A) include polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, polycyclohexane dimethyl terephthalate resin, polytrimethylene terephthalate resin and polytrimethylene naphthalate resin. It is preferably at least one selected from the group consisting of

Particularly preferred is at least one selected from the group consisting of polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin. Polyethylene terephthalate resin is particularly preferable.

Further, as the aromatic polyester resin (A) of the present invention, a polyester elastomer having the above repeating unit as a main repeating unit of a hard segment can also be used.

As the soft segment of the polyester elastomer having tetramethylene terephthalate or tetramethylene-2,6-naphthalene dicarboxylate as the main repeating unit of the hard segment, for example, dicarboxylic acid is selected from terephthalic acid, isophthalic acid, sebacic acid and adipic acid. At least one dicarboxylic acid, and the diol component comprises at least one diol selected from the group consisting of long-chain diols having 5 to 10 carbon atoms and H(OCH ₂ CH ₂ )iOH (i=2-5). Further, a polyester or polycaprolactone having a melting point of 100° C. or lower or amorphous can be used. The main component is a component of 80 mol% or more, preferably 90 mol% or more, of all dicarboxylic acid components or all glycol components, and the main repeating unit is 80 mol% or more, preferably 90 mol% of all repeating units. It is a repeating unit of not less than mol%.

The molecular weight of the aromatic polyester resin in the present invention has only to have an intrinsic viscosity that can be usually used as a molded product, and the intrinsic viscosity measured in orthochlorophenol at 35° C. is 0.5 to 1.6 dL/g. , Preferably 0.55 to 1.5 dL/g, more preferably 0.6 to 1.4 dL/g, and further preferably 0.62 to 1.3 dL/g.
(Pentaerythritol diphosphonate compound)
As the phosphorus-based flame retardant used in the flame-retardant polyester resin composition of the present invention, a pentaerythritol diphosphonate compound represented by the following formula (1) is used.

式（１）で表されるペンタエリスリトールジホスホネート化合物において、Ｒ２、Ｒ５は同一または異なっていてもよく、置換基を有しても良いフェニル基、置換基を有しても良いナフチル基、置換基を有しても良いアントリル基、または芳香族置換基を有しても良い炭素数１〜４の分岐状もしくは直鎖状のアルキル基である。

In the pentaerythritol diphosphonate compound represented by the formula (1), R2 and R5 may be the same or different, and may have a phenyl group which may have a substituent, a naphthyl group which may have a substituent, and a substituent. An anthryl group which may have a group, or a branched or linear alkyl group having 1 to 4 carbon atoms which may have an aromatic substituent.

R1, R3, R4 and R6 may be the same or different and each have a hydrogen atom, a branched or linear alkyl group having 1 to 4 carbon atoms, a phenyl group which may have a substituent or a substituent. It may be a naphthyl group or an anthryl group which may have a substituent.

Preferably, R2 and R5 are the same or different phenyl group, naphthyl group, anthryl group, benzyl group and phenethyl group, and R1, R3, R4 and R6 are the same or different hydrogen atoms, Methyl group, ethyl group, various propyl group, various butyl group, phenyl group, various toluyl group, naphthyl group, and anthryl group. More preferably, R2 and R5 are the same or different phenyl groups or benzyl groups, and R1, R3, R4 and R6 may be the same or different hydrogen atoms, methyl groups, ethyl groups or phenyl groups. Is.

Specific examples of such compounds include 3,9-bis(phenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9- Bis((2-methylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((3-methylphenyl ) Methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((4-methylphenyl)methyl)-3,9 -Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((2,4-dimethylphenyl)methyl)-3,9-dioxo-2, 4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((2,6-dimethylphenyl)methyl)-3,9-dioxo-2,4,8,10 -Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((3,5-dimethylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3, 9-diphosphaspiro[5.5]undecane, 3,9-bis((2,4,6-trimethylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] Undecane, 3,9-bis((2-sec-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5] Undecane, 3,9-bis((4-sec-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9 -Bis((2,4-di-sec-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9- Bis((2,6-di-sec-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-bis ((2,4,6-Tri-sec-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9- Bis((2-tert-butylphen Phenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((4-tert-butylphenyl)methyl)- 3,9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-bis((2,4-di-tert-butylphenyl)methyl)-3 , 9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((2,6-di-tert-butylphenyl)methyl)-3, 9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((2,4,6-tri-tert-butylphenyl)methyl)-3 ,9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((4-biphenyl)methyl)-3,9-dioxo-2,4 ,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((1-naphthyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3 ,9-Diphosphaspiro[5.5]undecane,3,9-bis((2-naphthyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5 ] Undecane, 3,9-bis((1-anthryl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis ((2-anthryl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis((9-anthryl)methyl) -3,9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(1-phenylethyl)-3,9-dioxo-2,4 ,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(2-methyl-2-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa -3,9-Diphosphaspiro[5.5]undecane, 3,9-bis(diphenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane , 3,9-bis(tri Phenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3-phenylmethyl-9-((2,6-dimethylphenyl)methyl) -3,9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3-phenylmethyl-9-((2,4-di-tert-butylphenyl)methyl )-3,9-Dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3-phenylmethyl-9-(1-phenylethyl)-3,9-dioxo- 2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3-phenylmethyl-9-diphenylmethyl-3,9-dioxo-2,4,8,10-tetraoxa-3, 9-diphosphaspiro[5.5]undecane, 3-((2,6-dimethylphenyl)methyl)-9-(1-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3 , 9-Diphosphaspiro[5.5]undecane, 3-((2,4-di-tert-butylphenyl)methyl)-9-(1-phenylethyl)-3,9-dioxo-2,4,8, 10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3-diphenylmethyl-9-(1-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9- Diphosphaspiro[5.5]undecane, 3-diphenylmethyl-9-((2,6-dimethylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5 .5] Undecane, 3-diphenylmethyl-9-((2,4-di-tert-butylphenyl)methyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[ 5.5] Examples include undecane.

Particularly preferably, 3,9-bis(phenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5. 5] Undecane (compound of the following formula (2)), 3,9-bis(1-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5 ] Undecane (compound of formula (3) below) 3,9-bis(2-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] Undecane (compound of formula (4) below), 3,9-bis(diphenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (below Compounds of formula (5)) are preferred.

(I) Organic Purity The pentaerythritol diphosphonate compound represented by the formula (1) has an (i) organic purity of 98% or more, preferably 98.5% or more, more preferably 99.0% or more. is there. By using the pentaerythritol diphosphonate compound having an organic purity within this range, it becomes possible to obtain a polyester resin composition having both high flame retardancy and good physical properties. In particular, the organic purity affects the flame retardancy of the obtained polyester resin composition, and when the organic purity is low, high flame retardancy cannot be obtained. Furthermore, the pentaerythritol diphosphonate compound having a low organic purity causes deterioration of hue and physical properties of the polyester resin composition obtained due to the influence of impurities, particularly deterioration of heat resistance.

(Ii) Total content of halogen component (ii) Total content of halogen component of the pentaerythritol diphosphonate compound represented by the formula (1) is 1000 ppm or less, preferably 800 ppm or less, more preferably 500 ppm or less, and further preferably 300 ppm or less. , Particularly preferably 100 ppm or less. The total halogen component (ii) is measured by a method according to JIS K7229.

Since one of the objects of the present invention is to provide a non-halogen flame-retardant polyester composition, it is preferable to use the pentaerythritol diphosphonate compound having a halogen content in this range. Further, by using the pentaerythritol diphosphonate compound having a halogen content represented by chlorine in this range, a polyester resin composition having good thermal stability and a polyester resin composition having excellent hue can be obtained. .. When the halogen content exceeds this range, the thermal stability of the polyester resin composition is lowered, and the hue is lowered due to the occurrence of burns during extrusion or high temperature molding.

(Iii) Total Volatile Organic Substance Content (iii) The total volatile organic substance content of the pentaerythritol diphosphonate compound represented by the formula (1) is 800 ppm or less, preferably 600 ppm or less, more preferably 500 ppm or less, More preferably, it is 400 ppm or less.

By using the pentaerythritol diphosphonate compound having a total volatile organic content within this range, a polyester resin composition having a high degree of flame retardancy can be obtained. When the pentaerythritol diphosphonate compound having a residual solvent content exceeding this range is used, it becomes difficult to obtain desired flame retardancy.

(Iv) ΔpH value The pentaerythritol diphosphonate compound represented by the formula (1) has a (iv) ΔpH value of preferably 1.0 or less, more preferably 0.8 or less, and still more preferably 0.1. It is 5 or less. By using the pentaerythritol diphosphonate compound having a pH of this range, a polyester fiber having good thermal stability can be obtained because the content of a trace amount of impurities such as pH fluctuation is small, and the hue is excellent. A polyester resin composition is obtained. If the ΔpH exceeds this range, the thermal stability of the polyester resin composition may be reduced, and the hue may be reduced due to the occurrence of burns during high-temperature molding.

(V) Acid value The (v) acid value of the pentaerythritol diphosphonate compound represented by the formula (1) is preferably 0.7 mgKOH/g, more preferably 0.5 mgKOH/g, further preferably 0.4 mgKOH. /G. By using the pentaerythritol diphosphonate compound having an acid value in this range, a molded article excellent in flame retardancy and hue can be obtained, and decomposition of the polyester resin is less likely to occur, and molding with good thermal stability The body is obtained. Here, the acid value means the amount (mg) of KOH necessary to neutralize the acid component in 1 g of the sample.

The pentaerythritol diphosphonate compound is 0.1 to 40 parts by weight, preferably 0.3 to 38 parts by weight, more preferably 0.5 to 35 parts by weight, and further preferably 100 parts by weight of the aromatic polyester resin. The amount is 1 to 30 parts by weight, particularly preferably 2 to 25 parts by weight. If the blending amount is too small, the flame retardance is poor, and if the blending amount is too large, the heat resistance decreases.

The suitable range of the blending ratio of the pentaerythritol diphosphonate compound is determined by the desired flame retardancy level, the type of polyester resin, and the like. Other components other than the polyester resin and the pentaerythritol diphosphonate compound constituting these compositions can be used if necessary, as long as they do not impair the object of the present invention, and other flame retardants and flame retardant aids. The blending amount of the pentaerythritol diphosphonate compound can also be changed by using the agent and the fluorine-containing resin.

(Method for producing pentaerythritol diphosphonate compound)
The pentaerythritol diphosphonate compound used in the present invention can be produced by synthesizing by the following method, washing, and optionally pulverizing.

<Synthesis process>
The pentaerythritol diphosphonate compound represented by the formula (1) can be synthesized by the following method.

The pentaerythritol diphosphonate compound is obtained, for example, by reacting pentaerythritol with phosphorus trichloride, subsequently treating the oxidized reaction product with an alkali metal compound such as sodium methoxide, and then reacting with an aralkyl halide.

It can also be obtained by a method of reacting pentaerythritol with aralkylphosphonic acid dichloride, or a method of reacting a compound obtained by reacting pentaerythritol with phosphorus trichloride with aralkyl alcohol and then performing Arbuzov rearrangement at high temperature. .. The latter reaction is disclosed in, for example, U.S. Pat. No. 3,141,032, JP-A-54-157156, and JP-A-53-39698.

The synthesis can be performed, for example, by the following method.
(I) a compound represented by the formula (2) in the pentaerythritol diphosphonate compound;
It can be obtained by reacting pentaerythritol with phosphorus trichloride, adding benzyl bromide to the reaction product of the obtained product and benzyl alcohol, and carrying out an Arbuzov rearrangement reaction at high temperature.
(II) a compound represented by the formula (3) in the pentaerythritol diphosphonate compound;
It can be obtained by reacting pentaerythritol with phosphorus trichloride and then oxidizing the reaction product with tertiary butanol with sodium methoxide to react with 1-phenylethyl bromide.
(III) a compound represented by the formula (4) in the pentaerythritol diphosphonate compound;
It can be obtained by reacting pentaerythritol with phosphorus trichloride and then oxidizing the reaction product with tertiary butanol with sodium methoxide to react with 2-phenylethyl bromide.
(IV) a compound represented by the formula (5) in the pentaerythritol diphosphonate compound;
It can be obtained by reacting pentaerythritol with diphenylmethylphosphonic acid dichloride.
Alternatively, it can be obtained by reacting pentaerythritol with phosphorus trichloride, adding a catalyst to the reaction product of the obtained product and diphenylmethyl alcohol, and performing the Arbuzov rearrangement reaction at high temperature.

<Washing steps 1 and 2>
The washing step is a step of washing the synthesized pentaerythritol diphosphonate compound with a solvent to remove impurities. The cleaning process includes cleaning processes 1 and 2.

The washing step 1 is a step of washing the pentaerythritol diphosphonate compound with an aromatic organic solvent such as xylene or toluene. In the washing step 1, it is preferable to perform repulp washing in which washing and filtration are repeated several times. By this cleaning step 1, impurities such as bromine compounds can be efficiently removed. The amount of the aromatic organic solvent used is preferably 0.1 to 5 mol/L, more preferably 0.3 to 3 mol/L, when expressed by the molar concentration of the pentaerythritol diphosphonate compound used in the present invention. is there.

Washing step 2 is a step of washing the obtained crude purified product with a compound represented by the following formula (8) or (9) at a washing temperature of 35°C to 120°C under reflux washing.

（Ｒ１０は、水素原子または炭素数１〜６の直鎖状もしくは分岐状のアルキル基、Ｒ１１およびＲ１２は同一または異なっていてもよく、炭素数１〜６の直鎖状もしくは分岐状のアルキル基である。）

(R10 is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R11 and R12 may be the same or different, and a linear or branched alkyl group having 1 to 6 carbon atoms. It is.)

The reflux cleaning is performed by heating the crude product and the solvent while stirring in a reaction vessel equipped with a condenser and a stirrer, evaporating the solvent, cooling the evaporated solvent with a condenser, and returning the crude product to the reaction vessel. It is a method of purification.

Examples of the compound represented by the formula R10-OH include water, methanol, ethanol, propanol, isopropyl alcohol, butanol and the like. Examples of the compound represented by the formula R11-C(O)-R12 include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Of these, methanol is preferred from the economical and operability viewpoints.

The washing temperature is 35°C to 120°C. Within the range of such a washing temperature, the produced pentaerythritol diphosphonate compound is less likely to be decomposed, the washing effect is high, and washing is necessary to obtain a pentaerythritol diphosphonate compound having a reduced content of residual volatiles. It is not necessary to repeat it many times and is preferable in terms of production efficiency. By adopting the above-mentioned washing method, the powdery pentaerythritol diphosphonate compound becomes scaly crystals and has excellent dryness.

The amount of the solvent used is preferably 0.1 to 5 mol/L, and more preferably 0.3 to 3 mol/L, in terms of the molar concentration of the pentaerythritol diphosphonate compound used in the present invention. In such a range, the amount of solvent used for washing is small, which is preferable from the economical point of view. Further, since the slurry concentration is low and the viscosity is appropriate, the load on the stirrer is small, which is preferable. Further, since the slurry concentration becomes low, the cleaning efficiency becomes high, and it is not necessary to repeat the cleaning to obtain the highly pure pentaerythritol diphosphonate compound, which is preferable from the viewpoint of production efficiency.

The washing time is preferably 4 hours or longer, more preferably 6 hours or longer. In the cleaning step 2, the solvent was not added or replaced, and the solvent cooled by the condenser was simply returned to the inside of the reactor. At the end of washing step 2, it is preferable to cool the temperature of the reaction vessel to room temperature, separate the crystals by filtration, and wash with a solvent.

<Drying process>
The drying step is a step of drying the washed pentaerythritol diphosphonate compound. The pentaerythritol diphosphonate compound is preferably dried before the grinding step.

<Crushing process>
The crushing step is a step of crushing the obtained washed pentaerythritol diphosphonate compound to adjust powder characteristics such as maximum particle size and volume-based median diameter.
The crushing is preferably performed by a high-speed vortex generated on the back surface of the rotating unit that rotates at high speed, and an air flow crusher that crushes the raw material by high-frequency pressure vibration. The washed pentaerythritol diphosphonate compound is supplied together with air to an air flow crusher to give a swirling flow, accelerated/dispersed by a distributor and evenly distributed to the crushing chamber. It is preferable to grind due to the resulting shock and high velocity vortex. An example of the airflow crusher is a turbo mill manufactured by Freund Turbo. The rotation speed of the rotating body is preferably 3,000 to 7,000 rpm.

(Acidic compound)
The flame-retardant polyester resin composition according to the present invention contains an acidic compound. Examples of the acidic compound include inorganic acids represented by hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, etc., or carboxylic acids, sulfonic acids, formic acid, acetic acid, citric acid, oxalic acid, amino acids, succinic acid. , Organic phosphorus compounds, and organic acids represented by phthalic acid. Among them, the acidic compound used in the present invention is preferably an organic acid, and among them, an organic phosphorus compound is particularly desirable.
Examples of the organic phosphorus compound include phosphite compounds and phosphate compounds.

Specific examples of the phosphite compound include tetrakis[2-tert-butyl-4-thio(2′-methyl-4′-hydroxy-5′-tert-butylphenyl)-5-methylphenyl]-1,6. -Hexamethylene-bis(N-hydroxyethyl-N-methylsemicarbazide)diphosphite, tetrakis[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert-butylphenyl)-5 -Methylphenyl]-1,10-decamethylenedicarboxylic acid dihydroxyethylcarbonylhydrazide diphosphite, tetrakis[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert-butylphenyl] )-5-Methylphenyl]-1,10-decamethylene dicarboquinic acid disalicyloyl hydrazide diphosphite, tetrakis[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'] -Tert-butylphenyl)-5-methylphenyl]-di(hydroxyethylcarbonyl)hydrazide diphosphate, tetrakis[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert] -Butylphenyl)-5-methylphenyl]-N,N'-bis(hydroxyethyl)oxamide diphosphite, distearyl pentaerythritol diphosphite, cyclic neopentatetraylbis(2,6-tert-butyl) -4-Methylphenyl)phosphite may be mentioned.

Among the phosphite-based compounds, a phosphite-based compound in which at least one P—O bond is bonded to an aromatic group is preferable. Specific examples thereof include tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenylenephosphonite, bis(2,4). -Di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,2-methylenebis(4,6-di-tert) -Butylphenyl)octylphosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl)phosphite, 1,1,3-tris(2-methyl-4-ditridecylphosphite Examples include phyto-5-tert-butyl-phenyl)butane, tris(nonylphenyl)phosphite, 4,4′-isopropylidene bis(phenyl-dialkylphosphite). Among them, tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylenephosphonite, bis(2,6-di-tert). -Butyl-4-methylphenyl)pentaerythritol diphosphite and 2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite are preferred.

Examples of commercially available product names of phosphite compounds include ADEKA ADEKA STAB C, PEP-4C, PEP-8, PEP-11C, PEP-24G, PEP-36, HP-10, 2112, 260, 522A. 329A, 1178, 1500, C, 135A, 3010, TPP, Ciba Specialty Chemicals Irgafos 168, Sumitomo Chemical Sumilizer P-16, Clariant Sandstub PEPQ, GE Weston 618, 619G, 624. Can be mentioned.

Specific examples of the phosphate compound include monostearyl acid phosphate, distearyl acid phosphate, methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, octyl acid phosphate, isodecyl acid phosphate, dioctadecyl phosphate. Of these, monostearyl acid phosphate and distearyl acid phosphate are preferable.

Commercially available product names of the phosphate compounds include, for example, Irganox MD1024 manufactured by BASF, inhibitor OABH manufactured by Eastman Kodak, ADEKA STAB CDA-1, CDA-6, and AX-71 manufactured by ADEKA.

In the present invention, it is preferable to use an organic phosphorus compound represented by the following formula (6) and/or the following formula (7) as the acidic compound.

（式中Ｒ７は炭素数１〜３０の分岐状もしくは直鎖状のアルキル基を表し、ｎは１または２を表す。）

(In the formula, R7 represents a branched or linear alkyl group having 1 to 30 carbon atoms, and n represents 1 or 2.)

（式中Ｒ８、Ｒ９は同一もしくは異なり、炭素数１〜３０の分岐状もしくは直鎖状のアルキル基を表す。）

(In the formula, R8 and R9 are the same or different and each represents a branched or linear alkyl group having 1 to 30 carbon atoms.)

In the above formulas (6) and (7), R7, R8 and R9 are preferably branched or straight chain alkyl groups having 4 to 26 carbon atoms, and branched or straight chain alkyl groups having 8 to 24 carbon atoms. An alkyl group is more preferable, a branched or linear alkyl group having 12 to 22 carbon atoms is further preferable, and a branched or linear alkyl group having 16 to 20 carbon atoms is particularly preferable.

Among them, octadecyl phosphate (a commercially available product, ADEKA Co., Ltd., ADEKA STAB AX-71 (trade name)), which is a linear alkyl group having 16 to 20 carbon atoms, and/or 3 , 9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (commercially available from ADEKA Corporation, ADEKA STAB PEP-8 (trade name) ) Are exemplified) are preferred.

The amount of these acidic compounds blended is 0.03 to 10 parts by weight, preferably 0.035 to 5 parts by weight, more preferably 0.04 to 4 parts by weight, and even more preferably 100 parts by weight of the aromatic polyester resin. The content is 0.05 to 3.5 parts by weight, particularly preferably 0.1 to 3 parts by weight. If the blending amount is less than the above range, a sufficient effect as an acidic oxide cannot be obtained, and the viscosity increase of the polyester resin composition will increase. If the blending amount exceeds the above range, it is difficult to maintain good physical properties and flame retardancy of the polyester resin composition.

(Characteristics of flame-retardant polyester resin composition)
The flame-retardant polyester resin composition according to the present invention has a molecular weight that has an intrinsic viscosity that can be usually used as a molded article, and the intrinsic viscosity measured in orthochlorophenol at 35° C. is preferably 0.4 to 1.5 dL/g, preferably 0.45 to 1.4 dL/g, more preferably 0.5 to 1.3 dL/g, and further preferably 0.52 to 1.2 dL/g. is there.

In the present invention, the viscosity increase of the flame-retardant polyester resin composition measured by the following method is preferably 200 Pa·s or less, more preferably 180 Pa·s or less, and further preferably 160 Pa·s or less. Yes, particularly preferably 140 Pa·s or less, and most preferably 120 Pa·s or less. When the viscosity increase is large, the resin pressure of the extruder is likely to increase during continuous production of yarns, sheets, and films, which may make it difficult to continuously produce each product.

The method for measuring the viscosity increase is that the flame-retardant polyester resin composition is dried for 12 hours in a hot air dryer at 120° C. for measurement, and TA Instruments' Rheometer ARES-G2 is used as a viscosity measuring device. The temperature is 300° C., the shear rate is 1 Hz, the upper jig is 25 mmφ cone plate (0.1 rad), the lower jig is 25φ parallel plate, and GAP is 0.50 mm. The difference between the resin viscosity 1 minute after the start of measurement (the measured value is μ1) and the resin viscosity 30 minutes after the start of the measurement (the measured value is μ2) is defined as the viscosity increase. The viscosity increase of the present invention is calculated by the following formula (II).
Viscosity increase=|μ2-μ1|...(II)
The flame retardancy of the flame-retardant polyester resin composition of the present invention is substantially halogen-free and has very high flame retardancy. The flame-retardant resin composition of the present invention can achieve at least V-2 at the flame-retardant level of UL-94 standard at a thickness of 1/32 inch (0.8 mm).

(Other)
The flame-retardant polyester resin composition of the present invention includes a thermoplastic resin (polycarbonate resin, polyarylate resin, polyamide resin, polyimide resin, polyetherimide resin, polyurethane resin, silicone resin) as long as the effect of the present invention is not impaired. , Polyphenylene sulfide resin, polysulfone resin, polyolefin resin such as polyethylene and polypropylene, polystyrene resin, acrylonitrile/styrene copolymer (AS resin), acrylonitrile/butadiene/styrene copolymer (ABS resin), polystyrene resin, high impact polystyrene resin , Syndiotactic polystyrene resin, polymethacrylate resin, and phenoxy or epoxy resin), antioxidants (phosphite compounds, phosphonite compounds, hindered phenol compounds and thioether compounds), flame retardant aids (silicone) Oil, etc., inorganic filler (glass fiber, glass flake, carbon fiber, carbon flake, talc, wollastonite, etc.), organic filler (aramid fiber, kenaf fiber, etc.), impact modifier (core shell type acrylic rubber, Core-shell type butadiene rubber etc.), UV absorbers (benzotriazole type, triazine type, benzophenone type etc.), light stabilizers (HALS etc.), mold release agents (saturated fatty acid ester, unsaturated fatty acid ester, paraffin wax, beeswax etc.) , Flow modifiers (polycaprolactone, etc.), colorants (carbon black, titanium diacid, various organic dyes, metallic pigments, etc.), end-capping agents (epoxy compounds, carbodiimide compounds, etc.), antistatic agents (dodecylbenzene sulfone) Quaternary ammonium salt such as sodium acid, polyether ester amide, etc.), inorganic and organic antibacterial agents, photocatalytic antifouling agents (fine particle titanium oxide, fine particle zinc oxide, etc.), infrared absorbers, compatibilizers, and You may mix|blend a photochromic agent ultraviolet absorber etc. These various additives can be used in known blending amounts.

(Master Badge)
The polyester composition containing the pentaerythritol diphosphonate compound represented by the above formula (1) of the present invention is a flame-retardant polyester resin masterbatch in which the concentration of the pentaerythritol diphosphonate compound represented by the above formula (1) is high. Is prepared and blended with the masterbatch and a polyester resin of an arbitrary type in a predetermined amount so that the concentration of the pentaerythritol diphosphonate compound represented by (1) as a whole becomes a predetermined amount and the flame-retardant polyester. A method for obtaining a resin composition is also suitably used. This method has an advantage that the content of the pentaerythritol diphosphonate compound can be easily adjusted. In addition, it is possible to avoid a situation where the content ratio is reduced from the initially assumed content due to an additive such as a pigment or a functional agent, so that there is an advantage that the handling property is high.

The method for producing a polyester resin masterbatch in which the concentration of the pentaerythritol diphosphonate compound represented by the above formula (1) is high is not limited, but, for example, using a vented twin-screw extruder, at 200 to 280°C Then, a method in which a powdered pentaerythritol diphosphonate compound is added to the melted polyester resin and kneading is performed. However, the method is not limited to this, and, for example, a method in which a polyester resin and a pentaerythritol diphosphonate compound are dry-blended in advance and then charged into a twin-screw extruder can also be used. The temperature at the time of melt-kneading is preferably 240 to 320°C.

(Fiber products)
INDUSTRIAL APPLICABILITY The flame-retardant polyester resin composition of the present invention does not substantially contain halogen and has extremely high flame retardancy, and is useful as a polyester fiber. When producing the polyester fiber, it is preferable to perform the melt spinning method and then the stretching operation. The flame-retardant polyester resin composition of the present invention can be introduced into the melt spinning process. After spinning, the unstretched yarn is wound and separately stretched, the unstretched yarn is continuously stretched without winding once, after melt spinning, the unstretched yarn is cooled and solidified in a coagulation bath, and then heated. A method of stretching in a medium or under contact heating with a heating roller or the like or with a non-contact type heater is adopted.

The spinning speed is preferably 800 to 4000 m/min. If the spinning speed is less than 800 m/min, it is difficult to obtain an undrawn yarn having a relatively high degree of orientation, and if the spinning speed is more than 4000 m/min, oriented crystallization of the undrawn yarn is promoted, which is high. Not suitable for strengthening. Here, when the melt-spun undrawn yarn is drawn, it is finally obtained by setting the total draw ratio (total draw ratio) to be preferably in the range of 2.5 to 6.0. The tensile strength of the fiber can be achieved at a high level, the yarn breaking rate in the drawing step is low, and the productivity is further improved. The total draw ratio is more preferably in the range of 2.8 to 5.5 times, and particularly preferably in the range of 3.0 to 5.0 times. The stretching step may be a single-stage stretching only, or may involve two or more stages of stretching. For example, when a method of two-stage stretching is adopted, the stretching ratio of the first stage is 2.0 to 5.5 times, and the second stage is The draw ratio may be adjusted to about 1.0 to 2.0 times, and the total draw ratio may be adjusted to 2.5 to 6.0 times.

The polyester fiber thus obtained may be used as it is, or after being bulked, for use in woven or knitting, or may be used for woven or knitting after being mixed or composite-processed with other fibers. In addition, these polyester fibers may contain small amounts of other polymers, antioxidants, antistatic agents, dye improving agents, dyes, pigments, matting agents and other additives.

The polyester fiber can be used as it is, or after being subjected to the above processing, for various fiber structure applications including the polyester fiber. The fibrous structure is preferably any structure in which fibers can be taken, such as a thread, a fibrous shape, a string shape, a woven fabric, a knitted fabric, a non-woven fabric, a felt, a papermaking machine, a three-dimensional mesh form, a cotton form, and a sheet form. Among them, preferred is at least one kind of fiber structure selected from the group consisting of threads, strings, processed threads, nets, knits, non-woven fabrics and woven fabrics. The method for producing these fibrous structures can be arbitrarily selected from production methods generally known by those skilled in the art according to the purpose.

(Molded body)
Further, the flame-retardant polyester resin composition of the present invention is molded into various molded articles such as home electric appliance parts, electric/electronic parts, automobile parts, machine/mechanical parts, cosmetic containers, etc. due to its excellent flame-retardant performance. It is also useful as a material. Specifically, breaker parts, switch parts, motor parts, ignition coil cases, power plugs, power outlets, coil bobbins, connectors, relay cases, fuse cases, flyback transformer parts, focus block parts, distributor caps, harness connectors, etc. Can be suitably used for. Furthermore, housings, casings or chassis, which are becoming thinner, are housings of electronic/electrical products (eg, home appliances such as telephones, personal computers, printers, fax machines, copiers, VCRs, audio equipments, office automation equipments, or parts thereof). , Useful for casing or chassis. It is also particularly useful as a printer casing, a fixing unit component, a machine/mechanical component for home electric appliances and OA products such as a fax machine, which requires excellent heat resistance and flame retardancy.

The molding method of the molded body is not particularly limited, such as injection molding, blow molding, compression molding, etc., but is preferably manufactured by injection molding a pelletized resin composition using an injection molding machine. ..

(Sheet, film)
Furthermore, the flame-retardant polyester resin composition of the present invention is useful as a material for a sheet or film because of its excellent flame-retardant performance.

The molding of the sheet or film is not particularly limited, such as injection molding, compression molding, injection compression molding, compression molding, etc., but preferably pelletized resin composition is extruded using an extruder. Manufactured by.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The evaluation was performed by the following method.

(A) Organic Purity Separations Module 2690 manufactured by Waters as an HPLC device, Dual λ Absorbance Detector 2487 (UV-264nm) manufactured by Waters as a detector, TSKgel ODS-120T 2.0 mm×150 mm (5 μm) manufactured by Tosoh Corporation as a column. ) Using a mixture of distilled water and acetonitrile as an eluent at a column temperature of 40° C., 0→12 min: acetonitrile 50%, 12→17 min: acetonitrile 50→80%, 17→27 min: acetonitrile 80%, 27→34 min: Acetonitrile 80→100%, 34→60 min: Measured by a gradient program of 100%. The measurement was carried out by dissolving 50±0.5 mg of the pentaerythritol diphosphonate compound in 25 ml of acetonitrile and then filtering with a PTFE filter having a pore size of 0.2 μm. From the measurement results, the area ratio was defined as the organic purity.

(B) Total content of halogen components The total content of halogen components of the pentaerythritol diphosphonate compound was measured by the method according to JIS K7229.

(C) Total Volatile Organic Compound Content Separations Module 2690 manufactured by Waters as an HPLC device, Dual λ Absorbance Detector 2487 (UV-264 nm) manufactured by Waters as a detector and a differential refraction detector, and TSKgel ODS manufactured by Tosoh Corporation as a column. Using −120T 2.0 mm×150 mm (5 μm) and using a mixed solution of distilled water and acetonitrile as an eluent, at a column temperature of 40° C., 0→12 min: acetonitrile 50%, 12→17 min: acetonitrile 50→80%. , 17→27 min: acetonitrile 80%, 27→34 min: acetonitrile 80→100%, 34→60 min: 100% by a gradient program. The measurement was carried out by dissolving 50±0.5 mg of the pentaerythritol diphosphonate compound in 25 ml of acetonitrile and then filtering with a PTFE filter having a pore size of 0.2 μm. A calibration curve was prepared in advance for the volatile organic substances used in the production of the compound, and the residual amount of the volatile organic substances in the pentaerythritol diphosphonate compound was determined.

(D) ΔpH
Using a commercially available pH measuring device, the measurement was carried out by the following method. 1 g of the dispersant was added to 99 g of distilled water used for the measurement, and the mixture was stirred and the pH of the obtained aqueous solution was measured (the measured value is set to pH 1). After adding 1 g of the pentaerythritol diphosphonate compound (1) of the present invention to the aqueous solution and stirring for 1 minute, the pentaerythritol diphosphonate compound (1) is filtered. The pH of the obtained filtrate was measured (the measured value is pH 2). The ΔpH value of the present invention is calculated by the following formula (I).
ΔpH value=|pH1-pH2|... (I)

(E) Acid value The acid value of the pentaerythritol diphosphonate compound was measured by the method according to JIS-K-3504.

(F) Intrinsic viscosity (IV value)
The intrinsic viscosity number is measured by measuring a fixed amount of the sample, dissolving it in o-chlorophenol at a concentration of 0.012 g/ml, then cooling it once, and measuring the solution using a Ubbelohde viscometer at a temperature of 35°C. It was calculated from the solution viscosity.

(G) Flame retardancy (UL-94 evaluation)
Flame retardancy was evaluated using a test piece with a thickness of 1/32 inch (0.8 mm) according to the vertical flame test defined in UL-94 of the US UL standard as a flame retardancy evaluation scale. It was In each test piece, flame or red heat combustion did not reach the holding clamp, combustion after extinguishing the flame was extinguished within 10 seconds, and drops did not cause cotton ignition V-0, combustion was V-2 is one that extinguishes within 30 seconds, and the dropped substance causes cotton ignition, and the one below this evaluation standard is defined as notV.
The test pieces were molded by drying the pellets obtained in each of the Examples and Comparative Examples for 12 hours with a hot air dryer at 120° C., and the dried pellets were injected into an injection molding machine (J75-ELII manufactured by Japan Steel Works, Ltd.). Was used under the conditions of a cylinder temperature of 240 to 320° C.

(H) Oxygen index (LOI evaluation)
The oxygen index was measured by the method according to JIS-K-7201. The higher the value, the better the flame retardancy.

(I) Thickening The polyester composition was dried in a hot air dryer at 120° C. for 12 hours and used for measurement. Rheometer ARES-G2 manufactured by TA Instruments is used as a viscosity measuring device, and measurement temperature is 300° C., shear rate is 1 Hz, upper jig 25 mm φ cone plate (0.1 rad), lower jig 25 φ parallel plate, GAP 0.50 mm. did. The difference between the resin viscosity 1 minute after the start of measurement (measurement value is μ1) and the resin viscosity 30 minutes after the start of measurement (measurement value is μ2) was defined as the viscosity increase.
The viscosity increase of the present invention is calculated by the following formula (II).
Viscosity increase=|μ2-μ1|...(II)

[Production Example 1]
2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-dibenzyl-3,9-dioxide (compound represented by formula (2), FR-1) Preparation <Synthesis process>
In a reaction vessel having a stirrer, a thermometer and a condenser, 3,55-dibenzyloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 22.55 g (0.055 mol) and benzyl were added. 19.01 g (0.11 mol) of bromide and 33.54 g (0.32 mol) of xylene were charged, and dry nitrogen was caused to flow with stirring at room temperature. Next, heating was started in an oil bath, and the mixture was heated and stirred at reflux temperature (130 to 140°C) for 4 hours.

<Cleaning process 1>
After heating, the mixture was allowed to cool to room temperature, 20 mL of xylene was added, and the mixture was stirred for 30 minutes to precipitate crystals. The precipitated crystals were separated by filtration, and the collected crystals were transferred to a beaker equipped with a stirrer, 20 mL of xylene was added to form a slurry, and the mixture was stirred. After that, the slurry was filtered again, and the crystals collected by filtration were transferred again to a beaker equipped with a stirrer, 20 mL of xylene was added to form a slurry, and the mixture was stirred. Finally, the slurry was filtered to obtain a crude product.

<Cleaning process 2>
The obtained crudely purified product and 40 mL of methanol were placed in a reaction vessel equipped with a condenser and a stirrer, and refluxed for 6 hours (internal temperature 63°C). After cooling to room temperature, the crystals were separated by filtration and washed with 20 mL of methanol.

<Drying process>
Then, the obtained filtered material was dried at 120° C. and 1.33×10 ² Pa for 19 hours to obtain 20.60 g (0.050 mol) of white scaly crystals. The product was analyzed by mass spectroscopy, 1H, 31P nuclear magnetic resonance spectroscopy and elemental analysis to give 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dibenzyl-3,9. -Confirmed that it is dioxide.

<Crushing process>
The obtained white scale-like crystals were pulverized by a pulverizer (Turbomill T400 manufactured by Freund Turbo Co., Ltd.) under the condition of 5,000 rpm.

<Characteristics>
(A) Organic purity was 99.5%, (B) Total halogen content was 100 ppm, (C) Total volatile organic content was 200 ppm, and (D) ΔpH value was 0.5. , (E) acid value was 0.06 mgKOH/g.

[Production Example 2]
2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-diα-methylbenzyl-3,9-dioxide (compound represented by formula (3), FR -2) Preparation <Synthesis step>
A reaction vessel equipped with a thermometer, a condenser and a dropping funnel was charged with 816.9 g (6.0 mol) of pentaerythritol, 19.0 g (0.24 mol) of pyridine and 2250.4 g (24.4 mol) of toluene and stirred. did. To the reaction vessel, 1651.8 g (12.0 mol) of phosphorus trichloride was added using the dropping funnel, and after the addition was completed, the mixture was heated and stirred at 60°C. After the reaction, the mixture was cooled to room temperature, 5180.7 g (61.0 mol) of methylene chloride was added to the obtained reaction product, and 889.4 g (12.0 mol) of tertiary butanol and 150. 2 g (1.77 mol) was added dropwise. The obtained crystals were washed with toluene and methylene chloride and filtered. The obtained filtered material was dried at 80° C. and 1.33×10 ² Pa for 12 hours to obtain 1341.1 g (5.88 mol) of a white solid. The obtained solid is 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dihydro-3,9-dioxide by 1H,31P nuclear magnetic resonance spectroscopy. I confirmed the thing.

2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dihydro-3,9-dioxide obtained in a reaction vessel equipped with a thermometer, a condenser and a dropping funnel. 1341.0 g (5.88 mol) and DMF6534.2 g (89.39 mol) were charged and stirred. 648.7 g (12.01 mol) of sodium methoxide was added to the reaction vessel under ice cooling. After stirring with ice cooling for 2 hours, stirring was performed at room temperature for 5 hours. After further distilling off DMF, 2613.7 g (35.76 mol) of DMF was added, and 2204.06 g (11.91 mol) of 1-phenylethyl bromide was added dropwise to the reaction mixture under ice cooling. After stirring under ice cooling for 3 hours, DMF was distilled off.

<Cleaning process 1>
After cooling to room temperature, 2 L of xylene was added and stirred for 30 minutes to precipitate crystals. The precipitated crystals were separated by filtration, and the crystals collected by filtration were transferred to a beaker equipped with a stirrer, 2 L of xylene was added to form a slurry, and the mixture was stirred. After that, the slurry was filtered again, and the crystals collected by filtration were transferred again to a beaker equipped with a stirrer, and 2 L of xylene was added to form a slurry and stirred. Finally, the slurry was filtered to obtain a crude product.

<Cleaning process 2>
The obtained crude product and 4 L of methanol were placed in a reaction vessel equipped with a condenser and a stirrer, and refluxed for 6 hours (internal temperature 63°C). After cooling to room temperature, the crystals were separated by filtration and washed with 2 L of methanol.

<Drying process>
Then, the obtained filtered material was dried at 120° C. and 1.33×10 ² Pa for 19 hours to obtain 1845.9 g (4.23 mol) of white scaly crystals. The product was analyzed by mass spectroscopy, 1H, 31P nuclear magnetic resonance spectroscopy and elemental analysis to give 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane,3,9-diα-methylbenzyl. It was confirmed to be -3,9-dioxide.

<Crushing process>
The obtained white scale-like crystals were pulverized by a pulverizer (Turbomill T400 manufactured by Freund Turbo Co., Ltd.) under the condition of 5,000 rpm.

<Characteristics>
(A) Organic purity was 99.0%, (B) Total halogen content was 150 ppm, (C) Total volatile organic content was 220 ppm, and (D) ΔpH value was 0.6. , (E) acid value was 0.08 mgKOH/g.

[Production Example 3]
2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-di(2-phenylethyl)-3,9-dioxide (compound represented by formula (4) , FR-3) <Synthesis step>
A reaction vessel equipped with a thermometer, a condenser and a dropping funnel was charged with 816.9 g (6.0 mol) of pentaerythritol, 19.0 g (0.24 mol) of pyridine and 2250.4 g (24.4 mol) of toluene and stirred. did. To the reaction vessel, 1651.8 g (12.0 mol) of phosphorus trichloride was added using the dropping funnel, and after the addition was completed, the mixture was heated and stirred at 60°C. After the reaction, the mixture was cooled to room temperature, 5180.7 g (61.0 mol) of methylene chloride was added to the obtained reaction product, and 889.4 g (12.0 mol) of tertiary butanol and 150. 2 g (1.77 mol) was added dropwise. The obtained crystals were washed with toluene and methylene chloride and filtered. The obtained filtered material was dried at 80° C. and 1.33×10 ² Pa for 12 hours to obtain 1341.1 g (5.88 mol) of a white solid. It was confirmed to be 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dihydro-3,9-dioxide by 1H, 31P nuclear magnetic resonance spectrum analysis.

2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dihydro-3,9-dioxide obtained in a reaction vessel equipped with a thermometer, a condenser and a dropping funnel. 1341.0 g (5.88 mol) and DMF6534.2 g (89.39 mol) were charged and stirred. 648.7 g (12.01 mol) of sodium methoxide was added to the reaction vessel under ice cooling. After stirring with ice cooling for 2 hours, stirring was performed at room temperature for 5 hours. After further distilling off DMF, 2613.7 g (35.76 mol) of DMF was added, and 2183.8 g (11.8 mol) of (2-bromoethyl)benzene was added dropwise to the reaction mixture under ice cooling. After stirring under ice cooling for 3 hours, DMF was distilled off.

<Cleaning process 1>
After cooling to room temperature, 2 L of xylene was added and stirred for 30 minutes to precipitate crystals. The precipitated crystals were separated by filtration, and the crystals collected by filtration were transferred to a beaker equipped with a stirrer, 2 L of xylene was added to form a slurry, and the mixture was stirred. After that, the slurry was filtered again, and the crystals collected by filtration were transferred again to a beaker equipped with a stirrer, and 2 L of xylene was added to form a slurry and stirred.
Finally, the slurry was filtered to obtain a crude product.

<Cleaning process 2>
The obtained crude product and 4 L of methanol were placed in a reaction vessel equipped with a condenser and a stirrer, and refluxed for 6 hours (internal temperature 63°C). After cooling to room temperature, the crystals were separated by filtration and washed with 2 L of methanol.

<Drying process>
Then, the obtained filtered material was dried at 120° C. and 1.33×10 ² Pa for 19 hours to obtain 1924.4 g (4.41 mol) of white scaly crystals. The product was analyzed by mass spectroscopy, 1H, 31P nuclear magnetic resonance spectroscopy and elemental analysis to give 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane,3,9-di(2-phenyl). It was confirmed to be ethyl)-3,9-dioxide.

<Crushing process>
The obtained white scale-like crystals were pulverized by a pulverizer (Turbomill T400 manufactured by Freund Turbo Co., Ltd.) under the condition of 5,000 rpm.

<Characteristics>
(A) Organic purity was 99.1%, (B) Total halogen content was 120 ppm, (C) Total volatile organic content was 250 ppm, and (D) ΔpH value was 0.3. , (E) acid value was 0.07 mgKOH/g.

[Production Example 4]
2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5,5]undecane,3,9-bis(diphenylmethyl)-3,9-dioxide (compound represented by formula (5), FR -4) Preparation <Synthesis step>
In a 10-liter three-necked flask equipped with a stirrer, a stirring blade, a reflux condenser, and a thermometer, 2058.5 g (7.22 mol) of diphenylmethylphosphonic acid dichloride and 468.3 g (3.44 mol) of pentaerythritol were added, Pyridine (1169.4 g, 14.8 mol) and chloroform (8200 g) were charged, and the mixture was heated to 60° C. under a nitrogen stream and stirred for 6 hours.

<Cleaning process 1>
After cooling to room temperature, 2 L of xylene was added and stirred for 30 minutes to precipitate crystals. The precipitated crystals were separated by filtration, and the crystals collected by filtration were transferred to a beaker equipped with a stirrer, 2 L of xylene was added to form a slurry, and the mixture was stirred. After that, the slurry was filtered again, and the crystals collected by filtration were transferred again to a beaker equipped with a stirrer, and 2 L of xylene was added to form a slurry and stirred. Finally, the slurry was filtered to obtain a crude product.

<Cleaning process 2>
The obtained crude product and 4 L of methanol were placed in a reaction vessel equipped with a condenser and a stirrer, and refluxed for 6 hours (internal temperature 63°C). After cooling to room temperature, the crystals were separated by filtration and washed with 2 L of methanol.

<Drying process>
Then, the obtained filtered material was dried at 120° C. and 1.33×10 ² Pa for 19 hours to obtain 1156.2 g (2.06 mol) of white scaly crystals. The product is 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane,3,9-bis(diphenylmethyl) by mass spectroscopy, 1H, 31P nuclear magnetic resonance spectroscopy and elemental analysis. It was confirmed to be -3,9-dioxide.

<Crushing process>
The obtained white scale-like crystals were pulverized by a pulverizer (Turbomill T400 manufactured by Freund Turbo Co., Ltd.) under the condition of 5,000 rpm.

<Characteristics>
(A) Organic purity was 98.9%, (B) Total halogen content was 200 ppm, (C) Total volatile organic content was 250 ppm, and (D) ΔpH value was 0.7. , (E) acid value was 0.10 mg KOH/g.

[Production Example 5]
2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-dibenzyl-3,9-dioxide (compound represented by formula (2), FR-5) Preparation <Synthesis process>
In a reaction vessel having a stirrer, a thermometer and a condenser, 3,55-dibenzyloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 22.55 g (0.055 mol) and benzyl were added. 19.01 g (0.11 mol) of bromide and 33.54 g (0.32 mol) of xylene were charged, and dry nitrogen was caused to flow with stirring at room temperature. Then, heating was started in an oil bath, and the mixture was heated and stirred at reflux temperature (about 130° C.) for 4 hours. After heating, cool to room temperature,
<Washing process>
20 mL of xylene was added, and the mixture was further stirred for 30 minutes. The precipitated crystals were separated by filtration, washed once with 20 mL of xylene, and white crystals were collected by filtration.

<Drying process>
It was dried at 120° C. and 1.33×10 ² Pa for 24 hours to obtain 21.22 g (0.052 mol) of white crystals. The product was analyzed by mass spectroscopy, 1H, 31P nuclear magnetic resonance spectroscopy and elemental analysis to give 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dibenzyl-3,9. -Confirmed that it is dioxide.

<Crushing process>
The obtained white crystals were pulverized with a pulverizer (Freund Turbo Turbo Mill).

<Characteristics>
(A) Organic purity was 96.0%, (B) Total halogen content was 1300 ppm, (C) Total volatile organic content was 1100 ppm, and (D) ΔpH value was 1.3. , (E) acid value was 2.52 mg KOH/g.

Table 1 shows the characteristics of the pentaerythritol diphosphonate compounds obtained in Production Examples 1 to 5.

[Examples 1 to 12, Comparative Examples 1 to 4]
The components shown in Table 2 were mixed in a tumbler in the amounts (parts by weight) shown in Table 2, and pelletized under a temperature condition of 220 to 280°C with a 15φ twin-screw extruder (KZW15 manufactured by Technobel). Table 3 shows various evaluation results of the obtained polyester resin composition.

[Example 13]
The flame-retardant polyester resin composition described in Example 3 (master pellets) and the aromatic polyester resin described in Table 2 were dry-blended in an amount (parts by weight) described in Table 2 and a 15φ twin-screw extruder (KZW15 manufactured by Technovel) ) Was pelletized under a temperature condition of 240 to 260° C. to obtain a flame-retardant polyester resin composition. Table 3 shows various evaluation results of the obtained polyester resin composition.

In addition, each symbol shown in Table 2 shows the following compound.
(I) Polyester resin (component A)
Pest-1; polyethylene terephthalate resin having an intrinsic viscosity of 0.80 dL/g (TR-BB manufactured by Teijin Ltd.)
Pest-2; polyethylene terephthalate resin having an intrinsic viscosity of 0.75 dL/g (TRN-8855 manufactured by Teijin Ltd.)
Pest-3; polyethylene terephthalate resin having an intrinsic viscosity of 0.65 dL/g (TRN-RT JC manufactured by Teijin Ltd.)
Pest-4; polyethylene terephthalate resin having an intrinsic viscosity of 1.22 dL/g (TRN-8890AD manufactured by Teijin Ltd.)
(II) Pentaerythritol diphosphonate compound (component B)
FR-1; 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dibenzyl-3,9-dioxide FR-2 synthesized in Production Example 1; Production Example 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-diα-methylbenzyl-3,9-dioxide FR-3 synthesized in 2; Synthesized 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-di(2-phenylethyl)-3,9-dioxide FR-4; in Preparation Example 4. Synthesized 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane,3,9-bis(diphenylmethyl)-3,9-dioxide FR-5; synthesized in Preparation Example 5 2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dibenzyl-3,9-dioxide (III) acidic compound (component C)
P-1: Octadecyl phosphate (ADEKA Corporation: ADEKA STAB AX-71 (trade name))
P-2; 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA Corporation; ADEKA STAB PEP-8 (trade name) ))

[Example 14]
The flame-retardant polyester resin composition obtained in Example 1 was spun from a spinneret at an atmospheric temperature of 250 to 280° C., and was taken out at a take-up speed of 1000 m/min. Subsequently, the filament was drawn in one stage or two stages so as to have a ratio of 4.0±0.5 times to obtain a filament of 80 to 88 decitex. The LOI value of this filament was 25.5. The obtained polyester fiber (filament) was manufactured into various fiber structures according to the following operations, and LOI evaluation was performed. The results are shown in Table 4.
(fabric)
All of the polyester fibers obtained in Example 14 were placed in the warp and weft, and a plain weave fabric was obtained by a normal weaving method.
(knitting)
The polyester fiber obtained in Example 14 was used for a front reed, a middle reed, and a back reed, and a knitted product was obtained by using an ordinary warp knitting machine.
(Nonwoven fabric)
The flame-retardant polyester composition obtained in Example 14 was melt-spun at 240 to 280° C., and long fibers collected at a high speed by an ejector were continuously supplied and conveyed on a moving net conveyor, and then embossed by an embossing roller. It thermocompression-bonded (100-200 degreeC) and obtained the long fiber nonwoven fabric.

The flame-retardant polyester resin composition of the present invention, due to its excellent flame-retardant performance, can be used for various molded articles such as various textile products, home electric appliance parts, electric/electronic parts, automobile parts, machine/mechanical parts, cosmetic containers, etc. It is useful as a molding material.

Claims (9)

With respect to 100 parts by weight of the aromatic polyester resin (A) having an intrinsic viscosity of 0.5 to 1.6 dL/g, the following formula (1) in which each physical property of (B) satisfies the following conditions (a) to (c): A flame-retardant polyester resin composition comprising 0.1 to 40 parts by weight of a pentaerythritol diphosphonate compound represented by and 0.03 to 10 parts by weight of the (C) acidic compound.
(A) Organic purity of 98% or more (a) Total halogen content of 1000 ppm or less (c) Total volatile organic content of 800 ppm or less

(In the formula, R2 and R5 may be the same or different, and may have a phenyl group which may have a substituent, a naphthyl group which may have a substituent, an anthryl group which may have a substituent or an aromatic group. It is a branched or linear alkyl group having 1 to 4 carbon atoms which may have a group substituent.R1, R3, R4 and R6 may be the same or different, and are a hydrogen atom and 1 to carbon atoms. 4 is a branched or linear alkyl group, a phenyl group which may have a substituent, a naphthyl group which may have a substituent or an anthryl group which may have a substituent.) The difficulty according to claim 1, wherein the pentaerythritol diphosphonate compound represented by the formula (1) is at least one compound selected from the group consisting of compounds represented by the following formulas (2) to (5). Flammable polyester resin composition.

The flame-retardant polyester resin composition according to claim 1, wherein the acidic compound (C) is a compound represented by the following formula (6) and/or the following formula (7).

(In the formula, R7 represents a branched or linear alkyl group having 1 to 30 carbon atoms, and n represents 1 or 2.)

(In the formula, R8 and R9 are the same or different and each represents a branched or linear alkyl group having 1 to 30 carbon atoms.) The flame-retardant polyester resin composition according to claim 1, which has a viscosity increase of 200 Pa·s or less evaluated by the following method.
Evaluation method of viscosity increase: A polyester composition dried by a hot air dryer at 120° C. for 12 hours was used as a viscosity measuring device using Rheometer ARES-G2 manufactured by TA Instruments, measurement temperature 300° C., shear rate 1 Hz, upper jig 25 mmφ. Cone plate (0.1 rad), lower jig 25φ parallel plate, GAP 0.50 mm. Increase the difference (calculated by the following formula (II)) between the resin viscosity 1 minute after the start of measurement (measurement value is μ1) and the resin viscosity 30 minutes after the start of measurement (measurement value is μ2) The viscosity was used.
Viscosity increase=|μ2-μ1|...(II) The aromatic polyester resin (A) comprises a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polyethylene naphthalate resin, a polybutylene naphthalate resin, a polycyclohexane dimethyl terephthalate resin, a polytrimethylene terephthalate resin and a polytrimethylene naphthalate resin. The flame-retardant polyester resin composition according to claim 1, which is at least one selected from the group. A masterbatch comprising the flame-retardant polyester resin composition according to claim 1. A molded product obtained by molding the flame-retardant polyester resin composition according to any one of claims 1 to 5. A fiber obtained by spinning the flame-retardant polyester resin composition according to claim 1. A sheet or film obtained by molding the flame-retardant polyester resin composition according to claim 1.