JP2006045525A - Flame-retardant polybutylene terephthalate composition and molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant polybutylene terephthalate composition having high flame retardancy, especially high stability to hydrolysis, usefulness suitable for electric/electronic parts such as connectors and relay parts. <P>SOLUTION: The flame-retardant polybutylene terephthalate composition comprises 3 to 50 parts by weight of a brominated aromatic compound flame retardant and 1 to 30 parts by weight of an antimony oxide compound blended in 100 parts by weight of a polybutylene terephthalate. The flame-retardant polybutylene terephthalate composition is prepared using the polybutylene terephthalate having a titanium content that is higher than 33 ppm and is 90 ppm or less in terms of atoms, terminal carboxy group concentration that is higher than 10 μeq/g and 30 μeq/g or less, and intrinsic viscosity that is higher than 0.83 dl/g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flame retardant polybutylene terephthalate composition. Specifically, the flame retardant polybutylene terephthalate composition has high flame retardancy and high stability to hydrolysis, and can be suitably used for electrical and electronic parts such as connectors and relay parts. The present invention relates to a flame-retardant polybutylene terephthalate composition that can be produced and a molded article comprising the composition.

  Polybutylene terephthalate (sometimes abbreviated as PBT), which is a typical engineering plastic among thermoplastic polyester resins, is easy to mold, mechanical properties, heat resistance, and other physical and chemical properties. Because of its superiority, it is widely used in fields such as automotive parts, electrical / electronic parts, and precision equipment parts.

  Since PBT has low hygroscopicity, it is essentially not affected by water at room temperature. However, at high temperatures, ester groups are hydrolyzed by water or water vapor to form hydroxyl groups and carboxyl groups, and the carboxyl groups become autocatalysts to further promote hydrolysis, limiting use in wet heat environments. For this reason, PBT which has high stability against hydrolysis and can be used even in a wet heat environment is desired.

  Resin materials used for electrical, electronic parts, automobile parts, other electrical parts, machine parts, and the like are required to have flame retardancy. In recent years, electrical and electronic parts and electrical parts have been made thinner and smaller due to the trend of miniaturization and weight reduction of various devices, and various molded products used therefor have been made smaller and thinner. In a thin molded article, flame retardancy corresponding to the thinnest part is often required, and the flame retardance of rank V-0 defined in UL-94 is used as an index as the flame retardance. In general, the thinner the molded product, the more difficult it becomes to achieve flame retardancy. When a large amount of a flame retardant is blended in order to achieve a predetermined flame retardancy, corrosion of metal contacts and deterioration of hydrolysis resistance due to an increase in generated gas are more likely to be caused.

  In general, as a means for improving the hydrolysis resistance of PBT, it is known to reduce terminal carboxyl groups (Patent Document 1). In addition, the terminal carboxyl group concentration is 30 μeq / g or less, the temperature-falling crystallization temperature is 175 ° C. or more, or the temperature-falling crystallization temperature is 175 ° C. or more, and the residual tetrahydrofuran amount is 300 ppm or less. Contains 100 parts by weight of PBT, 3-50 parts by weight of brominated aromatic flame retardant, 1-30 parts by weight of antimony compound, 0.1-5 parts by weight of polytetrafluoroethylene and 0-150 parts by weight of reinforcing filler. A flame retardant PBT composition is proposed (Patent Document 2). Such a composition has high flame retardancy, short molding cycle, excellent productivity, no corrosion of electrical contacts, high stability against hydrolysis, and suitable for electrical / electronic parts such as relay parts It can be used for. And about the manufacturing method of said flame-retardant PBT composition, using terephthalic acid and 1, 4- butanediol, Preferably using a titanium compound as a catalyst, The usage-amount of a catalyst is esterification reaction. It has been proposed that it is 30 to 300 ppm relative to the theoretical yield of PBT, and 300 ppm or less in the polycondensation step (Patent Document 2). However, although the amount of titanium remaining in the PBT and the effect thereof are not mentioned, since the titanium used as the catalyst remains in the resin almost quantitatively, the method proposed as Example 1 was used. When the amount of titanium in PBT is calculated from the amount of catalyst, it is about 194 ppm.

JP-A-9-316183 JP 2004-91583 A

  An object of the present invention is to provide a flame retardant polybutylene terephthalate composition which has high flame retardancy and at the same time has high stability against hydrolysis and can be suitably used for electrical and electronic parts such as connectors and relay parts. It is to provide.

  As a result of intensive studies, the present inventors have obtained the following knowledge. That is, if the content of titanium in the PBT affects the hydrolysis of the resin and the polybutylene terephthalate having a specific titanium content is combined with a specific flame retardant and a flame retardant aid, high flame resistance and excellent resistance A PBT composition expressing hydrolyzability is obtained. The present invention has been achieved on the basis of such findings, and consists of a group of related inventions. The gist of each invention is as follows.

  That is, the first gist of the present invention is a flame retardant comprising 3 to 50 parts by weight of a brominated aromatic compound-based flame retardant and 1 to 30 parts by weight of an antimony oxide compound with respect to 100 parts by weight of polybutylene terephthalate. The polybutylene terephthalate composition is a polybutylene terephthalate having a titanium content of more than 33 ppm and not more than 90 ppm in terms of atoms, a terminal carboxyl group concentration of more than 10 μeq / g and not more than 30 μeq / g, and an intrinsic viscosity of 0.83 dl A flame retardant polybutylene terephthalate composition characterized in that it comprises using polybutylene terephthalate higher than / g.

  The second gist of the present invention is that 3 to 50 parts by weight of at least one compound selected from a phosphate ester or phosphonitrile and 1 to 50 parts by weight of melamine cyanurate are blended with 100 parts by weight of polybutylene terephthalate. A flame retardant polybutylene terephthalate composition having a titanium content of more than 33 ppm and not more than 90 ppm in terms of atoms, a terminal carboxyl group concentration of more than 10 μeq / g and not more than 30 μeq / g, intrinsic viscosity In a flame retardant polybutylene terephthalate composition, characterized in that it comprises using polybutylene terephthalate higher than 0.83 dl / g.

  And the 3rd summary of this invention exists in the molded object characterized by comprising the said flame-retardant polybutylene terephthalate composition.

  According to the present invention, there is provided a flame retardant polybutylene terephthalate composition which has high flame retardancy and at the same time has high stability against hydrolysis and is suitable for electrical and electronic parts such as connectors and relay parts.

  Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of embodiments of the present invention, and the present invention is not limited to these contents.

  First, the PBT used in the present invention will be described. The PBT used in the present invention has a feature that the titanium content is more than 33 ppm and 90 ppm or less in terms of atoms, the terminal carboxyl group concentration is higher than 10 μeq / g and lower than 30 μeq / g, and the intrinsic viscosity is higher than 0.83 dl / g. Have.

  Titanium in PBT is usually derived from the polymerization catalyst of PBT, but if the titanium content is more than 90 ppm, the hydrolysis resistance is lowered. The reason for this is not clear, but it is thought that when the titanium content derived from the catalyst is large, the decomposition of PBT at a high temperature is promoted and the hydrolysis resistance is lowered. On the other hand, when the catalyst content is such that the titanium content is 33 ppm or less, not only the polymerization rate is lowered, but also the flame retardancy of the composition using the obtained PBT is lowered. The reason for this is not clear, but when the titanium content is high, the decomposition of PBT at a high temperature is promoted and it becomes easy to drip, the PBT drips down and combustion cannot be continued. It is considered that PBT is difficult to decompose, does not sag, and continues to burn, resulting in a decrease in flame retardancy.

  In the PBT having a titanium content defined in the present invention, for example, tetrabutyl titanate, which is a catalyst, is added to terephthalic acid and 1,4-butanediol in an amount of 33 ppm to 90 ppm as titanium atoms with respect to the theoretical yield of PBT. In the temperature range of 150 to 280 ° C., an ester reaction can be carried out under normal pressure to obtain an oligomer, followed by a 210-230 ° C. polycondensation reaction under reduced pressure. The titanium content can be obtained from the amount of catalyst added, but can also be obtained by analyzing the obtained PBT. Specifically, it can be measured by means such as atomic absorption, atomic emission, ICP (inductivery coupled plasma).

  The terminal carboxyl group concentration of the PBT used in the present invention is higher than 10 μeq / g and not higher than 30 μeq / g. The upper limit of the terminal carboxyl group concentration is preferably 25 μeq / g, more preferably 20 μeq / g. The terminal carboxyl group concentration can be determined by dissolving PBT in an organic solvent and titrating with an alkali hydroxide solution. When the terminal carboxyl group concentration of PBT is 30 μeq / g or less, the hydrolysis resistance of the PBT composition can be remarkably improved. Since the carboxyl group in PBT acts as an autocatalyst for hydrolysis, if there is a terminal carboxyl group exceeding 30 μeq / g, hydrolysis starts early, and the generated carboxyl group becomes an autocatalyst. The hydrolysis proceeds in a chain and the degree of polymerization of the resin rapidly decreases. On the other hand, by using PBT having a terminal carboxyl group concentration of 30 μeq / g or less, early hydrolysis is suppressed even under conditions of high temperature and high humidity.

  The PBT used in the present invention has an intrinsic viscosity greater than 0.83 dl / g. The upper limit of the intrinsic viscosity is usually 1.5 dl / g, preferably 1.3 dl / g, more preferably 1.1 dl / g. When the intrinsic viscosity of PBT exceeds 1.5 dl / g, the melt viscosity of the PBT composition is increased, the fluidity is deteriorated, and the moldability may be deteriorated. In the present invention, the intrinsic viscosity of PBT is a value determined from the solution viscosity measured at 30 ° C. using a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio 1/1). is there.

  Although the manufacturing method of PBT which has the above-mentioned characteristic is not specifically limited, it can be obtained by continuous polymerization using terephthalic acid and 1,4-butanediol as main raw materials. The main raw material means that terephthalic acid accounts for 50 mol% or more of the total dicarboxylic acid component, and 1,4-butanediol accounts for 50 mol% or more of the total diol component. The terephthalic acid preferably accounts for 80 mol% or more of the total dicarboxylic acid component, and more preferably 95 mol% or more. 1,4-butanediol preferably accounts for 80 mol% or more of the total diol component, and more preferably 95 mol% or more.

  The dicarboxylic acid component other than terephthalic acid is not particularly limited. For example, phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, 4 , 4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, It is possible to use alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc. I can do it.

  The diol component other than 1,4-butanediol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, polytetramethylene ether glycol, and 1,5-pentane. Diol, neopentyl glycol, 1,6-hexanediol, aliphatic diol such as 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4 -Arocyclic diols such as cyclohexane dimethylol, aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, etc. use To it can be.

  In the present invention, further, as a copolymerization component, hydroxycarboxylic acid such as glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, etc. Monofunctional components such as alkoxycarboxylic acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, Trifunctional or higher polyfunctional components such as trimethylolethane, trimethylolpropane, glycerol, pentaerythritol and the like can be used.

  The PBT used in the present invention is preferably a resin obtained by continuously polymerizing a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component. The method of continuous polymerization is not particularly limited, but it is preferable to perform continuous polymerization using a series continuous tank reactor. For example, first, in one or a plurality of esterification reaction tanks, in the presence of an esterification reaction catalyst, a temperature of usually 150 to 280 ° C, preferably 180 to 265 ° C, more preferably 220 to 240 ° C, usually The esterification reaction is carried out at a pressure of 20 to 133 kPa, preferably 40 to 101 kPa, more preferably 50 to 90 kPa (absolute pressure, the same shall apply hereinafter) for 2 to 5 hours. Subsequently, the oligomer which is the esterification reaction product obtained is usually 210 to 280 ° C., preferably 220 to 260 ° C. in the presence of a polycondensation reaction catalyst in one or a plurality of polycondensation reaction tanks. More preferably, at a temperature of 230 to 250 ° C., in at least one polycondensation reaction tank, the polycondensation reaction is usually 20 kPa or less, preferably 10 kPa or less, more preferably 5 kPa or less, and stirring for 2 to 5 hours. To do. The PBT obtained by the polycondensation reaction is transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted into a strand shape, and is cooled with water or after being cooled with water, and then cut with a pelletizer to form particles such as pellets. It is assumed to be a body.

  The type of the esterification reaction tank is not particularly limited, and examples thereof include a vertical stirring complete mixing tank, a vertical heat convection mixing tank, and a tower-type continuous reaction tank. The type of the polycondensation reaction tank is not particularly limited, and examples thereof include a vertical stirring polymerization tank, a horizontal stirring polymerization tank, and a thin film evaporation polymerization tank. The esterification reaction tank and the polycondensation reaction tank may be one, but may be a plurality of tanks in which a plurality of tanks of the same type or different types are connected in series.

  Examples of the titanium compound used as the esterification reaction catalyst include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. The amount of the titanium compound catalyst used is more than 33 ppm and not more than 90 ppm as a weight ratio of titanium atoms with respect to the theoretical yield of PBT, preferably 35 to 85 ppm, more preferably 40 to 70 ppm, and particularly preferably 40 to 50 ppm (weight). Ratio). In the present invention, tin compounds, lithium compounds, sodium compounds, potassium compounds, magnesium compounds, calcium compounds, antimony compounds and the like can be used in combination as reaction aids.

  In the polycondensation reaction, the titanium catalyst added during the esterification reaction can be used subsequently as a polycondensation reaction catalyst without adding a new catalyst. Further, a titanium catalyst can be further added during the polycondensation reaction. The amount used in this case is the sum of the esterification reaction catalyst, and the weight ratio of titanium atoms is more than 33 ppm and not more than 90 ppm, preferably 35 to 85 ppm, more preferably 40 to 70 ppm, relative to the theoretical yield of PBT. Especially preferably, it is 40-50 ppm (weight ratio).

  In the esterification reaction and / or polycondensation reaction, 2,6-di-t-butyl-4-octylphenol, pentaerythrityltetrakis [3- (3 ′, 5′-t-butyl-4) is used as an antioxidant. Phenol compounds such as' -hydroxyphenyl) propionate], thioether compounds such as dilauryl-3,3'-thiodipropionate, pentaerythrityltetrakis (3-laurylthiodipropionate), triphenyl phosphite, tris (nonyl) Phosphorus compounds such as phenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite can be added. Furthermore, paraffin wax, microcrystalline wax, polyethylene wax, long chain fatty acids such as montanic acid and montanic acid ester or esters thereof, silicone oil, and the like can be added as a release agent.

  As a method for producing PBT, there are a method through a transesterification reaction between dimethyl terephthalate and the like and 1,4-butanediol, and a method through a direct esterification reaction between terephthalic acid and 1,4-butanediol. The direct esterification reaction using terephthalic acid and 1,4-butanediol as starting materials is advantageous in terms of raw material cost and recovery of by-product tetrahydrofuran. Further, according to the direct esterification reaction using terephthalic acid and 1,4-butanediol as starting materials, PBT having a high crystallization rate can be easily obtained as compared with a method through a transesterification reaction.

  PBT production methods include batch reactions and continuous reactions. According to the method of continuously polymerizing terephthalic acid and 1,4-butanediol, the molecular weight decreases, the terminal carboxyl group concentration increases, and the residual tetrahydrofuran amount increases with the passage of time from the reaction vessel after completion of the reaction. This is preferable because a high-quality resin can be easily obtained.

  In the present invention, in the esterification reaction tank, at least a portion of 1,4-butanediol is supplied to the esterification reaction tank independently of terephthalic acid in the presence of a titanium catalyst, while terephthalic acid and 1,4 are added. A step of continuously esterifying with butanediol is preferably employed. That is, in the present invention, haze and foreign matters derived from the catalyst are reduced, and the catalytic activity is not lowered. Therefore, in addition to 1,4-butanediol supplied together with terephthalic acid as a raw slurry or solution, Independent of the acid, 1,4-butanediol is fed to the esterification reactor. Hereinafter, the 1,4-butanediol may be referred to as “separately supplied 1,4-butanediol”.

  The “separately supplied 1,4-butanediol” can be filled with fresh 1,4-butanediol independent of the process. In addition, “separately supplied 1,4-butanediol” collects 1,4-butanediol distilled from the esterification reaction tank with a condenser or the like and holds it in the reaction tank as it is or in a temporary tank. It can be refluxed, or can be supplied as 1,4-butanediol having a purity improved by separating and purifying impurities. Hereinafter, “separately supplied 1,4-butanediol” composed of 1,4-butanediol collected by a condenser or the like may be referred to as “recycled 1,4-butanediol”. From the viewpoint of effective utilization of resources and simplicity of equipment, it is preferable to apply “recycled 1,4-butanediol” to “separately supplied 1,4-butanediol”.

  In addition, 1,4-butanediol distilled from an esterification reaction tank is usually a component such as water, tetrahydrofuran (hereinafter abbreviated as “THF”), dihydrofuran, alcohol, etc., in addition to the 1,4-butanediol component. Is included. Therefore, it is preferable that the distillate 1,4-butanediol is separated and purified from components such as water and THF after being collected by a condenser or the like or collected, and then returned to the reaction vessel.

  In the present invention, it is preferable to return 10% by weight or more of “separately supplied 1,4-butanediol” directly to the reaction liquid phase part. Here, the reaction liquid phase part indicates the liquid phase side of the gas-liquid interface of the esterification reaction tank, and returning directly to the reaction liquid phase part means “separate supply 1, 4- This means that “butanediol” is supplied directly to the liquid phase part without going through the gas phase part. The ratio of returning directly to the liquid phase part of the reaction liquid is usually 30% by weight or more, preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more. When the amount of “separately supplied 1,4-butanediol” returned directly to the reaction liquid phase is small, the titanium catalyst tends to be deactivated.

  The temperature of “separately supplied 1,4-butanediol” when returning to the reactor is usually 50 to 220 ° C., preferably 100 to 200 ° C., more preferably 150 to 190 ° C. When the temperature of “separately supplied 1,4-butanediol” is too high, the amount of by-product of THF tends to increase, and when it is too low, the heat load tends to increase, which tends to cause energy loss.

  In the present invention, in order to prevent deactivation of the catalyst, it is preferable to supply 10% by weight or more of the titanium catalyst used in the esterification reaction directly to the reaction liquid phase part independently of terephthalic acid. . Here, the reaction liquid phase portion refers to the liquid phase side of the gas-liquid interface of the esterification reaction tank, and supplying directly to the reaction liquid phase portion uses piping or the like, and the titanium catalyst is the gas in the reactor. This means that it is directly supplied to the liquid phase part without going through the phase part. The proportion of the titanium catalyst added directly to the reaction liquid phase is usually 30% by weight or more, preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more.

  The titanium catalyst can be supplied directly to the reaction liquid phase part of the esterification reaction tank with or without being dissolved in a solvent or the like, but the supply amount is stabilized, and from the heating medium jacket of the reactor, etc. In order to reduce adverse effects such as heat denaturation, it is preferable to dilute with a solvent such as 1,4-butanediol. The concentration at this time is usually 0.01 to 20% by weight, preferably 0.05 to 10% by weight, more preferably 0.08 to 8% by weight, as the concentration of the titanium catalyst with respect to the whole solution. Further, from the viewpoint of reducing foreign matter, the water concentration in the solution is usually 0.05 to 1.0% by weight. The temperature for preparing the solution is usually 20 to 150 ° C., preferably 30 to 100 ° C., more preferably 40 to 80 ° C. from the viewpoint of preventing deactivation and aggregation. Moreover, it is preferable to mix a catalyst solution with a separate supply 1, 4- butanediol and piping etc., and supply to an esterification reaction tank from the point of deterioration prevention, precipitation prevention, and deactivation prevention.

  In the present invention, the molar ratio of terephthalic acid and 1,4-butanediol preferably satisfies the following formula (I).

  The above "1,4-butanediol supplied from the outside to the esterification reaction tank" refers to 1,4-butanediol supplied together with terephthalic acid as a raw slurry or solution, and independently supplied from these 1,4-butanediol, 1,4-butanediol used as a solvent for the catalyst, etc.

  When the above BM / TM value is smaller than 1.1, the conversion rate is lowered and the catalyst is deactivated. When it is larger than 5.0, not only the thermal efficiency is lowered but also by-products such as THF are increased. Tend to. The value of BM / TM is preferably 1.5 to 4.5, more preferably 2.0 to 4.0, and particularly preferably 3.1 to 3.8.

  Hereinafter, preferred embodiments of a method for producing PBT will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example of an esterification reaction step or transesterification reaction step employed in the present invention, and FIG. 2 is an explanatory diagram of an example of a polycondensation step employed in the present invention.

  In FIG. 1, terephthalic acid as a raw material is usually mixed with 1,4-butanediol in a raw material mixing tank (not shown), and supplied to the reaction tank (A) in the form of slurry from the raw material supply line (1). The On the other hand, when the raw material is a dialkyl terephthalate, it is usually supplied to the reaction vessel (A) as a molten liquid independently of 1,4-butanediol. Further, the titanium catalyst is preferably supplied from a catalyst supply line (3) after being made into a solution of 1,4-butanediol in a catalyst adjustment tank (not shown). FIG. 1 shows a mode in which a catalyst supply line (3) is connected to a recycle line (2) for recycle 1,4-butanediol, and both are mixed and then supplied to the liquid phase part of the reaction tank (A). It was.

  The gas distilled from the reaction tank (A) is separated into a high-boiling component and a low-boiling component in the rectifying column (C) through the distillation line (5). Usually, the main component of the high boiling component is 1,4-butanediol, and the main components of the low boiling component are water and THF in the case of the direct polymerization method.

  The high-boiling components separated in the rectification column (C) are extracted from the extraction line (6) and partly circulated from the recirculation line (2) to the reaction tank (A) via the pump (D). , Part is returned from the circulation line (7) to the rectification column (C). Further, the surplus is extracted outside from the extraction line (8). On the other hand, the light boiling components separated in the rectification column (C) are extracted from the gas extraction line (9), condensed in the condenser (G), and temporarily passed through the condensate line (10) to the tank (F). Can be stored. A part of the light boiling components collected in the tank (F) is returned to the rectification column (C) through the extraction line (11), the pump (E) and the circulation line (12), and the remainder is extracted. It is extracted outside through the line (13). The condenser (G) is connected to an exhaust device (not shown) via a vent line (14). The oligomer produced | generated within the reaction tank (A) is extracted through an extraction pump (B) and an extraction line (4).

  In the process shown in FIG. 1, the catalyst supply line (3) is connected to the recirculation line (2), but both may be independent. Moreover, the raw material supply line (1) may be connected to the liquid phase part of the reaction vessel (A).

  In FIG. 2, the oligomer supplied from the above-described extraction line (4) shown in FIG. 1 is polycondensed under reduced pressure in the first polycondensation reaction tank (a) to become a prepolymer, and then extracted. It is supplied to the second polycondensation reaction tank (d) through the gear pump (c) and the extraction line (L1). In the second polycondensation reaction tank (d), polycondensation usually proceeds at a lower pressure than that of the first polycondensation reaction tank (a) to become a polymer. The obtained polymer is extracted in the form of a melted strand from the die head (g) through the extraction gear pump (e) and the extraction line (L3), cooled with water, and then rotated with a rotary cutter ( It is cut into a pellet in h). Reference numeral (L2) is a vent line of the first polycondensation reaction tank (a), and reference numeral (L4) is a vent line of the second polycondensation reaction tank (d).

  By the above method, a PBT having a titanium content, a terminal carboxyl group concentration and an intrinsic viscosity as defined in the present invention can be obtained. Further, the PBT used in the present invention was melt polymerized with terephthalic acid and 1,4-butanediol as main raw materials in the same manner as described above to obtain a low molecular weight PBT having a desired titanium content and terminal carboxyl group concentration. Thereafter, it can also be obtained by a method of solid phase polymerization until a desired intrinsic viscosity is obtained.

  Next, the flame retardant PBT composition according to the first aspect of the present invention will be described. This flame-retardant PBT composition is formed by blending the above-mentioned PBT with a brominated aromatic compound-based flame retardant and an antimony oxide compound.

  The brominated aromatic compound-based flame retardant used in the present invention is an aromatic compound known as a brominated flame retardant used in a resin, for example, a brominated epoxy such as tetrabromobisphenol A epoxy oligomer. Examples thereof include resins, poly (pentabromobenzyl acrylate), polybromophenyl ether, brominated polystyrene, brominated imide, and brominated polycarbonate. Especially, since 1 type chosen from the group of brominated epoxy resin, poly (pentabromobenzyl acrylate), and brominated polycarbonate is favorable, it is used suitably. Two or more of these brominated aromatic compound-based flame retardants may be used in combination.

  The amount of the brominated aromatic compound-based flame retardant is 3 to 50 parts by weight with respect to 100 parts by weight of PBT. When the amount of the brominated aromatic compound-based flame retardant is less than 3 parts by weight, the flame retardant effect is insufficient, and when it exceeds 50 parts by weight, the mechanical strength is lowered and the thermal stability at the time of melting is low. descend. The amount of the brominated aromatic compound-based flame retardant is preferably 5 to 40 parts by weight, more preferably 6 to 30 parts by weight with respect to 100 parts by weight of PBT.

Examples of the antimony compound include antimony oxide and antimonate, and specific examples thereof include antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), and antimony pentoxide (Sb ₂ O). _And oxides such as ₅ ) and antimonates such as sodium antimonate.

  The compounding quantity of an antimony compound is 1-30 weight part with respect to 100 weight part of PBT. When the compounding amount of the antimony compound is less than 1 part by weight, a sufficient flame retardant effect cannot be obtained, and when it exceeds 30 parts by weight, the mechanical strength is lowered and the thermal stability at the time of melting is lowered. The compounding amount of the antimony compound is preferably 2 to 25 parts by weight, more preferably 3 to 20 parts by weight with respect to 100 parts by weight of PBT.

  Next, the flame retardant PBT composition according to the second aspect of the present invention will be described. This flame-retardant PBT composition is formed by blending at least one compound selected from a phosphate ester or phosphonitrile with melamine cyanurate in the aforementioned PBT.

  Examples of phosphate esters include a wide range of phosphate esters. Specific examples include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, etc. The phosphate ester represented by Formula (1) is preferable.

(In the formula, R ^{1 to} R ⁸ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m is 0 or an integer of 1 to 4. R ⁹ is a p-phenylene group. M-phenylene group, 4,4 ″ -biphenylene group or a divalent group selected from the following:

In the general formula (1), R ^{1 to} R ⁸ are preferably an alkyl group having 6 or less carbon atoms, more preferably an alkyl group having 2 or less carbon atoms, from the viewpoint of improving the hydrolysis resistance of the PBT composition. Particularly preferred is a methyl group. m is preferably 1 to 3, and more preferably 1. R ⁹ is preferably a p-phenylene group or an m-phenylene group, more preferably an m-phenylene group.

  Moreover, the phosphonitrile compound which has group represented by following General formula (2) can also be used conveniently.

(In the formula, X represents —O—, —S—, —NH— or a direct bond. R ¹⁷ and R ¹⁸ represent an aryl group, alkyl group or cycloalkyl group having 1 to 20 carbon atoms. ¹⁷ -X- and R ¹⁸ -X- may be the same or different, and n represents an integer of 1 to 12.)

In the general formula (2), specific examples of R ¹⁷ and R ¹⁸ include an alkyl group which may be substituted such as a methyl group, an ethyl group, a butyl group, a hexyl group and a benzyl group, a cycloalkyl group such as cyclohexyl, An aryl group such as a phenyl group and a naphthyl group can be mentioned. n is preferably 3 to 10, and more preferably 3 or 4. The phosphonitrile compound of the general formula (2) may be a linear polymer or a cyclic polymer, but a cyclic polymer is preferred. X is preferably —O— or —NH—, and particularly preferably —O—.

  Specific examples of the phosphonitrile compound represented by the general formula (2) include hexaphenoxycyclotriphosphazene, hexa (hydroxyphenoxy) cyclotriphosphazene, octaphenoxycyclotetraphosphazene, octa (hydroxyphenoxy) cyclotetraphosphazene, and the like. .

  The compounding quantity of phosphate ester or phosphonitrile is 3-50 weight part with respect to 100 weight part of PBT, Preferably it is 10-40 weight part. When the amount of the phosphate ester or phosphonitrile is less than 3 parts by weight, a highly flame-retardant PBT composition cannot be obtained, and when it exceeds 50 parts by weight, the mechanical strength of the PBT composition is lowered.

  The melamine cyanurate used in the present invention is a substantially equimolar reaction product of cyanuric acid and melamine. For example, an aqueous solution of cyanuric acid and an aqueous solution of melamine are mixed and reacted with stirring at a temperature of 90 to 100 ° C. And the resulting precipitate can be obtained by filtration. The particle size of melamine cyanurate is usually 0.01 to 1000 μm, preferably 0.01 to 500 μm. Some of the amino groups or hydroxyl groups of melamine cyanurate may be substituted with other substituents.

  The compounding amount of melamine cyanurate is 1 to 50 parts by weight, preferably 10 to 40 parts by weight with respect to 100 parts by weight of PBT. When the blending amount of melamine cyanurate is less than 1 part by weight, a highly flame-retardant PBT composition cannot be obtained, and when it exceeds 50 parts by weight, the mechanical strength of the PBT composition decreases.

  A reinforcing filler can be further blended in the flame retardant PBT composition of the present invention. The type of the reinforcing filler is not particularly limited, and examples thereof include glass fibers, carbon fibers, silica / alumina fibers, zirconia fibers, boron fibers, boron nitride fibers, silicon nitride potassium titanate fibers, metal fibers and other inorganic fibers, aromatic And organic fibers such as aromatic polyamide fibers and fluororesin fibers. These reinforcing fillers can be used in combination of two or more. In these, an inorganic filler, especially glass fiber are suitable.

  When the reinforcing filler is an inorganic fiber or an organic fiber, the average fiber diameter is usually 1 to 100 μm, preferably 2 to 50 μm, more preferably 3 to 30 μm, and particularly preferably 5 to 20 μm. The average fiber length is usually 0.1 to 20 mm, preferably 1 to 10 mm, and more preferably 2 to 0.5 mm.

  The reinforcing filler is preferably used after being surface-treated with a sizing agent or a surface treating agent in order to improve the interfacial adhesion with the PBT. Examples of the sizing agent or surface treating agent include functional compounds such as epoxy compounds, acrylic compounds, isocyanate compounds, silane compounds, and titanate compounds. The reinforcing filler can be surface-treated in advance with a sizing agent or a surface treatment agent, but can also be surface-treated by adding a sizing agent or a surface treatment agent during the preparation of the PBT composition.

  The compounding amount of the reinforcing filler is usually 150 parts by weight, preferably 5 to 100 parts by weight, and more preferably 10 to 70 parts by weight with respect to 100 parts by weight of PBT.

  Another filler can be mix | blended with the flame retardant PBT composition of this invention with a reinforcing filler. Other fillers include, for example, plate-like inorganic fillers, ceramic beads, asbestos, wollastonite, talc, clay, mica, zeolite, kaolin, potassium titanate, barium sulfate, titanium oxide, silicon oxide, aluminum oxide, Examples thereof include magnesium hydroxide. By blending the plate-like inorganic filler, the anisotropy and warpage of the molded product can be reduced. Examples of the plate-like inorganic filler include glass flakes, mica, and metal foil. Of these, glass flakes are particularly suitable.

  Other flame retardants other than brominated aromatic compounds, antimony compounds, phosphate esters, phosphonitriles and melamine cyanurate can be blended in the flame retardant PBT composition of the present invention. Examples of such flame retardants include fluorine resins, organic chlorine compounds, phosphorus compounds, other organic flame retardants, and inorganic flame retardants. An example of the fluororesin is polytetrafluoroethylene fiber. Examples of the phosphorus compound include phosphate ester, polyphosphoric acid, ammonium polyphosphate, and red phosphorus. Examples of other organic flame retardants include nitrogen compounds such as melamine and cyanuric acid. Examples of other inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, silicon compound, and boron compound.

  In the present invention, from the viewpoint of improving flame retardancy, it is preferable to use a dripping inhibitor, particularly polytetrafluoroethylene having fibril forming ability, as the dripping inhibitor. Fibril-forming ability refers to the tendency to easily disperse in PBT and to bind to itself (polytetrafluoroethylene) to form a fibrous material. Polytetrafluoroethylene having fibril-forming ability is classified into type 3 according to the ASTM standard. For example, “Polyflon FA-500” or “F-201L” of Daikin Chemical Industries, Ltd., “Fluon CD” of Asahi Glass Co., Ltd. -123 ", commercially available as" Teflon (registered trademark) (R) 6J "from Mitsui DuPont Fluorochemical Co., Ltd.

  The compounding quantity of polytetrafluoroethylene is 0.1-5 weight part normally with respect to 100 weight part of PBT, Preferably it is 0.2-4 weight part, More preferably, it is 0.3-3 weight part. When the blending amount of polytetrafluoroethylene is less than 0.1 parts by weight, the effect of blending is not exhibited, and when it exceeds 5 parts by weight, processability such as extrudability and moldability is impaired.

  In the flame-retardant PBT composition of the present invention, a conventional additive or the like can be blended with this type of resin composition, if necessary. Examples of such additives include stabilizers such as antioxidants and heat stabilizers, lubricants, mold release agents, catalyst deactivators, crystal nucleating agents, and crystallization accelerators. Moreover, in order to further improve hydrolysis resistance, an epoxy compound, carbodiimide, oxazoline, etc. can also be added. Furthermore, in order to impart desired performance to the PBT, stabilizers such as UV absorbers and weathering stabilizers, colorants such as dyes and pigments, antistatic agents, foaming agents, plasticizers, impact modifiers, etc. It can also be blended. These can be added during or after polymerization.

  In the flame-retardant PBT composition of the present invention, polyethylene, polypropylene, acrylic resin, polycarbonate, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polyester, polyacetal, polyphenylene oxide and other thermoplastic resins, epoxy resin, phenol You may mix | blend thermosetting resins, such as resin, a melamine resin, and a silicone resin. Two or more of these resins may be used in combination.

  The method for producing the flame-retardant PBT composition of the present invention is not particularly limited, and a batch blending method in which necessary components are mixed, melted and kneaded by a screw type extruder and pelletized, and PBT is melted by a screw type extruder. A split blending method in which kneading is performed, other components are supplied from another supply port of the extruder, and melted, kneaded and pelletized is exemplified.

  The molding method of the molded body of the flame-retardant PBT composition of the present invention is not particularly limited, and molding methods generally used for thermoplastic resins, that is, molding such as injection molding, hollow molding, extrusion molding, and press molding. The law can be applied.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. The physical property measurement method employed in the following PBT production examples is as follows.

(1) Esterification rate:
It calculated from the acid value and the saponification value by the following calculation formula (II). The acid value was obtained by dissolving the oligomer in dimethylformamide and titrating with a 0.1N KOH / methanol solution. The saponification value was determined by hydrolyzing the oligomer with a 0.5N KOH / ethanol solution and titrating with 0.5N hydrochloric acid.

(2) Terminal carboxyl group concentration:
PBT or oligomer 0.5g was melt | dissolved in benzyl alcohol 25mL, and it titrated using the 0.01 mol / L benzyl alcohol solution of sodium hydroxide.

(3) Intrinsic viscosity ([η]):
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) and measuring the number of seconds falling only at a polymer solution having a concentration of 1.0 g / dL and a solvent at 30 ° C., the following formula (III) I asked more.

(4) Titanium concentration in PBT:
PBT was wet-decomposed with high-purity sulfuric acid and nitric acid for electronic industry, and measurement was performed using a high resolution ICP (Inductively Coupled Plasma) -MS (Mass Spectrometer) (manufactured by ThermoQuest).

PBT production example:
Three types of PBT shown in Table 1 were produced using terephthalic acid and 1,4-butanediol as raw materials and varying the amount of tetrabutyl titanate catalyst. Specifically, the esterification step shown in FIG. 1 and the polycondensation step shown in FIG. 2 were used, and PBT was produced in the following manner.

  First, a 60 ° C. slurry mixed at a ratio of 1.80 moles of 1,4-butanediol with respect to 1.00 moles of terephthalic acid is passed through a raw material supply line (1) from a slurry preparation tank in advance with an esterification rate of 99. % Was continuously fed to a reaction tank (A) for esterification having a screw type stirrer filled with PBT oligomer at a rate of 41 kg / h. At the same time, the bottom component of the rectification column (C) at 185 ° C. is fed at 30 kg / h from the recirculation line (2), and 6.0 wt. % 1,4-butanediol solution was fed. The supply amount (g / h) was adjusted so that the Ti content in the PBT was as shown in Table 1. In addition, the water | moisture content in this solution was 0.20 weight%.

  The internal temperature of the reaction vessel (A) is 230 ° C., the pressure is 78 kPa, and the produced water, tetrahydrofuran and excess 1,4-butanediol are distilled from the distillation line (5), and the rectifying column (C) It separated into a high boiling component and a low boiling component. The high-boiling component at the bottom of the column after the system has been stabilized is 98% by weight or more of 1,4-butanediol, and the extraction line (8) so that the liquid level of the rectifying column (C) is constant. A part of it was extracted outside. On the other hand, the low boiling component was extracted from the top of the column in the form of gas, condensed by the condenser (G), and extracted from the extraction line (13) to the outside so that the liquid level of the tank (F) was constant.

  A certain amount of the oligomer generated in the reaction tank (A) is extracted from the extraction line (4) using the pump (B) so that the esterification rate at the outlet of the reaction tank (A) is 96% or more. The residence time was adjusted. The oligomer extracted from the extraction line (4) was continuously supplied to the first polycondensation reaction tank (a).

  The internal temperature of the first polycondensation reaction tank (a) was 240 ° C., the pressure was 2.1 kPa, and the liquid level was controlled so that the residence time was 120 minutes. An initial polycondensation reaction was performed while extracting water, tetrahydrofuran, and 1,4-butanediol from a vent line (L2) connected to a decompressor (not shown). The extracted reaction liquid was continuously supplied to the second polycondensation reaction tank (d).

  The conditions (internal temperature, pressure, residence time) of the second polycondensation reaction tank (d) were controlled as shown in Table 1. The obtained polymer was continuously extracted in a strand form from the die head (g) via the extraction line (L3) by the extraction gear pump (e), and was cut by the rotary cutter (h).

  The additive components used in the preparation of the flame retardant PBT composition are as shown in Table 2 below.

Examples 1-5 and Comparative Examples 1-10:
Each component was weighed at the ratio shown in Table 3 or Table 4, and all the components other than glass fiber were mixed together. That is, using a twin screw extruder (manufactured by Nippon Steel Works, model TEX30C, screw diameter 30 mm), melting each component while side feeding the glass fiber at a cylinder setting temperature of 255 ° C. and a screw rotation speed of 200 rpm. , Kneaded and pelletized. An ISO test piece for measuring mechanical properties was molded from the obtained pellets in the following manner. That is, using an injection molding machine (model SG-75SYCAP-MIII) manufactured by Sumitomo Heavy Industries, Ltd., pellets were molded under conditions of a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C. And performance evaluation was performed with the following test method, and the result was shown in Table 3 or Table 4.

Flame retardant test:
According to the UL94 test method, five 1/32 inch-thick test pieces were used to test flammability. For each of the five test pieces, the total combustion time after the second flame contact was defined as the total combustion time. A long total burning time means that even if the standard is passed, the specimen thickness is thin, and in the case of a prescription with a low flame retardant content, it tends to be rejected.

Hydrolysis resistance (strength retention after hydrolysis test):
A tensile test was performed using the above-described ISO test piece (TS is defined as an average tensile strength of 5 times). Thereafter, the same test piece was placed in a pressure vessel filled with pure water so as not to come into direct contact with water (placed in the space of the pressure vessel), sealed, and then treated for 100 hours under saturated steam pressure at 121 ° C., Similarly, a tensile test was performed (TS ′ is the average tensile strength of 5 times after treatment). From these values, the strength retention was calculated by the following formula (IV). The larger the strength retention, the better the hydrolysis resistance.

  As is apparent from the results shown in Table 3 and Table 4, the compositions of the examples of the present invention all exhibited V-0 flammability, which is in comparison with the comparative composition of V-0 having the same flammability. And since UL94 total combustion time is short, even if it is the same V-0 level, there is a margin in a flame retardance. That is, the composition of an Example has the high possibility of being able to hold | maintain V-0 even in the compounding prescription with few flame retardants. Moreover, the strength retention in the hydrolysis resistance test is also superior to the corresponding comparative example, and it can be seen that the PBT composition of the present invention retains both flame retardancy and hydrolysis resistance at good levels.

Explanatory drawing of an example of the esterification reaction process adopted in the production example of polybutylene terephthalate Explanatory drawing of an example of the polycondensation process adopted in the production example of polybutylene terephthalate

Explanation of symbols

1: Raw material supply line 2: Recirculation line 3: Catalyst supply line 4: Extraction line 5: Distillation line 6: Extraction line 7: Circulation line 8: Extraction line 9: Gas extraction line 10: Condensate line 11: Extraction line 12: Circulation line 13: Extraction line 14: Vent line A: Reaction tank B: Extraction pump C: Rectification tower D, E: Pump F: Tank G: Capacitor L1: Extraction line L3: Extraction lines L2, L4: Vent line a: First polycondensation reaction tank d: Second polycondensation reaction tank c, e: Extraction gear pump g: Dice head h: Rotary cutter

Claims (8)

  A flame retardant polybutylene terephthalate composition comprising 3 to 50 parts by weight of a brominated aromatic compound-based flame retardant and 1 to 30 parts by weight of an antimony oxide compound based on 100 parts by weight of polybutylene terephthalate, As butylene terephthalate, polybutylene terephthalate having a titanium content of more than 33 ppm and 90 ppm or less in terms of atoms, a terminal carboxyl group concentration of higher than 10 μeq / g and lower than 30 μeq / g, and an intrinsic viscosity of higher than 0.83 dl / g is used. A flame retardant polybutylene terephthalate composition characterized by comprising:   The flame-retardant polybutylene terephthalate composition according to claim 1, wherein the titanium content in the polybutylene terephthalate is 40 to 70 ppm in terms of atoms.   The flame-retardant polybutylene terephthalate composition according to claim 1 or 2, further comprising a reinforcing filler, the amount of which is 150 parts by weight or less with respect to 100 parts by weight of polybutylene terephthalate.   4. The flame retardant poly-resin according to claim 1, wherein the brominated aromatic compound-based flame retardant is one selected from the group consisting of a brominated epoxy resin, poly (pentabromobenzyl acrylate), and brominated polycarbonate. Butylene terephthalate composition.   Flame retardant polybutylene terephthalate composition comprising 3 to 50 parts by weight of at least one compound selected from phosphoric acid ester or phosphonitrile and 1 to 50 parts by weight of melamine cyanurate to 100 parts by weight of polybutylene terephthalate The polybutylene terephthalate is a polybutylene terephthalate having a titanium content of more than 33 ppm and not more than 90 ppm, a terminal carboxyl group concentration of more than 10 μeq / g and not more than 30 μeq / g, and an intrinsic viscosity of higher than 0.83 dl / g. A flame retardant polybutylene terephthalate composition comprising butylene terephthalate.   The flame-retardant polybutylene terephthalate composition according to claim 5, wherein the titanium content in the polybutylene terephthalate is 40 to 70 ppm in terms of atoms.   The flame-retardant polybutylene terephthalate composition according to claim 5 or 6, further comprising a reinforcing filler, the amount of which is 150 parts by weight or less with respect to 100 parts by weight of polybutylene terephthalate.   A molded article comprising the flame-retardant polybutylene terephthalate composition according to any one of claims 1 to 7.

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