JPH07133412A - Flame retardant polybutylene terephthalate-based resin composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a composition excellent in mechanical properties, heat resistance and hue capable of providing a molding in good moldability and a short time and having high productivity by blending a phosphorus-containing PBT with a brominated polycarbonate, an antimony compound and a nucleating aid. CONSTITUTION:This composition is obtained by blending (A) 100 pts.wt. of a polybutylene terephthalate previously blended with a phosphorus compound in a molten state with (B) 5-40 pts.wt. of a brominated polycarbonate, (C) 2-20 pts.wt. of an antimony compound, (D) 0.01-10 pts.wt. of a nucleating aid. The component A is obtained by blending 100 pts.wt. of the resin with 0.0001-1 pts.wt. of phosphorus atom. As the phosphorus compound, triphenylphosphite, etc., is used. The component B is preferably tetrabromobisphenol A. The component C is preferably antimony trioxide. As the component D, talc, calcium phosphate, etc., is used. The mechanical strength of the composition is further improved by adding glass fiber to the composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flame-retardant polybutylene terephthalate resin composition and a method for producing the same. In detail, it has excellent mechanical properties, heat resistance and hue,
Moreover, the present invention relates to a flame-retardant polybutylene terephthalate resin composition having excellent moldability and a method for producing the same.

[0002]

2. Description of the Related Art Polybutylene terephthalate resins are excellent in heat resistance, solvent resistance, electrical properties, moldability and the like, and can be easily made flame-retardant by adding a flame retardant. It is widely used for various applications such as electric / electronic parts, automobile parts, and mechanical parts. In particular, among the flame retardants, molded articles obtained from the polybutylene terephthalate resin composition containing the brominated polycarbonate flame retardant are polybutylene terephthalate resin containing other flame retardants such as brominated polystyrene and brominated acrylic resin. Compared with molded products obtained from the composition, various properties such as hue, heat resistance and mechanical properties are excellent, and brominated polycarbonate is widely used as a flame retardant for polybutylene terephthalate resin from this point. .

However, since brominated polycarbonate has a carbonate bond, which is one kind of ester bond, in its molecule, it undergoes an transesterification reaction with polybutylene terephthalate during melting to lower the crystallinity of polybutylene terephthalate. As a result, the solidification rate of polybutylene terephthalate becomes slower, for example, when injection molding is performed, it does not solidify rapidly in the mold and requires a long demolding time, which lengthens the molding cycle and increases productivity. Has the disadvantage that it decreases.

Further, a nucleating agent has been blended in order to enhance the crystallinity of the thermoplastic resin and improve the moldability. However, in the polybutylene terephthalate resin composition blended with the brominated polycarbonate, simply At present, even if a nucleating agent is added, the crystallinity does not increase and the moldability is not improved.

[0005]

The object of the present invention is to improve the properties such as the above-mentioned excellent hue, heat resistance and mechanical properties obtained by blending a polybutylene terephthalate resin with a brominated polycarbonate. It is to provide a flame-retardant polybutylene terephthalate-based resin composition which is excellent in moldability while being kept and can be molded in a short time, and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies to achieve the above-mentioned object, and found that a polybutylene terephthalate resin is premixed with a phosphorus compound in a molten state, and the resulting phosphorus compound is contained. For polybutylene terephthalate, when a brominated polycarbonate is mixed with an antimony compound flame retardant aid and a nucleating agent, the nucleating agent exerts its function even in the presence of the brominated polycarbonate, and a crystal of the polybutylene terephthalate resin composition is obtained. The moldability is improved and it solidifies quickly in the mold during molding,
The present invention has been completed by finding that a target molded article can be efficiently manufactured in a short molding time.

That is, the present invention is a flame-retardant polybutylene terephthalate resin characterized by containing a polybutylene terephthalate resin in which a phosphorus compound is previously added and mixed in a molten state, a brominated polycarbonate, an antimony compound and a nucleating agent. It is a composition.

Further, in the present invention, a polybutylene terephthalate resin is added to and mixed with a polybutylene terephthalate resin in a molten state to prepare a polybutylene terephthalate resin containing a phosphorus compound in advance, and a brominated polycarbonate, an antimony compound and a nucleus are added thereto. A method for producing a flame-retardant polybutylene terephthalate-based resin composition, which comprises mixing an agent.

In the polybutylene terephthalate resin (hereinafter referred to as "PBT resin") used in the present invention, at least 90 mol% of the acid component constituting the PBT resin is terephthalic acid or its ester-forming derivative, and diol. At least 90 mol% of the component is a polyester resin composed of 1,4-butanediol, and 10 mol%
Other copolymerized acid components and / or other copolymerized diol components may be used within the following ranges. At that time, when an ester-forming derivative of terephthalic acid is used as an acid component, a dialkyl ester, a diaryl ester of terephthalic acid or the like can be used.

Examples of other copolymerizable acid components that can be used in the range of 10 mol% or less include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene-1,4-dicarboxylic acid and diphenyldicarboxylic acid; Aliphatic dicarboxylic acids such as adipic acid, sebacic acid, mazelaic acid, succinic acid and oxalic acid; oxycarboxylic acids such as p-hydroxybenzoic acid and p-hydroxymethylbenzoic acid; or ester-forming derivatives thereof. These copolymeric acid components may be used alone or in combination of two or more.

Examples of the copolymerized diol component that can be used in the range of 10 mol% or less include ethylene glycol, propylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5.
-Pentanediol, 1,6-hexanediol, 1,
Aliphatic diols having 2 to 10 carbon atoms such as 9-nonanediol, 2-methyl-1,8-octanediol and decamethylenediol; alicyclic diols such as cyclohexanediol; 2,2-bis (4-hydroxyphenyl) ) Aromatic diols such as propane (bisphenol A); polyalkylene glycols such as polyethylene glycol, polytrimethylene glycol, and polytetramethylene glycol, and the like. These copolymerized diol components may be used alone. Alternatively, two or more kinds may be used.

The method for producing the PBT-based resin is not particularly limited, and it is conventional to use the above-mentioned acid component mainly composed of terephthalic acid or its ester-forming derivative and the above-mentioned diol component mainly composed of 1,4-butanediol. Any of the known aromatic polyesters produced by the transesterification reaction or the direct esterification reaction can be used.

In the present invention, the intrinsic viscosity of the PBT resin measured at 30 ° C. using a phenol / tetrachloroethane (1: 1 weight ratio) mixed solvent is 0.5-1.
It is preferable to use one in the range of 3 dl / g,
A PBT resin in the range of 0.7 to 1.1 dl / g is more preferable. When the intrinsic viscosity of the PBT resin is less than 0.5 dl / g, the mechanical performance of a molded article obtained from the PBT resin composition may be deteriorated, while the intrinsic viscosity of the PBT resin is 1.3 dl. If a PBT resin that exceeds / g is used, the melt viscosity at the time of molding becomes too high and the moldability decreases, and molding tends to be difficult, especially in the case of injection molding.

In the present invention, it is necessary to previously add and mix the phosphorus compound in the molten state to the PBT resin. When the phosphorus compound is not added to the PBT resin in a molten state in advance and is mixed with the PBT resin at the same time as or after other components such as brominated polycarbonate, antimony compound and nucleating agent, the PBT resin is used. Crystallization is not promoted, cooling and solidification in the mold takes time, and moldability is deteriorated. Further, the phosphorus compound needs to be added in a molten state of the PBT resin and uniformly mixed, and it is possible to shorten the cooling and solidifying time at the time of molding by simply premixing with the solid PBT resin. Therefore, the moldability is not improved.

Examples of the phosphorus compound added to the PBT resin include phosphoric acid, phosphoric anhydride, polyphosphoric acid, phosphorous acid, partial esters or total esters thereof, and one of these phosphorus compounds or Use two or more. In that case, as an example of the partial ester or total ester of phosphoric acid or phosphorous acid, an aliphatic and / or aromatic partial ester of phosphoric acid or phosphorous acid, or a total ester can be used. Is, for example, triphenyl phosphite, diphenyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-t-butylphenyl-di-
Tridecyl) phosphite, cyclic neopentanetetraylbis (octadecylphosphite), tris (nonylphenyl) phosphite, the following formula (I) or (II);

[0016]

[Chemical 1]

[0017]

[Chemical 2] A phosphite represented by: mono-stearyl phosphate, di-stearyl phosphate, tri-stearyl phosphate, stearyl diphenyl phosphate,
Examples thereof include triphenyl phosphate.

The phosphorus compound is added in the amount of PBT-based resin 10
0.001 to 1 in terms of phosphorus atom based on 0 part by weight
It is preferably part by weight, more preferably 0.1 to 0.5 part by weight. If the addition amount of the phosphorus compound is less than 0.001 part by weight, the crystallinity of the PBT-based resin composition containing the brominated polycarbonate may not be improved even if the nucleating agent is added, resulting in poor moldability. If it exceeds the amount, hydrolysis resistance tends to decrease.

As a method of previously adding the phosphorus compound to the PBT resin, a method of adding the phosphorus compound to the molten PBT resin and uniformly mixing the phosphorus compound into the PBT resin is used. Any of them is not particularly limited. Specifically, for example, a method of adding a phosphorus compound to a PBT-based resin, melt-kneading the mixture with a single-screw or twin-screw extruder, and then pelletizing it, and when the polymerization of the PBT-based resin is completed, Examples thereof include a method in which a phosphorus compound is added to the inside of the polymerization apparatus while in a molten state to uniformly mix the phosphorus compound in the PBT resin. The temperature at the time of adding and kneading the phosphorus compound to the PBT resin is the melting temperature usually adopted for pelletizing the PBT resin or the temperature at the latter stage of polymerization usually adopted for polymerizing the PBT resin. Preferably about 230-280 ° C.
The temperature of is preferably used.

The PBT resin containing the phosphorus compound prepared as described above may be cooled once to form pellets or other solids, and then mixed with other components such as brominated polycarbonate, or phosphorus. PB with added compound
When the T resin is not solidified by cooling and is still in a molten state, other components such as a brominated polycarbonate, an antimony compound and a nucleating agent may be subsequently mixed.

In the present invention, the PBT resin containing the phosphorus compound prepared as described above is mixed with a brominated polycarbonate flame retardant, an antimony compound (flame retardant auxiliary) and a nucleating agent. Examples of preferred brominated bisphenol-type polycarbonates include brominated bisphenol-type polycarbonates such as brominated bisphenol A, bisphenol F, and bisphenol S. Brominated bisphenol-type polycarbonates based on the above can be used, and among them, brominated bisphenol A-type polycarbonates are particularly preferable. As a more specific example, brominated bisphenol A such as tetrabromo-bisphenol A (eg 3,3 ′, 5,5′-tetrabromobisphenol A), dibromo-bisphenol A, hexabromobisphenol A and phosgene are reacted. And brominated polycarbonate obtained by reacting phosgene with a mixture of one or more of the above-mentioned brominated bisphenol A and bisphenol A not brominated. be able to.

Further, in the present invention, as the brominated polycarbonate, tetrahydrofuran is used as a solvent for GPC.
The weight average molecular weight when measured by
Those of 0000 are preferably used.

The blending amount of brominated polycarbonate is PB
The amount is preferably 5 to 40 parts by weight, and particularly preferably 15 to 30 parts by weight, based on 100 parts by weight of the T-based resin. If the blending amount of the brominated polycarbonate is less than 5 parts by weight, it becomes difficult to obtain a sufficient flame retarding effect, while if it exceeds 40 parts by weight, the mechanical performance of the obtained molded article deteriorates and the amount of harmful volatile components is increased. Is likely to occur.

In the PBT resin composition of the present invention, it is important to use a brominated polycarbonate as a flame retardant. Even though it is a brominated polymer, for example, a brominated acrylic resin, brominated polystyrene or brominated phenoxy resin. When such a compound is used, the heat resistance or hue of the molded article obtained from the PBT resin composition is inferior, and mechanical properties such as tensile strength are inferior depending on the type of flame retardant.

Further, in the present invention, an antimony compound is used as a flame retardant auxiliary together with the brominated polycarbonate flame retardant. Examples of the antimony compound that can be used in the present invention include antimony salts such as antimony trioxide, antimony tetraoxide, antimony pentoxide and sodium antimonate. The antimony compounds may be used alone or in combination of two or more. Among the above-mentioned antimony compounds, antimony trioxide is preferable.
The content of the antimony compound is preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the PBT resin. If the compounding amount of the antimony compound is less than 2 parts by weight, it becomes difficult to obtain a sufficient flame retardant effect, while if it exceeds 20 parts by weight, the mechanical performance of the molded product tends to be deteriorated.

Further, the PBT resin composition of the present invention contains a nucleating agent. As the nucleating agent, any of inorganic compounds and organic compounds known as crystal nucleating agents for thermoplastic resins can be used, and specific examples thereof include talc, calcium phosphate, various metal oxides and sodium stearate. The nucleating agent may be used alone or in combination of two or more kinds. The content of the nucleating agent is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 5 parts by weight, based on 100 parts by weight of the PBT resin. When the content of the nucleating agent is less than 0.01 part by weight, crystallization is not sufficiently promoted and it takes time to cool and solidify in the mold, so that the molding cycle may become long, while when it exceeds 10 parts by weight, The mechanical strength of the product is lowered, and discoloration easily occurs.

The above antimony compound and / or nucleating agent may be subjected to various surface treatments and other treatments, if necessary, as long as they do not interfere with their functions.

Further, the PBT resin composition of the present invention may contain glass fiber if necessary, and when glass fiber is blended, a molded article having further excellent mechanical properties can be obtained. When glass fiber is compounded, the compounding amount is usually added in an amount within the range of not more than 80% by weight based on the total amount.

Further, the PBT resin composition of the present invention contains, in addition to the above-mentioned components, various conventionally known additives such as a releasing agent, a stabilizer, an antistatic agent, a dye / pigment and a plasticizer, if necessary. , An inorganic filler, etc. may be contained. Further, the PBT resin composition of the present invention may contain other organic polymers such as polyethylene terephthalate, polypropylene and ethylene-vinyl acetate copolymer.

The mixing method of the brominated polycarbonate, the antimony compound, the nucleating agent and, if necessary, other components to the PBT resin to which the phosphorus compound has been added and mixed in the molten state is not particularly limited, and a conventionally known method is adopted. can do. For example, PBT-based resin pellets containing a phosphorus compound are uniformly mixed with the components in advance by a mixer such as a tumbler or a Henschel mixer, and then uniaxially or 2
A PBT system in which a phosphorus compound is added and mixed in advance in a molten state as described above even if a resin composition in the form of pellets or other shapes is prepared by feeding into a shaft extruder, melt-kneading, then extruding and cutting. The resin may subsequently be mixed with the brominated polycarbonate, antimony compound, nucleating agent and optionally other ingredients while it is still in the molten state.

The flame-retardant PBT resin composition of the present invention can be molded by using a molding method and a molding apparatus generally used for polyester resins. For example,
It can be molded by any molding method such as injection molding, extrusion molding, press molding, blow molding, calender molding, etc., so that electric parts, electronic parts, mechanical parts, automobile parts, pipes, sheets, films, daily necessities etc. It is possible to manufacture a molded product of any shape and application, and it is particularly suitable for manufacturing various molded products by injection molding or the like.

[0032]

[Examples] The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
Each value in the following examples and comparative examples was determined as follows.

Crystallization temperature (Tcc) : A 10 mg sample was cut out from the pellet of the PBT resin composition of each Example or Comparative Example, and the crystallization temperature was measured by DSC. The measurement was performed by raising the temperature from room temperature to 290 ° C. at a temperature rising rate of 20 ° C./minute, holding the temperature at 290 ° C. for 10 minutes, and then lowering the temperature at a rate of 20 ° C./minute.

Gate sealing time : Using the pellets of the PBT resin composition of each Example or Comparative Example as a molding material and using an 80 ton injection molding machine, the cylinder temperature was 2
Under the conditions of 60 ° C. and mold temperature of 70 ° C., a side-gate type mold having a box-shaped cavity [cavity inner diameter = length 10 mm × width 10 mm × depth 20 mm: cavity gap (wall thickness) 1. 2mm: Gate size = 1mm x
3 mm] injection-molded and cooled and solidified after injection
The time until the gate was sealed with the T resin composition was measured and used as the gate sealing time.

Solidification time : PBT of each Example or Comparative Example
Using a pellet of a resin composition as a molding material,
Mold for connector production under the conditions of cylinder temperature of 260 ℃ and mold temperature of 70 ℃ using a ton injection molding machine
(28 pins: mold cavity volume 15 cm ³ ) was injection-molded, and after injection, the shortest time until the molded product in the mold could be taken out without deformation was measured as the solidification time.

Tensile Strength : PBT of each Example or Comparative Example
Using a pellet of a resin composition as a molding material,
Ton injection molding machine was used to produce JIS No. 1 test pieces under the conditions of a cylinder temperature of 260 ° C. and a mold temperature of 70 ° C., and the tensile strength of the JIS No. 1 test pieces was measured according to the method of JIS K7113. It was measured.

Dry heat deterioration test : A JIS No. 1 test piece prepared in the same manner as above was put in a heating oven to obtain 150
The tensile strength when heated at 0 ° C. for 20 days was measured in the same manner as above, and the strength retention ratio to the initial tensile strength before heating was obtained.

Thermal discoloration test : J prepared in the same manner as above
The hue of the IS 1 test piece was measured using a color computer, the test piece was heated in an oven at 150 ° C. for 20 days, and the hue at that time was measured in the same manner.
Based on IS Z8729, the change amount ΔE from the initial value (value before heating) was obtained.

Flame retardance test : PB of each Example or Comparative Example
Using pellets of the T-based resin composition as a molding material, 1
Cylinder temperature 260 using 00 ton injection molding machine
Test piece for flame retardancy evaluation under conditions of ℃ and mold temperature of 70 ℃ (length 127 mm × width 12.7 mm × thickness 0.8 mm)
Was prepared, and flame retardancy was evaluated according to the method of UL-94 (vertical combustion test).

Example 1 (1) 0.3 part of phosphoric acid in 100 parts by weight of PBT resin (“KL263F” manufactured by Kuraray Co., Ltd.) having an intrinsic viscosity of 0.85 dl / g (hereinafter abbreviated as “part”) Was added, melt-kneaded at 240 ° C. using a twin-screw extruder (φ44 mm), extruded, cooled and solidified, and then cut to prepare PBT resin pellets containing phosphoric acid. (2) In the phosphoric acid-containing PBT resin pellets prepared in (1) above, brominated polycarbonate flame retardant (“BC-58” manufactured by Great Lakes) per 100 parts of PBT resin:
Number average molecular weight 3500; bromine content 53% by weight) 30 parts,
13 parts of antimony trioxide and 1 part of talc are fed to a twin-screw extruder (manufactured by Nippon Steel Co., Ltd., φ44 mm) and heated to 250 ° C.
After being melt-kneaded with, the mixture was extruded from a die, cooled and cut to produce pellets having a diameter of 2 mm and a length of 3 mm. The crystallization temperature (Tcc) was measured using this pellet. Further, a box-shaped molded product, a connector and a test piece were prepared as described above, and the gate sealing time, the setting time and the tensile strength were measured, and the dry heat resistance test, the thermal discoloration test and the flame retardancy test were performed. The results are shown in Table 1 below.

<Examples 2 and 3> (1) of Example 1 except that the addition amounts of phosphoric acid were changed to 0.05 parts (Example 2) and 1.0 parts (Example 2), respectively. Melt kneading and extrusion were carried out in the same manner to prepare PBT resin pellets containing a phosphorus compound. Thereafter, in the same manner as in (2) of Example 1, brominated polycarbonate, antimony trioxide and talc were added to give flame retardance. PBT resin composition pellets were produced, and the same test was conducted using the pellets. The results are shown in Table 1 below.

Examples 4 to 8 Instead of phosphoric acid, phosphorous acid (Example 4), phosphite represented by the above formula (I) (Example 5), and formula (II) were used. In the same manner as in (1) of Example 1, 0.3 parts each of the represented phosphite (Example 6), mono-stearyl phosphate (Example 7) or triphenyl phosphate (Example 8) was added. Melt kneading / extrusion is carried out to prepare PBT resin pellets containing a phosphorus compound, and thereafter brominated polycarbonate, antimony trioxide and talc are added in the same manner as in (2) of Example 1 to obtain a flame-retardant PBT resin. A pellet of the composition was produced and used for the same test. The results are shown in Table 1 below.

Example 9 When adding brominated polycarbonate or the like, glass fiber (“E” manufactured by Nippon Electric Glass Co., Ltd.) was added.
CS-03T-187 ") was added in the same manner as in Example 1 except that 50 parts were added. The results are shown in Table 1.

Examples 10 to 11 (1) and (2) of Example 1 except that calcium phosphate (Example 10) or sodium stearate (Example 11) was used as the nucleating agent instead of talc. ) Was carried out. The results are shown in Table 1.

COMPARATIVE EXAMPLE 1 Without carrying out the step (1) of Example 1 (without adding phosphoric acid), only the step (2) of Example 1 was carried out to prepare a brominated polycarbonate, A PBT resin composition containing antimony oxide and talc was prepared and tested in the same manner. The results are shown in Table 1.

Comparative Examples 2 to 3 Brominated acrylic resin flame retardant (“PBB-PA” manufactured by Dead Sea Bromine) (Comparative Example 2) or brominated phenoxy resin flame retardant (manufactured by Tohto Kasei) instead of brominated polycarbonate. YPB-43
C ") (Comparative Example 3), respectively, but in Example 1
The same steps as (1) and (2) in (1) were performed. The results are shown in Table 1.

[0047]

[Table 1]

From the results shown in Table 1 above, phosphorus compound-containing PBT resin pellets obtained by previously adding and mixing a phosphorus compound to the PBT resin in a molten state were added to brominated polycarbonate,
Examples 1 to 1 containing an antimony compound and a nucleating agent
In the case of the flame-retardant PBT-based resin composition of No. 11, the solidification rate is high (solidification time is short), the molding property is good in a short molding time,
Mechanical strength, heat resistance (dry heat resistance and heat discoloration resistance)
Also, it can be seen that a molded product having excellent flame retardancy can be obtained.

On the other hand, in the case of Comparative Example 1 in which no phosphorus compound is added, the solidification rate when injected into the mold is slow (cooling time is long), a long time is required for molding, and moldability is poor. In Comparative Example 2 and Comparative Example 3 using the brominated acrylic resin flame retardant having no ester bond or the brominated phenoxy resin flame retardant, although the cooling and solidification time was short, the obtained molded product had heat resistance (dry heat deterioration resistance). And the heat discoloration resistance), and Comparative Example 2 has lower mechanical strength.

Example 12 (1) A PBT resin was polymerized by a conventional method to produce a PBT resin having an intrinsic viscosity of 0.85 dl / g, and the PBT resin was in a molten state at the end of the polymerization (resin temperature 240 ℃)
Then, 0.3 part of phosphoric acid was added to 100 parts of the resin in the polymerization tank and mixed uniformly, and the mixture was discharged from the polymerization tank, cooled, solidified and cut to produce phosphoric acid-containing PBT resin pellets. . (2) Flame retardant PBT prepared by adding the brominated polycarbonate, antimony trioxide, talc and other additives to the phosphoric acid-containing PBT resin pellets produced in (1) in the same manner as in (2) of Example 1. A pellet of the resin composition was produced, and the same test was performed using the pellet. The results are shown in Table 2 below.

<Examples 13 to 15> In the same manner as (1) of Example 12, instead of phosphoric acid, phosphorous acid (Example 13) and the phosphite ester represented by the above formula (I). (Example 14) or 0.3 part of mono-stearyl phosphate (Example 15) was added at the time when the polymerization of the PBT resin was completed and uniformly mixed to prepare phosphorus compound-containing PBT resin pellets. Brominated polycarbonate, antimony trioxide, talc and other additives were added in the same manner as in (2) above to prepare pellets of a flame-retardant PBT resin composition, and the same test was performed using the pellets. The results are shown in Table 2 below.

<< Comparative Examples 4 to 7 >> Phosphoric acid (Comparative Example 4),
Phosphorous acid (Comparative Example 5), phosphite represented by formula (I) (Comparative Example 6) or mono-stearyl phosphate (Comparative Example 7) was the same PBT as used in Example 1.
Brominated polycarbonate, antimony trioxide and talc were added to the resin pellets at the same time to carry out the step (2) of Example 1 to produce pellets of a flame-retardant PBT resin composition. The same test as in Example 1 was performed. The results are shown in Table 2.

[0053]

[Table 2]

From the results shown in Table 2 above, PBT at the end of the polymerization
In the case of Examples 12 to 15 in which the phosphorus compound was added in advance while the resin was still in the molten state, the solidification rate was high (solidification time was short), the moldability was good in a short molding time, the mechanical strength and the heat resistance were high. While it is possible to obtain a molded product that is excellent in all properties (dry heat resistance and heat discoloration resistance) and flame retardancy, phosphorus compounds such as brominated polycarbonate without being pre-marked in the PBT resin in a molten state. In the case of Comparative Examples 4 to 7 in which the other components were added at the same time, it was found that the solidification rate when injected into the mold was slow (cooling time was long) and the molding required a long time.

[0055]

The flame-retardant P of the present invention obtained by previously adding a phosphorus compound in a molten state to a PBT resin and then mixing a brominated polycarbonate, an antimony compound and a nucleating agent.
When the BT resin composition is used, a molded article excellent in various properties such as mechanical properties, heat resistance, hue and flame retardancy can be efficiently manufactured with good moldability in a short cooling and solidifying time. It is possible to improve productivity.

Claims (3)

[Claims] 1. A flame-retardant polybutylene terephthalate resin composition comprising a polybutylene terephthalate resin in which a phosphorus compound has been added and mixed in a molten state, a brominated polycarbonate, an antimony compound and a nucleating agent. 2. A polybutylene terephthalate resin 10
0.001 to 1 part by weight of a phosphorus compound in terms of phosphorus atom relative to 0 part by weight, and 5 to 10 parts by weight of brominated polycarbonate
40 parts by weight, 2 to 20 parts by weight of the antimony compound and 0.01 to 10 parts by weight of the nucleating agent are contained.
Flame-retardant polybutylene terephthalate resin composition. 3. A polybutylene terephthalate resin is added to and mixed with a polybutylene terephthalate resin in a molten state to prepare a polybutylene terephthalate resin containing a phosphorus compound in advance, and a brominated polycarbonate, an antimony compound and a nucleating agent are mixed therein. A method for producing a flame-retardant polybutylene terephthalate-based resin composition, comprising: