JP3331698B2 - Polyester and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester comprising butylene terephthalate as a main repeating unit and a method for producing the same, and more particularly to a polybutylene terephthalate having excellent heat resistance and fluidity and a method for producing the same.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as P
Polyester (abbreviated as BT) etc. has mechanical properties, electrical properties,
It is a resin with excellent physical properties such as heat resistance.
It is widely used for electrical and electronic parts such as connectors and coil bobbins, and for automotive parts such as distributor caps.

Electric and electronic parts and automotive parts using engineering plastics such as PBT are becoming smaller and thinner, and it is desired to improve the fluidity and moldability of resin. In order to improve the fluidity, it is conceivable to lower the molecular weight of the resin. However, since the mechanical strength generally decreases as the molecular weight decreases,
It was difficult to obtain a polyester excellent in fluidity, moldability and mechanical strength.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester excellent in fluidity, moldability and heat resistance and a method for producing the same.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is that terephthalic acid or its lower alkyl ester is a main acid component, and that 1,4-butane In a polyester containing butylene terephthalate as a main repeating unit in which a diol is a main glycol component, an intrinsic viscosity (dl / g) of the polyester is 0.7 to 1.4 (30 in a mixed solvent of tetrachloroethane / phenol = 1/1). C.), and a melt index MI ₅₀₀₀ (g) of the polyester measured at 250 ° C. under a load of 5000 g.
/ 10 min) and melt index MI of the polyesters measured under a load 2160 g ₂₁₆₀ (g / 10 min) ratio of MI ₅₀₀₀ / MI ₂₁₆₀ satisfies the following formula _{(1), 2.35 ≦ MI 5000} / MI ₂₁₆₀ ≦ 10 (1) A polyester characterized in that a thioether group is bonded to the molecular chain terminal of the polyester in an amount of 0.01 to 2 mol% with respect to all acid components, and terephthalic acid as a main acid component Or a lower alkyl ester thereof and a main diol component of 1,4-butanediol are subjected to an esterification or transesterification reaction and then subjected to polycondensation to produce a polyester having butylene terephthalate as a main repeating unit. Thioether compounds having at least three ester groups or ester-forming functional groups in the molecule during polycondensation 0.01 ≦ a ≦ 1 / (f−2) (2) (a: amount of thioether compound added (mol% based on all acid components), f: thioether compound The intrinsic viscosity (dl / g) is 0.7 to 1.4 (measured in a mixed solvent of tetrachloroethane / phenol = 1/1 at 30 ° C.), and the viscosity measured at 250 ° C. under a load of 5000 g. Polyester melt index MI ₅₀₀₀
The ratio MI ₅₀₀₀ / MI _{2160 of} (g / 10 min) and the melt index MI ₂₁₆₀ (g / 10 min) of the polyester measured at a load of 2160 g satisfies the following formula (1): 2.35 ≦ MI ₅₀₀₀ / MI ₂₁₆₀ ≦ 10 (1) A method for producing a polyester characterized by producing a polyester containing butylene terephthalate as a main repeating unit.

Hereinafter, the present invention will be described in detail. The polyester having butylene terephthalate as a main repeating unit in the present invention is a polyester having terephthalic acid or a lower alkyl ester thereof as a main acid component and 1,4 butanediol as a main glycol component, but within a range that does not impair the original properties. May contain one or more other acid components, other glycol components, and oxyacid components. Other acid components include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, or aliphatic dicarboxylic acids such as sebacic acid and adipic acid And lower alkyl esters thereof. Other glycol components include ethylene glycol, neopentyl glycol, trimethylene glycol, hexamethylene glycol, decamethylene glycol, cyclohexane dimethanol, and the like. Further, as the oxyacid component, p-hydroxybenzoic acid,
m-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid and the like.

The intrinsic viscosity (measured in a mixed solvent of tetrachloroethane / phenol = 1/1 at 30 ° C.) of the polyester in the present invention is usually 0.7 to 1.4 (dl / d).
g), preferably 0.8 to 1.2 (dl / g). If the intrinsic viscosity is less than 0.7 (dl / g), the mechanical properties of the molded article will be reduced, and if it exceeds 1.4 (dl / g), the fluidity will be reduced and a problem will be caused in terms of moldability. Often.

[0008] In the polyester of the present invention,
Mel toy measured at 250 ° C with 5000g load
Index (MI₅₀₀₀Expressed by ) And at 250 ° C
Melt index (MI) measured at a load of 2160 g
₂₁₆₀Expressed by ) And MI ₅₀₀₀/ MI₂₁₆₀Is usually 2.
35 to 10, preferably 2.5 to 8. MI
₅₀₀₀/ MI₂₁₆₀Is less than 2.35 compared to normal PBT
However, the effect of improving the fluidity is hardly recognized. On the other hand, M
I₅₀₀₀/ MI₂₁₆₀Exceeds 10 when tensile elongation at break
It is not preferable because mechanical properties are deteriorated.

In the polyester of the present invention, a thioether group is bonded to the terminal of the molecular chain in an amount of 0.01 to 2 mol% based on all acid components. If it is less than 0.01 mol%, the effect of improving the fluidity and heat resistance is not sufficient, and if it exceeds 2 mol%, further improvement in fluidity and heat resistance cannot be expected. Here, the thioether group is a monovalent group represented by the following formula (3).

-R ¹ -SR ² (3) In the formula (3), R ¹ is usually an alkylene group having 1 to 12 carbon atoms or a divalent aryl group, and R ² is usually 1 carbon atom.
To 20 alkyl groups or aryl groups. Specific examples of the thioether group include a laurylthioethyl group (R ¹ : CH ₂ CH ₂ , R ² : C ₁₂ H ₂₅ ) and a myristylthioethyl group (R ¹ : CH ₂ CH ₂ , R ² : C
₁₄ H ₂₉ ), stearylthioethyl group (R ¹ : CH ₂ CH)
₂ , R ² : C ₁₈ H ₃₇ ) and the like.

The total acid component is an acid component used for forming a repeating unit in the polyester. In addition to the terephthalic acid component, other acid components such as the above-mentioned aromatic dicarboxylic acid or aliphatic dicarboxylic acid can be used. And an oxyacid component. The polyester of the present invention has an intrinsic viscosity (dl / g) in a specific range of 0.7 to 1.4, and a thioether group at a molecular chain terminal of the polyester is 0.01 to 2 with respect to all acid components. By having a mole% bond and having MI ₅₀₀₀ / MI ₂₁₆₀ in a specific range of 2.35 to 10, the melt viscosity in a high shear region, which is usually about injection molding, becomes low, and the moldability is excellent, and Excellent performance in heat resistance and mechanical properties. In order to form a thioether group at the molecular chain end of the polyester, a method of adding and reacting a thioether compound having an ester group or an ester-forming functional group in the molecule at the time of polycondensation may be used. The polyester having butylene terephthalate as a main repeating unit in the present invention is produced by reacting a dicarboxylic acid or an ester-forming derivative thereof with a glycol component. Specifically, an esterification or transesterification reaction is performed between a dicarboxylic acid component and a glycol component in the presence of a catalyst, and then a polycondensation reaction is performed in the presence of a catalyst. In order to obtain the polyester of the present invention, three or more ester groups or ester-forming functional groups are required in the molecule before the completion of the melt polycondensation reaction.
A production method in which a thioether compound having at least one thioether compound is added and reacted is preferable. The stage before the completion of the polycondensation reaction may be any of esterification / ester exchange reaction or polycondensation reaction. Further, a thioether compound may be charged together with the dicarboxylic acid component and the glycol component as raw materials. There is no particular limitation as long as it is before the completion of the polycondensation reaction, but if the reaction time between the thioether compound and the butylene terephthalate chain is too short, sufficient branching will not be produced. Therefore, the addition time is preferably 30 minutes before completion of the polycondensation reaction. Examples of the thioether compound having three or more, preferably three to six ester groups or ester-forming functional groups in the molecule of the present invention include pentaerythrityl-
Representative examples include tetrakis (3-laurylthiopropionate), pentaerythrityl-tetrakis (3-myristylpropionate), and pentaerythrityl-tetrakis (3-stearylpropionate).

For example, dimethyl terephthalate and 1,4-
A transesterification reaction is carried out by adding a hindered phenol compound and a catalyst to butanediol, and subsequently, pentaerythrityl-tetrakis (3-
Lauryl thiopropionate)

[0013]

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It is considered that when a polycondensation reaction is carried out under reduced pressure by adding 0.1 mol% and a catalyst to the acid component, products having the following structures are obtained.

[0015]

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In the method for producing a polyester of the present invention, the amount of the thioether compound to be added at the time of melt polycondensation is added in a ratio represented by the following formula (2). 0.01 ≦ a ≦ 1 / (f−2) (2) (a: amount of thioether compound added (mol% based on all acid components), f: number of functional groups of thioether compound) By adding a thioether compound having three or more ester groups or ester-forming functional groups to the polyester, a polymer chain having a branched chain together with a polymer chain having a specific amount of thioether bonded to a molecular chain terminal in the polyester is added. It can be formed moderately and has an intrinsic viscosity (dl / g) of a relatively high value of 0.7.
１1.4, the value of MI ₅₀₀₀ / MI ₂₁₆₀ was changed to 2.35.
It can be controlled in the range of 10 to 10.

As a catalyst for the esterification or transesterification reaction, a tin compound and a titanium compound are preferable, and among them, a titanium compound is most preferable. Examples of the titanium compound include a titanium alcoholate and a phenolate. Usually, a titanium alcoholate is used, and specific examples thereof include tetrabutyl titanate, tetraisopropyl titanate, and tetramethyl titanate.

In the polycondensation reaction, a titanium compound is preferred even though the same catalyst as that used in the above-mentioned esterification or transesterification reaction is used. If necessary, an oxide of antimony or germanium may be added. Here, the esterification or transesterification reaction is 15
The reaction is carried out at 0 to 280 ° C., preferably 180 to 260 ° C. for 2 to 4 hours.
This is performed at 0 to 300 ° C. for 2 to 5 hours. The amount of the catalyst is 3 to 300 ppm, preferably 5 to 200 ppm, in terms of the metal of titanium in the esterification or transesterification reaction, and the amount of the catalyst further added in the polycondensation reaction is 0 to 300 ppm, preferably 5 to 200 ppm.

In the polycondensation reaction step, a small amount of other additives may be present in addition to the catalyst. Other additives include phosphorus compounds such as phosphoric acid, phosphorous acid and its esters and metal salts, dilauryl 3,3'-thio-dipropionate, pentaerythrityl-tetrakis (3-lauryl thiopropionate) and the like. A thioether compound, and 2,6-di-t-butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate]. In particular, heat resistance is further improved by adding hindered phenol when producing the branched polyester of the present invention.

In addition, release agents such as polyethylene wax, polypropylene wax and montanic acid wax, silicate compounds such as talc and kaolin, charcoal, glass fibers and the like may be present in a small amount during polymerization. The polyester obtained by melt polycondensation may be further subjected to solid phase polycondensation. The solid-phase polycondensation is performed at a temperature of 3 torr or less or a temperature lower than the melting point of the polyester under a flow of an inert gas such as nitrogen gas.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In addition, "part" in the examples
Certain parts represent "parts by weight" and have an intrinsic viscosity [η] (dl
/ G) was determined from the solution viscosity measured at 30 ° C. in phenol / tetrachloroethane (1: 1 weight ratio).

The terminal thioether group was quantified by H ¹ -NMR. The heat resistance was evaluated by a change in color tone (b value) after treating the polymer pellets in hot air (air) at 180 ° C. for 24 hours. The smaller the change in color tone, the better the heat resistance. The color tone was made by Nippon Denshoku (Z-1001).
(P type).

The MI ₅₀₀₀ / MI ₂₁₆₀ was measured using a melt indexer manufactured by Takara Kogyo at 250 ° C. under a load of 5000 g, and the MI value (g / 10 minutes) was set to MI _5000.
The MI value (g / 10 minutes) measured at 0 g was determined as MI ₂₁₆₀ from the ratio. The melt viscosity was measured at a temperature of 260 ° C. and 1000 sec ⁻¹ corresponding to the injection molding conditions using a Capillograph (type 1B) manufactured by Toyo Seiki.
The tensile elongation at break was measured using an injection molding machine (Nissei FS-75) at a cylinder temperature of 260 ° C and a mold temperature of 80 ° C.
A TM piece was molded and measured according to ASTM D-638.

[Example 1] Dimethyl terephthalate 1
94 parts, 108 parts of 1,4-butanediol and 0.1 part of pentaerythrityltetrakis [3- (3,5-ditert-butyl-4-hydroxyphenyl) propionate] (0.1 mol% based on the total acid component) ) To tetrabutyl titanate 80 ppm (in terms of titanium metal /
Then, transesterification was carried out at 150 to 210 ° C. for 2.5 hours. Subsequently, pentaerythrityl-tetrakis (3-laurylthiopropionate) was added in an amount of 0.1 mol% (1.16 parts) based on the acid component, and tetrabutyl titanate was further added at 40 ppm.
The polycondensation reaction was performed at 0 to 245 ° C under reduced pressure. Gradually reduce the pressure from normal pressure to 3 torr over 2 hours.
Hold at rr.

Further, solid phase polymerization was carried out at 205 ° C. and 3 torr or less. For the polyester obtained by solid-state polymerization, the measurement results of [η], MI ₅₀₀₀ / MI ₂₁₆₀ , terminal group amount of thioether group, color tone thermal stability (b value change), melt viscosity and tensile elongation at break are shown in Table. 1 is shown.

Examples 2 to 4 In Example 1, the amount shown in Table 1 was added instead of 0.10 mol% of pentaerythrityl-tetrakis (3-laurylthiopropionate). A polyester was obtained in the same manner as in Example 1 except for the above.

Comparative Example 1 A polyester was obtained in the same manner as in Example 1 except that pentaerythrityl-tetrakis (3-laurylthiopropionate) was not added. Comparative Example 2 Polyester prepared in the same manner as in Example 1 except that the amount of pentaerythrityl-tetrakis (3-laurylthiopropionate) was changed to 0.60 mol% instead of 0.10 mol%. I got

Comparative Example 3 In Example 1, the amount of pentaerythrityl-tetrakis (3-laurylthiopropionate) was changed to 1.00 mol% instead of 0.10 mol%.
When the same procedure as in Example 1 was carried out except for the addition of 1%, the polyester was slightly gelled and could not be measured because it was partially insoluble in the [η] measurement solvent. No solid state polymerization is carried out and therefore M
The I value, the amount of terminal thioether groups, the color tone thermal stability, the melt viscosity, and the tensile elongation at break were not measured.

[0029]

[Table 1]

[0030]

Industrial Applicability The polyester of the present invention is excellent in fluidity at the time of melt molding, can easily obtain a good molded product, has excellent mechanical properties, and exhibits a change in color tone at high temperatures. Small and excellent in heat resistance. Further, by the method for producing a polyester of the present invention, a polyester excellent in moldability, heat resistance and mechanical properties can be easily produced.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-121756 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (2)

(57) [Claims] 1. A polyester comprising terephthalic acid or a lower alkyl ester thereof as a main acid component and 1,4-butanediol as a main glycol component, butylene terephthalate as a main repeating unit, and having an intrinsic viscosity (dl / g) is 0.7 to 1.4 (measured in a mixed solvent of tetrachloroethane / phenol = 1/1 at 30 ° C.), and the melt index MI ₅₀₀₀ (g) of the polyester measured at 250 ° C. under a load of 5000 g / 10 min) and a melt index MI _{2160 of the} polyester measured at a load of 2160 g.
(G / 10 min), the ratio MI ₅₀₀₀ / MI ₂₁₆₀ satisfies the following formula (1), and 2.35 ≦ MI ₅₀₀₀ / MI ₂₁₆₀ ≦ 10 (1) and the polyester has a thioether group at the molecular chain terminal. A polyester characterized by being bound in an amount of 0.01 to 2 mol% based on all acid components. 2. An esterification or transesterification reaction of terephthalic acid or a lower alkyl ester thereof as a main acid component and 1,4-butanediol as a main diol component, followed by polycondensation thereof, thereby obtaining butylene terephthalate. In the production of a polyester having as a main repeating unit, a thioether compound having three or more ester groups or ester-forming functional groups in the molecule at the time of polycondensation is added at a ratio satisfying the following formula (2): 0.01 ≦ a ≦ 1 / (f−2) (2) (a: added amount of thioether compound (mol% based on total acid components), f: number of functional groups of thioether compound) Intrinsic viscosity (dl / g) is 0.7 to 1.4 (measured in a mixed solvent of tetrachloroethane / phenol = 1/1 at 30 ° C.) and loaded at 250 ° C. The melt of the polyester, which is measured by the 000g index MI ₅₀₀₀
The ratio MI ₅₀₀₀ / MI _{2160 of} (g / 10 min) and the melt index MI ₂₁₆₀ (g / 10 min) of the polyester measured at a load of 2160 g satisfies the following formula (1): 2.35 ≦ MI ₅₀₀₀ / MI ₂₁₆₀ ≦ 10 (1) A method for producing a polyester, comprising producing a polyester containing butylene terephthalate as a main repeating unit.