JPH0649337A - Polybutylene terephthalate resin composition - Google Patents

Abstract

PURPOSE:To provide a polybutylene terephthalate resin composition excellent in toughness and moldability and suitable particularly for precision moldings, such as a connector, a relay and a switch, of which good toughness is required and to provide a method for producing the composition. CONSTITUTION:The composition consists of 95-70 pts.wt. polybutylene terephthalate (A) having an intrinsic viscosity [eta] of 0.95 to 1.30, 5-30 pts.wt. non-crystalline olefin polymer (B) containing an acid radical and/or an oxirane group, and a polybutylene terephthalate (C) having an intrinsic viscosity [eta]of 0.70 to 0.85 in an amount of 10-30 pts.wt. based on 100 pts.wt. of the total of components A and B.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polybutylene terephthalate resin composition which is excellent in toughness and moldability (heat stability and molding cycle), and is particularly suitable for precision molded products such as connectors, relays and switches that require toughness. And a method for manufacturing the same.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as P
Abbreviated as BT. ) Is excellent in balance of moldability, chemical resistance, heat resistance, dimensional stability, mechanical strength, and electrical characteristics.
It is used for components in the fields of electronics and automobiles, especially for connectors, relays and switches.

However, in recent years, (1) shortening the cycle in injection molding characteristics, (2) increasing the number of molded products in one shot, (3) reducing the wall thickness due to the demand for lighter products, (4) There is an increasing demand for maintaining toughness at higher temperatures due to higher operating temperatures.

To meet the above requirements (1), (2) and (3), PBT having a small molecular weight, that is,
If the value of [η] is small, it is possible to satisfy the requirement to some extent, but PBT becomes poorer in toughness as the molecular weight becomes smaller, so the molded product becomes fragile, and especially the high temperature toughness of (4) deteriorates. It's easy to do.

As a method for solving these problems, JP-A-1-101364 discloses a method of blending two kinds of PBT having a specific [η] value, and JP-A-1-10365.
No. 4, a method of blending a specific mold release agent and an antioxidant is proposed, but these methods do not sufficiently improve the properties related to toughness in general and the above-mentioned item (4). In addition, the proposed higher fatty acid metal salt has a light yellow color and may give a yellowing to the hue of PBT in some cases, and is expensive.

As a method for improving the above (4), a method of adding a bisoxazoline compound or the like to JP-A-2-294357, a method of adding a specific amide compound or the like to JP-A-3-244635, JP-A-3-252
Although a method of adding a specific hindadoin compound or the like has been proposed in Japanese Patent No. 452, improvement in properties relating to flow properties and toughness in general is not sufficient.

[0007]

To improve the toughness of PBT, it is considered that the addition of an ethylene copolymer, a butadiene rubber having a core-shell structure, an acrylic rubber, or a flexible polyester is effective. It is considered preferable that these modifiers are modified or copolymerized with α, β-unsaturated acid and / or glycidyl ester of α, β-unsaturated acid. However, specifically, these have not been sufficiently studied.

[0008]

As a result of earnest studies to solve the above-mentioned problems, the present inventor has found that two specific PBTs are used.
Further, they have found that the above problems can be solved by combining a specific olefin-based polymer, and have reached the present invention.

That is, the first aspect of the present invention is: (A) 95 to 70 parts by weight of polybutylene terephthalate having an intrinsic viscosity [η] of 0.95 to 1.30 and (B) a non-containing acid group and / or oxirane group. 5 to 30 parts by weight of the crystalline olefin polymer, 100 parts by weight in total, and (C) 10 to 30 parts by weight of polybutylene terephthalate having an intrinsic viscosity [η] = 0.70 to 0.85. The present invention relates to a characteristic polybutylene terephthalate resin composition.

The second aspect of the present invention is: step (I); (A) 95 to 70 parts by weight of polybutylene terephthalate having an intrinsic viscosity [η] of 0.95 to 1.30, and (B)
A step of melt-kneading 5 to 30 parts by weight of an amorphous olefin polymer containing an acid group and / or an oxirane group,

Step (II): Intrinsic viscosity [η] = 100 parts by weight of the resin composition obtained in the above step (I)
0.70 to 0.85 of polybutylene terephthalate 1
The present invention relates to a method for producing a polybutylene terephthalate resin composition, which comprises a step of adding 0 to 30 parts by weight and melt-kneading.

The present invention will be described in detail below.

The PBT used as the component (A) or the component (C) in the present invention comprises terephthalic acid or its ester-forming derivative as an acidic component and 1,4-butanediol or its ester-forming derivative as a diol component. Is a polyester obtained by polycondensation. Other polybasic acids such as phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid and trimellitic acid at about 30 mol% or less, ethylene glycol,
An alkylene glycol having 2 to 10 carbon atoms such as 1,3-propanediol, 1,6-hexanediol and 1,10-decanediol, or a polyol compound such as glycerin and pentaerythritol may be contained. Examples of the ester-forming derivative include ethylene oxide and the like.

The values of intrinsic viscosity [η] are different between the component A and the component C. The component A has a range of 0.95 to 1.30, and the component C has a value of 0.
It is in the range of 70 to 0.85. Here, the value of the intrinsic viscosity [η] is calculated based on the relative viscosity measured at 30 ° C. in a 40/60 (weight ratio) mixed solvent of tetrachloroethane / phenol.

The non-crystalline olefin copolymer in the non-crystalline olefin polymer containing an acid group and / or an oxirane group as the component (B) is an olefin such as ethylene or styrene and an acrylic acid such as butadiene or ethyl acrylate. It is a non-crystalline olefin-based copolymer that is a copolymer with an ester or vinyl acetate. Specifically, for example, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, graft copolymers of these polystyrenes, polymethacrylates, polyacrylonitrile-styrene copolymers, or ethylene-propylene copolymers. Polymer, hydrogenated styrene-butadiene-styrene block copolymer (commonly known as SEBS (styrene / ethylene / butylene / styrene block copolymer)) or hydrogenated styrene-butadiene-styrene Examples thereof include a rubber having a core-shell structure in which a random copolymer, a crosslinked acrylic rubber or a butadiene rubber is used as a core, and an amorphous copolymer is used as a shell.

The acid group can be introduced by copolymerization of α, β-unsaturated carboxylic acid or modification with the α, β-unsaturated carboxylic acid. Examples of α, β-unsaturated carboxylic acids include α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α, β-unsaturated dicarboxylic acids such as maleic acid and fumaric acid; and their anhydrides. Etc. Further, a maleimide compound such as maleimide may be used as the α, β-unsaturated carboxylic acid. Among these, acrylic acid and maleic anhydride are preferable.

The introduction of the oxirane group can be achieved by copolymerizing a glycidyl ester of α, β-unsaturated acid or by modifying it.
Specific examples of the glycidyl ester of α, β-unsaturated acid include acrylic acid glycidyl ester, methacrylic acid glycidyl ester, and ethacrylic acid glycidyl ester, with methacrylic acid glycidyl ester being preferred.

The acid group and the oxirane group may be used in combination. Further, the acid group-containing non-crystalline olefin polymer and the oxirane group-containing non-crystalline olefin polymer may be mixed and used.

Here, the term "modified" means that α, β-unsaturated carboxylic acid and glycidyl ester of α, β-unsaturated acid are melted or dissolved by heating in the presence of peroxide to chemically bond the two. It means to let.

The total content of acid groups and oxirane groups is preferably in the range of 0.05 to 5% by weight, preferably 0.05% by weight.
If it is less than 5% by weight, the toughness may not be improved, while if it exceeds 5% by weight, the fluidity may deteriorate.

The amorphous olefin polymer as the component (B) may have an unsaturated bond due to a certain amount of ethylenic carbon-carbon double bond depending on the kind of the monomer to be copolymerized. In such a case, in the present invention, the one which is substantially saturated by selectively hydrogenating such an ethylenic double bond is used. Therefore, for example, in the case of a styrene-butadiene-styrene block copolymer or a styrene-butadiene random copolymer, those obtained by selectively hydrogenating the double bond relating to the butadiene constituent part are used. For example, usually SEB
What is known as S (styrene / ethylene / butylene / styrene block copolymer) is exemplified. When an acid group or an oxirane group is introduced by modification, this hydrogenation can be carried out either before or after the modification operation. Preferably, hydrogenation is carried out after modification.

As described above, the polymer of component (B) is amorphous. The crystallinity of crystallinity is 40% or less when measured by the X-ray diffraction method. If it exceeds 40%, the toughness improving effect is impaired. It is preferably 20% or less.

As the preferred component (B) satisfying these conditions, specifically, ethylene-glycidyl methacrylate copolymer, ethylene-ethyl acrylate-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate copolymer; Α, β-unsaturated carboxylic acid modified products of these copolymers; graft copolymers of these copolymers with polystyrene, polymethacrylate, polyacrylonitrile-styrene copolymer; α of ethylene-propylene copolymer, Glycidyl ester modified product of β-unsaturated acid or α, β-unsaturated acid; hydrogenated styrene-butadiene-styrene block copolymer (usually known as SEBS) or hydrogenated styrene-butadiene random copolymer Combined α, β-
Glycidyl ester modified product of unsaturated acid or α, β-unsaturated acid; “α, β-unsaturated acid and / or α, β” having a crosslinked acrylic rubber or butadiene rubber as core
Examples thereof include a rubber having a core-shell structure in which a copolymer containing a “glycidyl ester of unsaturated acid” is used as a shell. Further, these may optionally contain other olefinic monomers in the range of 10% by weight or less.

The blending of the component (A), the component (B) and the component (C) is limited in order to exert the effects of the present invention. That is, the present invention provides a resin composition having excellent toughness with the component (B) while maintaining the moldability of the component (A) which is originally PBT having a high toughness. Then, the component (C) which is PBT is further added within a range that does not impair the toughness improving effect.

In general, according to the results of the study conducted by the present inventors, the toughness treatment effect of the component (B) differs greatly in the appearance degree depending on the value of [η] of the two types of PBT to be mixed, and is larger than that of [η]. Although a certain component (A) has an appropriate effect even if added in a small amount, a component (C) having a smaller [η] is obtained.
Requires the addition of a large amount for the effect to appear, and as a result, the strength and heat resistance are significantly reduced, and the originally high fluidity may be impaired.

As a result of studying these correlations, the present inventor found that the component (A) was 95 to 70 parts by weight and the component (B) was 5 to 30.
Component (C) 10 to 10 parts by weight in total.
It has been found that a resin composition containing 30 parts by weight is a resin composition having the intended effect of the present invention.
It is difficult to achieve the effects of the present invention with any compounding formulation outside this range.

The above resin composition can be made more effective by adding an additive exhibiting a releasing effect and a nucleating effect as the component (D).

As such an additive, crystalline polypropylene modified with an α, β-unsaturated carboxylic acid and / or a glycidyl ester of an α, β-unsaturated carboxylic acid has an excellent effect and a hue. It is possible to obtain an excellent resin composition.

Here, the α, β-saturated carboxylic acid is an α, β-unsaturated monocarboxylic acid such as acrylic acid and methacrylic acid; and the α, β-saturated acid such as maleic acid and fumaric acid.
Unsaturated dicarboxylic acids; and their anhydrides. A maleimide compound such as bismaleimide may be used as the α, β-unsaturated carboxylic acid. Among these, acrylic acid and maleic anhydride are preferable.

As the glycidyl ester of α, β-unsaturated carboxylic acid, acrylic acid glycidyl ester, methacrylic acid glycidyl ester, ethacrylic acid glycidyl ester and the like can be mentioned as mentioned above. Dil ester is preferred

The α, β-unsaturated carboxylic acid and the glycidyl ester of the α, β-unsaturated carboxylic acid can be used in combination. Modification means α, β-unsaturated carboxylic acid or α, β-
It means that the glycidyl ester of an unsaturated acid is heated and melted or dissolved in the presence of a peroxide to chemically bond the both.

The component (D) is obtained by modifying crystalline polypropylene, and the crystallinity of crystallinity is higher than 20% of crystal when measured by X-ray diffraction method. 20
% Or less, the toughness improving effect is impaired. Preferably 40
% Of high crystals.

The reason why the additive exerts its effect in the present invention is not clear, but it is presumed that an interaction occurs between the additive and the component (B) added to PBT. The addition amount is 0. 0 per 100 parts by weight of the resin composition of the present invention.
The amount is in the range of 1 to 2.0 parts by weight, and if the amount is less than 0.1 parts by weight, the effect is not sufficient, and if the amount exceeds 2.0 parts by weight, the toughness of the resin composition is significantly reduced.

As a method for producing the resin composition of the present invention, an appropriate method can be adopted. However, in order to exert the effect of the present invention more, it is necessary to add the component (C) as the step (II) to the resin composition obtained by melt-kneading the component (A) and the component (B) as the step (I). Is preferred. By separating these steps,
After the toughness of the component (A) is effectively improved, the fluidity is improved, and the effect is extremely effectively obtained. Although step (I) and step (II) can be performed separately,
Preferably, step (I) and step (II) are continuously carried out.
That is, for example, the component (A) and the component (B) are melt-kneaded using a continuous kneading extruder, and during this period, a predetermined amount of the component (C) is added to the kneading section of the kneader from the side feeder and further melt-kneaded. Is the way. The composition of the component (D) is
It can be blended in any order, but it is preferably blended with the component (C).

Inorganic fillers and organic fillers can be added to the resin composition as required. Further, a nucleating agent, a mold release agent, an antioxidant, a weather resistance agent, a lubricant, a heat resistance stabilizer, a coloring agent, an inorganic flame retardant, an organic flame retardant, a flame retardant aid, a foaming agent, etc. may be added. Other thermoplastic resins may be added as long as the effects of the invention are not impaired. Further, the present resin composition can be produced by any known plastic processing equipment (including an injection molding machine) capable of performing a melt-kneading step,
It is preferable that the raw materials are mixed in advance and produced by a single-screw or twin-screw kneader.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) The component (A), which is polybutylene terephthalate having [η] shown in the table, and the component (B) also shown in the table are blended in a predetermined mixing ratio, and “Irganox 1010” manufactured by Ciba-Geigy Co., Ltd. ”And“ Irgafos 168 ”each were added and mixed in a Henschel mixer.

(2) The mixture obtained above is melt-kneaded by a twin-screw continuous kneading extruder, and the component (C) which is polybutylene terephthalate having [η] shown in the table is melt-kneaded from the side feeder. Was added to prepare a resin composition having a predetermined composition, and the strand was cut into pellets. The component (D) was added together with the component (C).

(3) Using the obtained pellets, a four-piece connector mold is used, and molding is carried out using an injection molding machine with a mold clamping pressure of 100 tons at an injection molding temperature of 260 ° C., a mold temperature of 40 ° C., and a molding cycle of 30 seconds. Then, the moldability was evaluated. Further, the molding cycle was gradually shortened to find the shortest molding cycle that can obtain a good molded product.

(4) Test pieces were molded under the same molding conditions as in (3), and the mechanical properties (tensile yield strength, tensile elongation at break Izod impact value, thermal stability) were evaluated. The results are shown in Table 1 and Table 2.

[Table 1]

[Table 2]

Here, the contents of the abbreviations in the table are as follows. B-1: ethylene-ethyl acrylate-methacrylic acid glycidyl ester copolymer (methacrylic acid glycidyl ester content 5% by weight) B-2: ethylene-methacrylic acid glycidyl ester copolymer (70% by weight) and polystyrene (30% by weight) Graft copolymer with (methacrylic acid glycidyl ester content 3.5% by weight) B-3: Hydrogenated styrene-butadiene-styrene block copolymer modified methacrylic acid glycidyl ester (methacrylic acid glycidyl ester content 0.5 % By weight) B-4: Maleic anhydride modified product of hydrogenated styrene-butadiene-styrene block copolymer (maleic anhydride content 2% by weight) B-5: Kuraha Chemical Industry Co., Ltd. trade name "Paraloid
KCA-304 "core-shell type rubber; core (acrylic rubber) / shell (methyl methacrylate / methacrylic acid glycidyl ester copolymer) (methacrylic acid glycidyl ester content 2
% By weight) D-1: maleic anhydride modified product of crystalline polypropylene (maleic anhydride content 0.2% by weight) D-2: methacrylic acid glycidyl ester modified product (methacrylic acid glycidyl ester content 0.2) weight%)

Measurement Method: Tensile Yield Strength and Tensile Break Elongation; ASTM D63
0, Izod impact value; ASTM D25
6], Thermal stability: Process at 120 ° C temperature gear open for 500 hours.

[0042]

The resin composition of the present invention is a composition having good resin fluidity and high toughness at high temperatures. In particular, it is a polybutylene terephthalate resin composition suitable for precision molded products such as connectors, relays, and switches that require toughness.

Claims (4)

[Claims] 1. (A) Intrinsic viscosity [η] = 0.95 to 1.
30 to 90 parts by weight of polybutylene terephthalate and (B) 5 to 30 parts by weight of an acid group and / or oxirane group-containing non-crystalline olefin polymer, and (C) intrinsic viscosity [η ] = 0.70 to 0.85 of polybutylene terephthalate 10 to 30 parts by weight of polybutylene terephthalate resin composition. 2. The acid group and / or oxirane group-containing crystalline polypropylene is added in an amount of 0.1 to 100 parts by weight of the polybutylene terephthalate resin composition according to claim 1.
A polybutylene terephthalate resin composition containing 2.0 parts by weight. 3. Step (1); (A) 95 to 70 parts by weight of polybutylene terephthalate having an intrinsic viscosity [η] = 0.95 to 1.30, and (B)
Step of melt-kneading 5 to 30 parts by weight of olefin polymer containing acid group and / or oxirane group, step (II); resin composition 1 obtained in step (I) above
Intrinsic viscosity [η] = 0.70-0.
85. Polybutylene terephthalate No. 85: A process for producing a polybutylene terephthalate resin composition, which comprises the step of adding 10 to 30 parts by weight and melt-kneading. 4. The acid group and / or oxirane group-containing crystalline polypropylene in step (II) is blended in an amount of 0.1 to 2.0 parts by weight per 100 parts by weight of the resin composition. A method for producing a polybutylene terephthalate resin composition.