JPH04175366A - Polybutylene terephthalate resin composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. resistant to degradation in toughness at high temp. and excellent in rigidity and moldability by compounding a polybutylene terephthalate resin, a bisphenol A polycarbonate, and an epoxy compd. and/or a polycarbodiimide. CONSTITUTION:The title compsn. comprises 100 pts.wt. polybutylene terephthalate resin, 0.1-10 pts.wt. bisphenol A polycarbonate or oligomer thereof, and 0.1-5 pts.wt. at least one compd. selected from the group consisting of an epoxy compd. having at least two epoxy groups in the molecule and a polycarbodiimide having at least two carbodiimide groups in the molecule. The addition of a thermoplastic elastomer to the compsn. improves the toughness and durability of the compsn. synergistically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polybutylene terephthalate resin composition having excellent rigidity, toughness and heat resistance. More specifically, it has high strength and shows relatively little decrease in toughness even after being exposed to a high fA environment for a long period of time, so it is suitable for use in applications where stiffness and toughness of thin-walled parts are required. The present invention relates to a polybutylene terephthalate resin composition obtained.

[Prior art] Polybutylene terephthalate resin is an engineering plastic with excellent mechanical and physical properties.
Widely used in various industrial fields. In particular, the so-called natural grade, which is not reinforced with glass fiber, has an excellent balance of toughness and rigidity even when it is a thin-walled molded product with a thickness of 1 mm or less, so it is mainly used for automotive connector parts with hinge parts. It is increasing.

In recent years, there has been an increasing demand for materials that can withstand harsh high-temperature environments such as in engine compartments, especially in automotive parts applications. There was a problem in that the elongation at break decreased and the necessary toughness could not be maintained. According to studies conducted by the present inventors, the cause of this is that in addition to chemical deterioration occurring, crystallization of the polybutylene terephthalate resin itself occurs, accelerating the deterioration. Such a decrease in toughness is a significant problem particularly in thin-walled automotive parts that require a high degree of toughness, and therefore improvements are required.

Japanese Patent Publication No. 51-144452, Special Publication No. 48-6175.4
It is known from Japanese Patent No. 7-11669 that toughness can be improved by blending an epoxy compound with a polyester resin.

Furthermore, JP-A No. 60-210659.61-235455 discloses that impact resistance, hot water resistance, or melt stability is improved by blending a thermoplastic polyester elastomer and a carbodiimide compound or an epoxy compound with polybutylene terephthalate resin. It is written that there is something to be done.

However, although the above-mentioned composition improves durability under relatively low-temperature hydrolysis conditions, the effect of improving durability under high-temperature atmospheres that involve post-crystallization of the polymer was extremely insufficient. That is, in thin-walled parts such as those targeted by the present invention, it has not been possible to suppress a decrease in toughness in a high-temperature atmosphere.

On the other hand, JP-A-49-107354.51-144452
The publication describes that the toughness of a resin composition is improved by blending polycarbonate with polybutylene terephthalate.

Furthermore, JP-A-51-89558 discloses that aromatic polyester is blended with aromatic polycarbonate and a soft thermoplastic resin to improve impact resistance, thermal stability during melt retention, etc. There is. However, when this technology is applied to thin-walled molded products, which is the object of the present invention, in order to maintain viscosity at high temperatures for a long time, it is necessary to incorporate a large amount of polycarbonate resin, resulting in poor moldability such as fluidity and solidification rate. There was a problem in that it caused a significant decrease in Furthermore, since polycarbonate has a relatively high viscosity, there is a problem in that fluidity decreases and moldability is impaired, making it difficult to mold into thin walls.

Problems to be Solved by the Present Invention] As mentioned above, with the conventional technology, it is difficult to obtain a polybutylene terephthalate resin composition that exhibits little decrease in toughness in a high-temperature atmosphere and has good toughness, rigidity, and moldability. Ta.

The present invention improves toughness without reducing the inherent rigidity and moldability of polybutylene terephthalate resin, and
It is an object of the present invention to provide a resin composition suitable for producing thin-walled molded products with little decrease in toughness and excellent durability even in a high-temperature atmosphere.

"Means for Solving the Problems" That is, the present invention provides polybutylene terephthalate resin 1
00 parts by weight, (A) 0.1 to 10 parts by weight of bisphenol A polycarbonate or its oligomer (B) An epoxy compound having at least two epoxy groups in the molecule, or at least two carbodiimide groups in the molecule. At least one polycarbodiimide having
This is a polybutylene terephthalate resin composition containing 0.1 to 5 parts by weight of seeds.

Furthermore, by adding the thermoplastic polyester elastomer (C) to the composition, toughness and durability are synergistically improved.

The polybutylene terephthalate resin used in the present invention is
80mo means a polyester in which 1% or more of the polyester is composed of butylene terephthalate units. That is, ethylene glycol, trimethylene glycol, hexamethylene glycol, polyethylene glycol, polytetramethylene glycol, cyclohexane dimetatool, P
- One or more copolymerization components selected from xylylene glycol, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, sebacic acid, adipic acid, dodecanniic acid, dimer acid, etc. can be copolymerized.

The polyester used in the present invention must have the necessary physical properties as a molding material, and has a relative viscosity (η
r) is preferably within the range of 1.25 to 1.65, more preferably within the range of 1.4 to 1.6.

The bisphenol A polycarbonate or its oligomer (A) used in the present invention is produced using bisphenol A, that is, 2,2°-bis(4-hydroxyphenyl)propane as a main raw material. Specifically, polycarbonate or its oligomer obtained by a transesterification method or a phosgene method using bisphenol A as a dihydroxy component is preferred. Furthermore, part or all of bisphenol A may be substituted with other 4,4°-dihydroxydiphenyl alkane, 4,4°-dihydroxydiphenyl sulfone, 4,4°-dihydroxydiphenyl ether, or the like.

In addition, bisphenol A polycarbonate tends to have a higher viscosity and is less fluid than polybutylene terephthalate, so in order to obtain molded products with particularly thin wall parts, use polycarbonate with a melt index of 15 or more according to JIS-6719. The use of polycarbonate oligomers having a degree of polymerization of 2 to 20 is particularly preferred.

Usually, in order to control zero molecular weight, a terminal capping agent such as phenol, trimethylphenol, cresol, or P-tertbutylphenol is often used.

The amount of the polycarbonate or polycarbonate oligomer added should be 0.1 to 10 parts by weight, preferably 2 to 5 parts by weight, per 100 parts by weight of the polybutylene terephthalate resin. If it is less than 0.1 part by weight, the effect of improving durability will be small, and if it is more than 10 parts by weight, the crystallinity will be significantly lowered, the solidification rate and rigidity will be significantly lowered, and the transesterification reaction will occur, resulting in poor heat resistance.

The epoxy compound in component (B) is a compound having at least two epoxy groups in the molecule, such as bisphenol A type epoxy compounds obtained by reacting bisphenol A and epichlorohydrin in various ratios, polyalkylene glycols (e.g. Diglycidyl ethers obtained from polytetramethylene glycol, polyethylene glycol) and epichlorohydrin, P
- Glycidyl ether esters derived from hydroxyl amino acids, polyglycidyl esters obtained from polycarboxylic acids and epichlorohydrin, alicyclic compounds (
Examples include alicyclic epoxy compounds obtained from dicyclopentadiene), glycidyl ethers obtained from aliphatic compounds having an alcoholic hydroxyl group (for example, butanediol, glycerin, etc.) and epichlorohydrin, and the like. Preferred examples of these epoxy compounds include bisphenol A type epoxy compounds, (n=0-20) epoxy compounds derived from P-hydroxybenzoic acid, (n=1-20) epoxy of polytetramethylene glycol and polyethylene glycol. It is a compound.

The polycarbodiimide in component (B) is a compound having at least two carbodiimide groups in the molecule, and is usually derived from an isocyanate compound. For example, carbodiimide compounds derived from aromatic diisocyanates such as toluene diisocyanate, methylene bisphenyl diisocyanate, phenylene diisocyanate, and polyisopropylbenzene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate are preferably used.

The amount of the epoxy compound and carbodiimide compound added is 0.1 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, per 100 parts by weight of the polybutylene terephthalate resin.
Parts by weight are preferred. If it is less than 0.1, the effect of improving durability is poor, and if it is more than 15, fluidity decreases, resulting in poor moldability, and the elongation at break and toughness of the molded product are significantly decreased.

Furthermore, in the present invention, the effect can be enhanced in terms of equipment by using a thermoplastic polyester elastomer in combination.

Thermoplastic polyester elastomer (C
) is composed of a hard segment made of aromatic polyesters such as polybutylene terephthalate and polyethylene terephthalate and copolymerized polyesters containing them, and a soft segment made of polyalkylene glycol or polycaprolactone.

The ratio of hard segments to soft segments in the polyester elastomer is preferably 70/30 to 15/85. If it is 70/30 or more, the effect of improving toughness tends to decrease because the content of the low Tg component is small. Moreover, if it is less than 15/85, the affinity with the polybutylene terephthalate resin serving as the matrix component tends to decrease, and the mechanical properties tend to decrease.

In the present invention, the thermoplastic polyester elastomer needs to be added in a relatively small amount, and the amount added is 0.3 to 10 parts by weight, and 2 to 5 Parts by weight are preferred. When it is less than 0.3 parts by weight, the effect of improving toughness and its durability is small, and when it is more than 10 parts by weight, the toughness of the molded product is significantly reduced.

In addition, the composition of the present invention may contain known additives such as antioxidants, ultraviolet absorbers, heat stabilizers, lubricants, mold release agents, nucleating agents, pigments, etc., to the extent that they do not impair the purpose of the present invention. colorant,
One or more of flame retardants, flame retardant aids, antistatic agents, reinforcing agents, and fillers, as well as a small amount of thermoplastic resin and thermosetting! ! One or more types of fat and soft thermoplastic resin can be added.

The method for producing the composition of the present invention is not particularly limited. Necessary additives are added to polybutylene terephthalate resin in predetermined amounts, blended in a blender, and extruded using an extruder to create pellets. You can, but
It can also be produced by extrusion in two or more stages, in which a part of the additives is mixed in advance and extruded, then the remaining components are added and extrusion is performed again. Certain components can also be added during molding.

The composition produced by the above method can be molded using an injection molding machine. Because the composition of the present invention has excellent fluidity, it can be molded into a shape with a thin wall part of one inch or less, and the molded product has an extremely small decrease in physical properties even after being exposed to a high-temperature environment for a long time. has.

[Example] Examples 1 to 6 Commercially available bisphenol A polycarbonate oligomer ('tjL degree 7) (substance (a)) and bisphenol A type jepoxy compound (oil shell epoxy - Epicoat 828) or polycarbodiimide (Hiraizumi Yoko ■
Stavaxol P) (substance (b)) was added to the extruder for 25 minutes.
Melt and knead at 0°C and then use an injection molding machine to
C1 water-cooled mold (20°C) with a thickness of 111II JIS-
A No. 2 dumbbell was molded. Molding pressure is lower limit pressure + 5kg/
It was set as C1'12.

The obtained molded product was heat-treated in a gear oven at 150°C, and the physical properties thereof were measured (Table 1). The strength maintains the original value of polybutylene terephthalate resin. 50
The elongation at break after 0 hours of heat treatment is clearly higher than that of the case where the polycarbonate oligomer is not used in combination with epoxy or polycarbodiimide, and both break after necking and exhibit toughness. There is.

Comparative Examples 1 to 6 Similar to Examples 1 to 6, one in which one of the substances (a) to (b) is not added, and one in which all substances (a) to (b) are added, but the amount added is Examples of those that are not within the desired range are shown in Table 1. Heat treatment and physical property measurements were performed under the same conditions as in the examples.

As is clear from the comparison with Examples 1 to 6, the elongation at break after heat treatment is lower. In addition, all of them undergo brittle fracture without necking, and do not have toughness. Comparative Example 5, in which a large amount of epoxy was added, had a high minimum molding pressure and poor tensile strength.

Examples 7 to 14 Commercially available bisphenol A polycarbonate oligomer (substance (a)) or bisphenol A polycarbonate (Mitsubishi Gas Chemical ■ "Nipilon S-3000") was added to polybutylene terephthalate with a relative viscosity of ηr-1.47. )
and bisphenol A-type jepoxy compound (oiled shell epoxy ■Epico-871) or polycarbodiimide (Hiraito Yoko ■Stavaxol P) ((b)-substance), terephthalta 70mol1%, isophthalic acid 30
Table 2 shows an example of a thermoplastic polyester elastomer (substance (C)) containing 40.60% by weight of a hard segment consisting of m01% and a soft segment consisting of polytetramethylene glycol at 40.60% by weight. The heat treatment and physical property measurements were carried out under the same conditions as in Examples 1 to 6.

As is clear from the table, the elongation at break was significantly improved by adding the polyester elastomer, and remained at 100% or more even after 500 hours. Although the strength is slightly lower than when no polyester elastomer is added, it remains at a practically sufficient level.

Comparative Examples 7 to 13 Similar to Examples 7 to 14, one to one of the substances (a) to (c) was not added, and all of the substances (a) to (c) were added or not. Examples of amounts not within the desired range are shown in Table 2.

Heat treatment and physical property measurements were performed under the same conditions as in the examples.

When polycarbonate oligomer and epoxy or polycarbodiimide are not used together (Comparative Example 7.8.9.
13), the elongation at break after heat treatment decreased significantly, 250-5
After 00 hours, the toughness is lost and brittle fracture occurs.

Furthermore, if the amount of polycarbonate oligomer, epoxy, or polycarbodiimide added is outside the range of the present invention, the strength or fluidity will decrease.

[Effects of the Invention] 10 The present invention provides a molded product that can maintain toughness without impairing the excellent moldability and rigidity inherent to polybutylene terephthalate resin, and that exhibits extremely little decrease in toughness even when exposed to high-temperature atmospheres. This effect is particularly noticeable in so-called natural grades that are not reinforced with glass fibers or the like, and is extremely advantageous for molded products having thin parts such as hinge parts with a thickness of 1 mm or less.

2. The present invention can be used for wire harness connectors, various connectors, sockets, relays, various housings, cord caps, etc., and is particularly preferably used for wire harness connectors.

When the molded product of the present invention is applied to parts exposed to high temperatures for a long period of time, such as automobile parts in the engine compartment, it can maintain high toughness and good mechanical properties for a long period of time, increasing reliability.

Claims (3)

[Claims] (1) For 100 parts by weight of polybutylene terephthalate resin, (A) 0.1 to 10 parts by weight of bisphenol A polycarbonate or its oligomer (B) An epoxy compound having at least two epoxy groups in the molecule, or at least one polycarbodiimide having at least two carbodiimide groups in
A polybutylene terephthalate resin composition containing 0.1 to 5 parts by weight of seeds. (2) For 100 parts by weight of polybutylene terephthalate resin, (A) 0.1 to 10 parts by weight of bisphenol A polycarbonate or its oligomer (B) An epoxy compound having at least two epoxy groups in the molecule, or at least one polycarbodiimide having at least two carbodiimide groups in
Seed: 0.1-5 parts by weight (C) Thermoplastic polyester elastomer: 0.3-10
A polybutylene terephthalate resin composition containing parts by weight. (3) An injection molded article formed by molding the polybutylene terephthalate resin composition according to claim (1) or (2), and having at least a partially thin portion with a thickness of 1 mm or less.