KR20030047347A - Polyester resin composition - Google Patents

Abstract

PURPOSE: A polyester resin composition is provided, which is improved in the flexibility with increasing the maintenance ratio of an insulation breakdown voltage and is useful as the simple and complex product requiring the hydrolysis resistance. CONSTITUTION: The polyester resin composition comprises 100 parts by weight of a polyester resin represented by -£-C(O)-Ar-C(O)-O-(CH2)m-O-|n-; 1-20 parts by weight of a polycarbonate resin represented by the formula 2; 3-10 parts by weight of a polyester elastomer; and 10-30 parts by weight of a low molecular weight polyester resin having an intrinsic viscosity of 0.8-0.9, wherein Ar is a benzene ring; n is an integer of 50-300; m is an integer of 2-4; and R1 to R10 are the same or different each another and are H, CH3, C2H5, NH2 or OH.

Description

Polyester resin composition

The present invention relates to a polyester resin composition, more specifically, a polybutylene terephthalate as a main component and can minimize the degradation of the electrical properties and fluidity caused by hydrolysis can be used for a long time for electrical use The present invention relates to a polyester resin composition which is very suitable as a material for electric and electronic parts such as switches and focus packs and automotive parts such as spark plugs.

Polyester resins are engineering plastics having a relatively high degree of crystallinity, relatively excellent mechanical properties and heat resistance, and excellent dimensional stability against changes in temperature. It has a low water absorption and can be used for a relatively long time even under high humidity. It has excellent chemical resistance and chemical resistance, and is beautifully used for various purposes. In addition, because of the fast crystallization speed, the cycle time can be reduced, and the productivity is excellent, and the flowability is excellent, so it is easy to inject complex shaped products or small products.

Among the polyester resins, polybutylene terephthalate (hereinafter referred to as 'PBT') has a particularly low volume resistance, and has excellent electrical properties such as dielectric breakdown strength, arc resistance, and CTI, compared to other engineering plastics. It is a resin that is widely used as an electric and electronic use because of its good properties.

PBT as an electric and electronic material has been widely applied to lighting devices such as connectors, capacitors, switches, and the like, and its range of applications is continuously expanded to require high electrical characteristics such as focus packs and spark plugs. It is also used as a vehicle material.

PBT is suitable for being used as an electrical and electronic material because of its excellent electrical properties and low water absorption. However, PBT is degraded when used for a long time in a high temperature and high humidity environment, resulting in deterioration of physical properties and electrical properties.

As electrical and electronic devices have been gradually developed and their use has been fortunate, it has become necessary to have excellent electrical properties for a long time under more severe conditions and higher operating voltages.

In general, when a voltage is applied to a plastic material, a negative electrode is generated based on the movement of charged particles such as ions and electrons present in the material and the displacement of electrons, atoms, dipoles, and the like, which are structural units of the plastic. The movement of charged particles is known as electrical conduction, and the formation of negative electrode is known as dielectric phenomenon. When the voltage becomes very high, the electrical conductivity increases rapidly and insulation breakdown occurs.

This dielectric breakdown is common in all plastic materials. The dielectric breakdown voltage of polyester is about 1.5 times that of polyamide (PA) or polycarbonate (PC), which is a relatively high level among plastic materials. It is used in electrical and electronic parts that require breakdown voltage and electrical characteristics.However, when high humidity is encountered at high temperature, hydrolysis occurs, and if hydrolysis occurs, the charged particles in the material can be easily moved. The characteristics are greatly degraded.

It is important to maintain the electrical properties because the polyester-based resin is a material that is widely used for electrical applications, for this purpose, it is necessary to study to prevent hydrolysis.

The pressure cooker test (PCT) is widely used as a method for evaluating hydrolysis characteristics of plastic materials. PCT is designed to evaluate the phenomenon that may occur when plastic is exposed to moisture for a long time.The PCT is put into a pressure cooker at 121 ℃ and 2 atmospheres, and boiled with water vapor to test the physical and electrical properties of the specimen. It's a way to observe change. In the case of dielectric breakdown voltage, if it is maintained more than 50% after the first 100 hours PCT, it can be said that the problem due to hydrolysis does not show much in the use of electric and electronic parts.

In order to give stability to hydrolysis to a polyester resin, it is necessary to lower the content of the terminal carboxyl group, and in order to do so, the method of adding a chain extender generally has several reactors. Substances applied as chain extenders include epoxy compounds and oxazoline compounds.

In particular, Japanese Patent Application Laid-Open No. 55-82148 discloses a method of adding a divalent epoxy such as diglycidyl terephthalate, which shows better hydrolysis characteristics than conventional methods. However, since this method requires the addition of a large amount of epoxy in order to express hydrolysis resistance, there is a disadvantage in that the moldability is very poor due to the deterioration of flowability.

As a method of imparting hydrolysis characteristics without deteriorating flowability and formability, Japanese Patent Application Laid-Open No. 57-87452 proposes a method of adding a monovalent glycidyl ester compound to PBT. This method has the advantage of relatively low degradation of flowability and formability, but since the degradation of electrical properties after PCT is not greatly improved, it is also insufficient for practical application.

In addition, Japanese Patent Application Laid-Open No. 62-285947 proposes a method of adding a mixture of epoxy and rubbery polymers containing a copolymer, which has low flowability during molding and low stability to hydrolysis. Degradation of electrical properties is a major disadvantage.

There have been studies on adding a phenylenebisoxazoline compound as an additive to obtain a chain extension effect. In Japanese Patent Publication No. 50-59525, phenylenebisoxazoline is added to polyester to reduce carboxyl group and molecular weight. Japanese Patent Laid-Open Publication No. 60-161427 proposes a method of adding a quaternary ammonium salt compound to the compound and reacting the same. However, the above methods are limited in preventing the hydrolysis of the polyester, so that the deterioration of electrical properties is also a great disadvantage in a humid environment.

US Patent 4879328 proposes a method of adding an elastomer containing a bivalent epoxy and an epoxy or a carboxyl group to an polyester. This method is somewhat superior in terms of formability, but lacks the maintenance of electrical properties after PCT.

In addition, U.S. Patent No. 5110849 attempted to improve the stability to hydrolysis by adding a metal alcohol salt to the polyester, but also did not exhibit a sufficient level of hydrolysis characteristics.

MEANS TO SOLVE THE PROBLEM This inventor studies the polyester resin composition which minimizes the fall of a flow property, and minimizes the fall of the electrical insulation by hydrolysis, and improves hydrolysis characteristics by mixing an appropriate amount of polycarbonate resin in a polyester resin. Although this method has been proposed, this method has an advantage of satisfying both moldability and hydrolysis characteristics compared to the existing method, but this method also has difficulty in applying to a complicated type of product due to some fluidity deterioration.

Accordingly, an object of the present invention is to provide a polyester resin composition having a flowability such that a problem does not occur during molding while minimizing a decrease in electrical properties due to hydrolysis.

In the research for achieving the above object, the inventors of the present invention, when blending an appropriate amount of polycarbonate, low molecular weight polyethylene terephthalate and polyester elastomer in a high molecular weight polyester resin, the polyester resin composition excellent in both moldability and electrical properties The present invention was completed by discovering that it can be produced.

Therefore, according to the present invention, in the thermoplastic polyester resin composition, 100 parts by weight of the polyester resin of the formula (1) as a main component, 1 to 20 parts by weight of the polycarbonate resin of the formula (2) as an additional component, and 3 to 10 parts by weight of the polyester elastomer 10 to 30 parts by weight of a low molecular polyester resin having an intrinsic viscosity value of 0.8 to 0.9 is provided. The thermoplastic polyester resin composition having less fluidity deterioration due to hydrolysis and excellent fluidity is provided.

-[-C (O) -Ar-C (O) -O- (CH ₂ ) _m -O-] _n-

In Formula 1, Ar is a benzene ring, n is an integer of 50 to 300, m is an integer of 2 to 4.

In Formula 2, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ are the same or different functional groups, H, CH ₃ , C ₂ H ₅ , NH ₂ or OH, and x is an integer of 30 to 300.

Hereinafter, the present invention will be described in more detail.

In the present composition, the main component polyester resin has a structure represented by Chemical Formula 1, and preferred examples thereof include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), or two of them. And mixtures of species or more. Particularly preferred polyester resins of the general formula (1) are polybutylene terephthalate resins.

The polyester resin of Formula 1 can be prepared using conventional methods well known in the art. For example, an acid component, a glycol component, and an additive such as a catalyst and various stabilizers are added to a stainless reaction vessel equipped with a stirrer, and a low molecular weight ester condensation by-product is kept out of the system while maintaining the temperature of the reaction tube at 200 to 230 ° C. At the same time as the removal of the ester reaction proceeds, the conversion rate of the ester reaction is terminated based on the time point when 95% or more of the theoretical effluent of the low molecular weight ester by-product has flowed out. While increasing to 280 ° C., the pressure in the tube is reduced to 1 mm Hg or less to induce condensation polymerization of the polyester. In this way, the polycondensation is carried out, and the reaction is stopped at a suitable stirring load, and the desired main component polyester resin can be prepared by breaking the vacuum as nitrogen and discharging the reactant. The acid component which can be used here can mainly use terephthalic acid or its lower alkyl ester compound alone, or a small amount of isophthalic acid, orthophthalic acid, terephthal or aliphatic dicarboxylic acid, or a mixture with these lower alkyl ester compounds, and is mainly a glycol component. Ethylene glycol, propylene glycol or butylene glycol alone or mixtures thereof, or mixtures with other small amounts of 1.6-nucleic acid diols, 1.4-cyclonucleic acid dimethanol, etc. may be used, and as catalysts, mainly an oxide of antimony or tetrabutyl titanate, The use of organic titanium compounds such as tetraisopropyl titanate and the like is a common method, and other alkali metals, acetate compounds and the like can also be used. In addition, when using organic titanium, magnesium acetate, lithium acetate, etc. can also be used as a cocatalyst. In addition to these components, it is also possible to use subsidiary materials such as antioxidants, antistatic agents and various additives.

The composition contains, as essential additives, a polycarbonate resin of formula (2), a polyester elastomer, and a low molecular polyester resin having an intrinsic viscosity value of 0.8 to 0.9. The addition amount of these additional components should be 1 to 20 parts by weight of polycarbonate resin, 3 to 10 parts by weight of polyester elastomer, and 10 to 30 parts by weight of low molecular polyester resin per 100 parts by weight of the main component polyester resin.

Polycarbonate resin in the present composition is excellent in the reactivity of the end group of the main component polyester resin, by reducing the absolute number of the end group to prevent the movement of the charged particles to improve the hydrolysis characteristics, the reaction is impact resistance It has the effect of improving the physical properties and also improves the electrical insulation by reducing the polarization in the plastic material. When the content is less than 1 part by weight per 100 parts by weight of the main component polyester, the hydrolysis resistance is enhanced. If the effect is insufficient, and more than 20 parts by weight, the electrical properties are very excellent, while the flowability is excessively lowered, the surface is poor, and molding problems occur.

The polyester elastomer provides the surface improvement effect by delaying the crystallization at the same time as the soft segment improves the fluidity of the polyester resin itself and delays the crystallization, and improves mechanical properties such as impact resistance and bending characteristics. When the content is less than 3 parts by weight per 100 parts by weight of the main component polyester, the improvement effect in terms of flowability and physical properties is insufficient, and when more than 20 parts by weight, the compounding conditions are hard (Hard). ), And in hydrolysis resistance, has the adverse effect of sharp decrease after 80 hours of PCT. Particularly preferred examples of the polyester elastomer are thermoplastic polyether ester copolymers having a hard segment of Formula 3 and a soft segment of Formula 4 below.

In Formula 3, D is a radical from which two hydroxy groups are removed from C ₂ to C ₈ saturated aliphatic diols and cyclic diols alone or in a mixture of two or more, and R is an aromatic, aliphatic and cyclic dicarboxylic acid having a molecular weight of 500 or less. It is a radical with two carboxyl groups removed alone or in a mixture of two or more.

In the formula (4), G is a polyether glycol having a molecular weight of 400 to 4000 alone or a mixture of two or more thereof, and two hydroxy groups are removed, and R is an aromatic, aliphatic and cyclic dicarboxylic acid having a molecular weight of 500 or less, or two In the above mixture, two carboxyl groups have been removed.

However, the addition of such polyester elastomer alone has a limit in improving fluidity, which does not reach the level at which complex products can be injected. Therefore, when the polyester elastomer is mixed with the addition of the low molecular polyester, the effect is maximized to satisfy both hydrolysis resistance, mechanical properties and injection properties.

Low molecular polyester resins have an intrinsic viscosity within the range of 0.8 to 0.9, and have excellent fluidity and excellent injection properties compared to medium-weight polyesters used for compounding for general injection purposes, but have lower mechanical properties. . The same method as in the production of the main component polyester described above can be applied to the production of such a low molecular polyester resin.

The polycarbonate resin of Formula 2 may be prepared, for example, by reaction of a bisphenol A-based material with phosgene.

In addition, the polyester elastomer of the formula (3) is a low molecular weight glycol and aromatic diisocyanate component, for example in a conventional polyester reactor, and stirred at 150 ℃ for 30 minutes to terminate the aromatic diisocyanate terminal with an excess of a single glycol After sufficiently reacting, in addition to dicarboxylic acid and polyalkylene oxide glycol, a reaction catalyst and a reaction aid are added thereto, and low molecular weight components such as methanol and water are distilled out about twice as much as the equivalents of acid components while heating to 200-230 ° C. It can be prepared by heating the reactor temperature to 250 ~ 280 ℃ while gradually applying a vacuum to 1mmHg or less, and then stopping the reaction at a suitable stirring load. In this case, the reaction catalyst may be a complex of tinate produced from an ester compound of tetraalkyl titanate, an inorganic titanate compound such as lanthanum titanate, a compound of calcium acetate and antimony trioxide, and the like.

Additives, such as a fibrous or inorganic filler, a heat stabilizer, a lubricating agent, an antistatic agent, a plasticizer, and a nucleating agent, can be suitably mix | blended with this composition in the range which does not impair the objective which concerns on this invention as needed.

Furthermore, the resin composition which concerns on this invention can be manufactured using a conventional twin screw extruder, for example.

The composition of the present invention has a melt index (Melt Index) of 20 or more measured at 250 ℃, the dielectric breakdown voltage of the molded article made of this composition is maintained at 60% or more after 100 hours PCT at 121 ℃, thus In addition to excellent hydrolysis characteristics with very low electrical insulation deterioration, the composition having sufficient formability and physical properties that the product does not cause problems during molding is used for electric and electronic parts that are used for a long time as an electric and material. It is very useful for materials and automobile parts, for example, electric coil bobbins, various connectors, small electric parts such as housings and plugs, switches, and home appliance parts such as focus packs.

Features and other advantages of the present invention as described above will become more apparent from the following examples. However, the present invention is not limited to the following examples, of course.

Hydrolysis resistance and electrical insulation shown in the following Examples and Comparative Examples were tested by the following method.

※ Hydrolysis and Electrical Insulation Test Method: 100 mm diameter and 3.2 mm thick disc specimens are used as measurement specimens.In order to measure the hydrolysis resistance and electrical insulation, ASTM D-149 and The dielectric breakdown strength was measured according to the method specified in DIN53481. PCT for evaluating hydrolysis resistance is carried out by placing the specimen in a normal autoclave, adding distilled water to the extent that the specimen is not locked, and then closing the lid and heating it to 121 ° C. The pressure is maintained at 2 atm when the temperature is raised to 121 ℃. Insulation breakdown strength was used by Beckman PA70 Model. This equipment is supplied with high voltage of 60㎐ when the sample is destroyed by current. Will appear on the screen. The dielectric breakdown strength was measured by taking 5 samples every 25 hours after starting PCT, and the test was performed after the surface moisture was completely removed. In measuring the dielectric breakdown strength, an electrode was used in the form of a plate-cylinder, and the test was performed in an insulating oil. The voltage step-up speed for measuring the dielectric breakdown strength was fixed at 20KV / 10sec, and the breakdown voltage was expressed by dividing the broken voltage by the thickness of the specimen, and the unit was KV / mm.

<Example 1>

100 parts by weight of polybutylene terephthalate (SPESIN KP210 of Kolon Co., Ltd.) as a primary raw material inlet using a twin screw extruder heated to 250 to 265 ° C, and tris- (2.4-dibutyl butyl), a heat-resistant agent, to prevent thermal decomposition Iganox B1171, a one-to-one mixture of phenyl) -phosphite and N-N'-hexamethylene bis (3.5-dibutyl butyl-4-hydroxy-hydrocyanamide) ) Was added 0.15 parts by weight of a mixture, and 3 parts by weight of a polycarbonate resin [PC: outgoing petrochemical products], a polyester elastomer (a ratio of the hard segment and the soft segment was 4: 6 with a D scale hardness of 55). 5 parts by weight of PEL 3355) of Kolon Co., Ltd., 10 parts by weight of low molecular weight polyester (KP200 of Kolon Co., Ltd.), 0.15 parts by weight of a flame retardant [Wujin Polymer CXB-3000H / Ilsung Sb ₂ O ₃ = 12 / 4.5 mixture] 22.2 parts by weight of glass fiber The resin composition was prepared through a hot melt kneading process while feeding into the secondary inlet.

The prepared resin was dried using a dehumidifying dryer for 5 hours at 130 ° C., and then the flowability of the resin was evaluated by a melt index. Also, a screw injection machine heated to 240 to 265 ° C. was manufactured to prepare original test specimens. After the PCT, the breakdown voltage was evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, both functionality and moldability were satisfactory.

<Examples 2-3

The same procedure as in Example 1 was repeated except for changing the content of the composition as shown in Table 1 below. The melt index of each case and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, both functionality and moldability were satisfactory.

Comparative Example 1

The same procedure as in Example 1 was repeated except that no polycarbonate resin, polyester elastomer and low molecular weight polyester were combined. The melt index of this example and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, it was applicable to general molded products that do not require high functionality.

Comparative Example 2

The same procedure as in Comparative Example 1 was repeated except that 0.8 parts by weight of oxazoline was added. The melt index of this example and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, it was found that there is almost no effect on improving hydrolysis resistance.

Comparative Example 3

The same procedure as in Comparative Example 1 was repeated except that 3 parts by weight of a hexavalent epoxy resin (Kukdo Chemical YDCN 800) was added. The melt index of this example and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, it was impossible to apply the product due to the reduced flow.

<Comparative Example 4>

The same procedure as in Example 1 was repeated except that no polyester elastomer and low molecular weight polyester were combined. The melt index of this example and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, the applicability of the actual product was evaluated, and the level was applicable to the uncomplicated functional product.

Comparative Example 5

The same procedure as in Example 2 was repeated except that no low molecular weight polyester was incorporated. The melt index of this example and the dielectric breakdown voltage after PCT were evaluated, and the results are shown in Table 1. In addition, as a result of evaluating the applicability of the actual product, it was found that the surface was somewhat rough due to the slight deterioration in flowability.

division Example Comparative example One 2 3 One 2 3 4 5 Composition (part by weight) KP210 100 100 100 100 100 100 100 100 Flame retardant 24.2 24.2 24.2 24.2 24.2 24.2 22.2 22.2 PC 3 3 3 - - - 3 3 PEL 3355 5 10 10 - - - - 10 KP200 10 10 20 - - - - - 7 gaepoxy - - - - - 3 - - Oxazoline - - - - 0.8 - - - Heat-resistant 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Fiberglass 22.2 22.2 22.2 22.2 22.2 22.2 22.2 22.2 Insulation breakdown voltage according to PCT time (KV / ㎜) 0 hours 17.4 17.5 17.2 17.6 16.5 17.5 17.5 17.5 25 hours 17.2 17.4 17.0 17.5 15.2 17.5 17.5 17.5 50 hours 16.9 16.8 16.7 13.5 13.1 17.1 17.1 17.2 75 hours 16.2 16.8 16.1 10.1 10.6 16.8 16.8 16.1 100 hours 15.1 15.0 14.8 8.0 8.1 16.4 16.4 15.5 125 hours 14.5 14.1 14.0 5.2 5.4 15.1 14.2 14.1 150 hours 11.1 11.2 10.2 5.0 5.6 12.4 10.4 11.5 MeltIndex g / 10 min (250 ° C) 20.1 22.1 25.9 20.1 18.4 9.1 14.1 18.1

As can be seen from the results in Table 1, the conventional method of adding an oxazoline-based compound to enhance the hydrolysis characteristics of the polyester resin (Comparative Example 2) has little effect on improving hydrolysis resistance, and epoxy The conventional method of adding a resin (Comparative Example 3) is extremely poor in flowability to apply the product, and the comparative examples 4 and 5 in which only polycarbonate is added are poor in flowability to be applied to complex molded products. Although there is a limit, in Examples 1 to 3 to which polycarbonate, polyester elastomer and low molecular polyester are added according to the present invention, as well as exhibit the required level of hydrolysis characteristics, there are some enhancement effects in terms of physical properties. In addition, the flowability is higher than that of the general grade as well as the hydrolysis grade, which is a problem in forming. It does not occur, it is possible to obtain an excellent surface. The melt index of the compositions of Examples 1 to 3 and the dielectric breakdown voltage of the specimens molded from this composition are superior to the electrical and molding conditions of general electrical and electronic materials.

Claims (2)

In the thermoplastic polyester resin composition, 100 parts by weight of a polyester resin of formula (1) as a main component, 1 to 20 parts by weight of polycarbonate resin of formula (2), 3 to 10 parts by weight of polyester elastomer, and intrinsic viscosity as essential components A polyester resin composition comprising 10 to 30 parts by weight of a low molecular polyester resin having a value of 0.8 to 0.9: [Formula 1] -[-C (O) -Ar-C (O) -O- (CH ₂ ) _m -O-] _n- [Formula 2] The melt composition according to claim 1, wherein the resin composition has a Melt Index of at least 20 g / 10 minutes, and the breakdown voltage of a molded article made of the composition is 60% after 100 hours of PCT at 121 ° C. The thermoplastic polyester resin composition which is maintained above.