KR100919135B1 - Polyester resins composition - Google Patents

Abstract

The present invention relates to a polyester resin composition, more specifically, the initial tensile strength of 1100 to 1300 kg / cm ² ; Initial impact strength of 18 to 23 kg.cm/cm; Based on the Temperature / Humidity Cycling Test (USCAR) CLASS-III standard) Results Polyester polyester resins with tensile strength over 80% and impact strength over 60% It relates to a composition.

The polyester resin composition of the present invention is excellent in resistance to high temperature and high humidity environment, and is very suitable for application to automobile engine parts requiring excellent high heat resistance and long-term heat and humidity characteristics.

Polyester, Polybutylene Terephthalate, Polycarbonate, Automotive, ISA

Description

Polyester resin composition {POLYESTER RESINS COMPOSITION}

1 is a graph of temperature / time conditions according to the USCAR CLASS-III method.

2 is a humidity / time condition graph according to the USCAR CLASS-III method.

[Industrial use]

The present invention relates to a polyester resin composition, and more particularly, to a polyester resin composition having excellent long-term heat and humidity characteristics.

[Private Technology]

As the development trend of automobiles is developed as hybrid cars and electric vehicles through long-term heat resistance, modularization, intelligence, and sensitivity, long-term heat resistance and long-term heat and humidity characteristics of electric components are required. In addition, as the warranty period increases during the development of auto parts, these requirements must be satisfied in the development of parts.

Among the automotive parts, polyester resins are used for electrical parts such as sensors, and engine parts that require long-term heat and long-term heat / humidity characteristics around the engine.In addition, initial tensile strength and impact are applied to areas where mechanical rigidity is required. This mechanical property must be satisfied because the strength must be sufficiently satisfied to satisfy the metal replacement or the weight reduction.

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

Among the polyesters, polybutylene terephthalate (PBT) has a particularly low volume resistance and electrical properties such as dielectric breakdown strength, arc resistance, and CTI are relatively superior to other engineering plastics. In particular, it is widely used for automotive engine parts and automotive wire-harness parts.

In addition, PBT as an electrical and electronic material is widely applied to lighting devices such as connectors, capacitors, switches, etc., and its application range 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 due to its excellent electrical properties and low water absorption rate, but is also degraded when used for a long time in a high temperature and high humidity environment, resulting in degradation of mechanical properties and electrical properties. However, as electric and electronic components are gradually developed and diversified in their use in automobile parts, mechanical properties that can maintain electrical properties for a long time under more severe conditions and higher operating voltages are required.

In general, when a voltage is applied to a plastic material, polarization 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 former is known as the electrical conduction phenomenon, the latter is known as the dielectric phenomenon. When the voltage becomes very high, the electrical conductivity increases rapidly, resulting in breakdown of the insulation due to the deterioration of mechanical properties.

This breakdown phenomenon is common in all plastic materials. The breakdown voltage of polyester is about 1.5 times that of polyamide or polycarbonate, which is quite high among plastic materials. Therefore, although it is used in electric and electronic parts that require high dielectric breakdown voltage and electrical characteristics, when the high humidity is encountered at high temperature, hydrolysis phenomenon that mechanical properties due to resonance, which is a characteristic of polyester resin, is significantly lowered than the initial stage occurs. .

In particular, it is important that polyester resins have a small mechanical property deterioration to maintain electrical properties because they are used in automotive electronic parts. Therefore, research for preventing property deterioration by hydrolysis is essential.

In order to give the polyester resin stability against hydrolysis, which is a long-term heat-resistant temperature-humidity property, it is necessary to lower the content of the terminal carboxyl group. come. Substances used as chain extenders include epoxy compounds and oxazoline compounds.

In the prior art, Japanese Patent Application Laid-Open No. 55-82148 discloses a method of adding a divalent epoxy such as diglycidyl terephthalate as a chain extender to provide a long-term heat and temperature resistance that is superior to conventional methods. Showed hydrolysis characteristics. However, since this method requires the addition of a large amount of epoxy to express hydrolysis resistance, there is a disadvantage in that the flowability during molding decreases and the moldability is poor.

Japanese Patent Application Laid-Open No. 57-87452 has the advantage of relatively low flowability and moldability by adding monovalent glycidyl ester compound to PBT, but the disadvantage of inferior hydrolysis property, which is long-term heat and humidity characteristic. have.

In addition, Japanese Patent Application Laid-Open No. 62-285947 proposed a method of adding a mixture of epoxy and rubbery polymer containing a copolymer, but this method also has disadvantages in that the flowability during molding and the stability to hydrolysis are low.

In addition, a study was conducted on adding a phenylenebisoxazoline compound as an additive to obtain a chain extension effect. Japanese Patent Laid-Open No. 50-59525 describes the addition of phenylenebisoxazoline to polyester to reduce carboxyl groups. Japanese Patent Laid-Open Publication No. 60-161427 proposes a method of adding a quaternary ammonium salt compound to the compound and reacts it. It has a disadvantage in that the hydrolysis property, which is heat and temperature resistant, is inferior.

U.S. Patent No. 4,879,328 proposes a method of adding an elastomer containing a divalent epoxy and an epoxy or a carboxyl group to a polyester, but it is somewhat superior in terms of moldability, but has a disadvantage in that the hydrolysis property, which is a long-term heat-resistant / humidity property, is inferior. . In addition, U.S. Patent No. 5,110,849 attempted to improve the stability against hydrolysis by adding a metal alcohol salt to polyethylene terephthalate, but did not express a sufficient level of hydrolysis property, which is a long-term heat-resistant temperature-humidity characteristic.

The present invention is to solve the above problems, an object of the present invention is the idle speed actuator for controlling the various ignition coil cases, idle speed of the engine part of the vehicle that requires long-term heat resistance and long-term heat and humidity characteristics (Idle Speed It is an object of the present invention to provide a polyester resin composition having excellent long-term heat and humidity characteristics by minimizing a decrease in physical properties due to hydrolysis so as to be used in an Actuator, ISA), a wire harness connection for an automobile, and the like.

The present invention to achieve the above object, the initial tensile strength 1100 to 1300 kg / cm ² ; Initial impact strength of 18 to 23 kg.cm/cm; Based on the Temperature / Humidity Cycling Test (USCAR) CLASS-III standard) Results Polyester polyester resins with tensile strength over 80% and impact strength over 60% To provide a composition.

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

The present invention relates to a polyester resin composition, and more specifically, polybutylene terephthalate (hereinafter referred to as PBT) as a main component, and supplements the characteristics particularly susceptible to hydrolysis, and parts around automobile engines The present invention relates to a polyester resin composition having excellent long-term thermal and heat-resistant temperature-humidity properties even at a high temperature and high humidity atmosphere that can be used for a wire-harness connector.

In particular, the polyester resin composition of the present invention has an initial tensile strength of 1100 to 1300 kg / cm ² ; Initial impact strength of 18 to 23 kg.cm/cm; Based on the Temperature / Humidity Cycling Test method according to the USCAR CLASS-III standard, the tensile strength property is over 80% compared to the initial stage, and the impact strength property is over 60% compared to the initial stage. do.

The most widely used method for evaluating the hydrolysis characteristics of plastic materials is the temperature / humidity cycle evaluation (Temperature / Humidity Cycling) among the USCAR CLASS standards set by PCT (Pressure Cooker Test) and three American automobiles, namely, Ford, GM and DaimlerChrysler. Test, hereinafter THCT) method.

The PCT method is a method designed to evaluate the phenomenon that may occur when the plastic is exposed to moisture for a long time in a short time to put the specimen in a pressure cooker of 121 ℃, 2 atm and boiled with steam, the change of the physical properties and electrical properties of the specimen In the case of dielectric breakdown voltage, it is generally judged that the problem due to hydrolysis does not appear significantly in the use of electric and electronic parts if it is maintained more than 50% after the initial 100 hours of PCT.

In addition, the temperature / humidity cycle evaluation (THCT) in the USCAR CLASS standard is evaluated by the USCAR CLASS-III standard, which is a high temperature and humidity in electronic components. The temperature range is -40 ℃ ~ + 125 ℃, and 8 hours is 1 cycle under the relative humidity of 0 ~ 95%. After 40 cycles, the property retention rate is compared to the initial physical properties. It is judged that the hydrolysis characteristics are excellent when the abnormality is maintained. In the case of the impact strength retention rate, it is judged that the hydrolysis property is excellent when the temperature is maintained at 60% or more due to the properties related to thermal shock due to heat between low and high temperatures.

 Since the condition of the engine part of the automotive parts high temperature and high humidity is evaluated above the USCAR CLASS-III standard evaluation, the present invention used THTC according to the USCAR CLASS-III standard.

The polyester resin composition of the present invention satisfying the above physical properties includes a PBT resin as a main component, and the intrinsic viscosity of the PBT resin may be 0.8 to 1.4 dL / g. When the intrinsic viscosity is 0.8 dL / g or more, suitable properties for industrial use can be exhibited, and an intrinsic viscosity of 1.4 dL / g or less is easy for molding processing.

The polyester resin composition of this invention which satisfy | fills the said physical property contains a polycarbonate resin with PBT.

Ester bond (-O-CO-) of PBT has good resonance structure, so that the molecular bond is broken easily by acid or alkali, and hydrolysis occurs, especially in high temperature and humidity environment where heat and humidity are generated at the same time. This facilitates the increase of the end group due to hydrolysis, thereby reducing the mechanical properties and the movement of the charged particles, leading to a decrease in the electrical properties, in particular the breakdown strength.

On the other hand, the polycarbonate resin is excellent in reactivity with the end groups of PBT to reduce the absolute number of end groups in a high temperature and high humidity environment to prevent the movement of charged particles, thereby maintaining the mechanical properties of the resin composition It is effective and also the mixing of such polycarbonate resin serves to reduce the polarization in the plastic material to maintain electrical properties. That is, the addition of the polycarbonate resin, which is an amorphous resin, has a physical property effect of impact resistance to compensate for the electrical and mechanical properties of the entire polyester resin composition.

As such, the polycarbonate serves to complement the hydrolysis characteristics of the PBT resin while minimizing the deterioration in flowability of the entire resin composition. In particular, the polycarbonate resin content added in order to supplement the long-term heat and humidity characteristics and impact resistance of the polyester resin should be 10 parts by weight or more relative to 100 parts by weight of PBT. The impact strength retention can be maintained at 60% or more, and should be included at 15 parts by weight or less to obtain mechanical properties that meet the object of the present invention without losing compatibility with PBT and polycarbonate.

In addition, the polycarbonate resin preferably has a weight average molecular weight of 20,000 to 35,000, but is not necessarily limited thereto.

The polyester resin composition may further include 1.5 to 3.0 parts by weight of a phosphorus heat resistant agent based on 100 parts by weight of the PBT. The phosphorus heat resistant agent has an effect of maintaining mechanical properties by having heat resistance and long-term heat resistance of the polyester resin. In particular, when the content of the phosphorus-based heat resistant agent is 1.5 parts by weight or more based on 100 parts by weight of PBT may exhibit an effect of improving the long-term heat resistance, when included in excess of 3.0 parts by weight is less than the effect of increasing the content. However, the content range is only a range for showing the desired effect, the present invention is not limited only to the above range.

The phosphorus heat resistant agent may be selected from at least one of various kinds of phosphorus heat resistant agents generally known, but in the present invention, it is preferable to include a phosphorus heat resistant agent represented by the following Chemical Formula 1.

[Formula 1]

Where

R ¹ is a methyl group, R ² and R ³ are the same or different substituents selected from the group consisting of alkyl groups having 1 to 5 carbon atoms.

The polyester resin composition of the present invention may further include a copolymer represented by the following formula (2).

[Formula 2]

Wherein R is a hydrogen atom, an alkyl group or an aryl group, and x and y are each independently an integer of 2-50.

The copolymer of Formula 2 is added to improve the impact strength characteristics of the polyester resin composition, when included in more than 10 parts by weight based on PBT 100 parts by weight is excellent in improving the impact strength retention rate, the initial strength strength And 20 parts by weight or less in terms of tensile strength retention. In addition, the copolymer of Formula 2 may be included in 13 to 17 parts by weight based on 100 parts by weight of PBT.

Specific examples of the copolymer of Chemical Formula 2 include a random ethylene-methylacrylate-glycidyl methacrylate terpolymer (hereinafter, referred to as 'EMG'), but are not necessarily limited thereto.

The polyester resin composition of the present invention may also further comprise glass fibers depending on the use used. The glass fiber serves to increase the stiffness, particularly in the mechanical properties of the polyester resin composition, in terms of the effect of improving the initial tensile strength and impact strength may be included in more than 50 parts by weight based on the PBT 100 parts by weight, the tensile strength of the initial physical properties It may be included in an amount of 60 parts by weight or less in order to prevent degradation, surface condition during molding and degradation of flowability.

In addition, the polyester resin composition of the present invention may further include a heat stabilizer, a lubricant and the like according to the required properties, preferably from 0.1 to 0.3 of the hindered phenol (Hindered phenol) system based on 100 parts by weight of PBT It may further comprise 0.1 parts by weight, 0.1 to 0.7 parts by weight of a stearate-based lubricant, or both.

The thermal stabilizer improves the thermal stability of the polyester resin composition, in particular serves as an antioxidant. Representative examples of the hindered phenol-based heat stabilizer is Iganox 1010 of Shivagai Co., Inc. In addition, all of the similar type of heat stabilizer may be used in the present invention.

In addition, the lubricant serves to increase the flowability of the polyester resin and the releasability to the mold after molding. Representative examples of the stearate-based lubricants include ethylene bis stearamide, and in addition, all similar types of lubricants may be used in the present invention.

The polyester resin composition of the present invention may be prepared according to a conventional method of melting, kneading and extruding by selecting the components and contents described above, wherein the extrusion temperature may be 230 to 280 ℃, but is not limited thereto. It doesn't happen.

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Example 1

12 parts by weight of polycarbonate resin, random ethylene-methylacrylate-glycidyl methacryl, based on 100 parts by weight of PBT (Kolon's SPESIN KP210) resin as a primary raw material inlet using a twin screw extruder heated to 260 to 280 ° C. 15 parts by weight of ternary terpolymer, bis (2,6-di-ter-butyl-1-methylphenyl) pentaerythritol-di-phosphate, a phosphorus heat-resistant compound used as a heat-resistant [Bis-2,6-di-ter- butyl-1-methylphenyl] pentaerythritol-di-phospate] 2.0 parts by weight, 0.2 parts by weight of Iganox 1010 (Shibagai Co., Ltd.), a heat-resistant agent, 0.3 parts by weight of ethylene-bis-stearic acid, and 100 parts by weight of the PBT resin 55.0 parts by weight of glass fiber (glass fiber) was introduced into the secondary inlet located in the middle of the cylinder, and the resin composition was prepared in the form of a chip through a hot melt kneading process.

The prepared chip was dried at 110 ° C. for 5 hours using a dehumidifying dryer, and then a test specimen for ASTM standard evaluation was produced using a screw injection machine heated at 260 ° C. to 280 ° C.

Examples 2 to 3 and Comparative Examples 1 to 6

The same as in Example 1 except that the content of the polycarbonate resin, random ethylene-methylacrylate-glycidyl methacrylate terpolymer, and the phosphorus heat-resistant compound with respect to 100 parts by weight of the PBT resin was changed as shown in Table 1 The polyester resin composition and the test piece for ASTM specification evaluation were produced from this by the conditions and the method.

Table 1

                                            [Unit: parts by weight]

division A B C D Example 1 100 12 15 2.0 Example 2 100 10 19 2.5 Example 3 100 15 12 1.6 Comparative Example 1 100 7 14 2.0 Comparative Example 2 100 12 7 2.0 Comparative Example 3 100 7 7 2.0 Comparative Example 4 100 16 25 2.0 Comparative Example 5 100 12 14 1.0 Comparative Example 6 100 12 14 5.0

A: polybutylene terephthalate resin

B: polycarbonate resin

C: random ethylene-methylacrylate-glycidyl methacrylate terpolymer

D: Sodium 2,2-methylene bis- (4,6-di-tert -butyl phenyl) phosphate)

The long-term heat-resistant temperature and humidity characteristics of the test specimens for ASTM standard evaluation prepared according to Examples 1 to 3 and Comparative Examples 1 to 6 were measured according to the following evaluation method, and the results are shown in Table 2.

* Long-term heat and humidity test method

The test was conducted according to the USCAR CLASS-III method.

1 is a graph of temperature / time conditions according to the USCAR CLASS-III method, Figure 2 is a graph of humidity / time conditions according to the USCAR CLASS-III method.

In the USCAR CLASS-III method, when one cycle is a condition that simultaneously satisfies the temperature and humidity conditions of the graphs shown in FIGS. 1 and 2, the property retention rate after 40 cycles, that is, 40 cycles compared to the initial tensile strength and impact strength After the tensile strength and impact strength retention was measured.

* Tensile and impact measurement

Tensile Strength and Tensile Elongation: Measured according to ASTM-D-638

Izod Impact Strength: measured according to ASTM-D-256

TABLE 2

Initial tensile strength Tensile Strength after THCT 40 Cycle Evaluation Tensile Strength Retention Rate (%) Initial impact strength Impact strength after THCT 40Cycle evaluation Impact Strength Retention Rate (%) Remarks Example 1 1190 1047 88 20 14 70 Example 2 1120 952 85 22 14 65 Example 3 1250 1037 83 18 11.5 63 Comparative Example 1 1150 747 65 15 5 50 Comparative Example 2 1350 1080 80 10 4.5 45 Comparative Example 3 1320 750 50 8 2.0 25 Comparative Example 4 910 746 82 32 22.7 71 Mold Release Problems in Molding Comparative Example 5 1185 770 65 18 9 50 Comparative Example 6 1180 1062 90 18 13 72

※ Unit: Tensile Strength (Kg / cm ² ), Impact Strength (Kg.cm/cm)

As shown in Table 2, it can be confirmed that the polyester resin composition according to Examples 1 to 3 has excellent long-term heat and humidity characteristics, and requires long-term heat and humidity characteristics such as automotive engine parts, automotive wire-harness parts, etc. It can be seen that it is very preferable to be used as the material of the part.

On the other hand, it can be seen that the polyester resin composition of the comparative example outside the content range of the present invention is not satisfactory in the tensile strength, impact strength characteristics, and long-term heat and humidity characteristics by promoting hydrolysis after THCT 40 Cycle evaluation.

 The polyester resin composition of the present invention is excellent in resistance to high temperature and high humidity environment, and is very suitable for application to automobile engine parts requiring excellent high heat resistance and long-term heat and humidity characteristics.

Claims (9)

Polybutylene terephthalate; Polycarbonate; Phosphorus heat resistant agent; Random ethylene-methylacrylate-glycidylmethacrylate terpolymers; And Polyester resin composition containing a glass fiber. The method of claim 1, Polyester resin composition comprising 10 to 15 parts by weight of the polycarbonate relative to 100 parts by weight of the polybutylene terephthalate. The method of claim 1, Polyester resin composition comprising 1.5 to 3.0 parts by weight of the phosphorus heat-resistant agent based on 100 parts by weight of the polybutylene terephthalate. The method of claim 1, The phosphorus heat resistant agent is a polyester resin composition represented by the following formula (1): [Formula 1]

Where R ¹ is a methyl group, R ² and R ³ are the same or different substituents selected from the group consisting of alkyl groups having 1 to 5 carbon atoms. The method of claim 1, A polyester resin composition comprising 10 to 20 parts by weight of the random ethylene-methylacrylate-glycidyl methacrylate terpolymer with respect to 100 parts by weight of the polybutylene terephthalate. The method of claim 1, Polyester resin composition comprising 50 to 60 parts by weight of the glass fiber with respect to 100 parts by weight of the polybutylene terephthalate. The method according to any one of claims 1 to 6, The polyester resin composition further comprises 0.1 to 0.3 parts by weight of the heat stabilizer of the hindered phenol (Hindered phenol) based on 100 parts by weight of the polybutylene terephthalate. The method according to any one of claims 1 to 6, A polyester resin composition further comprising 0.1 to 0.7 parts by weight of a stearate-based lubricant based on 100 parts by weight of the polybutyrene terephthalate. The method according to any one of claims 1 to 6, Initial tensile strength between 1100 and 1300 kg / cm 2; Initial impact strength of 18 to 23 kg.cm/cm; Based on the Temperature / Humidity Cycling Test method according to the USCAR CLASS-III standard) Result Tensile strength properties over 80% of the initial value; And Polyester resin composition having an impact strength of 60% or more compared to the initial stage.

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