KR100839530B1 - High Viscosity Polybutylene Terephthalate Resin - Google Patents

Abstract

The present invention provides a high-viscosity polybutylene terephthalate resin which is particularly useful for various component materials in the electrical and electronic fields due to its excellent hydrolysis and electrical insulation properties and less deterioration of electrical properties even under high temperature and humidity conditions and high voltage.

The polybutylene terephthalate resin of the present invention has a load of 2160 g and a melt flow index (Melt Flow Index) of 6 to 15 g / 10 min at a temperature of 250 ° C., and has a temperature of 121 ° C. and a pressure of 2 atm. The breakdown voltage and the tensile strength retention after the hydrolysis test (Pressure Cooker Test) for 100 hours in the pressure cooker is characterized by more than 90% of the initial breakdown voltage and the tensile strength retention.

Polybutylene terephthalate, hydrolysis resistance, electrical insulation, high viscosity, solid phase polymerization.

Description

High viscosity polybuthyleneterephthyalate resin

The present invention relates to a high viscosity polybutylene terephthalate (hereinafter abbreviated as "PBT") resin having excellent heat resistance and hydrolysis resistance, and in particular, even under high temperature and high humidity conditions, material degradation such as material stiffness and elastic modulus is almost reduced. It is about missing PBT resin

Hydrolysis test of 100 hours in a pressure cooker with a load of 2160 g and a melt flow index at a temperature of 250 ° C. of 6 to 15 g / 10 minutes and a temperature of 121 ° C. and a pressure of 2 atm. The dielectric breakdown voltage and the tensile strength retention after the cooker test are each 90% or more of the initial dielectric breakdown voltage and the tensile strength retention.

In general, PBT resin is excellent in heat resistance, chemical resistance, electrical properties, mechanical strength and molding processability and is widely used in automobiles, electrical, electronic components and the like. PBT resins are particularly widely used for electrical and electronic applications because they have a low volume resistance and are superior to other engineering plastics in electrical properties such as dielectric breakdown strength and arc resistance. It is widely applied to small electric parts such as connectors, capacitors and switches, and parts of home appliances such as focus packs, and cases of lighting devices such as fluorescent lamps and perk balls. Increasingly, it is also used as a vehicle material requiring high electrical characteristics such as a spark plug.

However, in the high temperature and high humidity environment, the ester bond is hydrolyzed by water to promote the hydrolysis very rapidly. As a result, the molecular weight of the resin decreases, so that mechanical properties such as strength, elongation, elastic modulus, impact strength, etc. are drastically decreased, and electrical properties such as dielectric breakdown voltage and arc resistance are also reduced.

Therefore, in order to solve such a problem, a method of reducing the end group using a special additive to the PBT resin or blending with other resins is generally used.

In general, when a voltage is applied to a plastic material, polarization is generated based on the movement of charged particles such as ions or electrons present in the material and the displacement of electrons, atoms, dipoles, etc., which are plastic constituent units. 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 conduction increases rapidly and the dielectric breakdown phenomenon occurs.

This dielectric breakdown is common in all plastic materials. The dielectric breakdown voltage of polyester is about 1.5 times that of polyamide or polycarbonate, which is a relatively high level of plastic materials. Therefore, electricity requiring high breakdown voltage and electrical characteristics. Although used in electronic components, hydrolysis occurs when high humidity is encountered at high temperatures. If hydrolysis occurs, the movement of charged particles in the material is facilitated and the electrical properties are greatly degraded. Since polyester resin is a material that is widely used especially for electrical use, it is important to maintain electrical properties, and for this, research to prevent hydrolysis may be essential.

A widely used method of evaluating the hydrolysis characteristics of plastic materials is the Press Cooker Test (hereinafter referred to as "PCT"). This method is designed to evaluate the phenomena that can occur when plastic is exposed to moisture for a long time. Put the specimen in a pressure cooker at 121 ℃ and 2 atmospheres and boil it with steam to change the physical and electrical properties of the specimen. Observation method. In the case of dielectric breakdown voltage, electricity is generally maintained after more than 50% after 100 hours PCT. In using it as an electronic component, the problem by hydrolysis does not appear to be large.

In the prior art, Japanese Patent Laid-Open Publication No. 51-91958 discloses a method of improving the moist heat resistance by introducing kneaded by introducing 1-2 epoxy groups into PBT and an olefin vinyl acetate copolymer. In order to solve the problem of elongation deterioration when compounding flame retardants, decabromodiphenyl and hexabromo diphenylether, epoxy compounds having 1 to 2 epoxy groups are added to improve toughness and elongation. How to improve is posted.

Japanese Patent Application Laid-Open No. 61-221459 discloses a method for improving mechanical properties and surface properties using a styrene resin in which an epoxy group is contained in polyester.

Korean Patent Publication 94-6470 suppresses hydrolysis by adding an epoxy compound and mono oxazoline to polyester, but the strength decreases significantly in the heat and moisture resistance test.

In Japan Special Publication No. 51-91958, the heat resistance was improved by kneading a mixture of PBT and α-olefin vinyl acetate copolymer by introducing one or two epoxy resins, but the hydrolysis resistance was not improved, and there was a problem of poor injection during molding. .

Japanese Patent Application No. 61-39973 proposes a method of adding an oxazoline derivative to PBT, but has a disadvantage in that the improvement of hydrolysis property is small.

Japanese Patent Application Laid-Open No. 55-82148 discloses a method for adding a divalent epoxy such as diglycidyl terephthalate as a chain extender. However, the method showed better hydrolysis characteristics than conventional methods, but in order to express hydrolysis resistance, since a large amount of epoxy must be added, flowability deteriorates and moldability is very poor. There is a difficulty.

Japanese Patent Laid-Open No. 62-285947 proposes a method of adding a copolymer containing an epoxy and a rubbery polymer containing a copolymer, but this method has low flowability and low stability against hydrolysis during molding, and thus also has electrical properties after PCT. Degradation occurs.

Japanese Patent Application Laid-Open No. 50-59525 proposes a method of reducing carboxyl groups and increasing molecular weight by adding phenylenebisoxazoline to polyester, and Japanese Patent Application Laid-Open No. 60-161427 adds a quaternary ammonium compound to the compound. The method was proposed but it was limited in preventing the hydrolysis of polyester.

US Patent No. 4,879,328 proposed a method of adding an elastomer containing a divalent epoxy and an epoxy or a carboxyl group to a polyester, which lacked the degree of maintenance of electrical properties after PCT. In addition, US Pat. No. 5,110,849 attempted to enhance the stability against hydrolysis by adding a metal alcohol salt to polyethylene terephthalate, but did not exhibit sufficient level of hydrolysis characteristics.

In order to solve the problems of the prior art, the present invention is to provide a PBT resin which is excellent in heat resistance and hydrolysis resistance and has low mechanical and electrical properties even under high temperature and high humidity conditions and high voltage.

PBT resin of the present invention for achieving this problem has a load of 2,160g and a melt flow index (Melt Flow Index) of 6 ~ 15g / 10 minutes at a temperature of 250 ℃, 121 ℃ temperature and 2 atmospheric pressure The breakdown voltage and the tensile strength retention after the hydrolysis test (Pressure Cooker Test) for 100 hours in a pressure cooker having a characteristic characterized in that more than 90% of the initial breakdown voltage and tensile strength maintenance rate.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail. PBT resin having a high viscosity characteristics of the present invention can be prepared in the same manner as a conventional polyester production method.

 In the method of preparing a polyester by transesterification of a terephthalate derivative and 1.4 butanediol, and polycondensation of the terephthalate derivative, the following structural formula (I) is used based on 100 parts by weight of the titanium compound and the PBT resin as a transesterification catalyst. 0.01 to 0.1 parts by weight of a phosphorus compound, 0.1 to 2 parts by weight of an aromatic polycarbodiimide compound of the following structural formula (II), 0.1 to 2 parts by weight of an oxazoline compound of the following structural formula (III), and a tin type of the following structural formula (IV) 0.003 to 0.02 parts by weight of the compound, 0.005 to 0.02 parts by weight of the siloxane compound represented by the following structural formula (V) and 0.01 to 0.2 parts by weight of the phosphorous compound represented by the following structural formula (VI), followed by melt polymerization to form a chip. Solid phase polymerization is carried out as a product to prepare the PBT number of the present invention.

Structural Formula (Ⅰ)

[Wherein R 3 is an aryl group having 6 to 7 carbon atoms, R 2 is a hydrogen atom, a methyl group, an ethyl group, isopropyl group, a butyl group or a tertiary butyl group, and R 1 is hydrogen or an alkyl group having 1 to 5 carbon atoms. .]

Structural Formula (Ⅱ)

[Wherein n is an integer of 2 to 20 and R is a hydrogen atom, an alkyl group or an aryl group.]

Structural Formula (Ⅲ)

[Wherein R4 is an aryl group having 6 to 7 carbon atoms, and R5 and R6 are the same or different hydrogen atoms, methyl group, ethyl group, isopropyl group, butyl group or tertiary butyl group.]

Structural Formula (Ⅳ)

[Wherein R7 is hydrogen, methyl group, ethyl group, isopropyl group or butyl group, and R8, R9 and R10 are -H, -OH, alkyl group, alkoxy group, phenyl group.]

Structural Formula (Ⅴ)

[Wherein, R11, R12 and R13 are hydrogen or alkyl group, n is 10-100 integer.]

Structural Formula (Ⅵ)

[Wherein, R14 is hydrogen, methyl group, ethyl group, isopropyl group, butyl group or tertiary butyl group, R15 is methylene group or ethylene group and M is sodium, potassium or lithium.]

In case of adding less than 0.01 part by weight of the phosphorus-based compound of Structural Formula (I) in the transesterification reaction during melt polymerization, the problem of poor physical properties at long-term heat resistance and thermal breakdown voltage of the prepared PBT resin occurs and 0.1 part by weight. In case of excessive input, the effect on excess was found to be insignificant.

The content of the polycarbodiimide compound of formula (II) and the oxazoline compound of formula (III) is preferably 0.1 to 2 parts by weight based on 100 parts by weight of the PBT resin, and the total content (total amount) of these two compounds is It is good that it is 0.8-4 weight part, More preferably, it is 1-3 weight part. If the total content of the two compounds is less than 0.8 parts by weight can not effectively block the carboxyl groups at the end, when the content exceeds 4 parts by weight remains unreacted, causing decomposition during processing, causing discoloration and deterioration of physical properties.

 Examples of the carbodiimide compound represented by Structural Formula (II) in the present invention include polytolyl carbodiimide, poly-4,4-diphenylmethanecarbodiimide, polyparaphenylene carbodiimide, polymethaphenylene carbodiimide and Poly-3,3-dimethyl-4,4-diphenylmethanecarbodiimide and the like.

When the content of the phosphorus-based compound of formula (VI) is less than 0.01 parts by weight, or the content of the tin-based compound of formula (IV) is less than 0.003 parts by weight, extrusion molding of the manufactured PBT resin and molding of small thin film battery electronic material parts When the crystallization rate is slow, the injection and extrusion defects and the solid phase polymerization rate are delayed. When the content of tin compound of Structural Formula (IV) exceeds 0.02 parts by weight, the PBT resin is solid phase polymerized, but the color of the polymer chip If the b-value measured in the color meter (colormeter) is 15 or more, there is a problem that the color defect of the polymer chip occurs, and if the phosphorus compound of the formula (VI) exceeds 0.2 parts by weight, It can't be used as an impurity to delay melt polymerization or to be used for extrusion or small thin film electronics parts after solid state polymerization.

In general, the b value after solid state polymerization is yellowish than the b value after melt polymerization, and when used as an injection or extrusion product, the b value should be 9 or less. The appearance is too yellowish after 9 seconds, and there is a limitation in appearance when molding the product in the state of a solid state polymerized chip.

In addition, when the content of the siloxane compound of Structural Formula (V) is less than 0.005 parts by weight, the pressure is increased during thin film injection or extrusion of the manufactured PBT resin. If the amount is more than 0.02 parts by weight, the effect of improving the flow rate of the melt (Metion Flow Inex) was little compared with the 0.02 parts by weight.

In the present invention, by applying the siloxane compound of the formula (V) to the particle surface of the phosphorus compound of the formula (VI) added to the present invention to increase the affinity between the polymer to improve the melt flow during injection or extrusion molding.

This is because the hydroxyl group on the right side of the siloxane compound may be bonded to the terminal of the polyester, thereby increasing the affinity between the particles and the polymer to uniformly inject or extrude the melt flow index.

 PBT resin prepared in melt polymerization with the above composition has a low viscosity and is not suitable for use as a material for extrusion or thin film electric and electronic injection, and thus undergoes a solid-phase polymerization process under high temperature vacuum of about 190 to 220 ° C. to improve viscosity. In the solid state polymerization process, both ends of the chain of PBT resin react to generate by-product butanediol or water, and the molecular weight increases continuously. The process of increasing molecular weight goes through the process where the end of the socks starts to join from the surface of the PBT resin chip and gradually goes to the inside. For faster progress, the by-products generated in the vacuum state are removed by long-term stay of 8 hours or more at high temperature. Should be.

The reason for the solid phase polymerization is to minimize the carboxyl end groups of the PBT resin remaining after the melt polymerization to prevent hydrolysis and increase toughness.

 The solid phase polymerization process is described in more detail in the condensation polymerization reaction in which the low molecular weight PBT molecules having 1,4 butanediol as a terminal meet each other and condensate to produce 1.4 butanediol as a condensation byproduct. In addition, the surrounding heat and vacuum generate 1.4 butanediol and remove the generated 1.4 butanediol from the periphery of the reaction tube to destroy the continuous chemical equilibrium to accelerate the reaction rate. In the other dehydration condensation reaction, the PBT molecule at 1.4 butanediol terminal and the PBT molecule at carboxyl group (acid) terminal meet to form water, which is much slower than the polycondensation reaction and thus contributes to the increase in molecular weight. .

The high-viscosity PBT resin of the present invention prepared by the method as exemplarily described above has a melt flow index of 6 to 15 g / 10 min at a load of 2160 g and a temperature of 250 ° C., and a temperature of 121 ° C. The insulation breakdown voltage and the tensile strength retention after the hydrolysis test (Pressure Cooker Test) for 100 hours in a pressure cooker having a pressure of 2 atm are characterized by more than 90% of the initial breakdown voltage and the tensile strength maintenance rate.

If the melt flow index is more than 15, the flowability is not maintained due to high flowability during extrusion or injection of thin-film molded products, and if less than 6, flowability is too low and molding of extruded or thin-film molded products is poor. Since the molding must be carried out at a high temperature, it may cause decomposition of the PBT resin or severe wear of the device during injection and extrusion.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.

Example 1

With respect to 100 parts by weight of PBT resin to be polymerized simultaneously with 800 g of dimethyl terephthalate and 600 g of butanediol (BD), 0.06 part by weight of tetrabutyl titanate as the main catalyst, and hydrated monobutyltin oxide of formula (IV) ) 0.015 parts by weight of tin-based compound, 0.03 parts by weight of phosphorus-based compound of formula (VI) [Sodium 2,2'-methylene bis- (4,6-di-tert-butyl phenyl) phosphate], Iganox 1010 (Ciba) Gaiji company) 0.015 parts by weight and 0.05 parts by weight of phosphorus compound [Bis (2,6-di-tert-butyl-4 -methylphenyl) pentaerythritol-di-phosphite] of the formula (I) After transesterification, prior to polyreaction transfer, 0.008 parts by weight of polydimethylsiloxane of formula (V), 0.01 parts by weight of lithium acetate, 0.05 parts by weight of tetrabutyl titanate, and 1 part of formula (III) based on 100 parts by weight of the PBT resin. , 3-phenylene-bis-jade 0.8 parts by weight of sleepiness and 0.8 parts by weight of BASF company Staboxol-1, a carbodiimide-based system of formula (II), were injected, and then discharged, cooled, and cut into a spaghetti shape through a condensation polymerization reaction under high temperature vacuum. PBT resin having an intrinsic viscosity (IV) 0.85 was prepared. PBT resin prepared as described above was gradually raised from 40 ° C. to 220 ° C., and at the same time, the PBT resin was subjected to solid phase polymerization in the usual manner with a residence time of 23 hours with a vacuum degree of 750 mmHg or more, thereby preparing a final product of PBT resin. The results of evaluating the physical properties of the prepared PBT resin are shown in Table 2.

Example 2-Example 3 and Comparative Examples 1 to 5

1,3-phenylene-bis-oxazoline, stavoxol-1, a carbodiimide family, a phosphorus compound of formula I [Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-di-phosphite ] And monobutyl tin oxide, phosphorus compounds of formula (VI) [Sodium 2,2'-methylene bis- (4,6-di-tert-butyl phenyl) phosphate], polydimethylsiloxane, respectively A PBT resin as a final product was prepared in the same manner as in Example 1 except that the addition amount (content) of was changed as shown in Table 1.

The results of evaluating the physical properties of the prepared PBT resin are shown in Table 2.

Manufacturing conditions [Unit: parts by weight] division Melt polymerization composition A B C D E F Example 1 0.8 0.8 0.05 0.015 0.03 0.008 Example 2 0.8 0.8 0.03 0.015 0.03 0.008 Example 3 0.8 0.8 0.09 0.01 0.03 0.008 Comparative Example 1 3 4 0.05 0.015 0.03 0.008 Comparative Example 2 0.7 - 0.008 0.015 0.03 0.008 Comparative Example 3 0.8 0.8 0.05 0.005 0.002 0.008 Comparative Example 4 0.7 0.9 0.05 0.03 0.03 0.008 Comparative Example 5 0.6 0.8 0.09 0.08 0.03 0.002

In Table 1, A is 1,3-phenylene-bis-oxazoline of formula (III), B is carboximide-based staxol-1, and C is phosphorus compound of formula (I). Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-di-phosphite], D is a monobutyltin oxide of formula (IV), E is a phosphorus compound of formula (VI) [ Sodium 2,2'-methylene bis- (4,6-di-tert-butyl phenyl) phosphate], F represents polydimethylsiloxane of formula (V), respectively.

Physical properties of the final product PBT resin division Properties before hydrolysis Properties after hydrolysis Tensile Strength (㎏ / ㎠) Insulation Breakdown Voltage (KV / ㎜) b value Melt Flow Indes Injection and Extrusion Productivity Tensile Strength (㎏ / ㎠) Breakdown Voltage (KV / mm) Example 1 570 17.8 6.0 13 Good 530 16.7 Example 2 572 17.5 6.1 12 Good 528 16.3 Example 3 575 18.0 5.5 10 Good 540 17.0 Comparative Example 1 550 15.0 6.0 10 Molding defect (surface) 350 9.2 Comparative Example 2 568 16.5 6.2 12 Good 295 5.9 Comparative Example 3 570 17.2 6.4 4 Molding defect (surface) 490 9.4 Comparative Example 4 567 17.3 15 10 Good (poor color) 480 9.2 Comparative Example 5 563 17.0 18 5 Molding defect 490 9.4

From the results of Table 2, in Examples 1 to 3, each of the tensile strength and the dielectric breakdown voltage retention after the hydrolysis test (PCT) was maintained at 90% or more compared to the molarity before the hydrolysis test (PCT), and also the initial product. Color, melt flow, injection and extrusion productivity is also excellent. In other words, the initial physical properties are an important factor, but the change in tensile strength after the hydrolysis test (PCT) is a very important factor. This is because when it is used as a connector material of the automobile engine part, it may be a serious defect due to the occurrence of breakage and breakage of the installed connector when heat and hydrolysis characteristics are insufficient due to hydrolysis by heat or moisture in high temperature and high humidity environment. Because.

However, in Comparative Examples 1 to 6, the tensile strength and the dielectric breakdown voltage retention after the hydrolysis test (PCT) were significantly lowered compared to the physical properties before the hydrolysis test (PCT), and the color and melt flowability, etc. Also not desirable.

Various physical properties of Table 2 were evaluated in the following manners, respectively.

Hydrolysis Test (PCT)

Place the test specimen (diameter 100 mm, thickness 3.2 mm) into the autoclave (pressure cooker), put distilled water to the extent that the specimen does not immerse, close the lid, heat to 121 ℃, and keep the internal pressure at 2 atmospheres. Treat for 100 hours.

Breakdown voltage and tensile strength

For each of the test specimens before and after the hydrolysis test (PCT) as described above, the breakdown voltage is measured by the ASTM D149 method, the tensile strength is measured by the ASTM D-638 method.

Specifically, a PA 70 model from Beck Man, Inc. was used. The electrode was plate-cyliner type and tested in insulating oil.

In addition, when the breakdown voltage was measured, the voltage was boosted at a rate of 20 KV / 10 seconds, and the breakdown voltage was expressed as a value obtained by dividing the voltage at which the specimen was broken down by the thickness of the specimen (KV / mm).

Chip color (b value)

Measure with a color meter (Japanese Minolta CR-200).

Melt Flow Index

It is measured by ASTM D-1238 method.

Specifically, MPINI 987 of TINIOUS OLSEN of USA was used as measuring machine, measuring temperature was 250 ℃, measuring load was 2,160g, and the lower orifice diameter of measuring machine was 2.0mm It was set as.

PBT resin according to the present invention is very excellent in heat resistance and hydrolysis characteristics, there is little degradation of mechanical properties and electrical insulation properties even under high temperature and high humidity environment and high voltage.

Therefore, the present invention is very useful for materials such as connectors, coil bobbins, focus packs, sockets, and fuse cases, which are electrical and electronic components.

Claims (3)

delete 0.01 to 0.1 parts by weight of a phosphorus compound of the following structural formula (I), 0.1 to 2 parts by weight of an aromatic polycarbodiimide compound of the following structural formula (II) and an oxa of the following structural formula (III) based on 100 parts by weight of polybutylene terephthalate resin 0.1-2 parts by weight of a sleepy compound, 0.003-0.02 parts by weight of a tin compound of the following structural formula (IV), 0.005-0.02 parts by weight of a siloic acid compound of the following structural formula (V) and 0.01-0.2 weight of a phosphorus compound of the following structural formula (VI) A high viscosity polybutylene terephthalate resin comprising a part. Structural Formula (Ⅰ)

[Wherein R 3 is an aryl group having 6 to 7 carbon atoms, R 2 is a hydrogen atom, a methyl group, an ethyl group, isopropyl group, a butyl group or a tertiary butyl group, and R 1 is hydrogen or an alkyl group having 1 to 5 carbon atoms. .] Structural Formula (Ⅱ)

[Wherein n is an integer of 2 to 20 and R is a hydrogen atom, an alkyl group or an aryl group.] Structural Formula (Ⅲ)

[Wherein R4 is an aryl group having 6 to 7 carbon atoms, and R5 and R6 are the same or different hydrogen atoms, methyl group, ethyl group, isopropyl group, butyl group or tertiary butyl group.] Structural Formula (Ⅳ)

[Wherein R7 is hydrogen, methyl group, ethyl group, isopropyl group or butyl group, and R8, R9 and R10 are -H, -OH, alkyl group, alkoxy group, phenyl group.] Structural Formula (Ⅴ)

[Wherein, R11, R12 and R13 are hydrogen or alkyl group, n is 10-100 integer.] Structural Formula (Ⅵ)

[Wherein, R14 is hydrogen, methyl group, ethyl group, isopropyl group, butyl group or tertiary butyl group, R15 is methylene group or ethylene group and M is sodium, potassium or lithium.] The total content of the aromatic polycarbodiimide compound of the formula (II) and the oxazoline compound of the formula (III) is 0.8 to 4 parts by weight based on 100 parts by weight of the polybutylene terephthalate resin. High viscosity polybutylene terephthalate resin.