Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
  • C08G63/181—Acids containing aromatic rings
  • C08G63/183—Terephthalic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
  • C08G63/181—Acids containing aromatic rings
  • C08G63/185—Acids containing aromatic rings containing two or more aromatic rings
  • C08G63/187—Acids containing aromatic rings containing two or more aromatic rings containing condensed aromatic rings
  • C08G63/189—Acids containing aromatic rings containing two or more aromatic rings containing condensed aromatic rings containing a naphthalene ring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/66—Polyesters containing oxygen in the form of ether groups
  • C08G63/668—Polyesters containing oxygen in the form of ether groups derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/672—Dicarboxylic acids and dihydroxy compounds

Definitions

• the present invention relates to polyester resins and resin compositions directed to molding, and a formed product using the same.
• the polyester resins and resin compositions of the present invention are particularly suitable for low pressure molding applications to secure electrical electronic components in a waterproof manner.
• One known method of reducing the viscosity is to impregnate the electrical electronic component with a resin that is dissolved in a solvent to take a liquid form, and then vaporizing the solvent.
• this method had various problems such as bubbles remaining when the solvent is vaporized as well as degrading the working environment if an organic solution is used as the solvent.
• a two-part epoxy resin has been used in view of also the durability after molding, as disclosed in various publications such as Japanese Patent Laying-Open No.2000-239349 and EP 0 307 665 A2.
• a base resin and a curing agent are mixed immediately before the molding process at a predetermined ratio, molded at low viscosity, warmed and then left for several days to promote cure reaction and be completely solidified.
• this method imposes various problems such as the adverse effect of the epoxy towards the environment, requiring accurate adjustment of the mixing ratio of the two liquids, and the short available period of time prior to mixing being restricted to only one to two months.
• Low productivity is also noted due to the requirement of a cure period of several days for hardening.
• there was a problem of the stress caused by contraction in the resin after curing being concentrated at an area where the physical strength is relatively weak such as at the solder portion bonding an electrical electronic component and the wiring to cause delamination thereat.
• the hot melt type resin can be cited as the resin for molding.
• the problems associated with the working environment based on the usage of the solvent containing type and epoxy based type are overcome in the hot melt adhesive that requires only the resin to be heated and melted in order to reduce the viscosity for molding. Since the hot melt type resin is solidified by just being cooled after molding to express its capability, the productivity is increased. Because it is noted that a thermoplastic resin is generally employed, recycling of the material when ended as a product is allowed by heating and removing the resin by melting. The reason why a hot metal type resin having high potentiality as a resin for molding has not become the material to replace the conventionally-used two-part epoxy resin is due to the fact that a base material suitable therefor has not been proposed.
• EVA Ethylene Vinyl Acetate
• Polyamide that is another hot melt type has high adhesion towards various substrates as a resin without any additives, and is suitable as a resin material for low-pressure molding by virtue of its low melt viscosity and high cohesive force, as disclosed in, for example, EP 1 052 595 B1.
• polyamide is basically highly hygroscopic and will gradually absorb moisture. Electrical insulation which is one of the most important property is often degraded over time.
• Polyester that has high electrical insulation and water resistance can be thought of as an extremely useful material for the present application.
• the melt viscosity is generally high.
• an injection molding step at a high pressure of at least several thousand N/cm 2 will be required.
• An object of the present invention is to provide a base material that meets the requirements of various capabilities such as waterproof, electrically insulation, working environment, productivity, durability and the like for a polyester resin or a resin composition for molding directed to an electrical electronic component having a sophisticated configuration.
• the present invention includes a polyester resin for molding, a resin composition for molding, and a formed product using the same.
• the present invention is a saturated polyester resin for molding, wherein the melt viscosity at 200° C. is at least 5 dPa ⁇ s and not more than 1000 dPa ⁇ s, and the product of a x b is at least 500, where a (N/mm 2 ) is the tensile breaking strength and b (%) is the tensile breaking elongation of a film-shape formed product.
• the present invention is a saturated polyester resin for molding, wherein the glass transition temperature is not more than ⁇ 10° C., and the melting point is at least 70° C. and not more than 200° C.
• the present invention is a saturated polyester resin for molding, wherein the ester group concentration of polyester is at least 1000 equivalents/10 g and not more than 8000 equivalents/10 6 g.
• the present invention is a saturated polyester resin for molding, wherein at least 2 mole % of a diol component of polyester is a polyalkylene glycol when total amounts of a diol component of the polyester is 100 mole %.
• the polyalkylene glycol is a polytetramethylene glycol having a number-average molecular weight of at least 400 and not more than 10000.
• the present invention is a saturated polyester resin for molding, wherein at least 2 mole % of a diol component of polyester is an aliphatic and/or alicyclic diol having at least 10 carbon atoms when total amounts of a diol component of the polyester is 100 mole %.
• the present invention is a saturated polyester resin for molding, wherein at least 2 mole % of a dicarboxylic acid of polyester is an aliphatic and/or alicyclic dicarboxylic acid having at least 10 carbon atoms when total amounts of a dicarboxylic acid component of the polyester is 100 mole %.
• At least 60 mole % of the dicarboxylic acid is a terephthalic acid and/or naphthalene dicarboxylic acid
• at least 40 mole % of the diol component is a 1,4-butanediol and/or ethylene glycol when respective total amounts of the dicarboxylic acid component and the diol component of the polyester are 100 mole %.
• the present invention is preferably a polyester resin composition for molding, including at least 50% by weight of a saturated polyester resin among the entire amount. Also, the present invention is preferably a polyester resin composition for molding, including the above saturated polyester resin and an anti-oxidant.
• the present invention is a polyester resin composition for molding, wherein the retention of the melt viscosity after a heat treatment test for 100 hours at 121° C. and 0.2 MPa is at least 70% to the melt viscosity prior to being subjected to the heat treatment test.
• the present invention is a polyester resin composition for molding, wherein the melt viscosity at 200° C. is at least 5 dPa ⁇ s and not more than 1000 dPa ⁇ s, and the product of a ⁇ b is at least 500 where a (N/mm 2 ) is the tensile breaking strength and b (%) is a tensile breaking elongation of a film-shape formed product.
• the present invention is preferably a formed product using a saturated polyester resin or a polyester resin composition for molding of the above respective aspects.
• Molding in the present specification refers to molding injected at the low pressure of 10 N/cm 2 to 800 N/cm 2 .
• the molding process is carried out at an extremely low pressure as compared to injection molding carried out at a high pressure of the average of approximately 4000 N/cm 2 conventionally employed for general plastic molding.
• the principle is similar to that of general injection molding, wherein a melted resin is injected to a mold cavity in which an electrical electronic component is set to encapsulate the component. Over molding can be effected without fracturing the delicate component.
• the polyester resin for molding of the present invention has a melt viscosity of at least 5 dPa ⁇ s and not more than 1000 dPa ⁇ s at 200° C. These values of the melt viscosity at 200° C. have been measured as set forth below. A sample dried to 0.1% or below in moisture was used. The viscosity when a polyester resin heated and stabilized at 200° C. was passed through a die having a hole diameter of 1.0 mm and a thickness of 10 mm under the pressure of 98N/cm 2 with a flow tester available from Shimadzu Corporation (Part No. CFT-500C).
• melt viscosity becomes as high as 1000 dPa ⁇ s or above
• a polyester for molding having a melt viscosity of not more than 1000 dPa ⁇ s, preferably not more than 500 dPa ⁇ s a molded component superior in electrical insulation can be obtained at a relatively low injection pressure of several hundred N/cm 2 .
• the property of the electrical electronic component is not degraded.
• the lower limit is at least 5 dPa ⁇ s, preferably at least 10 dPa ⁇ s, more preferably at least 50 dPa ⁇ s, and most preferably at least 100 dPa ⁇ s taking into consideration the adhesion and cohesive force of the resin.
• the upper limit of the melting point is 200° C.
• the upper limit is preferably 190° C., and more preferably 180° C.
• the lower limit is to be set to 5° C. to 10° C. higher than the heat resistant temperature required in the corresponding application. Taking into consideration the ease in handling at ordinary temperature and the normal heat resistance, the lower limit is at least 70° C., further preferably at least 100° C., more preferably at least 120° C., particularly preferably at least 140° C., and most preferably at least 150° C.
• the tensile breaking strength and elongation of the polyester of the present invention were measured at 50% RH atmosphere at 23° C., based on a film formed product under thermal pressing. Specifically, a polyester resin dried to 0.1% or below in moisture was sandwiched between two polyethylene fluoride sheets and pressed for 10 seconds at 200° C., and then rapidly cooled down to ordinary temperature to obtain a polyester film. At this stage, it is desirable that a spacer, if necessary, is used to adjust the thickness to 0.2 mm. A sample 50 mm in length and 15 mm in width was cut out from such a film.
• the tensile breaking strength and elongation of the present invention were measured by subjecting this sample under the conditions of distance of 30 mm between the chucks and the tensile rate of 50 mm/min. in a 50% RH atmosphere at 23° C.
• the product a ⁇ b is at least 500 where a (N/cm 2 ) is the tensile breaking strength and b (%) is the tensile breaking elongation.
• the product a ⁇ b is at least 1000, further preferably at least 2000, and most preferably at least 2500. If the product a ⁇ b is less than 500, sufficient durability may not be achieved with respect to various impacts that will be received in various use conditions.
• the upper limit is not particularly limited, the upper limit is preferably not more than 20000, more preferably not more than 15000, and most preferably not more than 12000 taking into consideration the resin distortion towards the interior electronic component.
• the electrical electronic component may not be held at the sufficient strength, inducing the possibility of being detached or the like.
• the tensile breaking strength a is at least 2 (N/cm 2 ).
• the resin may be brittle and not capable of withstanding the mechanical load on the electrical electronic component, inducing the possibility of a crack or the like in the resin. Therefore, the tensile breaking elongation b is preferably at least 200 (%).
• the aliphatic based and/or alicyclic and aromatic based compositions must be adjusted.
• a polyester copolymer based on terephthalic acid and ethylene glycol, terephthalic acid and 1,4-butanediol, naphthalene dicarboxylic acid and ethylene glycol, or naphthalene dicarboxylic acid and 1,4-butanediol is suitable.
• the polyester copolymer is preferably based on terephthalic acid and 1,4-butanediol, or naphthalene dicarboxylic acid and 1,4-butanediol, both of rapid crystallization.
• the sum of either one or both thereof is preferably at least 60 mole %, more preferably at least 70 mole %, and further preferably at least 80 mole % in the dicarboxylic acid component.
• the sum of either one or both is preferably at least 40 mole %, more preferably at least 45 mole %, further preferably at least 50 mole %, and most preferably at least 55 mole % in the diol component.
• the total amount of the terephthalic acid and 1,4-butanediol or the naphthalene dicarboxylic acid and 1,4-butanediol is preferably at least 120 mole %, more preferably at least 130 mole %, further preferably at least 140 mole %, and most preferably at least 150 mole %. If the total amount is less than 120 mole %, the crystallization rate is reduced, whereby the mold releasability will be degraded.
• the total amount of the terephthalic acid and 1,4-butanediol or the naphthalene dicarboxylic acid and 1,4-butanediol is preferably not more than 180 mole %, and more preferably not more than 170 mole %. If the total amount thereof exceeds 180 mole %, the crystallization rate becomes so high that distortion during contraction easily occurs to reduce the adherence towards the electrical electronic component.
• an aliphatic or alicyclic dicarboxylic acid such as adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexane dicarboxylic acid, 1, 3-cyclohexane dicarboxylic acid, 1, 2-cyclohexane dicarboxylic acid, 4-methyl-1,2-cyclohexane dicarboxylic acid, or an aliphatic or alicyclic diol such as 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentane diol, 1,6-hexane diol, 3-methyl-1,5-pentane diol, neopentyl glycol, diethylene glycol, di
• the glass transition temperature can be lowered while maintaining the high melting point. Therefore, from the standpoint of achieving both heat resistance of the polyester resin and adherence towards the electrical electronic component, it is preferable that these are included as the dicarboxylic acid component or diol component in copolymerization.
• a derivative of the aliphatic or alicyclic dicarboxylic acid refers to a derivative of carboxylic acid and that can be a copolymer component, such as ester, acid chloride or the like.
• a dimer acid refers to an aliphatic or alicyclic dicarboxylic acid generated by an unsaturated fatty acid being converted into a dimer by polymerization or Diels-Alder reaction and the like (in addition to most dimers, many include several mole % of a trimer, a monomer, or the like).
• a hydrogenated dimer acid refers to hydrogen added to the unsaturated bonding portion of the above dimer acid.
• a dimer diol or hydrogenated dimer diol refers to a reduction of the two carboxylic acids of the relevant dimer acid or hydrogenated dimer acid to hydroxyl groups.
• EMPOL or SOVERMOL from Cognis Corporation or PRIPOL from Uniqema can be enumerated.
• a small amount of aromatic based copolymer component may also be used if the melt viscosity is maintained at a low range.
• an aromatic dicarboxylic acid such as isophthalic acid and orthophthalic acid
• an aromatic based glycol such as ethylene oxide additions and propylene oxide additions of bisphenol A
• it is particularly preferable to introduce in blocks an aliphatic based component of relatively high molecular weight such as polytetramethylene glycol that exhibits rapid crystal solidification after molding.
• copolymerization of a monomer that has a high molecule weight is preferable from the standpoint of facilitating rapid crystal solidification.
• the above cited dimer acid, hydrogenated dimer acid, a derivative thereof, dimer diol, hydrogenated dimer diol and the like are suitable.
• heat cycle durability refers to the capability to be absent of resin delamination and resin cracks at the interface region with an electronic component or the like that differs in the coefficient of linear expansion when repeatedly subjected to temperature change between a high temperature and a low temperature. Delamination and generation of cracks will easily occur if the modulus of elasticity of the resin is increased during cooling.
• the glass transition temperature is preferably not more than ⁇ 10° C., more preferably not more than ⁇ 20° C., further preferably not more than ⁇ 40° C., and most preferably not more than ⁇ 50° C.
• the lower limit is not particularly cited, at least ⁇ 100° C. can be cited for practical usage taking into consideration adhesion and the anti-blocking capability.
• the upper limit of the ester group concentration is not more than 8000 equivalents/10 6 g.
• the upper limit of the ester group concentration is preferably not more than 7500 equivalents/10 6 g, and more preferably not more than 7000 equivalents/10 6 g.
• the lower limit is at least 1000 equivalents/10 6 g.
• the lower limit is preferably at least 1500 equivalents/10 6 g, and more preferably at least 2000 equivalents/10 6 g.
• the ester group concentration is a value calculated from the composition and the copolymer ratio of the polyester resin represented in equivalent mole per 1000 kg of resin.
• the dimer acid, hydrogenated dimer acid, dimer diol, hydrogenated dimer diol, polytetramethylene glycol and the like are preferably at least 2 mole %, more preferably at least 5 mole %, further preferably at least 10 mole %, and most preferably at least 20 mole %.
• the upper limit is not more than 70 mole %, preferably not more than 60 mole %, and more preferably not more than 50 mole % taking into consideration the heat resistance and handleability of blocking.
• the number-average molecular weight of the polytetramethylene glycol is preferably at least 400, more preferably at least 500, further preferably at least 600, and particularly preferably at least 700.
• the upper limit is preferably not more than 10000, more preferably not more than 6000, further preferably not more than 4000, and most preferably not more than 3000. If the number-average molecular weight of the polytetramethylene glycol is below 400, the heat cycle durability and hydrolyzable resistance may be degraded. In contrast, if the number-average molecular weight exceeds 10000, the compatibility with the polyester portion will be degraded to render copolymerization in blocks difficult.
• the number-average molecular weight of polyester is preferably at least 3000, more preferably at least 5000, and further preferably at least 7000.
• the upper limit of the number-average molecular weight is preferably not more than 50000, more preferably not more than 40000, and further preferably not more than 30000. If the number-average molecular weight is below 3000, the product of a ⁇ b cannot easily satisfy the defined value. If the number-average molecular weight exceeds 50000, the melt viscosity at 200° C. may become higher.
• the polyester resin for molding of the present invention is a saturated polyester resin that does not contain an unsaturated group.
• an unsaturated polyester there is a possibility of crosslinking or the like occurring during melting to degrade the melt stability during molding.
• 1 H-NMR and 13 C-NMR measuring a polyester resin dissolved in a solvent such as chloroform deuteride, an assay by gas chromatography that measures after methanolysis of the polyester resin and the like can be cited.
• 1 H-NMR is simple and convenient.
• the polyester of interest can be obtained by subjecting the above dicarboxylic acid and diol component to an esterification reaction at 150° C. to 250° C., and then effecting polycondensation at 230° C. to 300° C. while reducing the pressure.
• the polyester of interest can be obtained by subjecting the above-described derivative of dimethyl ester of the dicarboxylic acid and the diol component to transesterification at 150° C. to 250° C., and then effecting polycondensation at 230° C. to 300° C. while reducing the pressure.
• the polyester resin for molding of the present invention can be blended with a polyester of another composition, another resin such as polyamide, polyolefine, epoxy, polycarbonate, acryl, ethylene vinyl acetate, phenol and the like, a curing agent such as an isocyanate compound, melamine, or the like, a filler such as talc and mica, a pigment such as carbon black, titanium oxide or the like, and a flame retardant such as antimony trioxide, polystyrene bromide or the like to be used in the application of molding as a resin composition.
• another resin such as polyamide, polyolefine, epoxy, polycarbonate, acryl, ethylene vinyl acetate, phenol and the like
• a curing agent such as an isocyanate compound, melamine, or the like
• a filler such as talc and mica
• a pigment such as carbon black, titanium oxide or the like
• a flame retardant such as antimony trioxide, polystyrene bromide or the
• the polyester resin is included at least 50% by weight, more preferably at least 60% by weight, further preferably at least 70% by weight, and particularly preferably at least 90% by weight with respect to the entire composition. If the amount of the polyester is below 50% by weight, the fastening adhesion, various durability, water resistance for a good electrical electronic component, inherent to the polyester resin, may be degraded.
• an antioxidant for example, as a hindered phenol type, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanrate, 1,1,3-tri (4-hydroxy-2-methyl-5-t-butylphenyl) butane, 1,1-bis (3-t-butyl-6-methyl-4-hydroxyphenyl) butane, 3,5-bis (1,1-dimethyl ethyl)-4-hydroxy benzene propanoic acid, penta erytrityl tetrakis (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3-(1,1-dimethyl ethyl)-4-hydroxy-5-methyl-benzene propanoic acid, 3,9-bis [1,1-dimethyl-2-[(3-t-butyl)
• the retention of the melt viscosity of the polyester resin composition of the present invention after a heat treatment test for 100 hours at 121° C. and 0.2 MPa is at least 70% to the melt viscosity prior to being subjected to the heat treatment test.
• a resin or a composition thereof for molding is cut to a dimension of 1 cm ⁇ 1 cm ⁇ 1 cm, and processed under the condition of 121° C. ⁇ 0.2 MPa ⁇ 100 hours.
• the melt viscosity retention thereof is preferably at least 75%, more preferably at least 80%, and most preferably at least 90%. There is no restriction in the upper limit, and a value closer to 100% is favorable. If the retention of the melt viscosity is below 70%, the durability when used at high temperature may be degraded.
• the polyester resin or resin composition for molding of the present invention is poured into a die in which an electrical electronic component is set and then molded. More specifically, the polyester resin or resin composition of the present invention is heated in a heat tank at approximately 130-220° C. to melt, poured into a die through an injection nozzle, cooled down for a predetermined period of time, and then taken out from the die as a formed product.
• Mold-man 8000 available from The Cavist Corporation of USA
• WS102/MX3006 available from Nordson Corporation of Germany
• DYNAMELT series available from ITW Dynatec of USA
• the present invention will be described in further detail based on examples. Respective measurements in the examples have been obtained as set forth below.
• the ester group concentration is a value calculated from the composition and copolymer ratio of the polyester resin represented in equivalent mole per 1000 kg of resin.
• MELTING POINT, GLASS TRANSITION TEMPERATURE Using a differential scanning calorimeter “DSC220 Type” available from Seiko Instruments Inc., an under-measurement specimen 5 mg was placed in an aluminum pan and sealed with the lid pressed. The specimen was held for five minutes at 250° C. to be completely melted, and then rapidly cooled with liquid nitrogen, followed by an increase in temperature from ⁇ 150° C. to 250° C. at the rate of 20° C./min. for measurement. The inflection point of the obtained curve was taken as the glass transition temperature, and the endothermic peak was taken as the melting point.
• DSC220 Type available from Seiko Instruments Inc.
• MELT VISCOSITY Using a flow tester (CFT-500C type) available from Shimadzu Corporation, a cylinder located at the center of a heating unit set to 200° C. was filled with a resin specimen dried to 0.1% or below in moisture. At an elapse of one minute after the filling, a load (98N) was applied on the specimen by means of a plunger, whereby the melted specimen is extruded from the die at the bottom of the cylinder (hole diameter: 1.0 mm; thickness: 10 mm). The dropping distance and dropping time of the plunger were recorded to calculate the melt viscosity.
• CFT-500C type available from Shimadzu Corporation
• TENSILE BREAKING STRENGTH, TENSILE BREAKING ELONGATION A polyester sheet (width 15 mm, thickness 0.2 mm, length 50 mm) was prepared. The tensile breaking strength and tensile breaking elongation at 23° C. and 50% RH were measured using a tensile tester under the conditions of distance of 30 mm between the chucks and a tensile rate of 50 mm/min.
• NUMBER-AVERAGE MOLECULAR WEIGHT Using a gel permeation chromatography (GPC) 150c from Waters Corporation with a chloroform as an eluate, GPC measurement was conducted at the column temperature of 35° C. and flow rate of 1 cm 3 /min. Based on calculation from the results, the measured value converted in polystyrene was obtained.
• GPC gel permeation chromatography
• a polyester resin (A) was obtained as set forth below.
• a reactor equipped with an agitator, a thermometer and a cooler for distillation 166 weight parts of terephthalic acid, 180 weight parts of 1,4-butanediol, and 0.25 weight parts of tetrabutyl titanate were added and subjected to esterification for 2 hours at 170-220° C.
• 300 weight parts of polytetramethylene glycol “PTMG1000” (product of Mitsubishi Chemical) with a number-average molecular weight of 1000 and 0.5 weight parts of a hindered phenol based antioxidant “Irganox1330” (Ciba-Geigy Ltd.) were introduced.
• polyester resin (A) had a melting point of 165° C. and a melt viscosity of 250 dPa ⁇ s.
• Polyester resins (B) to (K) were synthesized in a manner similar to that of the above polyester resin (A). Respective compositions and values of physical properties are shown in Table 1.
• Polyester resins (A) to (H) satisfy the requirements of the claims.
• Polyester resin (I), polyester resin (J), and polyester resin (K) do not satisfy the requirements of the claims in the melt viscosity at 200° C., the product of the tensile breaking strength and tensile breaking elongation, and the melt viscosity at 200° C. as well as the product of the tensile breaking strength and tensile breaking elongation, respectively.
• Polyester resin (K) was used as the material to fabricate a polyester resin composition that will be described afterwards.
• TPA Terephthalic acid
• NDCA naphthalene dicarboxylic acid
• IPA isophthalic acid
• AA adipic acid
• DIA hydrogenated dimer acid
• DDA dodecane dicarboxylic acid
• BD 1,4-butanediol
• EG ethylene glycol
• PTG1000 polytetramethylene glycol (number-average molecular weight of 1000)
• PTG2000 polytetramethylene glycol (number-average molecular weight of 2000)
• DID hydrogenated dimerdiol
• NPG neopentyl glycol.
• a polyester resin composition (M) was prepared as set forth below. 76 weight parts of polyester resin (A), 6 weight parts of antimony trioxide and 18 weight parts of poly styrene dibromide as a flame retardant were mixed uniformly, and then melted and kneaded at a die temperature of 170° C. using a two-shaft extruder.
• Polyester resin compositions (N) to (S) were prepared in a manner similar to that of the above polyester resin composition (M). Respective compositions and values of physical properties are shown in Table 2.
• Polyester resin compositions (M) to (Q) satisfy the requirements of the claims.
• Polyester resin composition (R) does not satisfy the requirements of the claims in the type of the polyester resin and the product of the tensile breaking strength and tensile breaking elongation.
• Polyester resin composition (S) does not satisfy the requirements of the claims in the polyester resin ingredient ratio and the product of the tensile breaking strength and tensile breaking elongation.
• polyester resins (A) to (J) and a dimer acid based polyamide resin were melted at 200° C., and subjected to injection molding using an applicator “WS102/MX3006” available from Nordson Corporation for low pressure (up to 300 N/cm 2 ) injection molding.
• the material to be molded was molded over a circuit board of 20 mm ⁇ 15 mm with two lead wires of polyvinyl chloride in an aluminum die having an inside dimension of 25 mm ⁇ 20 mm ⁇ 50 mm.
• the period of time of release from the die without any defect in the shape of the formed product (mold release time) and the formed state corresponding to the circuit board were observed.
• the circuit board was left for 100 hours at 80° C. ⁇ 95% RH.
• the retention of the circuit resistance was measured. A higher retention indicates its higher suitability for the insulation material of an electrical electronic component.
• each resin sample was subjected to a pressure cooker test (121° C., 0.2 MPa, 100 hours), and the retention of melt viscosity was obtained.
• the hydrolyzable resistance of the polyester resin became lower in proportion to a lower retention, having the tendency of degradation in the durability over a long period of time.
• the appearance of the formed product after a heat cycle test (twenty times from ⁇ 40° C. to 80° C. was observed). The results are shown in Table 3.
• a formed product was produced in a manner as described above for each of polyester resin compositions (M) to (S).
• the mold release time, forming workability, appearance of the formed product, retention of the circuit resistance, retention of the melt viscosity, and the appearance after the heat cycle were observed. The results are shown in Table 4.

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