JP2012255100A - Copolymerization polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin that excels in flexibility at normal temperature, has improved brittleness, excels also in wet heat durability, and further in crystallinity; and more specifically to provide a copolymerization polyester resin suitable to the molding application and the potting processing application of an electricity and electronic part or the like.SOLUTION: The copolymerization polyester resin includes: an aromatic dicarboxylic acid and a dimer acid as an acid component; and 1,4-butanediol and polybutadiene glycol as a glycol component, wherein the content of the dimer acid in the acid component is 10-50 mole%, the content of the 1,4-butanediol in the glycol component is at least 80 mole%, the content of the polybutadiene glycol in the glycol component is 1-20 mole%, and an inorganic based nucleating agent is included and its content in the copolymerization polyester resin is 0.01-5.0 mass%.

Description

  The present invention is a copolyester resin containing dimer acid in an acid component and 1,4-butanediol and polybutadiene glycol in a glycol component, and contains an inorganic crystal nucleating agent as a crystal nucleating agent. The present invention relates to a copolyester resin excellent in flexibility, wet heat durability and crystallinity.

  Polyester, particularly polyethylene terephthalate (hereinafter abbreviated as PET) or polybutylene terephthalate (hereinafter abbreviated as PBT) units as a main component, and a copolymerized polyester obtained by copolymerizing an aliphatic dicarboxylic acid or various diols are excellent. Since it has heat resistance, weather resistance, solvent resistance, flexibility, etc., it is widely used as a film, fiber, sheet, adhesive, and sealant.

  However, when the above-mentioned copolymerized polyester is used for an application that requires high flexibility, it is brittle due to lack of flexibility at low temperature or room temperature, and there is a limit to the use that can be used.

  In order to improve such a defect, a method of copolymerizing a soft segment with a polyester resin has been considered. A polyester-polyether block copolymer having a polyether compound as a soft segment has a low glass transition point of the resin, high fluidity, and the resin is flexible even when the molecular weight is reduced. For this reason, it is widely used as a material such as a molding material used in electric / electronic parts or automobile parts. Such a polyester-polyether block copolymer is disclosed in Patent Document 1, for example.

  However, this polyester-polyether block copolymer is susceptible to hydrolysis due to the ester bond of the hard segment, and the polyether compound that is a soft segment is likely to undergo oxidative degradation, thermal decomposition, etc. when exposed to high temperatures. As a result, there was a problem in wet heat durability of the copolymer itself.

  Furthermore, in addition to the above-described flexibility and wet heat durability, considering workability at the time of molding, it is also required to have a performance excellent in crystallinity. That is, by having high crystal performance, the cooling time for obtaining a molded product is shortened, and the product can be obtained in a short molding cycle. Such a polyester resin excellent in flexibility, wet heat durability and crystallinity has not yet been proposed.

JP-A-2-3429

  The present invention solves the above-described problems, and is a polyester resin that has excellent flexibility at room temperature and improved brittleness, and is excellent in wet heat durability and also in crystallinity. It is a technical problem to provide an excellent polyester resin, more specifically, to provide a copolyester resin suitable for molding applications such as electrical and electronic parts and potting processing applications.

The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems.
That is, the present invention is a copolyester resin containing an aromatic dicarboxylic acid and a dimer acid as an acid component and 1,4-butanediol and polybutadiene glycol as a glycol component, The dimer acid content is 10 to 50 mol%, the 1,4-butanediol content in the glycol component is 80 mol% or more, and the polybutadiene glycol content in the glycol component is 1 to 20 mol%. And a copolyester resin characterized by containing an inorganic crystal nucleating agent and having a content in the copolyester resin of 0.01 to 5.0% by mass.

The copolymer polyester resin of the present invention contains a dimer acid as an acid component and a specific amount of polybutadiene glycol as a glycol component. Therefore, the copolymer polyester resin has excellent flexibility at room temperature, has an appropriate hardness, and is brittle. Is improved and has excellent wet heat durability. Furthermore, since it contains a specific amount of an inorganic crystal nucleating agent, it has excellent crystal performance.
Therefore, the copolymerized polyester resin of the present invention can be used for molded articles such as films, fibers, sheets, etc., and can also be used for adhesives, and can be used for various applications. The copolymer polyester resin of the present invention is excellent in fluidity at the time of melting and can be injection-molded at a low pressure. Therefore, it can be melt-molded even for parts having thin walls or complicated shapes, and is suitable for molding applications. Can be used. Moreover, it can use suitably also for the potting use which puts components in a housing or a base | substrate, casts resin in this, and integrates a housing, a board | substrate, and components.
And since the copolyester resin of the present invention is excellent in wet heat durability, it can be suitably used for parts that can be used even in harsh environments such as electrical / electronic parts or automobile parts. . Furthermore, since the crystal performance is also high, when obtaining a molded product, it is possible to obtain the product in a short molding cycle, and the operability is excellent.

Hereinafter, the present invention will be described in detail.
The copolyester resin of the present invention comprises an acid component containing an aromatic dicarboxylic acid and a dimer acid, and a glycol component containing 1,4-butanediol and polybutadiene glycol.
First, the acid component will be described. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, and the like. Derivatives may be used.

  The aromatic dicarboxylic acid contributes to increasing the melting point of the copolyester, imparting heat resistance and increasing mechanical strength, and the content in the acid component is preferably 50 to 90 mol%. . When the content of the aromatic dicarboxylic acid is less than 50 mol%, the melting point of the copolyester becomes low, the heat resistance is inferior, and the mechanical strength tends to be low. On the other hand, when it exceeds 90 mol%, the ratio of dimer acid decreases, and the flexibility of the copolyester resin tends to be poor.

  The dimer acid in the present invention is obtained by thermally polymerizing an unsaturated fatty acid such as a refined vegetable fatty acid obtained from a drying oil or semi-drying oil, or by partially or completely hydrogenating it. Saturated fatty acid. These dimer acids are mainly composed of dimers of unsaturated fatty acids or hydrogenated products thereof, but also include trimers and tetramers. Commercially available products such as “Pripole”, “Plyplast” (manufactured by Croda), “Enpole”, “Sobamol” (manufactured by Cognis), “Unidim” (manufactured by Arizona Chemical) and the like can be used.

  And content of dimer acid in an acid component needs to be 10-50 mol%, and it is preferable that it is 15-40 mol% especially. By containing dimer acid as a copolymerization component, the resulting copolymerized polyester resin has excellent flexibility. Moreover, wet heat durability is also improved. When the content of the dimer acid in the acid component is less than 10 mol%, it becomes difficult to impart flexibility to the resulting copolyester resin, and the effect of improving wet heat durability is poor. On the other hand, when the content of dimer acid exceeds 50 mol%, the melting point of the resulting copolyester is lowered, the crystal performance is inferior, the moldability is inferior, the heat resistance is also inferior, and the mechanical strength is reduced. Tends to be low.

  The copolyester resin of the present invention contains the aromatic dicarboxylic acid and dimer acid as described above in the acid component, but other components are contained as long as the effects of the present invention are not impaired. It may be. Examples of such other components include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and eicosanedioic acid.

  The copolymerized polyester resin of the present invention contains 1,4-butanediol as a glycol component. The content of 1,4-butanediol in the glycol component is 80 mol% or more, and preferably 85 to 98 mol%. By containing 80 mol% or more of 1,4-butanediol as the glycol component, the resulting copolymer polyester resin has a high melting point, excellent heat resistance, and excellent moldability. When 1,2-ethylene glycol is used instead of 1,4-butanediol, the resulting copolymer polyester resin has a low crystallization rate and poor moldability. When 1,6-hexanediol is used instead of 1,4-butanediol, the resulting copolymer polyester has a low melting point and is inferior in heat resistance.

Furthermore, polybutadiene glycol is contained in the glycol component of the copolyester resin of the present invention. The content of polybutadiene glycol in the glycol component is required to be 1 to 20 mol%, preferably 2 to 18 mol%, more preferably 3 to 16 mol%.
When polybutadiene glycol is contained in the glycol component, the resulting copolymer polyester resin is excellent in flexibility and wet heat durability. When the proportion of polybutadiene glycol is less than 1 mol%, it is difficult to make the resulting copolyester resin excellent in flexibility and wet heat durability. On the other hand, when the proportion of polybutadiene glycol exceeds 20 mol%, the resulting copolymerized polyester has a low melting point, poor crystal performance, inferior moldability, inferior heat resistance, and mechanical strength. It tends to be low.

  The polybutadiene glycol preferably has an average molecular weight of 350 to 6000, and more preferably 500 to 4500. When the average molecular weight of the polybutadiene glycol exceeds 6000, the compatibility is deteriorated and copolymerization tends to be difficult. On the other hand, if the molecular weight is less than 350, it tends to be difficult to improve the flexibility of the resulting copolymerized polyester resin.

  As the polybutadiene glycol, 1,2-polybutadiene glycol, 1,4-polybutadiene glycol, or the like can be used. Examples of such commercially available polybutadiene glycol include “G-1000”, “G-2000”, “G-3000”, “GI-1000”, “GI-2000”, “GI-” manufactured by Nippon Soda Co., Ltd. 3000 ”,“ Poly bd ”,“ Poly ip ”,“ Epaul ”, etc., manufactured by Idemitsu Petrochemical Co., Ltd.

  In the copolymerized polyester resin of the present invention, components other than 1,4-butanediol and polybutadiene glycol may be contained in the glycol component as long as the effects of the present invention are not impaired. Examples of such other components include ethylene glycol, propylene glycol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, bisphenol A ethylene oxide adduct and propylene oxide. Examples include adducts, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Furthermore, the copolyester resin of the present invention contains an inorganic crystal nucleating agent. The content of the inorganic crystal nucleating agent in the copolymerized polyester resin needs to be 0.01 to 5.0% by mass, and preferably 0.1 to 3.0% by mass. By containing an appropriate amount of the inorganic crystal nucleating agent, the crystal performance can be improved without impairing the flexibility and wet heat durability performance of the copolyester resin.
When the content of the inorganic crystal nucleating agent is less than 0.01% by mass, the crystal performance of the copolyester resin cannot be improved, and the moldability is inferior. On the other hand, the content of the inorganic crystal nucleating agent is low. When it exceeds 5.0 mass%, the softness | flexibility of copolyester resin will be impaired especially.

  As the inorganic crystal nucleating agent in the present invention, carbon black, silica, calcium carbonate, synthetic silicic acid and silicate, zinc white, halocyto clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatom Examples include soil, dolomite cake, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, and the like, and it is preferable to use at least one of these inorganic compounds. Among them, as the inorganic crystal nucleating agent in the present invention, it is preferable to use at least one of talc, mica, kaolin, and silica, and it is preferable to use talc.

And as a parameter | index which shows that the copolyester resin of this invention is excellent in crystal | crystallization performance, it is preferable that the DSC curve which shows the temperature-fall crystallization calculated | required from DSC satisfies following formula (1).
b / a ≧ 0.05 (mW / mg · ° C.) (1)

  The DSC curve showing the temperature-falling crystallization obtained from the DSC of the copolyester resin in the present invention is a temperature range of -20 ° C to 250 ° C in a nitrogen stream using a differential scanning calorimeter (Diamond DSC) manufactured by PerkinElmer. The temperature is measured at a rate of temperature increase (temperature decrease) of 20 ° C./min and a sample amount of 2 mg.

  Said b / a is calculated | required from the DSC curve which shows the temperature-fall crystallization calculated | required from DSC. As shown in FIG. 1, in the DSC curve of the polyester resin, a is the temperature A1 (° C.) at the intersection of the tangent line and the base line where the slope is maximum in the DSC curve indicating the temperature drop crystallization, and the slope is the minimum. The difference (A1−A2) between the temperature A2 (° C.) at the intersection of the tangent line and the baseline, and b is the heat amount B1 (mW) of the baseline and the heat amount B2 (mW) of the peak top at the peak top temperature. It is a value obtained by dividing the difference (B1-B2) by the sample amount (mg).

  b / a is an index representing the crystallinity when the temperature is lowered, and the higher the b / a value, the faster the crystallization rate, and vice versa, the closer to 0, the slower the crystallization rate. That is, the higher the value of b / a, the better the crystallinity at lowering the temperature, so that a molded product can be obtained in a short molding cycle and the productivity is excellent. On the other hand, when b / a is less than 0.05 (mW / mg · ° C.), the crystallization rate is slow, so the molding cycle for obtaining a molded product becomes long and the productivity is poor. In addition, blocking tends to occur when the polyester resin is chipped, stored or transported, or in the drying process.

The copolymer polyester resin of the present invention is excellent in flexibility by having the composition as described above, but as an index indicating flexibility, the Young's modulus at 20 ° C. is preferably 100 MPa or less, and in particular, 60 MPa. The following is preferable.
The Young's modulus is injection molded using the PS20E2ASE injection molding machine “PS20E2ASE” manufactured by Nissei Plastic Industry Co., Ltd., to produce a molded sample having a thickness of 1 mm and a width of 3 mm. (UTM-4-100 type manufactured by Orientec Co., Ltd.) is used and measured at 20 ° C. and a tensile speed of 10 mm / min.

Furthermore, the copolyester resin of the present invention is excellent in flexibility by having the composition as described above, and at the same time has an appropriate hardness and improved brittleness. As an index indicating such moderate hardness and improved brittleness, the Shore D hardness at 20 ° C. is preferably 50 or less, and particularly preferably 46 or less.
For the Shore D hardness, the copolymer polyester resin of the present invention was injection molded using an injection molding machine “PS20E2ASE” manufactured by Nissei Plastic Industry Co., Ltd., and a molded sample having a thickness of 3 mm and a width of 20 mm was created. In addition, it is measured using a Shore D hardness meter (WESTOP WR-105D) at 20 ° C.

  If the Young's modulus at 20 ° C. exceeds 100 MPa, the copolymer polyester resin tends to be poor in flexibility. When the Shore D hardness at 20 ° C. exceeds 50, the copolymer polyester resin becomes a brittle resin with insufficient hardness, and is likely to be difficult to use for various applications.

  The copolyester resin of the present invention is excellent in flexibility by having the composition as described above, has moderate hardness and improved brittleness, but has a Young's modulus at 20 ° C. And Shore D hardness at 20 ° C. are preferably within the above range.

Furthermore, the copolyester resin of the present invention is excellent in wet heat durability by having the above composition. As an index showing wet heat durability, the strain retention shown below is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. When the strain retention is less than 80%, the strength of the resin is greatly reduced by wet heat treatment, and a molded body using such a resin is inferior in shape stability. That is, the resin is inferior in wet heat durability.
The strain retention rate in the present invention is calculated as follows. Using the injection molding machine “PS20E2ASE” manufactured by Nissei Plastic Industry Co., Ltd., the copolymerized polyester resin of the present invention was injection-molded into a mold at a pressure of 1 MPa at a temperature of 50 ° C. higher than the melting point. A molded sample having a width of 3 mm is prepared, and tensile fracture strain is measured according to the method described in ISO standard 527-2 (tensile fracture strain before treatment). Using a thermo-hygrostat (IG400 type manufactured by Yamato Kagaku Co., Ltd.), the obtained molded sample is stored for 200 hours in an environment of a temperature of 60 ° C. and a humidity of 95% RH, and is subjected to a wet heat treatment. The tensile fracture strain of the sample after the wet heat treatment is measured in the same manner as described above, and is calculated by the following formula.
Strain retention (%) = [(Tensile fracture strain after treatment) / (Tensile fracture strain before treatment)] × 100

The copolyester resin of the present invention is also excellent in heat resistance, and the melting point is preferably 120 to 180 ° C, and more preferably 130 to 170 ° C. When the melting point is less than 120 ° C., the heat resistance is poor, and the use is limited. On the other hand, if it exceeds 180 ° C., it is necessary to increase the processing temperature at the time of molding, which is disadvantageous in terms of cost, and at the same time, thermal degradation of the resin also increases.
The melting point is measured by using a Perkin Elmer Diamond DSC, raising and lowering the temperature at 10 ° C./min, and the melting peak temperature.

The copolymer polyester resin of the present invention preferably has a melt viscosity at 200 ° C. of 1 Pa · s to 300 Pa · s, and more preferably 10 to 150 Pa · s. When the melt viscosity is within this range, molding at a low pressure is possible, which is suitable for hot melt molding applications and potting applications. When the melt viscosity exceeds 300 Pa · s, the fluidity becomes low and molding at low pressure becomes difficult. Further, when the melting temperature is increased in order to reduce the melt viscosity, the load on the apparatus is increased and the thermal deterioration of the copolyester resin becomes remarkable. On the other hand, when the melt viscosity is less than 1 Pa · s, the strength of the copolyester resin tends to be low.
The melt viscosity is measured by a flow tester (manufactured by Shimadzu Corporation, model CFT-500) using a nozzle having a nozzle diameter of 1.0 mm and a nozzle length of 10 mm and a shear rate of 1000 sec ^−1. is there.

  Next, the manufacturing method of the copolyester resin of this invention is demonstrated. After the esterification reaction of the above acid component, glycol component and inorganic crystal nucleating agent at 150 to 250 ° C., the copolymer polyester resin of the present invention can be obtained by polycondensation at 230 to 300 ° C. while reducing the pressure. . Alternatively, by a transesterification reaction at 150 ° C. to 250 ° C. using a derivative such as dimethyl ester of an aromatic dicarboxylic acid, a glycol component, and an inorganic crystal nucleating agent, and polycondensation at 230 ° C. to 300 ° C. while reducing the pressure, The copolymerized polyester resin of the present invention can be obtained.

The copolymerized polyester resin of the present invention has a pigment, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a plasticizer, a lubricant, a release agent, an antistatic agent, and a filler as long as the properties are not significantly impaired. Etc. may be added.
Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. As the flame retardant, a halogen-based flame retardant, a phosphorus-based flame retardant, and an inorganic flame retardant can be used. However, in consideration of the environment, it is desirable to use a non-halogen flame retardant. Non-halogen flame retardants include phosphorus flame retardants, hydrated metal compounds (aluminum hydroxide, magnesium hydroxide, etc.), nitrogen-containing compounds (melamine-based, guanidine-based), inorganic compounds (borates, Mo compounds, etc.) Is mentioned. In addition, the method of adding these to the copolyester resin of this invention is not specifically limited.

  Moreover, when using the copolyester resin of the present invention, polyethylene, polypropylene, polybutadiene, polystyrene, AS resin, ABS resin, poly (acrylic acid), poly (acrylic acid ester), as long as the effect is not impaired. A resin such as poly (methacrylic acid), poly (methacrylic acid ester), polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and a copolymer thereof may be added and used.

Next, the present invention will be specifically described using examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(1) Melting point, melt viscosity, DSC curve showing temperature drop crystallization determined from DSC Measurement was performed in the same manner as above.
(2) Polymer composition The obtained copolymer polyester resin was dissolved in a mixed solvent having a volume ratio of 1/20 of deuterated hexafluoroisopropanol and deuterated chloroform, and the LA-400 NMR apparatus manufactured by JEOL Ltd. was used. 1H-NMR was measured and determined from the integrated intensity of the proton peak of each copolymer component in the obtained chart.
(3) Shore D hardness, Young's modulus It measured by the method similar to the above.
(4) Tensile fracture strain, strain retention (wet heat durability)
It measured by the method similar to the above.
(5) Tensile strength Using a molding sample obtained in the same manner as in (4), using a tensile tester “Tensilon” (UTM-4-100 manufactured by Orientec Co., Ltd.), a tensile rate of 10 mm / min at 20 ° C. It is to measure with.
(6) Formability (molding cycle)
An ISO dumbbell-shaped test piece was molded with an injection molding machine (trade name “IS-80G” manufactured by Toshiba Machine Co., Ltd.). The resin composition was melted at a molding temperature 50 ° C. higher than the melting point, and filled in a mold having a mold temperature of 20 ° C. When the resin composition is injected into the mold, the total of the injection time and the pressure applied after the injection is 10 seconds, and then the molded body can be fixed to the mold or taken out without resistance. The total time (molding cycle) (seconds) with the time required to release the mold without any deformation due to the protruding pin was measured and evaluated according to the following criteria.
A: Required time is 15 seconds or less.
○: The required time is longer than 15 seconds and shorter than 20 seconds.
X: The required time exceeds 20 seconds.

Example 1
As an acid component, 62 parts by mass of terephthalic acid, 9 parts by mass of isophthalic acid, 74 parts by mass of hydrogenated dimer acid having 36 carbon atoms (Pripol 1009, manufactured by Croder Japan), and 64 parts by mass of 1,4-butanediol as a diol component Part, 1,2-polybutadiene glycol (manufactured by Nippon Soda Co., Ltd., GI-1000), 2 parts by mass of tetra-n-butyl titanate was added, and the mixture was heated to 240 ° C. to carry out the esterification reaction. . Next, talc having an average particle diameter of 1.0 μm is added as an inorganic crystal nucleating agent in such an amount that the content in the resulting copolymerized polyester resin becomes 1.0% by mass, and gradually, at a temperature of 240 ° C. over 60 minutes. While raising the degree of vacuum to 10-30 Pa, a polycondensation reaction was performed for 4 hours to obtain a copolyester resin having the composition shown in Table 1.

Examples 2-10, Comparative Examples 1-2, 5-10
Other than changing the type and amount of addition of terephthalic acid, isophthalic acid, hydrogenated dimer acid, 1,4-butanediol, 1,2-polybutadiene glycol, talc, and the composition (content) shown in Table 1 Was carried out in the same manner as in Example 1 to obtain a copolyester resin. In Example 5, as the dimer acid, a dimer acid having 36 carbon atoms (Cropder Japan, Pripol 1013) was used. In Example 9, talc having an average particle diameter of 2.0 μm was used. In Example 10, GI-2000 manufactured by Nippon Soda Co., Ltd. was used as 1,2-polybutadiene glycol.

Comparative Example 3
The same procedure as in Example 1 was conducted except that 1,4-butanediol and 1,6-hexanediol were used as glycol components, and the composition (content) shown in Table 1 was used. Obtained.

Comparative Example 4
A copolymer polyester resin was obtained in the same manner as in Example 1 except that only 1,6-hexanediol was used as the glycol component and the composition (content) shown in Table 1 was used.

  Table 1 shows the compositions, characteristic values, and evaluation results of the copolyester resins obtained in Examples 1 to 10 and Comparative Examples 1 to 10.

As is clear from Table 1, the copolymer polyester resins obtained in Examples 1 to 10 had a composition satisfying the present invention, so the Young's modulus at 20 ° C. was 53 MPa or less and the shore at 20 ° C. The D hardness was 46 or less, excellent flexibility, moderate hardness, and improved brittleness. And the value of tensile fracture strain and the retention rate were both high, and it was excellent in strength and wet heat durability. Furthermore, since the crystal performance is high and the DSC curve indicating the temperature drop crystallization obtained from DSC satisfies the formula (1), a molded product can be obtained in a short molding cycle, and the moldability can be evaluated. It was excellent.
On the other hand, the copolymerized polyester resin obtained in Comparative Example 1 has a low content of dimer acid in the acid component, and therefore has a high Shore D hardness, Young's modulus and poor flexibility, and a strain retention rate. Was low and inferior in wet heat durability. The copolymerized polyester resin obtained in Comparative Example 2 had a high content of dimer acid in the acid component and a low content of aromatic dicarboxylic acid, so the melting point could not be measured (non-crystalline one). It was inferior in heat resistance, crystal performance, and moldability. Moreover, the tensile strength was also inferior. Since the copolymer polyester resin obtained in Comparative Example 3 had a ratio of 1,4-butanediol as the diol component of less than 80 mol%, the copolymer polyester resin obtained in Comparative Example 4 was 1 as the diol component. However, both resins were low in melting point and inferior in heat resistance. Further, the crystal performance was inferior, the DSC curve did not satisfy the formula (1), the molding cycle was long, and the moldability was inferior. Since the copolymer polyester resin obtained in Comparative Example 5 did not contain polybutadiene glycol as a glycol component, the copolymer polyester resin obtained in Comparative Example 6 had a low content of polybutadiene glycol as a glycol component. The Young's modulus and Shore D hardness were high and the flexibility was poor, and the strain retention was low and the wet heat durability was poor. The copolymerized polyester resin obtained in Comparative Example 7 contained too much polybutadiene glycol as a glycol component, so the melting point was low, the heat resistance was inferior, the crystal performance was inferior, and the DSC curve satisfied the formula (1). However, the molding cycle was long and the evaluation of moldability was inferior. Moreover, the tensile strength was also inferior. Since the copolyester resin obtained in Comparative Example 8 did not contain an inorganic crystal nucleating agent, the copolyester resin obtained in Comparative Example 9 had too little content of the inorganic crystal nucleating agent. In either case, the crystal performance was inferior, the DSC curve did not satisfy the formula (1), the molding cycle was long, and the moldability was inferior. The copolymerized polyester resin obtained in Comparative Example 10 had a high Young's modulus and poor flexibility because the content of the inorganic crystal nucleating agent was too large.

Claims (5)

A copolymer polyester resin containing an aromatic dicarboxylic acid and a dimer acid as an acid component, and 1,4-butanediol and polybutadiene glycol as a glycol component, the content of the dimer acid in the acid component 10 to 50 mol%, the content of 1,4-butanediol in the glycol component is 80 mol% or more, the content of polybutadiene glycol in the glycol component is 1 to 20 mol%, and inorganic crystals A copolyester resin comprising a nucleating agent and having a content in the copolyester resin of 0.01 to 5.0% by mass. The copolymer polyester resin according to claim 1, wherein the inorganic crystal nucleating agent is at least one of talc, mica, kaolin, and silica. The copolyester resin according to claim 1 or 2, wherein the DSC curve showing the temperature-falling crystallization obtained from DSC satisfies the following formula (1).
b / a ≧ 0.05 (mW / mg · ° C.) (1)
Note that a is the temperature A1 (° C.) of the intersection between the tangent line and the baseline having the maximum inclination in the DSC curve indicating the temperature-falling crystallization, and the temperature A2 (° C.) of the intersection of the tangent line and the baseline having the minimum inclination. B) is the difference (B1-B2) between the baseline heat quantity B1 (mW) and the peak top heat quantity B2 (mW) at the peak top temperature (mg) The value divided by. The copolyester resin according to any one of claims 1 to 3, wherein Young's modulus at 20 ° C is 100 MPa or less. The copolymer polyester resin according to any one of claims 1 to 4, which has a Shore D hardness of 50 or less at 20 ° C.