JP7600984B2 - Polyester elastomer resin and blow moldings - Google Patents

Description

The present invention relates to a polyester elastomer resin suitable for blow molding. More specifically, the present invention relates to a polyester elastomer resin that has good shear rate dependency of melt viscosity characteristics and can achieve both inner surface smoothness and good moldability of blow molded products.

Polyester elastomer blow molded products have been widely used as air duct products for automobiles to reduce weight compared to metal ducts. Recently, the demands on the shape of air duct products have been increasing in line with the trend to save space in engine rooms, and there has been active progress in making air duct products with more complex shapes, thinner walls, and longer lengths.

On the other hand, in order to reduce the number of parts and labor, quick connectors with a crimped structure are being used at the connections between air duct products and surrounding parts, and from the standpoint of sealing the connections, the smoothness of the inner surface of the molded product is an extremely important requirement.

As the shape of air duct products changes, it is becoming more difficult to ensure smoothness of the inner surface of the molded product. In some cases, special blow molding methods are used, such as 3D blow molding to create 3D shapes and suction blow molding, which forces the parison to follow the shape before blow molding.

One of the reasons why good inner surface smoothness cannot be obtained is the melt fracture phenomenon, which occurs due to excessively high melt viscosity characteristics when passing through the die of the blow molding machine. The melt fracture phenomenon is caused by disturbances in the resin flow due to high shear stress on the molten resin. Therefore, in order to suppress the melt fracture phenomenon, it is necessary to lower the melt viscosity when high shear stress is applied. Increasing the molding temperature and using a material with low viscosity are effective ways to ensure inner surface smoothness, but on the other hand, molding defects such as drawdown of the parison, unstable shape when blowing, and tearing occur.

Based on the above, it is believed that molding materials that can be used for various blow molding processes are suitable and preferable to have high melt viscosity in the low shear rate region, excellent drawdown resistance and shape stability during blowing, and low melt viscosity in the high shear rate region, in other words, materials whose melt viscosity has a high shear rate dependency.

Various attempts have been made to improve the melt viscosity characteristics of polyester elastomers, but there have been few effective studies on the shear rate dependency of melt viscosity.
For example, Patent Document 1 discusses molding stability in blow molding of complex shapes, but does not go so far as to discuss melt viscosity characteristics in depth.
Furthermore, in Patent Document 2, a resin that has excellent moldability not only in blow molding but also in injection blow molding, extrusion molding, and injection molding is discussed. However, the shear rate dependency of melt viscosity is not discussed, and it is considered that a poor appearance (melt fracture phenomenon) occurs when a high shear rate is applied.
Furthermore, in Patent Document 3, the melt viscosity characteristics are improved by using a glycidyl group-modified olefin resin composition, but since the chain is extended by reaction with the polyester elastomer resin composition, it is considered that the shear rate dependency of the melt viscosity is small.

Patent No. 5066822 JP 2017-043687 A Patent No. 5786256

The object of the present invention is to provide a polyester elastomer resin that can suppress the roughness of the inner surface of a blow-molded product caused by the melt fracture phenomenon in blow molding, which requires molding technology, and can simultaneously achieve good moldability such as shape stabilization of the parison and molded product and reduction of thickness deviation.

The inventors have discovered that by appropriately combining tri- or higher functional components and block copolymers having a number average molecular weight of 1,000 to 4,000, the melt viscosity can be effectively increased, and excellent melt viscosity characteristics that exhibit shear rate dependency that can be used in various types of blow molding can be achieved, thereby arriving at the present invention.
That is, the present invention is as follows.
[1] A polyester elastomer resin comprising, as constituent components, an acid component containing an aromatic dicarboxylic acid, an aliphatic and/or alicyclic diol, and an alcohol component containing a polyalkylene glycol, the polyester elastomer resin contains, as a copolymerization component, 0 to 1.0 mol% of one or more trifunctional or higher functional components when the total acid components are 100 mol% and the total alcohol components are 100 mol%, the polyalkylene glycol is a block copolymer and has a number average molecular weight of 1,000 to 4,000;
A polyester elastomer resin characterized in that, as a melt viscosity characteristic measured with a capillary rheometer, the polyester elastomer resin has a melt viscosity of 6,000 Pa·s or more at a shear rate of 6.08 sec ^-1 , measured at a temperature that is 20°C or more higher than the melting point of the polyester elastomer resin and at which the melt viscosity at a shear rate of 6,080 sec ^-1 is 120 Pa·s.
[2] The polyester elastomer resin according to [1], wherein the polyalkylene glycol is polyoxyethylene polyoxypropylene glycol.
[3] The polyester elastomer resin according to [1], wherein the polyalkylene glycol is a block copolymer having a polyethylene glycol (PEG)-polypropylene glycol (PPG)-polyethylene glycol (PEG) structure.
[4] The polyester elastomer resin according to [2] or [3], wherein the propylene glycol component contained in the polyester elastomer resin is 18% by mass or more in the polyester elastomer resin.
[5] The polyester elastomer resin according to any one of [1] to [4], wherein the tri- or higher functional component is an acid component.
[6] The polyester elastomer resin according to any one of [1] to [5], wherein the tri- or higher functional component is trimellitic acid.
[7] A blow molded product comprising the polyester elastomer resin according to any one of [1] to [6].

The polyester elastomer resin of the present invention is a polyester elastomer resin whose constituent components are an acid component containing an aromatic dicarboxylic acid, an aliphatic and/or alicyclic diol, and an alcohol component containing a polyalkylene glycol, and is a resin that contains 0 to 1.0 mol% of one or more trifunctional or higher components as copolymerization components when the total acid components are 100 mol% and the total alcohol components are 100 mol%. The polyester elastomer resin of the present invention is a block copolymer in which a hard segment made of a polyester whose constituent components are an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol is bonded to a soft segment whose constituent component is a polyalkylene glycol.

In the polyester elastomer resin of the present invention, the aromatic dicarboxylic acid is not particularly limited, but examples of the main aromatic dicarboxylic acid include terephthalic acid, and examples of other aromatic dicarboxylic acids include isophthalic acid, naphthalene-2,6-dicarboxylic acid, etc. Two or more of these acid components may be copolymerized.
When the total acid components constituting the polyester elastomer resin is taken as 100 mol %, the aromatic dicarboxylic acid preferably accounts for 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more.

When the total acid components constituting the polyester elastomer resin are taken as 100 mol %, terephthalic acid is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 85 mol % or more. In this case, it is also a preferred embodiment to contain 2 to 15 mol % of an aromatic dicarboxylic acid other than terephthalic acid, particularly isophthalic acid, from the viewpoint of melt viscosity characteristics.
As the acid component constituting the polyester elastomer resin, an aliphatic dicarboxylic acid and/or an alicyclic dicarboxylic acid may also be used so long as it is 30 mol % or less.

In the polyester elastomer resin of the present invention, the aliphatic and/or alicyclic diol is not particularly limited, but is preferably an alkylene glycol having 2 to 8 carbon atoms. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Of these, in order to impart heat resistance, either ethylene glycol or 1,4-butanediol is preferred, and 1,4-butanediol is more preferred.

When the total alcohol components constituting the polyester elastomer resin are taken as 100 mol%, the aliphatic and/or alicyclic diols preferably account for a total of 70 mol% or more and 98 mol% or less, more preferably 80 mol% or more and 97 mol% or less, and even more preferably 85 mol% or more and 97 mol% or less.

In the polyester elastomer resin of the present invention, the polyalkylene glycol has a number average molecular weight between 1000 and 4000. If the number average molecular weight is less than 1000, the blocking property of the polyester elastomer resin is low, and the low temperature characteristics required for duct products are not met. On the other hand, if it exceeds 4000, the compatibility of the hard segment and the soft segment decreases, resulting in reduced physical properties. A more preferred range of number average molecular weight is 1000 to 3600, and even more preferably 1000 to 3500.

Furthermore, in the present invention, the polyalkylene glycol is a block copolymer. Common polyalkylene glycols include polyethylene glycol (PEG), polypropylene glycol (PEG), polytetramethylene glycol, polyhexamethylene oxide glycol, and polyneopentyl glycol. On the other hand, common block copolymers include polyoxyethylene polyoxypropylene glycol (copolymer of polyethylene glycol and polypropylene glycol), copolymer of polyneopentyl glycol and polyethylene glycol, and ethylene oxide addition polymer to polypropylene glycol terminal. These copolymers have the characteristics of each of the polyalkylene glycols that constitute them, and can obtain a composite effect that compensates for the shortcomings of each glycol.

For example, among polyoxyethylene polyoxypropylene glycols, those called Pluronic (registered trademark) type are common, and those having a polyethylene glycol (PEG)-polypropylene glycol (PPG)-polyethylene glycol (PEG) structure (including the above-mentioned ethylene oxide addition polymer to the polypropylene glycol terminal) are preferably used. By adopting a structure in which PEG is present at both terminals of PPG, which has a methyl group in the side chain and a rigidified resin skeleton, it is possible to enhance the reaction efficiency by compensating for the low reactivity of the secondary hydroxyl group terminal, which is a drawback of PPG, in addition to the shear rate-dependent effect of the melt viscosity due to the rigidification, which is a characteristic of PPG.
A preferred block copolymer is polyoxyethylene polyoxypropylene glycol because of its availability, and a more preferred block copolymer is one having a polyethylene glycol (PEG)-polypropylene glycol (PPG)-polyethylene glycol (PEG) structure.

The propylene glycol component (oxypropylene unit) contained (copolymerized) in the polyester elastomer resin of the present invention is preferably 18% by mass or more in the polyester elastomer resin, more preferably 20% by mass or more. It is believed that the shear rate dependency of the melt viscosity is expressed due to the rigidification of the resin skeleton caused by the methyl group of propylene glycol, so the higher the propylene glycol content, the better the shear rate dependency of the melt viscosity. A content of less than 18% by mass has a small contribution to the melt viscosity and may not satisfy good moldability. The propylene glycol component contained in the polyester elastomer resin is preferably less than 40% by mass in the polyester elastomer resin, more preferably 35% by mass or less.

When the total alcohol components constituting the polyester elastomer resin are taken as 100 mol%, the polyalkylene glycol is preferably 2 mol% or more and 30 mol% or less, more preferably 3 mol% or more and 20 mol% or less, and even more preferably 3 mol% or more and 15 mol% or less.

In a preferred embodiment, the polyester elastomer resin of the present invention contains one or more trifunctional or higher functional components as copolymerization components. By copolymerizing a trifunctional or higher functional component into the polyester elastomer resin, branching can be introduced into the polyester elastomer resin skeleton, improving the shear rate dependency of the melt viscosity, but the trifunctional or higher functional component is not particularly limited. The component may be either an acid component or an alcohol component, and two or more components may be copolymerized.

Examples of trifunctional or higher acid components include 1,1,2,2-ethanetetracarboxylic acid, citric acid, 3-hydroxyglutaric acid and dihydroxyglutaric acid, trimellitic acid, trimesic acid, pyromellitic acid, etc.

Examples of trifunctional or higher alcohol components include triols such as glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane, and 2-hydroxy-2-methyl-1,4-butanediol, tetraols such as ditrimethylolpropane and pentaerythritol, dipentaerythritol, polyglycerin, as well as trimethylolpropane ethylene oxide adduct, trimethylolpropane propylene oxide adduct, trimethylolpropane tetrahydrofuran adduct, trimethylolpropane caprolactone adduct, pentaerythritol ethylene oxide adduct, pentaerythritol propylene oxide adduct, pentaerythritol tetrahydrofuran adduct, pentaerythritol caprolactone adduct, dipentaerythritol ethylene oxide adduct, dipentaerythritol propylene oxide adduct, dipentaerythritol tetrahydrofuran adduct, and dipentaerythritol caprolactone adduct.

The trifunctional or higher alcohol component may be a polyalkylene glycol. For example, polyethylene glycol or polypropylene glycol may have a trifunctional or higher polyol such as glycerin attached to the terminal. The combination of the additional component and the polyether component is not particularly limited.

As the trifunctional or higher functional component, an acid component is preferable, and with a trifunctional or higher functional acid component, branching can be effectively introduced into both the hard segment and the soft segment. Furthermore, a trifunctional acid component is more preferable, and trimellitic acid is particularly preferable. Since a large number of functional groups reduces the continuous production stability during polymerization of the polyester elastomer, a trifunctional acid component is more preferable, and among them, trimellitic acid, which has a highly heat-resistant aromatic ring as a skeleton and is inexpensive, is particularly preferable. Trimellitic anhydride and methyl esters of trimellitic acid can also be used as raw materials for polymerizing polyester elastomer resins.

The blending (copolymerization) amount of trifunctional or higher components is 0 to 1.0 mol%, and more preferably 0 to 0.7 mol%, when the total acid components and the total alcohol components constituting the polyester elastomer resin are 100 mol%, and 100 mol%, respectively. If the copolymerization amount exceeds 1.0 mol%, gelation occurs in batch polymerization, making machine cleaning necessary, and the yield during polymerization and continuous productivity decrease. The copolymerization amount of trifunctional or higher components may be 0 mol% by appropriately selecting a polyalkylene glycol that is effective for improving melt viscosity, such as PEG-PPG-PEG, which has a large PPG content. In order to further exert the effects of the present invention, it is preferable to copolymerize trifunctional or higher components, and in that case, it is preferable that the amount is 0.05 to 0.7 mol%, and more preferably 0.1 to 0.5 mol%.

The hardness of the polyester elastomer resin of the present invention is preferably 40 or more and 60 or less, more preferably 46 or more and 55 or less, in Shore D hardness. If the hardness is less than 40, the hardness is too low and there is a risk of tearing when repeatedly pressurized, and if the hardness exceeds 60, the hardness is too high and the elongation of the product is reduced, and there is a risk of cracking when repeatedly pressurized.

The polyester elastomer resin of the present invention has high shear rate dependency in melt viscosity.
The present inventors have found the following points through intensive research. A good smoothness of the inner surface of a blow molded article can be obtained without the occurrence of melt fracture when the melt viscosity (a) at a shear rate of 6080 sec ^-1 measured by a capillary rheometer is 120 Pa·s or less. Therefore, it can be said that the shear rate dependency is good when the melt viscosity (b) at a shear rate of 6.08 sec ^-1 is large at the measurement temperature at which the melt viscosity (a) at a shear rate of 6080 sec ^-1 is 120 Pa·s. In general, when (b) is 6000 Pa·s or more, drawdown does not occur during molding, and good moldability that allows continuous molding is shown. The larger (b) is, the better the moldability is, and more preferably (b) is 8000 Pa·s or more, and even more preferably 9000 Pa·s or more. The upper limit of (b) is not particularly limited, but is preferably 16000 Pa·s or less.
The melt viscosity is measured using a capillary rheometer. However, in actual blow molding, the temperature is set to be at least 20° C. higher than the melting point of the resin, taking into account the load on the molding machine. Therefore, the measurement temperature is set to be at least 20° C. higher than the melting point, just like in the actual molding.

The polyester elastomer resin of the present invention can be polymerized using a typical polyester elastomer manufacturing method, and there are no particular limitations on the catalyst used during polymerization, and typical catalysts can be used.

The reduced viscosity of the polyester elastomer resin is not particularly specified, but is preferably 2.0 dl/g or more, more preferably 2.2 dl/g or more, so that the melt viscosity (b) at a shear rate of 6.08 sec ^-1 reaches 6000 Pa.s or more. If the reduced viscosity exceeds 3.0 dl/g, the measurement temperature for making the melt viscosity (a) at a shear rate of 6080 sec ^-1 120 Pa.s exceeds 270°C, and the contribution of the decomposition behavior of the resin to the molding temperature of the polyester elastomer resin becomes large, so the reduced viscosity is preferably 2.2 dl/g to 3.0 dl/g.

In addition, the method for increasing the reduced viscosity (thickening) of the polyester elastomer resin is not particularly limited. Melt polycondensation, solid-phase polymerization, and a kneading extrusion method utilizing the reaction of the terminal groups of the polyester elastomer with a thickener, such as the reaction of an acid terminal group with a glycidyl-based thickener, can also be applied.

The polyester elastomer resin of the present invention can also be used as a resin composition by blending various additives described below.
It is preferable to blend a general-purpose antioxidant such as an aromatic amine-based, hindered phenol-based, phosphorus-based, sulfur-based, etc., in the polyester elastomer resin of the present invention. The antioxidant may be blended in the polymerization stage, or may be blended by kneading extrusion after the polyester elastomer resin is obtained.

The polyester elastomer resin of the present invention can be blended with various other additives. As additives, resins other than those of the present invention, inorganic fillers, stabilizers, and antioxidants can be added to the extent that the characteristics of the present invention are not impaired.

Other additives that can be added include release agents, color pigments, inorganic and organic fillers, coupling agents, tack enhancers, quenchers, metal deactivators and other stabilizers, flame retardants, etc.

The following examples are provided to further explain the present invention, but the present invention is not limited to these examples. The measurements described in the examples were measured by the following methods.

Melt Viscosity:
Using a capillary rheometer (F-1 manufactured by Toyo Seiki Seisakusho), the melt viscosity was measured when the shear rate was changed from 0.5 mm/min (6.08 sec ^-1 ) to 500 mm/min (6080 sec ^-1 ). The measurement temperature was set to a temperature 20°C or more higher than the melting point of the polyester elastomer resin and at which the melt viscosity at a shear rate of 6080 sec ^-1 was 120 Pa·s. (Melt viscosity at a shear rate of 6080 sec ^-1 : melt viscosity (a), melt viscosity at a shear rate of 6.08 sec ^-1 : melt viscosity (b))
The nozzle shape was such that the capillary diameter was 1.0 mm and the capillary length was 10 mm.

Blow moldability evaluation:
The cylinder temperature of the direct blow molding machine (single screw extruder: L/D = 25, full flight screw, screw diameter 65 mm) was set to the measurement temperature of the melt viscosity, and a direct blow molding bottle was produced. A parison forming die lip was attached to the tip of the cylinder, and blow air was sealed in the mold to mold a bottle. The parison holding state at this time was evaluated.
⊚: No drawdown was observed and the shape was maintained.
◯: Drawdown is small and shape is maintained.
Δ: Drawdown is large and the shape tends to collapse, but blow molding is possible.
×: Drawdown is so large that the shape is distorted and blow molding is impossible.

Melting Point:
In accordance with the test method described in JIS K7121, a differential scanning calorimeter V4.0B2000 manufactured by DuPont was used in an argon atmosphere with a sample mass of 10 mg, a heating start temperature of 30° C., and a heating rate of 20° C./min. The endothermic peak temperature obtained by measurement was taken as the melting point.

Surface hardness:
The surface hardness was measured in an environment of 23° C. according to the test method (Shore D) described in ASTM D2240. Three injection molded products (width 100 mm, length 100 mm, thickness 2.0 mm) made at a cylinder temperature of the melting point of the resin + 20° C. and a mold temperature of 50° C. were stacked, and the instantaneous value of Shore D when a needle tip was dropped was read to measure the surface hardness.

Reduced Viscosity:
0.02 g of the thoroughly dried polyester elastomer resin was dissolved in 10 ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4), and the viscosity was measured at 30° C. using an Ubbelohse viscometer.

Resin compatibility:
After the resin was produced, the compatibility between the hard segment and the soft segment was evaluated by visually inspecting the appearance of the resin when molten.
◯: The molten resin is transparent and has sufficient compatibility.
Δ: The molten resin was semi-transparent (slightly cloudy), and the compatibility was low.
×: The molten resin was cloudy and the compatibility was extremely low.

Tensile elongation:
An injection molded product (width 100 mm, length 100 mm, thickness 2.0 mm) was prepared at a cylinder temperature of the melting point of the resin + 20°C and a mold temperature of 50°C. A JIS No. 3 dumbbell-shaped test piece was punched out perpendicular to the direction of resin flow. The tensile elongation (elongation at break) was then measured in accordance with JIS K6251:2010.

Example 1: A polyester elastomer resin having a terephthalic acid/trimellitic acid/1,4-butanediol/PPG-PEG#3000 ratio of 99.9/0.1/96/4 (mol%) was produced according to the method described in JP-A-9-59491. Solid-phase polymerization was then carried out to increase the reduced viscosity. The melting point of this polyester elastomer resin was 218°C, and the reduced viscosity was 2.4 dl/g.

In a similar manner, polyester elastomer resins of Examples 2 to 7 (Example 6 is a reference example) and Comparative Examples 1 to 6 were produced. The raw materials used, compositions, and evaluation results are shown in Table 1. The polyalkylene glycols used are as follows:
PPG-PEG #2900: PEG-PPG-PEG block copolymer (number average molecular weight 2900, PG/EG=60/40 (mass%), Sanyo Chemical Industries, Ltd., Newpol PE-64)
PPG-PEG#1100: PEG-PPG-PEG block copolymer (number average molecular weight 1100, PG/EG=90/10 (mass%), Adeka Pluronic L-31 manufactured by ADEKA)
PPG-PEG #4200: PEG-PPG-PEG block copolymer (number average molecular weight 4200, PG/EG=50/50 (mass%), NOF Corp. Poloxamer 185)
PEG#1000: Polyethylene glycol (number average molecular weight 1000, manufactured by NOF Corp.)
PPG#3000: Polypropylene glycol (number average molecular weight 3000, Sannix PP-3000 manufactured by Sanyo Chemical Industries)
PTMG#1000: Polytetramethylene glycol (number average molecular weight 1000, manufactured by Mitsubishi Chemical)
PTMG#3000: Polytetramethylene glycol (number average molecular weight 3000, manufactured by Mitsubishi Chemical)

The number average molecular weight of each polyalkylene glycol was measured as follows: 16 mg of polyalkylene glycol was weighed out and dissolved in 8 ml of chloroform, and the solution was filtered through a 0.2 μm membrane filter to obtain a sample solution, which was then subjected to gel permeation chromatography.
The molecular weight was calculated based on standard polystyrene.
The apparatus used was a TOSOH HLC-8320GPC, and the solvent was a mixed solvent of chloroform/hexafluoroisopropanol = 98/2 (volume ratio). Measurements were performed under conditions of a flow rate of 0.6 ml/min, a concentration of 0.2%, an injection amount of 20 ml, and a temperature of 40°C.

Examples 1 to 7 are examples where (b) is 8000 Pa·s or more at the measurement temperature where the melt viscosity (a) is 120 Pa·s. Examples 1 to 3 show that increasing the amount of trifunctional or higher components increases the melt viscosity (b), and improves moldability. Examples 4 and 5 show that sufficient melt viscosity characteristics can be achieved even when different acid components are copolymerized. Example 6 shows that the propylene glycol content in polyoxyethylene polyoxypropylene glycol is high, and melt viscosity characteristics sufficient for good moldability can be obtained even without trifunctional or higher components.

Comparative Examples 1 to 6 show examples in which the blow moldability and product characteristics are not sufficient.
In Comparative Example 1, the melt viscosity was low, drawdown occurred, and moldability was poor.
In Comparative Example 2, the number average molecular weight of polyoxyethylene polyoxypropylene glycol is large, and the resin compatibility is poor. Although an increase in apparent melt viscosity due to low compatibility is observed, sufficient elongation properties are not satisfied.
In Comparative Example 3, the polyalkylene glycol is polyethylene glycol, not a block copolymer with polypropylene glycol, and the melt viscosity is low, resulting in poor moldability, and the crystallinity is high, so that the elongation properties are not sufficient.
In Comparative Example 4, the polyalkylene glycol is polypropylene glycol, and due to the presence of terminal secondary hydroxyl groups, the degree of polymerization and reduced viscosity are difficult to increase, sufficient melt viscosity characteristics are not exhibited, and the elongation characteristics are also insufficient.
In Comparative Example 5, the polyalkylene glycol is polytetramethylene glycol, which is not a block copolymer with polypropylene glycol or the like, and does not satisfy sufficient melt viscosity characteristics.
In Comparative Example 6, the polyalkylene glycol is polytetramethylene glycol and the number average molecular weight is large, so that the resin compatibility is low, the moldability is poor, and the tensile elongation property is not sufficient.

The polyester elastomer resin of the present invention is a resin that can be applied to a wide range of blow molding techniques, enabling it to accommodate the increasing length and complexity of blow molded products that will be required in the future to reduce the weight of automobiles, and it will make an enormous contribution to the industry.

Claims (5)

The polyester elastomer resin comprises an acid component including an aromatic dicarboxylic acid, an aliphatic and/or alicyclic diol, and an alcohol component including a polyalkylene glycol as constituent components,
When the total acid components are 100 mol % and the total alcohol components are 100 mol %, the copolymerization component contains 0.05 to 1.0 mol % of one or more trifunctional or higher functional components,
the polyalkylene glycol is a block copolymer and has a number average molecular weight of 1,000 to 4,000;
the polyalkylene glycol is polyoxyethylene polyoxypropylene glycol,
The propylene glycol component contained in the polyester elastomer resin is 18 to 35% by mass in the polyester elastomer resin,
A polyester elastomer resin for blow molding, characterized in that, as a melt viscosity property measured with a capillary rheometer, the melt viscosity at a shear rate of 6.08 sec ^-1 is 6000 Pa-s or more, measured at a temperature that is 20°C or more higher than the melting point of the polyester elastomer resin and at which the melt viscosity at a shear rate of 6080 sec ^-1 is 120 Pa-s. 2. The polyester elastomer resin for blow molding according to claim 1, wherein the polyalkylene glycol is a block copolymer having a polyethylene glycol (PEG)-polypropylene glycol (PPG)-polyethylene glycol (PEG) structure. 3. The polyester elastomer resin for blow molding according to claim 1, wherein the tri- or higher functional component is an acid component. 4. The polyester elastomer resin for blow molding according to claim 1, wherein the tri- or higher functional component is trimellitic acid. A blow molded article comprising the polyester elastomer resin according to any one of claims 1 to 4 .