WO2010110273A1 - Heat-shrinkable polyester tubing - Google Patents

Abstract

Provided is a heat-shrinkable polyester tubing which exhibits excellent heat resistance for practical use and which also exhibits satisfactory characteristics for heat-shrinkable tubing, such as electrical characteristics, chemical resistance, and electrolytic solution resistance. A heat-shrinkable polyester tubing which is made of a resin composition (A) that comprises, as the main components, both (a) a crystalline polyester prepared from a terephthalic acid-based acid component and an ethylene glycol-based diol component and (b) an amorphous polyester prepared from a terephthalic acid-based acid component and a diol component containing a copolymerizable component other than ethylene glycol, and which exhibits an enthalpy of melting, ?Hm, of 15 to 35J/g in a temperature re-rise process as determined by means of a differential scanning calorimeter (DSC) according to JIS-K7121.

Description

Polyester heat shrinkable tube

The present invention relates to a polyester-based heat-shrinkable tube, and more particularly to a polyester-based heat-shrinkable tube that is particularly excellent in practical heat resistance and is suitable for coating electronic components, particularly capacitors such as aluminum electrolytic capacitors. .

Conventionally, a heat-shrinkable tube mainly made of polyvinyl chloride resin has been used as an electrical insulating material for coating electronic parts such as capacitors and batteries. However, due to the recent trend toward smaller size and thinner walls, the mounting environment on electronic boards has been increased in density, and the usage environment has become much more severe than before due to self-heating and thermal stress from the surroundings. High heat resistance has also been required for aluminum electrolytic capacitors used for substrates. Polyvinyl chloride resin tubes are inexpensive but have insufficient heat resistance, and there are concerns about environmental problems associated with the generation of hydrogen chloride gas during combustion. As a result, heat-shrinkable tubes made of polyethylene terephthalate resin have been used.

The characteristics required for heat shrinkable tubes used for insulating materials for electronic parts such as capacitors are required to be properties such as coating finish, heat resistance, chemical resistance, and electrolyte resistance. For example, in Patent Document 1, a heat shrink tube made of polyethylene terephthalate containing 9 to 15 mol% of neopentyl glycol as a diol component is used as a heat-shrinkable tube that is completely in close contact with the groove portion of the capacitor even in the dry heat treatment after the capacitor is coated and washed with water. Shrink tubing has been proposed. Moreover, in patent document 2, in order to improve the heat resistance in a reflow furnace, the crystallinity degree after performing heat processing for 105 degreeC x 30 minutes is 16% or less, and the melting | fusing point peak of the aromatic polyester resin calculated | required by DSC measurement A heat-shrinkable tube characterized by a temperature of 220 ° C. or higher has been proposed.

However, in heat-shrinkable tubes used for insulating materials for electronic components such as capacitors, the heat resistance at the time of capacitor manufacturing process and board mounting has not been sufficient yet. For example, when a capacitor covered with a heat-shrinkable tube adheres with electrolyte or dirt and is cleaned and then heat-treated, or when mounting a board, the soldering surface is flux-cleaned and then mounted through a solder reflow furnace. In some cases, there is a problem that a part of the tube expands or wrinkles occur.

JP 09-148177 A JP 2002-264210 A

The present invention has been made to solve the above-mentioned problems. The problems of the present invention are particularly excellent in practical heat resistance, and are required for heat-shrinkable tubes such as electrical characteristics, chemical resistance, and electrolytic solution resistance. An object of the present invention is to provide a polyester heat-shrinkable tube that satisfies the characteristics.

In order to solve the above-mentioned problems, the present inventors have intensively studied on a polyester-based resin. As a result, they have found a polyester-based heat-shrinkable tube particularly excellent in practical heat resistance, and have completed the present invention.
That is, an object of the present invention is to provide a crystalline polyester (a) in which the main component of the acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and the main component of the acid component is terephthalic acid. Consists of a resin composition (A) whose main component is an amorphous polyester (b) containing a copolymer component other than ethylene glycol, and a differential thermal scanning calorimeter (DSC) according to JIS-K7121 This is achieved with a polyester heat-shrinkable tube (hereinafter also referred to as “tube of the present invention”) having a melting enthalpy ΔHm value of 15 J / g to 35 J / g.

In the tube of the present invention, the content of the amorphous polyester (b) is preferably 1% by mass or more and 40% by mass or less with respect to 100% by mass of the resin composition (A).

In the tube of the present invention, the resin composition (A) further contains a crystalline polyester (c) in which the main component of the acid component is terephthalic acid and the main component of the diol component is 1,4-butanediol. Is preferred.

In the tube of the present invention, the amorphous polyester (b) preferably contains a diol component having an alicyclic structure as the diol component.

In the tube of the present invention, the diol component having an alicyclic structure is preferably 1,4-cyclohexanedimethanol.

According to the present invention, it is possible to provide a polyester-based heat-shrinkable tube that is particularly excellent in practical heat resistance and satisfies the characteristics required for a heat-shrinkable tube such as electrical characteristics, chemical resistance, and electrolytic solution resistance. . Therefore, the present invention is useful as a coating material for electronic components including capacitors such as aluminum electrolytic capacitors.

Hereinafter, the tube of the present invention will be described in detail.

In the tube of the present invention, the main component of the acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and the main component of the acid component is terephthalic acid. Consists of a resin composition (A) composed mainly of an amorphous polyester (b) containing a copolymer component other than ethylene glycol, and measured by a differential thermal scanning calorimeter (DSC) according to JIS-K7121. The value of the melting enthalpy ΔHm in the reheating process is 15 J / g or more and 35 J / g or less.

1. Resin composition (A)
The resin composition (A) used in the tube of the present invention has a crystalline polyester (a) in which the main component of the acid component is terephthalic acid and the main component of the diol component is ethylene glycol, and the main component of the acid component is It is terephthalic acid, and the diol component contains amorphous polyester (b) containing a copolymer component other than ethylene glycol as a main component.

<Crystalline polyester (a)>
In the present invention, the crystalline polyester means that the temperature is raised from −50 ° C. to 300 ° C. at a heating rate of 10 ° C./min using DSC according to JIS-K7121, and kept at 300 ° C. for 1 minute, and then −50 ° C. When the temperature was lowered to 10 ° C. at a cooling rate of 10 ° C./min, held at −50 ° C. for 1 minute, and then heated again to 300 ° C. at a heating rate of 10 ° C./min, a clear melting peak was observed at the second temperature rise. It refers to the polyester resin that appears. Among the copolymer components of the crystalline polyester (a), the acid component is mainly composed of terephthalic acid, and the diol component is mainly composed of ethylene glycol. The main components terephthalic acid and ethylene glycol are contained in the acid component or diol component in a proportion of 51 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more. The crystalline polyester (a) may contain other copolymerization components in the acid component or the diol component as long as they are in the range of 49 mol% or less, preferably 30 mol% or less, more preferably 20 mol% or less. .

Examples of other copolymerizable acid components include isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbene dicarboxylic acid, 4,4-biphenyl Dicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4 -Aromatic dicarboxylic acid components derived from diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3 -From cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. Aliphatic dicarboxylic acid component to be electrically and the like. Of these, aromatic dicarboxylic acid components such as isophthalic acid and 2,6-naphthalenedicarboxylic acid are preferred.

Examples of other copolymerizable diol components include diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and trans-tetramethyl- 1,3-cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, decamethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, spiroglycol, p-xylenediol, bisphenol A
And diol components derived from tetrabromobisphenol A, tetrabromobisphenol A-bis (2-hydroxyethyl ether), and the like. Of these, diethylene glycol, 1,3-propanediol and the like are preferable.

These crystalline polyesters (a) may be used alone or in combination of two or more.

Examples of commercially available crystalline polyester (a) include “Novapex” series (manufactured by Mitsubishi Chemical Corporation), “Unipet” (manufactured by Nippon Unipet Corporation), and the like.

<Amorphous polyester (b)>
In the present invention, the non-crystalline polyester means that, according to JIS-K7121, the temperature is raised from −50 ° C. to 300 ° C. at a heating rate of 10 ° C./min using DSC, and is kept at 300 ° C. for 1 minute, When the temperature was lowered to 50 ° C. at a cooling rate of 10 ° C./min, held at −50 ° C. for 1 minute, and then heated again to 300 ° C. at a heating rate of 10 ° C./min, a clear melting peak was obtained at the second temperature rise. Refers to a polyester resin that does not appear. The acid component of the amorphous polyester (b) is mainly composed of terephthalic acid, the diol component is mainly composed of ethylene glycol, and the copolymer component other than ethylene glycol is 1 mol% or more, preferably 15 mol% or more, more preferably 25 mol. % Or more and 49 mol% or less, preferably 45 mol% or less.

Other acid components and diol components that can be copolymerized are the same as those shown for the crystalline polyester (a), but the diol components are diethylene glycol, trans-tetramethyl-1,3-cyclobutanediol, 2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3- It is preferably at least one selected from the group consisting of cyclohexanediol, spiroglycol, and polytetramethylene glycol. In particular, trans-tetramethyl-1,3-cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1, A diol component having at least one alicyclic structure selected from the group consisting of 4-cyclohexanediol, 1,3-cyclohexanediol, and spiroglycol is preferably used, and is economical, industrially available, and crystalline. In view of miscibility with the polyester (a), 1,4-cyclohexanedimethanol and spiroglycol are particularly preferable.

Here, the content of the diol component having an alicyclic structure is 1 mol% or more, preferably 15 mol% or more, more preferably 25 mol% or more in the total diol component of the amorphous polyester (b), and the upper limit is 49 mol. % Or less, preferably 45 mol% or less. When the content of the diol component having an alicyclic structure is in the above range, the temperature is increased from −50 ° C. to 300 ° C. at a heating rate of 10 ° C./min using DSC in accordance with JIS-K7121, and 1 at 300 ° C. The temperature is lowered to −50 ° C. at a cooling rate of 10 ° C./min, held at −50 ° C. for 1 minute, and then heated again to 300 ° C. at a heating rate of 10 ° C./min. It can be made into resin which does not show a clear melting peak at the time of warm.

In the tube of the present invention, the glass transition temperature (Tg) of the amorphous polyester (b) is preferably 80 ° C. or higher and 120 ° C. or lower, and those having a higher Tg than the crystalline polyester (a) to be used are further included. preferable. When the glass transition temperature (Tg) of the amorphous polyester (b) is in the above range, the heat resistance derived from the high Tg and the content of the amorphous polyester (b) melt the resin composition (A). Since it is easy to control the enthalpy ΔHm value, (1) a flux swell test, (2) a cleaning swell test, and (3) a high temperature storage test described later can be satisfied at the same time, which is preferable.

As a commercial item of amorphous polyester (b), for example, “Eastar Copolyester 6863”, “Easter Copolyester GN001” (manufactured by Eastman Chemical), “TRITAN” (manufactured by Eastman Chemical), “SKYGREEN PETG S2008” (Manufactured by SK Chemical Co., Ltd.), “ALTERSTER” (manufactured by Mitsubishi Gas Chemical Company, Inc.) and the like.

The content of the amorphous polyester (b) contained in the resin composition (A) is 1% by mass or more, preferably 100% by mass or more, preferably 100% by mass of the crystalline polyester (a) and the amorphous polyester (b). It is 5 mass% or more, More preferably, it is 10 mass% or more, 40 mass% or less, Preferably it is 35 mass% or less, More preferably, it can be 30 mass% or less. If the content of the amorphous polyester (b) is within the above range, the resin composition (A) is provided with practically excellent heat resistance without impairing the characteristics of the crystalline polyester such as chemical resistance. Can do.

<Crystalline polyester (c)>
The tube of the present invention further comprises a crystalline polyester (c) in which the main component of the acid component is terephthalic acid and the main component of the diol component is 1,4-butanediol in the resin composition (A). Can do. By including the crystalline polyester (c) in the resin composition (A), the glass transition temperature Tg and the crystallization speed of the resin composition (A) can be adjusted. In order to obtain such an effect, the content of the crystalline polyester (c) is 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass with respect to 100% by mass of the resin composition (A). The following is desirable.

Examples of commercially available crystalline polyester (c) include “Novaduran” (manufactured by Mitsubishi Chemical Engineering Plastics), “Duranex” (manufactured by Wintech Polymer), and the like.

The tube of the present invention is not limited to the resin composition (A) as long as the effects of the present invention are not hindered, such as thermoplastic elastomers such as polyester-based, olefin-based copolymers, and polystyrene-based resins. Resin). Furthermore, other components can be appropriately added to the resin composition (A) depending on the application. For example, an organic lubricant, an inorganic lubricant, an inorganic filler, or an impact resistance improver, a filler, an ultraviolet absorber, a surface treatment agent, a light stabilizer, a pigment, an antistatic agent for improving easy lubricity of the tube, Auxiliaries such as antibacterial agents, crosslinking agents, antioxidants, flame retardants, plasticizers, processing aids, foaming agents and the like can be blended.

2. Melting enthalpy ΔHm
According to JIS-K7121, the tube of the present invention has a melting enthalpy ΔHm of 15 J / g or more, preferably 18 J / g or more, more preferably 20 J / g or more in the reheating process measured by DSC. , 35 J / g or less. The tube of the present invention can exhibit heat resistance when the value of the melting enthalpy ΔHm is in the above range, and thus can be suitably used as a coating material for capacitors and batteries. When the value of melting enthalpy ΔHm exceeds 35 J / g, the tube that is once in close contact with the coating such as a capacitor loosens due to crystal growth when exposed to a high temperature such as a capacitor mounting process. Dots tend to occur. If it is less than 15 J / g, the characteristics of the crystalline resin such as heat resistance and chemical resistance may be impaired.

As means for bringing the value of the melting enthalpy ΔHm of the tube of the present invention within the above range, a copolymer composition of the crystalline polyester (a) in the resin composition (A), an amorphous polyester (b), and others The method of adjusting the combination of these resin, a compounding ratio, and intrinsic viscosity is mentioned. In the present invention, a method for adjusting the copolymer composition of the crystalline polyester (a) in the resin composition (A) or a method for adjusting the blending ratio of the resin composition (A) is preferably used. For example, when it is desired to increase the melting enthalpy ΔHm, the content of the crystalline polyester (a) is increased, the content of the amorphous polyester (b) is decreased, and the crystalline polyester (c ) And a means for reducing the types of monomers used for the acid component and the diol component in the copolymer composition of the crystalline polyester (a) in the resin composition (A). When it is desired to reduce the melting enthalpy ΔHm, the content of the crystalline polyester (a) is decreased and the content of the amorphous polyester (b) is increased or the crystal in the resin composition (A). In the copolymer composition of the reactive polyester (a), there are means such as increasing the types of monomers used for the acid component and the diol component. For example, in the case of homo-PET (terephthalic acid 100 mol%, ethylene glycol 100 mol%) which is a crystalline polyester (a), the value of the melting enthalpy ΔHm is usually in the range of 45 J / g or more and 60 J / g or less. The value of ΔHm can be reduced by adjusting the type and number of monomers used for the acid component and diol component of the copolymer composition.

However, if ΔHm is controlled only by the method of adjusting the copolymer composition of the crystalline polyester (a) to be used, the melting temperature Tm also decreases, and the heat resistance of the entire resin composition (A) decreases. More preferably, the content of the amorphous polyester (b) is also adjusted in combination.
In addition, the kind and content of the acid component and diol component which are copolymerization components can be qualitatively and quantitatively analyzed by a well-known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus and other instrumental analyzers.

The melting enthalpy ΔHm was measured from -50 ° C. at a heating rate of 10 ° C./min according to JIS-K7121, using 10 mg of the sample cut from the heat-shrinkable tube formed using DSC-7 manufactured by Perkin Elmer. The temperature was raised to 300 ° C., held at 300 ° C. for 1 minute, cooled to −50 ° C. at a cooling rate of 10 ° C./minute, held at −50 ° C. for 1 minute, and then again heated to 300 ° C. at a heating rate of 10 ° C./minute. It can be obtained from the thermogram when the temperature is raised to.

3. The tube manufacturing method of the present invention is a tube manufacturing method of the present invention, which can be formed by a normal tubular method, and after the above-described polyester raw material is melted, it is extruded into a cylindrical shape with an annular die and molded. Is achieved. In the tube of the present invention, the unstretched tube is 1.2 times or more in the radial direction, preferably 1.3 times or more, more preferably 1.4 times or more and 3.0 times or less, preferably 2.5 times or less. , More preferably in the range of 2.0 times or less and in the length direction 1.0 times or more, preferably 1.02 times or more to 2.0 times or less, preferably 1.5 times or less, more preferably Those obtained by stretching at a magnification in the range of 1.3 times or less are preferred. Here, if the draw ratio in the radial direction of the tube is 1.2 times or more, a contraction amount sufficient for coating can be obtained, and if it is 3.0 times or less, the tendency to increase the thickness fluctuation can be suppressed. In addition, a reduction in shrinkage due to orientation crystallization can be suppressed. On the other hand, if the draw ratio in the length direction of the tube is 2.0 times or less, the shrinkage amount in the length direction becomes too large, and the coating position shifts when the electronic parts are coated, or the cut length Since it is not necessary to lengthen the length, cost increase can be suppressed.

Although the thickness of the tube obtained as described above is not particularly limited, the thickness of the tube generally used for a capacitor is typically in a range from about 0.05 mm to 1.0 mm depending on the rated voltage of the capacitor. The one in the range from 0.07 mm to 0.2 mm is used. Further, a tube having a folded width (hereinafter referred to as “folded diameter”) in the range of 4 mm to 300 mm is preferable in that it can be applied to general-purpose capacitors and battery coatings and general-purpose battery packaging in general.

4). Characteristics of the tube of the present inventionThe tube of the present invention is composed of the above resin composition, and the one having a specific heat shrinkage is particularly excellent in performance as a coating material for capacitors and batteries,
(1) The shrinkage in the length direction when immersed in warm water at 100 ° C. for 10 seconds is 2% or more, preferably 3% or more, more preferably 5% or more, 20% or less, preferably 15% or less. More preferably, it is 12% or less. The shrinkage in the radial direction is 15% or more, preferably 20% or more, more preferably 25% or more, and is 60% or less, preferably 50% or less, more preferably 45% or less.
More preferably, those satisfying the following characteristics as in (1) are preferred.
(2) The shrinkage in the length direction when immersed in warm water at 80 ° C. for 10 seconds is 2% or more, preferably 3% or more, more preferably 5% or more, and 15% or less, preferably 12% or less. More preferably, it is 10% or less. The shrinkage in the radial direction is 10% or more, preferably 15% or more, more preferably 20% or more, and is 60% or less, preferably 50% or less, more preferably 45% or less.

A tube that does not satisfy the heat shrinkage characteristics of (1) above, preferably (1) and (2), has a poor coating appearance, and requires a large amount of heat when coated on the object to be coated. Cost tends to be high. If the characteristics of (1) and (2) are satisfied, it is possible to coat under the same conditions as the PVC tube using an existing coating machine.

In addition, since the tube of the present invention has a melting enthalpy ΔHm value within a predetermined range, the heat-shrinkable tube does not expand after completion of the capacitor manufacturing process and the board mounting process, and has heat resistance in practical use. In addition, it has excellent performance as a coating material for capacitors and batteries.
(1) Here, the cleaning swelling test is a test method for evaluating the expansion of the heat-shrinkable tube in the capacitor manufacturing process. Specifically, after coating with a nichrome wire heater at 300 ° C. for 3.6 seconds, it was immersed continuously in normal temperature water for 15 minutes, 60 ° C. warm water for 30 minutes, and further in normal temperature water for 15 minutes. After exposure in an oven at 95 ° C. for 60 minutes, the appearance of the coated heat-shrinkable tube (hereinafter also referred to as “coated tube”) is visually evaluated. The cause of the expansion of the heat-shrinkable tube after the cleaning swell test is that water enters the gap between the coated tube and the capacitor when immersed in water at normal temperature and 60 ° C hot water twice. When exposed to a medium 95 ° C atmosphere, the water entering the gap evaporates and the volume increases, so the pressure in the gap between the coated tube and the capacitor rises, and the coated tube is expected to expand. .
(2) The flux swell test is a test method for evaluating the expansion of the tube during board mounting. Specifically, it is coated with a 300 ° C. nichrome wire heater for 3.6 seconds, heat-treated in a hot air circulation oven in an atmosphere at 85 ° C. for 60 minutes, and then a flux (for example, Hiroki Co., Ltd.) is formed on the sealing portion of the capacitor. JS-E-11) was applied, and the substrate mounted so that the substrate and the capacitor sealing part were in close contact with each other was again exposed to 160 ° C in a hot air circulation oven for 2 minutes. Evaluate by The cause of the expansion of the tube after the flux expansion test is that the flux applied to the sealing portion of the capacitor penetrates into the gap between the coated tube and the capacitor and is then exposed to a 160 ° C. atmosphere in a hot air circulation oven. Since the flux that has entered between the coated tube and the capacitor evaporates and the volume increases, it is assumed that the pressure in the gap between the coated tube and the capacitor increases and the coated tube expands.
(3) The high-temperature standing test is a test method for evaluating heat resistance, which is covered with a nichrome wire heater at 300 ° C. for 3.6 seconds and subjected to aging in a hot air circulation oven for 60 minutes in an 85 ° C. atmosphere. After that, the appearance of the coated tube after being exposed to a 150 ° C. atmosphere for 60 minutes in a hot air circulation oven again is visually evaluated. The cause of the expansion of the tube after the high-temperature standing test is that the heat-shrinkable tube made of a conventional polyethylene terephthalate resin crystallizes when exposed to a 150 ° C. atmosphere in a hot-air circulating oven, and the crystal itself It is presumed that the volume of the tube increases due to the expansion and interference between the crystals, and the expansion of the coated tube occurs.

A heat-shrinkable tube that does not clear any of the above (1) flux swell test, (2) cleaning swell test, and (3) high-temperature standing test does not cause the tube to expand after the capacitor manufacturing process or the board mounting process is completed. As a result, mounting processing cannot be performed, and heat resistance in actual use deteriorates. On the contrary, if it is a heat shrinkable tube that clears all the tests of (1), (2), and (3) above, it can be mounted without impairing the appearance of the coated tube after the capacitor manufacturing process or board mounting process. Can be processed.

In order to clear all the tests of (1), (2) and (3) above, the tube of the present invention contains a copolymer composition of crystalline polyester (a), amorphous polyester (b), and other resins. The value of the melting enthalpy ΔHm in the re-heating process measured by a differential thermal scanning calorimeter (DSC) according to JIS-K7121 is adjusted from 15 J / g to 35 J / g, preferably 20 J. / G to 35 J / g.

5). The member covered with the tube of the present invention The tube of the present invention can be suitably used for covering a capacitor such as an aluminum electrolytic capacitor, but other uses such as electric wires (round wire, square wire), dry batteries, It can also be used as a secondary battery such as a lithium ion battery, an electric device such as a steel tube or a motor coil end, a transformer, a small motor, or a fluorescent lamp covering tube of a light bulb, a fluorescent lamp, a facsimile or an image scanner.

It should be noted that the expression “main component” in the present invention includes the intention that a component other than the main component may be contained. Although the content ratio with respect to all components is not particularly limited, it is necessary to occupy at least 50% (mol% or mass%) of all components (when the main component is 2 components or more, the total value is 50% or more) In particular, it is preferably 60% or more, particularly preferably 70% or more, and more preferably 90% or more (including 100%).

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
In addition, the various measured value and evaluation about the heat-shrinkable tube displayed in this specification were performed as follows.

(1) Glass transition temperature Tg and melting enthalpy ΔHm
The enthalpy of fusion ΔHm was determined according to JIS-K7121 by using DSC-7 manufactured by PerkinElmer Co., Ltd. The temperature was raised from −50 ° C. to 300 ° C. in minutes, held at 300 ° C. for 1 minute, then cooled to −50 ° C. at a cooling rate of 10 ° C./minute, held at −50 ° C. for 1 minute, and then heated again at a heating rate of 10 It calculated | required from the thermogram when it heated up to 300 degreeC by degC / min.
The glass transition temperature Tg was also determined in the same manner as ΔHm according to JIS-K7121.

(2) Shrinkage The length and fold diameter of the heat-shrinkable tube before and after being immersed in warm water at 100 ° C. or 80 ° C. for 10 seconds were measured and calculated.
Lengthwise shrinkage [%] = [(length of tube before immersion−length of tube after immersion) / length of tube before immersion] × 100
Radial shrinkage [%] = [(folded diameter of tube before immersion−folded diameter of tube after immersion) / folded diameter of tube before immersion] × 100

(3) Flux swell test An aluminum electrolytic capacitor with a diameter of 5 mm and a length of 11.0 mm and a tube with a folding diameter of 8.6 mm, a thickness of 0.07 mm and a length of 14.7 mm for 3.6 seconds using a 300 ° C nichrome wire heater. And then heat-treated in a hot air circulating oven at 85 ° C. for 60 minutes. After that, flux (Hiroki Co., Ltd. JS-E-11) was applied to the sealing part of the capacitor and mounted on the board so that the board and the capacitor sealing part were in close contact with each other again in a hot air circulation oven at 160 ° C atmosphere. And the capacitor-coated tube appearance after heating was visually evaluated as follows.
(○) Good appearance with no swelling or loosening of the tube.
(X) The tube swells and loosens significantly, and cannot be used due to poor appearance.

(4) Cleaning swell test A tube having a folding diameter of 16.8 mm, a wall thickness of 0.08 mm, and a length of 16.1 mm is placed on an aluminum electrolytic capacitor having a diameter of 10 mm and a length of 12.5 mm for 3.6 seconds with a 300 ° C. nichrome wire heater. After being coated, the film was immersed in normal temperature water for 15 minutes, 60 ° C. warm water for 30 minutes, and further normal temperature water for 15 minutes. Then, it exposed to 95 degreeC atmosphere in a hot-air circulation type oven for 60 minutes, and the external appearance of the capacitor | condenser covering tube after a heating was evaluated visually as follows.
(○) Good appearance with no swelling or loosening of the tube.
(X) The tube swells and loosens significantly, and cannot be used due to poor appearance.

(5) High-temperature standing test A tube with a folding diameter of 16.8 mm, a wall thickness of 0.08 mm, and a length of 16.1 mm for 3.6 seconds with a 300 mm Nichrome wire heater on an aluminum electrolytic capacitor with a diameter of 10 mm and a length of 12.5 mm. And then aged for 60 minutes in an 85 ° C. atmosphere in a hot air circulating oven, and then again exposed to a 150 ° C. atmosphere in a hot air circulating oven for 60 minutes, and the heat resistance was evaluated visually as follows. .
(○) Good appearance with no swelling or loosening of the tube.
(X) The tube swells and loosens significantly, and cannot be used due to poor appearance.

(6) Solvent resistance test A tube having a folding diameter of 16.8 mm, a wall thickness of 0.08 mm, and a length of 16.1 mm is mounted on an aluminum electrolytic capacitor having a diameter of 10 mm and a length of 12.5 mm with a 300 ° C. nichrome wire heater. Then, heat treatment was performed in an oven at 85 ° C. for 60 minutes in a hot air circulating oven. After immersing in each test solvent for a predetermined time, the appearance of the capacitor-coated tube dried at room temperature for 1 hour was visually evaluated as follows.
Test solvent 1: Acetone Immersion time: 30 seconds Test solvent 2: Xylene Immersion time: 5 minutes (○) Good appearance without swelling and cracking in the tube.
(X) Swelling, cracking, etc. occur remarkably in the tube and it cannot be used due to poor appearance.

[Resin used in Examples and Comparative Examples]
PET1: Novapex BK2180 (crystalline polyester, manufactured by Mitsubishi Chemical Corporation; acid component: 98.6 mol% terephthalic acid, 1.4 mol% isophthalic acid, diol component: 97.3 mol% ethylene glycol, 2.7 mol diethylene glycol %, Tg = 77.1 ° C., Tm = 250.8 ° C., [η] = 0.79, polyethylene terephthalate / isophthalate resin)
PET2: Novapex GS900 (crystalline polyester, manufactured by Mitsubishi Chemical Corporation; acid component: 100 mol% terephthalic acid, diol component: 98.1 mol% ethylene glycol, 1.9 mol% diethylene glycol, Tg = 82.1 ° C. Tm = Polyethylene terephthalate resin at 255.3 ° C. and [η] = 0.994)
PET3: ALTERSTER45 (Amorphous polyester, manufactured by Mitsubishi Gas Chemical Company; acid component: 100 mol% terephthalic acid, diol component: 49.7 mol% ethylene glycol, 6.3 mol% diethylene glycol, 44.0 mol% spiroglycol Tg = 101.8 ° C., Tm = 107.3 ° C., [η] = 0.732 amorphous polyethylene terephthalate resin)
PET4: Eastar Copolyester GN001 (Amorphous polyester, manufactured by Eastman Chemical; acid component: 100 mol% terephthalic acid, diol component: 65.3 mol% ethylene glycol, 2.5 mol% diethylene glycol, 1,4-cyclohexane (Amorphous polyethylene terephthalate resin with dimethanol 32.2 mol%, Tg = 72.7 ° C., [η] = 0.824)
PET5: Unipet IG154K (crystalline polyester, manufactured by Nihon Unipet Corporation; acid component: 94.7 mol% terephthalic acid, 5.3 mol% isophthalic acid, diol component: ethylene glycol 95.2 mol%, diethylene glycol 4. 8 mol%, Tg = 72.8 ° C., Tm = 232.0 ° C., [η] = 0.72 polyethylene terephthalate / isophthalate resin)
PBT: Novaduran 5505 (crystalline polyester, manufactured by Mitsubishi Chemical Engineering Plastics; acid component: 100.0 mol% terephthalic acid, diol component: 92.0% by mass of 1,4-butanediol, polytetramethylene glycol 8. (Polytetramethylene glycol copolymer polybutylene terephthalate resin of 0% by mass, Tg = 57.0 ° C., Tm = 219.0 ° C., [η] = 0.897)
Inorganic lubricant 1: Silica having an average particle size of 4.0 μm Hydrolysis inhibitor 1: Starbazole 100 (manufactured by Rhein Chemie; high molecular weight polycarbodiimide compound)

[Examples 1 to 5 and Comparative Examples 1 to 4]
The resin composition prepared with the composition described in Table 1 is dissolved in an extruder set at a cylinder temperature of 280 ° C., extruded through a round die, immersed in water, and cooled and solidified to obtain an original tube before stretching. The original tube was subsequently heated with hot water at 90 ° C., stretched 1.05 to 1.1 times in the length direction and 1.7 to 1.8 times in the radial direction, and then cooled to a folding diameter of 8.6 mm. A polyester heat-shrinkable tube having a thickness of 70 μm, a folding diameter of 16.8 mm, and a thickness of 80 μm was obtained. Table 1 shows the results of evaluating the characteristics of the tube obtained by tubular molding.

From Table 1, the tubes of the present invention (Examples 1 to 5) are free of blistering and loosening even at high temperatures, have a good coating appearance, and have good flux swell test and washing swell test. Also in the solvent property test, the tube had good appearance without swelling or cracking. In contrast, tubes (Comparative Examples 1 to 4) in which the value of the melting enthalpy ΔHm in the re-heating process measured by the differential thermal scanning calorimeter (DSC) is outside the specified range of the present invention (Comparative Examples 1 to 4) It can be confirmed that any one or more of the cleaning blister test, the high temperature storage test and the solvent resistance test is inferior. As a result, the tube of the present invention is a polyester heat-shrinkable tube that is particularly excellent in practical heat resistance and satisfies the characteristics required for heat-shrinkable tubes such as electrical properties, chemical resistance, and electrolytic solution resistance. I understand.

Claims (8)

Crystalline polyester (a) in which the main component of the acid component is terephthalic acid and the main component of the diol component is ethylene glycol; and the copolymer component in which the main component of the acid component is terephthalic acid and the diol component is other than ethylene glycol In a reheating process comprising a resin composition (A) containing amorphous polyester (b) as a main component and measured by a differential thermal scanning calorimeter (DSC) according to JIS-K7121 A polyester heat-shrinkable tube having a melting enthalpy ΔHm of 15 J / g or more and 35 J / g or less. 2. The polyester heat-shrinkable tube according to claim 1, wherein the content of the amorphous polyester (b) is 1% by mass to 40% by mass with respect to 100% by mass of the resin composition (A). The resin composition (A) further contains a crystalline polyester (c) in which the main component of the acid component is terephthalic acid and the main component of the diol component is 1,4-butanediol. Polyester heat shrinkable tube. The polyester heat-shrinkable tube according to any one of claims 1 to 3, wherein the amorphous polyester (b) contains a diol component having an alicyclic structure as a diol component. The polyester heat-shrinkable tube according to claim 4, wherein the diol component having an alicyclic structure is 1,4-cyclohexanedimethanol. The polyester-based heat-shrinkable tube according to claim 4, wherein the diol component having an alicyclic structure is spiroglycol. A member coated with the polyester heat-shrinkable tube according to any one of claims 1 to 6. The member according to claim 7, which is used for an electronic device or an electric device.