KR100392161B1 - Polyester-based thermal contraction tube - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat shrinkable tube for condenser coating having a polyester resin or a copolyester resin as a main component and having a density of 1.330 to 1.339, which is a polybutylene terephthalate resin containing a polyethylene terephthalate copolymer resin and a pigment. It is manufactured in a certain density range by adjusting the temperature of the die and the temperature of the cooling tank with the composition containing sodium stearate or elastomer as a main component, and the obtained heat shrinkable tube not only has excellent coating adhesion after coating on the condenser Excellent adhesion in the shrinkage process and drying process.

Description

Polyester-based thermal contraction tube for capacitor coating

The present invention relates to a polyester-based heat-shrinkable tube for condenser coating, and a method of manufacturing the same, and more particularly, to a polyester-based heat-shrinkable tube coated for protection and electrical insulation of an electrolytic capacitor. .

In general, a heat shrinkable tube is used as a capacitor coating for protecting an electrolytic capacitor and electric insulation. In the past, the heat shrinkable tube has been made of polyvinyl chloride resin (PVC), which is a synthetic resin.

In the application example of the heat shrinkable tube, the electrolytic capacitor was coated with the heat shrinkable tube, heated and contracted at 230 to 250 ° C. for 2 to 3 seconds, and then washed with water at 70 to 80 ° C., followed by drying and heat resistance test. It is used after dry heat treatment for about a minute. In addition, as a test of a coating film, a pinhole and a drop test are performed.

As described above, polyvinyl chloride resin thermally shrinkable tubes are generally used for coating electrolytic capacitors. However, polyvinyl chloride resins have poor heat resistance and strength, and are easily torn when dry-heated after pinhole testing. Not only is the condition poor, but the pass rate is low in the drop test. For this reason, it is required to coat | cover an electrolytic capacitor with resin excellent in heat resistance and strength. In addition, polyvinyl chloride resins are not recyclable, and since incineration generates dioxin, which seriously affects environmental pollution, they have been actively studied for alternative materials.

As a part of this research, Japanese Patent Laid-Open No. 1974-32972 used a polyester resin as a shrink tube for a capacitor. As a result, coating and shrinking of the capacitor resulted in a close contact with the components of the capacitor even in dry heat treatment. It is disclosed that this excellent heat shrinkable tube can be obtained.

On the other hand, the heat-shrinkable tube is coated on the condenser, and when contracted, the upper and lower surfaces of the condenser are covered, and the close contact with the bent portion of the condenser side part. This adhesion affects the shape deformation of the coated tube in the high temperature cleaning process and drying process after coating and shrinking the condenser. A resin composition for securing such adhesion performance has been presented in Korean Patent Application No. 2000-2686.

By the way, the above-mentioned compositions showed excellent coating performance in the washing process and drying process of the commonly used condenser, but did not show perfect coating adhesion in a special drying process of 200 ℃ or more.

As a result, the final tube product must have a certain level of density in order to ensure good coating adhesion. The final product density is influenced by the composition and crystallinity of the tube. In particular, the degree of crystallinity of the tube changes according to the tube manufacturing process, which leads to a change in the final physical properties of the tube. The coating adhesion to the is changed.

Accordingly, the inventors of the present invention are trying to manufacture a heat shrinkable tube that can be completely adhered to the component parts of the capacitor even after drying and coating the capacitor, and then dry heat treatment. As a main component, but as a result of having a certain level of density, it was found that the above conditions are satisfied to complete the present invention.

Accordingly, it is an object of the present invention to provide a polyester-based heat-shrinkable tube that can be completely adhered to the constituent parts of a capacitor even in a dry heat treatment after coating and shrinking, thereby exhibiting excellent protection and electrical insulation of the capacitor.

The polyester-based heat-shrinkable tube of the present invention for achieving the above object has a polyester-based resin or a copolyester-based resin as a main component, and has a density of 1.330 to 1.339.

The present invention will be described in more detail as follows.

The thermoplastic polyester resin constituting the heat-shrinkable tube of the present invention is not only polyethylene terephthalate containing terephthalic acid as the acid component and ethylene glycol as the glycol component, but also isophthalic acid and naphthalenedicarboxyl mixed with a large amount of terephthalic acid as the acid component. Copolymers having dicarboxylic acids such as acids, diphenoxyethanedicarboxylic acids, diphenyldicarboxylic acids, diphenyletherdicarboxylic acids, propanediol, butanediol, and pentanediol mixed with ethylene glycol as glycol components , Hexanediol, neopentylglycol, copolymer with polyethylene glycol, or a combination composition of such polyester.

Examples of the preferred polyester resins are copolymerized polyester resins composed of 1 to 15 mol% of ethylene naphthalate components and 85 to 99 mol% of ethylene terephthalate components by copolymerization, and copolymer resins having an intrinsic viscosity of 0.65 to 1.0 dl / g. Can be mentioned.

In the present invention, such a copolymer polyester resin is not only used alone, but also a resin composition in which 80 to 99% by weight of the copolymerized polyester resin and 1 to 20% by weight of the polybutylene terephthalate and the pigment are melt-mixed. Can be used.

Here, the copolymerized polyester resin comprising 1 to 15 mol% of ethylene naphthalate components and 85 to 99 mol% of ethylene terephthalate components by copolymerization is a polyethylene terephthalate copolymer obtained by copolymerizing a predetermined amount of dimethyl ester of naphthalenedicarboxylic acid. And polyethylene terephthalate resin are mixed, but it is also possible to use a mixture containing 1 to 15 mol% of ethylene naphthalate as the copolymerization component of the mixture.

It is preferable that the ethylene naphthalate copolymerization component is 1 to 15 mol%, so that the resulting polyethylene terephthalate polymer shows appropriate crystallinity to facilitate tube formation.

If the ethylene terephthalate copolymerization component is less than 1 mol%, it is difficult to form the tube. If the ethylene terephthalate copolymerization component is more than 15 mol%, the crystallization progression of the obtained polyester-based heat shrinkable tube is greatly increased and the heat resistance is lowered.

The copolymerized polyethylene terephthalate copolymer containing an ethylene naphthalate copolymer component can be easily manufactured according to the manufacturing method of a normal polyethylene terephthalate resin. That is, when preparing a polyester obtained by reacting terephthalic acid or its ester-forming derivative with ethylene glycol or its ester-forming derivative, it is possible to substitute 1 to 15 mol% of the acid component with naphthalene carboxylic acid or its ester-forming derivative. Do.

The molecular weight of the copolymerized resin of polyethylene naphthalate and polyethylene terephthalate is good because it exhibits good mechanical properties when the intrinsic viscosity is 0.65 or more, and when the intrinsic viscosity is 1.0 or more, it is impossible to form a film having a thickness of 150 μm or less, and thus the intrinsic viscosity It is preferable that it is 0.65-1.0.

In addition, when a polybutylene terephthalate resin containing a pigment is added to the copolymerized resin, it is easy to process by controlling the crystallization rate of the entire resin composition, and the shrinkable heat shrinkable tube is coated with a condenser for 3 minutes at 170 ° C. Dry heat treatment can impart a characteristic that substantially no space is generated in the components of the capacitor. When adding the polybutylene terephthalate resin containing a pigment to said copolymerized resin, it is preferable that the addition amount is 1-20 weight%. If the amount is less than 1% by weight, it is not effective to control the crystallization rate. If the amount is more than 20% by weight, the crystallization rate is rapid and it is difficult to form the stretched tube.

On the other hand, it is preferable that the quantity of the pigment contained in polybutylene terephthalate resin is 10-30 weight%.

In addition, the heat-shrinkable tube composition of the present invention may further contain 0.01 to 1.0% by weight of a metal salt of benzoic acid or stearic acid in order to finely control the crystallization rate in the above composition. By adding a metal salt of benzoic acid or stearic acid, the crystallization rate can be changed appropriately according to the size of the capacitor to be coated to increase the heat resistance.

On the other hand, by adding 1 to 5% by weight of polyester elastomer resin may be supplemented with flexibility and adhesion.

It is also possible to add external particles to improve heat resistance. Examples of the external particles include inorganic particles such as calcium carbonate, talc, clay, mica, aluminum silicate, silica, calcium metasilicate and alumina trihydrate, and organic particles such as teflon powder, and two or more of them may be used together. It is possible. Preferably, silica, talc, etc. are suitable.

In addition, the polyethylene terephthalate copolymer resin may be mixed with additives such as stabilizers, pigments, dyes, clays, lubricants, flame retardants and the like to prepare a heat shrinkable tube.

Method for producing a polyester-based heat shrinkable tube according to the present invention is as follows.

To prepare a heat shrinkable tube from a copolymerized polyethylene terephthalate copolymer resin containing an ethylene naphthalate copolymer component, a method of biaxially stretching after forming a tubular body by melt extrusion by a molding method such as a tube method and an inflation method is used.

For example, the copolymer is extruded from an annular die of an extruder to obtain an unstretched tubular body, and the tubular body is quenched in a cooling bath, followed by a secondary transition point temperature of the copolymer or copolymer mixture and a temperature below the pour point. While heating at 0, a compressed body such as air and nitrogen is introduced and expanded to extend in the radial direction of the tubular body, and also stretched in the longitudinal direction using a differential speed roll or the like to obtain a heat shrinkable tube. This biaxial stretching may be performed continuously by extrusion molding of a tubular body, or after winding up to a roll in an unstretched state. The thickness of the heat-shrinkable tube after biaxial stretching is suitable for producing an unstretched tubular body, and the boiling water shrinkage rate of the heat-shrinkable tube after biaxial stretching is 40 in the radial direction for biaxially stretching the unstretched tubular body. -60% and 5-15% of a longitudinal direction are suitable. A draw ratio can be achieved by selecting 1.7-2.5 times and extending | stretching magnification of a longitudinal direction suitably in the range of 1-1.5 times.

On the other hand, in order to show perfect coating adhesion in a special drying process of 200 ° C or higher, it is preferable that the density of the final tube product has a value of 1.330 to 1.339. The density of the polyester-based tube is related to the degree of crystallinity. The higher the degree of crystallinity of the final tube product, the worse the shrinkage of the tube, and the microcrystalline parts add to the thermal history and do not maintain perfect coating adhesion at high temperatures above 200 ° C. On the other hand, when the crystallinity of the final product is lowered, the heat-resistance is drastically reduced due to the decrease of the crystal parts that have heat resistance in the product.

Factors affecting the density of the final tube product include the composition of the resin, the temperature of the annular die, the temperature of the cooling bath, and the like.

The temperature of the annular die is preferably 250 to 300 ° C, preferably 260 to 280 ° C. If the temperature is high, decomposition of the resin may occur. If the temperature is low, the heat history of the final tube product is increased, resulting in poor coating adhesion.

On the other hand, 10-70 degreeC is suitable for the temperature of a cooling tank, Preferably 20-60 degreeC is suitable. If the temperature of the cooling bath is high, the crystallinity of the final tube product is too high, and if the temperature of the cooling bath is low, the opposite occurs.

As described above, 80 to 99% by weight of polyvinylene terephthalate having an intrinsic viscosity of 0.65 to 1.0 dl / g composed of 1 to 15 mol% of polyethylene naphthalate and 85 to 99 mol% of polyethylene terephthalate according to the present invention. And a polyester-based heat shrinkable tube for coating a polyester-based electrolytic capacitor, which was formed from a resin composition of 1 to 20% by weight of a resin obtained by melting and mixing a pigment, and a condenser (length 24mm, outer diameter 12.5mm, bottom 2-5mm It has a concave-convex structure with a curved surface, and the deepest part of the part is 11mm in diameter, located 4mm from the bottom), and the inner heat treatment after coating shrinkage is performed when coating shrinkage tube of 13.3mm and 75㎛ thickness. 3 minutes), substantially no space is generated in the components of the capacitor. In addition, even after 3 minutes of washing in 100 ℃ water shows excellent coating adhesion.

The coating adhesiveness of the electrolytic capacitor-coated polyester-based heat-shrinkable tube was heat-shrinked on the capacitor, and the density was 1.342 to 1.353.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

Polybutylene tere containing 95.4 wt% of PET copolymer (high viscosity 0.84) and 30 wt% of pigment, copolymerized with 5 mol% of dimethyl ester of naphthalenedicarboxylic acid dried in a hot air circulation dryer at 150 ° C. for 6 hours. 2.5% by weight of phthalate resin, 0.1% by weight of sodium salt of stearic acid, and polyester elastomer were mixed at 2 parts by weight based on the total weight of the resin, and an outer diameter of 7 mm at a cylinder temperature of 220 to 280 ° C and a die temperature of 260 ° C from an extruder equipped with an annular die. The tubular body of 150 micrometers in thickness was extruded, it cooled in the 40 degreeC water tank, and wound up on the roll.

0.7kg / cm 2 compressed air is injected into the end of the obtained tubular body, heated in hot water at 90 ° C, expanded and tensioned in the longitudinal direction using a differential speed roll to extend the longitudinal stretch ratio of 1.05 and the radial stretch ratio of 2.0. The coaxial stretching was performed at a drawing speed of 10 m / min.

The resulting heat-shrinkable tube had an inner diameter of 13.3 mm, a thickness of 75 µm, a shrinkage rate of 48% in the radial direction, and a shrinkage rate of 8% in the longitudinal direction.

Examples 2-5 and Comparative Examples 1-5

A heat shrinkable tube was manufactured in the same manner as in Example 1, except that its composition and processing conditions were changed as shown in Table 1 below.

Furtherance Processing condition Copolymer Resin Content (wt%) NDC content in the copolymer resin (mol%) PBT content (% by weight) with pigment Pigment content in PBT (wt%) Sodium stearate content (% by weight) Elastomer Content (wt%) Die temperature (℃) Cooling water tank temperature (℃) Example One 96.4 5 2.5 30 0.1 One 270 35 2 97.4 8 2.5 30 0.1 - 280 35 3 84.7 13 15 30 0.3 - 260 35 4 94.95 5 5 20 0.05 - 270 55 5 96.9 5 3 20 0.1 - 270 45 Comparative example One 97.4 5 2.5 30 0.1 One 270 90 2 97.4 5 2.5 30 0.1 - 280 80 3 99.9 5 - - 0.1 - 290 5 4 69.9 5 30 30 0.1 - 280 10 5 97.4 5 2.5 30 1.5 - 300 30

Experimental Example

The heat shrinkable tubes obtained according to Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated in the following manner.

(1) Coating adhesiveness: The obtained heat-shrinkable tube was covered with a 12.5 mm diameter condenser and heat-treated and contracted at 260 to 280 ° C. for 8 seconds to obtain a condenser in which the tube was completely in contact.

○: completely adhered to the outer wall of the capacitor,

X: Uneven part generate | occur | produced without being fully adhered to the outer wall of a capacitor | condenser.

(2) Hot water heat resistance: The obtained heat shrinkable tube was coated on a condenser having a diameter of 12.5 mm, and heat-treated and contracted at 260 to 280 ° C. for 8 seconds, and the condenser in which the tube was tightly adhered was subjected to hot water treatment for 10 minutes at 100 ± 2 ° C. water.

○: completely adhered to the outer wall of the capacitor,

X: Uneven part generate | occur | produced without being fully adhered to the outer wall of a capacitor | condenser.

(3) High temperature heat resistance: The resultant heat-shrinkable tube was covered with a 12.5 mm diameter condenser, heat treated and contracted at 260 to 280 ° C. for 8 seconds, and the condenser in which the tube was tightly adhered was subjected to dry heat treatment at 210 ± 5 ° C. for 3 minutes.

○: completely adhered to the outer wall of the capacitor,

X: Uneven part generate | occur | produced without being fully adhered to the outer wall of a capacitor | condenser.

(4) Tube Density: Density Gradient Test Method Specification ASTM D 1505

density Post-Shrink Density Cloth adhesion Hydrothermal Resistance High temperature heat resistance Example One 1.336 1.349 ○ ○ ○ 2 1.337 1.347 ○ ○ ○ 3 1.330 1.343 ○ ○ ○ 4 1.333 1.348 ○ ○ ○ 5 1.336 1.350 ○ ○ ○ Comparative example One 1.341 1.351 ○ × × 2 1.342 1.351 ○ × × 3 1.340 1.349 ○ × × 4 1.325 1.335 × × × 5 1.345 1.353 × × ×

As described in detail above, according to the present invention, the heat shrinkage is made within a predetermined density range with a composition containing a polyethylene terephthalate copolymer resin and a polybutylene terephthalate resin containing a pigment as a main component and sodium stearate or an elastomer added thereto. In addition to excellent coating adhesion after coating on the condenser, it can be seen that the coating tube has excellent coating adhesion in the shrinkage and drying processes.

Claims (5)

(Correction) It consists of 1-15 mol% of polyethylene naphthalates and 85-99 mol% of polyethylene terephthalates, and consists of a co-polyester resin containing the copolymer resin which has an intrinsic viscosity of 0.65-1.0 dl / g, The density is 1.330 Polyester type heat shrinkable tube for capacitor | condenser coating of -1.339. (delete) (Correction) The copolymerized resin 80 to 99 according to claim 1, wherein the copolymerized polyester resin is composed of 1 to 15 mol% polyethylene naphthalate and 85 to 99 mol% polyethylene terephthalate, and has an intrinsic viscosity of 0.65 to 1.0 dl / g. Weight percent; A polyester-based heat-shrinkable tube for condenser coating, characterized in that it is a mixed resin of 1 to 20% by weight of resin produced by melt-mixing polybutylene terephthalate and pigment. (Correction) The copolymerized resin 80 to 98.99 according to claim 1, wherein the copolymerized polyester resin comprises 1 to 15 mol% of polyethylene naphthalate and 85 to 99 mol% of polyethylene terephthalate, and has an intrinsic viscosity of 0.65 to 1.0 dl / g. weight%; 1 to 19.99% by weight of resin produced by melt-mixing polybutylene terephthalate and pigment; And 0.01 to 1.0% by weight of a metal salt of benzoic acid or stearic acid. The polyester-based heat-shrinkable tube for condenser coating according to any one of claims 1 to 4, wherein the density of the tube is 1.342 to 1.353 after coating the capacitor-based heat-shrinkable tube for condenser coating. .