JP2011052122A - Flame-retardant heat-shrinkable tube and member covered with the same - Google Patents

Abstract

Disclosed is a flame-retardant heat-shrinkable tube having excellent flame retardancy, excellent in shrinkage characteristics and heat resistance, and having no bromine compound, phosphorus compound or antimony compound added.
In a flame-retardant heat-shrinkable tube, a polyester resin (A), a melamine derivative compound (B), and a crosslinking agent having a glass transition temperature of 0 ° C. or lower and a crystal melting temperature of 70 to 120 ° C. The resin composition composed of (C) and the carbodiimide compound (D) is a main component, the gel fraction of the polyester resin (A) is 70% by mass or more, and the total amount of this resin composition is 100% by mass. The content of the melamine derivative compound (B) is 20 to 60% by mass or less, the content of the crosslinking agent (C) is less than 0.1 to 0.7% by mass, and the content of the carbodiimide compound (D) is It shall be 0.1-3 mass% or less.
[Selection figure] None

Description

  The present invention provides a flame-retardant heat-shrinkable tube excellent in shrinkage characteristics and heat resistance, and capable of imparting excellent flame retardancy without adding a bromine-based compound, phosphorus-based compound, or antimony-based compound, and the tube It relates to a coated member.

  Conventionally, a heat-shrinkable tube mainly made of polyvinyl chloride has been widely used as an electrical insulating material used for capacitor coating applications. However, the heat shrink tube made of polyvinyl chloride generates hydrogen chloride gas during combustion, and there is a problem that the incinerator is liable to be damaged during disposal such as incineration. As an alternative to tubes, heat-shrinkable tubes made of polyolefin resin or polyester resin have been used.

  However, when a flame-retardant property is imparted in order to use a heat-shrinkable tube made of polyolefin resin for capacitor coating, it is necessary to add a large amount of an inorganic flame retardant such as aluminum hydroxide or magnesium hydroxide. Not only does the mechanical strength decrease, but also the product weight increases due to the higher specific gravity.

  On the other hand, as for the crosslinking technique of polyester-based resin, for example, a shrinkable material that is crosslinked by adding a monomer having an allyl group to polylactic acid is exemplified (see Patent Document 1). Is as high as 150 ° C., which may cause deterioration of the material to be coated. Further, the technology has insufficient flame retardancy, and it is very difficult to apply to coating materials such as electronic materials that require high flame retardance. Moreover, in the said technique, when there is little addition amount of a crosslinking agent, sufficient crosslinking density is not obtained, but when using with a tube, practically sufficient shrinkage | contraction characteristics and heat resistance may not be obtained.

Japanese Patent Laid-Open No. 2005-125684

  Conventionally, it is very difficult to provide a tube made of a polyester resin that has all of shrinkage characteristics, heat resistance, and flame retardancy with the disclosed technology, and in particular, bromine compounds and phosphorus compounds. It is very difficult to achieve the flame retardancy of VW-1 without containing an antimony compound, and it is listed as an important issue.

  This invention is made | formed in view of the said subject, The subject of this invention is flame-retardant by mix | blending a melamine derivative compound with respect to the polyester-type resin which has a specific glass transition temperature and a crystal melting calorie | heat amount. And providing a tube excellent in shrinkage characteristics and heat resistance by constituting an excellent crosslinked structure by using a crosslinking agent and a carbodiimide compound in combination.

  In order to solve the above-mentioned problems, the present inventors have focused on the characteristics of the melamine derivative compound, the crosslinking agent, and the carbodiimide compound, and as a result of earnestly examining the resin composition mixed with the polyester resin, the present invention is completed. It came to.

  That is, an object of the present invention is to provide a polyester resin (A), a melamine derivative compound (B), a crosslinking agent (C) having a glass transition temperature of 0 ° C. or lower and a crystal melting temperature of 70 ° C. or higher and 120 ° C. or lower. ) And a carbodiimide compound (D) as a main component, a heat-shrinkable tube, wherein the polyester resin (A) has a gel fraction of 70% by mass or more, and the polyester resin (A ), When the total amount of the melamine derivative compound (B), the crosslinking agent (C), and the carbodiimide compound (D) is 100% by mass, the content of the melamine derivative compound (B) is 20% by mass to 60% by mass. Yes, the content of the crosslinking agent (C) is 0.1% by mass or more and less than 0.7% by mass, and the content of the carbodiimide compound (D) is 0.1% by mass or more and 3% by mass or less. Flame-retardant heat shrinkable tube, wherein the door (hereinafter, also referred to as "tube of the present invention".) Is accomplished by.

  In the tube of the present invention, the cross-linking agent (C) is preferably trimethallyl isocyanate.

  Moreover, the tube of this invention can be 30% or more and 80% or less of the shrinkage | contraction of radial direction, when left still for 20 second in a 120 degreeC hot air.

  In the tube of the present invention, the polyester resin (A) is preferably polybutylene succinate, polybutylene succinate-adipate copolymer, or a mixture thereof.

  In the tube of the present invention, the heat of crystal melting of the polyester resin (A) is preferably 5 J / g or more and 40 J / g or less.

  The tube of the present invention is preferably used by covering a member for use in electronic equipment or electrical equipment.

  According to the present invention, a flame-retardant heat-shrinkable tube having excellent shrinkage characteristics, heat resistance, and flame retardancy is coated without adding a bromine-based compound, a phosphorus-based compound, or an antimony-based compound, and the tube. A member can be provided.

  Hereinafter, an example of an embodiment of the present invention will be described, but the scope of the present invention is not limited to the embodiment described below.

<Polyester resin (A)>
It is important that the polyester-based resin (A) used in the present invention has a glass transition temperature of 0 ° C. or lower, preferably −10 ° C. or lower, more preferably −20 ° C. or lower. When the glass transition temperature of the polyester-based resin (A) exceeds 0 ° C., the resin is in a glass state in a normally used temperature range (0 ° C. to 40 ° C.), so that the impact resistance may be inferior. When blended, it may be difficult to develop practically sufficient mechanical properties.

  The polyester resin (A) used in the present invention has a crystal melting temperature of 70 ° C. or higher, preferably 80 ° C. or higher, more preferably 85 ° C. or higher, and 120 ° C. or lower, preferably 115 ° C. or lower. It is important that the temperature is preferably 110 ° C. or lower. If the crystal melting temperature of the polyester-based resin (A) is less than 70 ° C, sufficient heat resistance cannot be obtained, and if the crystal melting temperature exceeds 120 ° C, low temperature shrinkability may not be obtained.

  Examples of the polyester resin (A) include aliphatic polyesters, aliphatic-aromatic polyesters, and mixtures thereof. Examples of the aliphatic polyester include dibasic acid components not containing an aromatic ring such as succinic acid, adipic acid, and sebacic acid, 1,4-butanediol, propylene glycol, 1,6-hexanediol, cyclohexanediol, and ethylene. Examples thereof include copolymers composed of diol components such as glycol and diethylene glycol. Among them, polybutylene succinate / adipate copolymer and polybutylene succinate are preferable.

  Examples of commercially available aliphatic polyesters include “GSPla” AZ series and AD series manufactured by Mitsubishi Chemical Corporation, “Bionore” # 1000 series and # 3000 series manufactured by Showa Polymer Co., Ltd., and the like.

  Examples of the aliphatic-aromatic polyester include polycondensation polymers of a dibasic acid component containing an aromatic ring and a diol component and / or a dibasic acid component not containing an aromatic ring. Specific examples of the dibasic acid component used as a raw material monomer for the aromatic polyester include terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, and the like, and specific examples of the diol component include ethylene. Examples include glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, and polyoxylene glycol.

  Commercially available products of aliphatic-aromatic polyesters include, for example, “Ecoflex” series manufactured by BASF, “Easter Bio” series manufactured by Eastman Chemicals, “Byron” (registered trademark) series manufactured by Toyobo Co., Ltd., Nippon Synthetic Chemical Co., Ltd. Examples include “Nichigo Polyester” series manufactured by Kogyo Co., Ltd.

  The lower limit of the weight average molecular weight of the aliphatic polyester and aliphatic-aromatic polyester is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, and the upper limit is 400,000 or less, preferably Is 300,000 or less, more preferably 250,000 or less. When the weight average molecular weight of the aliphatic polyester and the aliphatic-aromatic polyester is 50,000 or more, deterioration of mechanical properties and the like during use does not occur, and the weight average molecular weight of the aliphatic polyester is 400,000 or less. In this case, the viscosity at the time of processing becomes optimum, and the problem of poor thickness of the laminate or poor dispersion of the melamine derivative compound does not occur.

  The weight average molecular weight was measured by the following method. That is, measurement was performed using gel permeation chromatography using chloroform as a solvent (solution concentration 0.2 wt / vol%, solution injection amount 200 μl, solvent flow rate 1.0 ml / min, solvent temperature 40 ° C.). The weight average molecular weight of the polyester resin was calculated in terms of polystyrene. The weight average molecular weight of the standard polystyrene used is 2,000,000, 430,000, 110,000, 35,000, 10,000, 4,000, 600.

    Further, the heat of crystal melting (ΔHm) of the polyester resin (A) is 5 J / g or more, preferably 10 J / g or more, more preferably 15 J / g or more, and 40 J / g or less, preferably 35 J / g. g or less, more preferably 30 J / g or less. If ΔHm is within the above range, a tube having both excellent heat resistance and impact resistance can be provided.

  The tube of the present invention performs crosslinking by irradiation with ionizing radiation for the purpose of imparting shrinkage characteristics. Under the present circumstances, the gel fraction of the said polyester-type resin (A) is 70 to 100 mass%, Preferably it is 75 to 100 mass%, More preferably, it is 80 to 100 mass%. is important. When the gel fraction of the polyester resin (A) is less than 70% by mass, sufficient shrinkage characteristics and heat resistance imparting effect may not be obtained.

  The content of the polyester resin (A) is 30% when the total amount of the polyester resin (A), the melamine derivative compound (B), the crosslinking agent (C), and the carbodiimide compound (D) is 100% by mass. % Or more, preferably 40% by mass or more, more preferably 50% by mass or more, 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less. If the content rate of a polyester-type resin (A) is 30 mass% or more, the shrinkable tube which has the outstanding shrinkage | contraction characteristic can be provided. Moreover, if the content rate of a polyester-type resin (A) is 90 mass% or less, the shrinkable tube which has the outstanding mechanical characteristic can be provided.

<Melamine derivative compound (B)>
In the tube of the present invention, the melamine derivative compound (B) is used. The flame retardants used so far are generally bromine-based compounds or phosphorus-based compounds, and these can give excellent flame retardancy, but brominated compounds have problems in terms of environment and safety. In some cases, the phosphorous compound may cause a decrease in heat resistance due to plasticization of the resin, or bleeding of the phosphorous compound to the surface of the molded product. In contrast, a melamine derivative compound is a kind of organic nitrogen compound having a triazine ring at the center of the structure, is widely known as a flame retardant aid, and can impart excellent flame retardancy when used in combination with a phosphorus compound. However, there is no known technology that imparts excellent flame retardancy with a melamine derivative compound alone. The inventors of the present invention have found that the melamine derivative compound exhibits flame retardancy based on a two-stage combustion suppression mechanism of endothermic by sublimation and dilution of a combustible gas by an inert gas. Used for tubes.

  The melamine derivative compound used in the tube of the present invention refers to a compound represented by the following general formula (1).

In the above formula (1), R _{1 to} R ₆ are H, OH, —CH ₂ OCH ₃ , —CH ₂ OC ₂ H ₅ , —CH ₂ OH, —CH ₂ CH ₂ OH, —CH ₂ CH ₂ CH _2. It is either OH, and R _{1 to} R ₆ may be the same substituent or different substituents. Among them, melamine in which R _{1 to} R ₆ are H is preferably used.

  The average particle size of the melamine derivative compound (B) is 10 μm or less, preferably 8 μm or less, more preferably 5 μm or less. By setting the average particle size of the melamine derivative compound (B) to 10 μm or less, the flame retardancy and mechanical strength of the tube of the present invention can be improved. The average particle diameter is a value calculated with melamine as an equivalent circle.

  The content of the melamine derivative compound (B) is 20% by mass or more when the total amount of the polyester resin (A), the melamine derivative compound (B), the crosslinking agent (C) and the carbodiimide compound (D) is 100% by mass. It is important that the content is 25% by mass or more, more preferably 30% by mass or more, and 60% by mass or less, preferably 55% by mass or less, and more preferably 50% by mass or less. If the content of the melamine derivative compound (B) is 20% by mass or more, sufficient flame retardancy can be obtained, and if it is 60% by mass or less, deterioration of mechanical properties is suppressed, and the tube of the present invention is used. Occurrence of damage or the like can be suppressed.

  As a commercial item of a melamine derivative compound (B), differential melamine (made by Nissan Chemical Industries), a melamine (made by Mitsui Chemicals), etc. are mentioned, for example.

<Crosslinking agent (C)>
The cross-linking agent (C) used in the tube of the present invention is a compound having two or more functional groups such as acryl group, methacryl group, allyl group and vinyl group in the molecule and having a weight average molecular weight of about 2,000 or less. It is preferable that Specifically, diallyl isocyanate, triallyl isocyanate, dimethallyl isocyanate, trimethallyl isocyanate, diallyl monoglycidyl isocyanate, 1,4-butanediol dimethacrylate, polyethylene glycol methacrylate, pentaerythritol dimethacrylate, dipenta Examples include erythritol hexaacrylate, trimethylolpropane acrylate, divinylbenzene, trivinylbenzene, and hexamethylbenzene. In particular, by blending trimethallyl isocyanate, a high gel fraction of the polyester resin (A) can be achieved with a lower addition amount.

  The content of the crosslinking agent (C) is 0.1 mass when the total amount of the polyester resin (A), the melamine derivative compound (B), the crosslinking agent (C), and the carbodiimide compound (D) is 100 mass%. % Or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and less than 0.7% by mass, preferably 0.6% by mass or less, more preferably 0.5% by mass or less. It is important that If the content of the crosslinking agent (C) is 0.1% by mass or more, a sufficient crosslinking effect can be obtained, and if it is less than 0.7% by mass, occurrence of problems in molding due to an increase in viscosity is suppressed. And the external appearance fall by gelation of resin can be suppressed.

  As a commercial item of a crosslinking agent (C), Nippon Kasei Co., Ltd. triallyl isocyanate "TAIC", trimethallyl isocyanate "TMAIC", etc. are mentioned, for example.

<Carbodiimide compound (D)>
In order to improve the crosslinking efficiency of the resin composition constituting the tube of the present invention, to achieve a sufficient gel fraction in the case of a low addition amount of the crosslinking agent, and to impart excellent shrinkage characteristics and heat resistance, a carbodiimide compound It is important to blend (D). Examples of the carbodiimide compound (D) include those having a basic structure represented by the following general formula (2).

  In the above formula, n represents an integer of 1 or more. R represents another organic bond unit. In these carbodiimide compounds, the R portion may be aliphatic, alicyclic, or aromatic. Usually, n is appropriately determined between 1 and 50.

  Specifically, for example, bis (dipropylphenyl) carbodiimide, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly ( Diisopropylphenylenecarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide) and the like. A carbodiimide compound (D) can be used 1 type or in combination of 2 or more types.

  Examples of commercially available carbodiimide compounds include “STABAXOL P” manufactured by Rhein Chemie, “Carbodilite” series manufactured by Nisshinbo Co., Ltd., and the like.

  The content of the carbodiimide compound (D) is 0 when the total amount of the polyester resin (A), the melamine derivative compound (B), the crosslinking agent (C), and the carbodiimide compound (D) is 100% by mass. 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and 3.0% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass. It is important that it is less than mass%. If the content of the carbodiimide compound (D) is 0.1% by mass or more, an effect of improving the crosslinking rate and an effect of imparting hydrolysis resistance are obtained, and if it is 3.0% by mass or less, the resin composition Softening and bleeding of the carbodiimide compound (D) can be suppressed.

  The tube of the present invention may contain other additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, a lubricant, a nucleating agent, a plasticizer, a pigment, and a dye, as long as the effects of the present invention are not impaired. it can.

  Next, the manufacturing method of the tube of this invention is demonstrated. The method for producing the tube of the present invention is not particularly limited. Usually, after unextended tube is extruded using a round die, it is crosslinked by irradiating with ionizing radiation, and then subjected to crosslinking treatment. A preferred method is to stretch the unstretched tube into a heat-shrinkable tube. In addition, a method in which a film extruded and stretched using a T die or an I die is bonded by fusing, welding, or bonding to form a tube, and further, the tube or film is bonded in a spiral to form a tube. Etc.

  Here, the method of extruding an unstretched tube using a round die and then stretching it into a heat-shrinkable tube will be described in more detail. The resin composition described above is heated and melted to a temperature equal to or higher than the melting point by a melt extrusion apparatus, continuously extruded from a round die, and then forcibly cooled and molded into an unstretched tube. As a means for forced cooling, a method of immersing in low-temperature water, a method using cold air, or the like can be used. Among them, the method of immersing in low-temperature water is effective with high cooling efficiency. The unstretched tube may be continuously supplied to the next stretching step, or after being wound up into a roll, the unstretched roll may be used as a raw material for the next stretching step. From the viewpoint of production efficiency and thermal efficiency, a method of continuously supplying an unstretched tube to the next stretching step is preferable.

  In the present invention, for the purpose of imparting shrinkage characteristics to the tube obtained by the above production method, crosslinking is performed by irradiation with ionizing radiation. Examples of the ionizing radiation include ultraviolet rays / electron beams / α rays, β rays, γ rays, neutron rays, and the like. In order to advance the crosslinking more efficiently, it is preferable to use γ rays. The irradiation dose of ionizing radiation is 10 kGy or more, preferably 20 kGy or more, more preferably 30 kGy or more, 100 kGy or less, preferably 80 kGy or less, more preferably 70 kGy or less. By irradiating with ionizing radiation at an irradiation dose in such a range, the crosslinking proceeds sufficiently, and excellent shrinkage characteristics and heat resistance can be imparted to the tube of the present invention.

  Next, the unstretched tube subjected to the crosslinking treatment by the above method is pressurized with a compressed gas from the inside of the tube and stretched. The stretching method is not particularly limited, but, for example, it is sent out from one end of an unstretched tube at a constant speed while applying pressure by a compressed gas to the inside of the tube, and then heated by hot water or an infrared heater, etc. In order to regulate the draw ratio, drawing at a fixed ratio is performed through a cooled cylindrical tube. The temperature conditions and the like are adjusted so that the cylinder tube is stretched at an appropriate position. The stretched tube cooled by the cylindrical tube is sandwiched by a pair of nip rolls and is taken up and wound as a stretched tube while maintaining the stretching pressure. Stretching may be performed in any order in the length direction or the radial direction, but is preferably performed simultaneously.

  The stretching ratio in the length direction is determined by the ratio of the feed speed of the unstretched tube and the nip roll speed after stretching, and the stretching ratio in the radial direction is determined by the ratio of the unstretched outer diameter to the stretched tube outer diameter. As another stretching and pressurizing method, a method of maintaining the internal pressure of the compressed gas in which both the unstretched tube feed side and the stretched tube take-up side are sandwiched and sealed between nip rolls can be employed.

  Stretching conditions are adjusted according to the type of polyester resin (A), the blending ratio with other mixtures, the target heat shrinkage, etc., but the normal stretching temperature is -20 ° C. or higher, the melting point of the polyester resin. It is carried out in the range of + 40 ° C. or lower, more preferably −10 ° C. or higher and + 30 ° C. or lower, more preferably −10 ° C. or higher and + 20 ° C. or lower.

  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. Is not more than twice, more preferably not more than 2.0 times, and not less than 1.0 times in the length direction, preferably not less than 1.02 times, not more than 2.0 times, preferably not more than 1.5 times More preferably, it is obtained by stretching in a range of 1.3 times or less.

  If the draw ratio in the radial direction of the tube is less than 1.2 times, there may be a case where a sufficient amount of shrinkage cannot be obtained. On the other hand, when the draw ratio in the radial direction of the tube exceeds 3.0 times, the thickness fluctuation tends to increase. Moreover, when the draw ratio in the length direction of the tube exceeds 2.0 times, the contraction amount in the length direction becomes large, and the coating position may be shifted when an electronic component or the like is coated.

  The tube of the present invention has a thermal shrinkage rate of 30% or more, preferably 35%, more preferably 40% or more in the radial direction of the tube when immersed in silicon oil at 120 ° C. for 20 seconds, and 80% or less, preferably 70% or less, more preferably 60% or less. In the tube length direction, it is 40% or less, preferably 15% or less, more preferably 5% or less, and most preferably 0%. If the thermal shrinkage rate when immersed in silicone oil at 120 ° C. for 20 seconds is in the above range, it has excellent low temperature shrinkage characteristics, so there is no risk of damaging the contents of the capacitor and the like. It is expected that the coating finish in the process of shrinking and coating the capacitor will be improved, and that the coating speed will be increased.

  Although the thickness of the heat-shrinkable tube obtained as described above is not particularly limited, the thickness after coating (after shrinkage) of the tube generally used for a capacitor is approximately 0.05 m or more depending on the rated voltage of the capacitor. Those having a diameter of 1 mm or less, typically 0.07 mm or more and 0.2 mm or less are used.

  The mixed resin composition used in the tube of the present invention may be used by previously mixing each component with a mixer such as a tumbler, V-type blender, Banbury mixer, kneading roll, or extruder, or extruding an unstretched tube. Alternatively, the components weighed may be directly supplied to the supply port of the extruder for feeding, or the components weighed separately may be supplied to the supply ports of the extruder having two or more supply ports. Furthermore, in this invention, a well-known method can be used for the mixing method of a polyester-type resin (A), a melamine derivative compound (B), a crosslinking agent (C), a carbodiimide compound (D), and other additives.

  For example, a method for separately preparing a master batch in which various additives are mixed with a suitable base resin such as polyester resin (A) at a high concentration, and adjusting the concentration to the resin to be used, or using the master batch And a method of directly mixing various additives with the resin to be treated.

  In order to avoid hydrolysis of the polyester resin (A) in the extruder, the mixed resin composition used in the tube of the present invention has a water content of 0.1% by mass or less, preferably 0.05% by mass or less in advance. It is important that the product is sufficiently dried. For example, the film is dried at 60 ° C. under a vacuum under reduced pressure for 8 hours or more. Moreover, the method of performing so-called non-drying extrusion which performs a vacuum vent using a same-direction twin-screw extruder is also mentioned as a suitable method.

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

  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 values and evaluation about the tube displayed in this specification were performed as follows. Here, the flow direction from the extruder of a tube is called a length direction, and the orthogonal direction is called a radial direction.

  First, the evaluation method performed in the examples will be described.

(1) Measurement of glass transition temperature Using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., measuring the temperature dependence of the tensile modulus while applying a strain that changes in a sinusoidal shape with a frequency of 1 Hz to the polyester resin (A). did. The measurement conditions were a sample thickness of 0.5 mm, a maximum strain of 1%, a temperature increase rate of 3 ° C./min, and measurement was performed in the range of −100 ° C. to 200 ° C. From the obtained chart, the peak value of the loss tangent was read and taken as the glass transition temperature.

(2) Measurement of crystal melting temperature and crystal melting heat amount Based on JIS K7121, about 10 mg of sample was cut from 30 ° C. to 200 ° C. at a rate of 10 ° C./min using DSC-7 manufactured by Perkin Elmer. The temperature was raised, and the crystal melting temperature and the heat of crystal melting were read from the obtained thermogram.

(3) Measurement of gel fraction The measuring method of the gel fraction of the polyester-type resin (A) which comprises the tube of this invention is demonstrated below.
a) A 0.25 g test piece cut from the obtained heat shrinkable tube was dissolved in 20 ml of chloroform at 23 ° C. for 5 hours.
b) Using the table top high-speed cooling centrifuge 3-18K manufactured by Sigma Laborentrifgen GmbH, the solution prepared in the above a) was separated at a rotational speed of 11,400 rpm.
c) After drying the insoluble matter obtained in b) and subtracting components other than the polyester resin (A) (melamine derivative compound (B), cross-linking agent (C), carbodiimide compound (D), etc.) The gel fraction was calculated by the following formula.
Gel fraction (mass%) = A / B × 100
A: Mass of insoluble matter of resin component after subtracting mass of components other than polyester resin (A) obtained in c) B: Polyester resin (A) occupying in the obtained heat shrinkable tube The theoretical mass of the resin component minus the mass of components other than

(4) Thermal contraction rate
The shrinkage rate in the radial direction after immersing a tube having a diameter of 30 mm and a length of 100 mm in a silicon bath containing silicon oil at 120 ° C. for 20 seconds was calculated based on the following equation.
Thermal contraction rate (%) = [(L ₀ −L ₁ ) / L 0] × 100
Here, L ₀ means a dimension before shrinkage, and L ₁ means a dimension after shrinkage.

(5) Heat resistance Using a constant temperature hot air oven NH-402 manufactured by Nagano Chemical Machinery Co., Ltd., a stainless steel rod with a diameter of 18 mm and a length of 200 mm was covered with a tube with a diameter of 30 mm and a length of 100 mm, and then allowed to stand at 200 ° C. for 30 minutes. The tube was evaluated visually for defects such as pinholes and tears. A case where no defects such as pinholes or tears occurred was indicated by ◯, and a case where defects were generated was indicated by ×.

(6) Flame retardancy (VW-1)
Based on the UL 1581VW-1 standard combustion test method, 15 seconds of ignition and 15 seconds of rest were repeated 5 times using a tyryl burner, and a pass / fail judgment was made based on the burning time of the test piece, the indicator damage rate, and whether or not the absorbent cotton was ignited by drip. . VW-1 passed if the burning time was 60 seconds or less, the indicator damage rate was 25% or less, and the absorbent cotton was not ignited by drip.

  Next, resins and additives used in the examples will be described.

"Polyester resin (A)"
(A) -1: GSPla AD92W manufactured by Mitsubishi Chemical Corporation (polybutylene succinate-adipate copolymer, glass transition temperature = −45 ° C., crystal melting temperature = 88 ° C., heat of crystal melting = 35 J / g)
(A) -2: GSPla AZ91T manufactured by Mitsubishi Chemical Corporation (polybutylene succinate, glass transition temperature = −32 ° C., crystal melting temperature = 110 ° C., heat of crystal melting = 54 J / g)
(A) -3: Polyester SP154 manufactured by Nippon Synthetic Chemical Co., Ltd. (polybutylene adipate terephthalate, glass transition temperature = −20 ° C., crystal melting temperature = 120 ° C., heat of crystal melting = 10 J / g)

“Melamine derivative compound (B)”
(B) -1: Fine melamine manufactured by Nissan Chemical Industries, Ltd. (average particle size = 3 μm)

"Crosslinking agent (C)"
(C) -1: Nippon Kasei Co., Ltd. TMAIC (trimethallyl isocyanate)

“Carbodiimide compound (D)”
(D) -1: Carbodilite LA-1 (polycarbodiimide) manufactured by Nisshinbo Industries, Ltd.

Example 1
After (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 79.25: 20: 0.25: 0.5, φ40 mm It knead | mixed at 200 degreeC using the same direction twin-screw extruder, extruded using the round die | dye, immersed in water, and cooled and solidified, and the outer diameter 20mm and thickness 0.2mm unstretched tube were obtained. Next, after irradiating the unstretched tube with radiation at an irradiation dose of 50 kGy, it was heated with hot water at 85 ° C., stretched 1.09 times in the length direction and 1.8 times in the diameter direction, and then cooled to an outer diameter of 11 mm. A heat-shrinkable tube having a thickness of 0.1 mm was obtained. Table 1 shows the results of evaluating the heat shrinkage rate, flame retardancy, and heat resistance of the obtained heat shrinkable tube.

(Example 2)
Example 1 except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 59.5: 40: 0.25: 0.5 A heat-shrinkable tube was prepared and evaluated in the same manner as described above. The results are shown in Table 1.

(Example 3)
Example 1 except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 39.5: 60: 0.25: 0.5. A heat-shrinkable tube was prepared and evaluated in the same manner as described above. The results are shown in Table 1.

Example 4
A heat-shrinkable tube was prepared and evaluated in the same manner as in Example 2 except that (A) -2 was used instead of (A) -1 and the stretching temperature was 105 ° C. The results are shown in Table 1.

(Example 5)
A heat-shrinkable tube was prepared and evaluated in the same manner as in Example 2 except that (A) -3 was used instead of (A) -1 and the stretching temperature was 115 ° C. The results are shown in Table 1.

(Example 6)
Example 1 except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 59.9: 40: 0.1: 0.5 A heat-shrinkable tube was prepared and evaluated in the same manner as described above. The results are shown in Table 1.

(Example 7)
Same as Example 1 except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 59: 40: 0.5: 0.5. The heat shrinkable tube was prepared and evaluated by the method described above. The results are shown in Table 1.

(Example 8)
In Example 2, an unstretched tube having an outer diameter of 28 mm and a thickness of 0.28 mm was prepared, irradiated with radiation at an irradiation dose of 50 kGy, heated with 85 ° C. warm water, and 1.09 times in the length direction. After stretching 2.5 times in the radial direction, it was cooled to obtain a heat shrinkable tube having an outer diameter of 11 mm and a thickness of 0.1 mm. Table 1 shows the results of the same evaluation as in Example 1 for the obtained tube.

Example 9
Examples except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 58.25: 40: 0.25: 1.5 A heat-shrinkable tube was prepared and evaluated by the same method as in Example 1. The results are shown in Table 1.

(Example 10)
A heat-shrinkable tube was prepared and evaluated in the same manner as in Example 1 except that (C) -2 was used instead of (C) -1. The results are shown in Table 1.

(Comparative Example 1)
Example 1 except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 89.25: 10: 0.25: 0.5. A heat-shrinkable tube was prepared and evaluated in the same manner as described above. The results are shown in Table 1.

(Comparative Example 2)
Examples except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 59.45: 40: 0.05: 0.5 A heat-shrinkable tube was prepared in the same manner as in Example 1, but the cross-linking was not sufficient and the tube could not be stretched.

(Comparative Example 3)
Example except that carbodiimide compound (D) was not blended and (A) -1, (B) -1 and (C) -1 were dry blended at a mixing mass ratio of 59.75: 40: 0.25. A heat-shrinkable tube was prepared and evaluated by the same method as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
NW4032D (hereinafter referred to as PLA-1; glass transition temperature = 55 ° C., crystal melting temperature = 165 ° C., heat of crystal melting = 42 J / g) manufactured by Nature Works as PLA-based resin, PLA-1, (B) − 1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 59.25: 40: 0.25: 0.5 in the same manner as in Example 1 to obtain a heat shrinkable tube. Fabrication and evaluation were performed. The results are shown in Table 1.

(Comparative Example 5)
Examples except that (A) -1, (B) -1, (C) -1, and (D) -1 were dry blended at a mixing mass ratio of 29.25: 70: 0.25: 0.5 A heat-shrinkable tube was produced by the same method as in No. 1, but cracking occurred in the unstretched tube forming step, and the tube could not be formed.

(Comparative Example 6)
A heat-shrinkable tube was produced in the same manner as in Example 1 except that the irradiation dose was changed to 10 kGy. However, the tube was not sufficiently crosslinked and the tube could not be stretched.

  From Table 1, the flame-retardant shrinkable tubes of Examples 1 to 10 have excellent shrinkage characteristics in which the shrinkage ratio in the radial direction when immersed in silicon oil at 120 ° C. for 20 seconds is 30% or more, and UL1581VW-1 In addition, it has heat resistance that does not cause defects such as pinholes and tears even when left in hot air at 200 ° C. for 30 minutes.

  On the other hand, since the content rate of the melamine derivative compound (B) was small from Table 2, the comparative example 1 was inferior to a flame retardance. In Comparative Example 2, the amount of the crosslinking agent was small, so the gel fraction was not sufficient, and the tube could not be stretched. Moreover, since the comparative example 3 had little content of the carbodiimide compound (D), the gel fraction was inadequate and sufficient shrinkage rate was not obtained. In Comparative Example 4, the crystal melting temperature of the polyester-based resin (A) is higher than 120 ° C., and a sufficient gel fraction cannot be obtained, so that a sufficient shrinkage rate cannot be obtained, and heat resistance and flame retardancy are not obtained. It was inferior in nature. Moreover, since the comparative example 5 had too much content rate of the melamine derivative compound (B), shaping | molding of the tube was impossible. In Comparative Example 6, since the irradiation dose was small, the gel fraction of the polyester resin (A) was insufficient, and the tube could not be stretched.

  As described above, the heat-shrinkable tube of the present invention has excellent shrinkage characteristics, flame retardancy, and heat resistance. Therefore, the heat-shrinkable tube includes a tube for covering a capacitor such as an aluminum electrolytic capacitor, and an electric wire (round wire, square wire). Widely used in applications such as secondary batteries such as dry batteries and lithium-ion batteries, steel pipes or motor coil ends, transformers and other electrical equipment and small motors, and fluorescent lamp tubes for light bulbs, fluorescent lamps, facsimiles and image scanners can do.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is limited to the embodiments disclosed herein. Rather, the flame retardant heat-shrinkable tube and the member covered with the tube can be changed as appropriate without departing from the gist of the invention read from the claims and the entire specification, or in a range not violating the idea. Should also be understood as being included within the scope of the present invention.

Claims (7)

Polyester resin (A), melamine derivative compound (B), crosslinker (C), and carbodiimide compound (D) having a glass transition temperature of 0 ° C. or lower and a crystal melting temperature of 70 ° C. or higher and 120 ° C. or lower. A heat-shrinkable tube comprising a resin composition comprising:
The gel fraction of the polyester resin (A) is 70% by mass or more,
When the total amount of the polyester resin (A), the melamine derivative compound (B), the crosslinking agent (C), and the carbodiimide compound (D) is 100% by mass, the content of the melamine derivative compound (B) is 20% by mass or more. 60 mass% or less, the content of the crosslinking agent (C) is 0.1 mass% or more and less than 0.7 mass%, and the content of the carbodiimide compound (D) is 0.1 mass% or more and 3 mass%. % Flame retardant heat-shrinkable tube characterized by being less than or equal to%. The flame retardant heat-shrinkable tube according to claim 1, wherein the crosslinking agent (C) is trimethallyl isocyanate. The flame-retardant heat-shrinkable tube according to claim 1 or 2, wherein a shrinkage ratio in the radial direction when immersed in silicon oil at 120 ° C for 20 seconds is from 30% to 80%. The flame-retardant heat shrink according to any one of claims 1 to 3, wherein the polyester resin (A) is polybutylene succinate, polybutylene succinate-adipate copolymer, or a mixture thereof. tube. The flame-retardant heat-shrinkable tube according to any one of claims 1 to 4, wherein the heat of crystal melting of the polyester resin (A) is 5 J / g or more and 40 J / g or less. A member coated with the flame-retardant heat-shrinkable tube according to claim 1. The member according to claim 6, which is used for an electronic device or an electric device.