JP2011116010A - Polyphenylene sulfide-based heat shrinkable tube and member coated therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyphenylene sulfide-based heat shrinkable tube having superior shrinking function imparted while keeping flame retardancy and heat resistance. <P>SOLUTION: In the polyphenylene sulfide-based heat shrinkable tube formed of a resin composition containing a polyphenylene sulfide-based resin (A) and a phosphorus-based plasticizer (B), a temperature difference T2-T1 between temperature T1 of 5% mass reduction time and temperature T2 of 10% mass reduction when heating the tube from 20°C to 600°C at a temperature raising speed of 10°C/min in an air atmosphere by a thermogravimetric analyzer is set to 10-100°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a polyphenylene sulfide-based heat-shrinkable tube and a member coated with the tube, and more specifically, polyphenylene sulfide suitable for coating battery members for automobiles, electronic parts, particularly aluminum electrolytic capacitors. The present invention relates to a heat-shrinkable tube and these members coated with the tube.

  Conventionally, a heat-shrinkable tube mainly made of polyvinyl chloride has been widely used as an electrical insulating material used to coat batteries, capacitors and the like. In recent years, products are becoming lighter, thinner and smaller, and electronic components such as capacitors have become denser, and heat shrinkable tubes are required to have good shrink finish. In addition, since fields with high operating temperatures, such as automotive electrical components, are rapidly expanding, heat-shrinkable tubes are required to have high heat resistance. In addition, with the progress of automation and speeding up of manufacturing equipment for electronic parts and the like, it is required to cope with this trend of speeding up, but on the other hand, the demand for the finished appearance of heat-shrinkable tubes has become more severe. Yes.

  However, heat-shrinkable tubes made of polyvinyl chloride have insufficient heat resistance, and hydrogen chloride gas is generated during combustion, causing problems such as incinerators being easily damaged during disposal such as incineration. . From such a side, heat shrinkable tubes made of crystalline resins such as polyester resins and polyphenylene sulfide resins have come to be used as an alternative to polyvinyl chloride tubes.

  Above all, polyphenylene sulfide resin is not only heat resistant but also excellent in flame retardancy, chemical resistance, electrolyte resistance, etc., so it is suitable for automotive electrical parts and electronic parts. Focusing on such characteristics, a heat-shrinkable tube using a polyphenylene sulfide-based resin has been studied (Patent Document 1). However, the tube obtained by the method described in Patent Document 1 cannot cope with shrinkage in a short time because the glass transition temperature Tg of the resin is high, and as described above, the manufacturing equipment has been speeded up for the purpose of improving productivity. Along with this, there has been a problem that it cannot be applied to recent production conditions, that is, production conditions in which the coating conditions are short at high temperatures.

  In order to solve the above problem, the present inventors have proposed a tube excellent in low-temperature shrinkage, which is mainly made of a polyphenylene sulfide resin in Patent Document 2.

JP-A-9-157402 International Publication No. 2008/114731 Pamphlet

  However, when the tube of Patent Document 2 is coated on a capacitor or a battery, a problem has been pointed out that the end surface of the tube curls the inner surface. For this reason, there has been a demand for further improvement on shrink finish.

  Furthermore, the temperature at which the polyphenylene sulfide resin is melt-extruded becomes very high at around 300 ° C., and the low-temperature shrinkability of the heat-shrinkable tube made of polyphenylene sulfide resin sometimes becomes poor.

  As a result of examining the above problems, the present inventors have lost the plasticizing effect of the resin material because the plasticizer in the heat-shrinkable tube volatilizes from the resin surface under high temperature conditions during melt extrusion. The present inventors have found that the heat shrinkable tube has a poor shrink finish. Moreover, since the volatilized plasticizer gas contaminates surrounding air, it discovered that it was necessary to suppress generation | occurrence | production of a plasticizer gas also from the point of work environment.

  Based on the above insight, the present inventors use a low volatility phosphorus plasticizer to maintain the flame retardancy and heat resistance of the polyphenylene sulfide-based heat-shrinkable tube while having excellent shrinkage function. The present invention has been completed.

  The first aspect of the present invention comprises a resin composition comprising a polyphenylene sulfide resin (A) and a phosphorus plasticizer (B), and is heated at 10 ° C./min in an air atmosphere by a thermogravimetric analyzer. Polyphenylene sulfide system in which the difference T2-T1 between the temperature T1 at the time of 5% mass reduction and the temperature T2 at the time of 10% mass reduction when heated from 20 ° C. to 600 ° C. at a rate is 10 ° C. or more and 100 ° C. or less It is a heat-shrinkable tube.

  The polyphenylene sulfide-based heat-shrinkable tube of the first aspect of the present invention is heated from 20 ° C. to 300 ° C. at a heating rate of 500 ° C./min in an air atmosphere by a thermogravimetric analyzer and held at 300 ° C. for 10 minutes. The mass reduction rate is preferably 0% or more and 5% or less.

  In 1st this invention, it is preferable that a phosphorus plasticizer (B) is contained 0.5 mass% or more and 15 mass% or less with respect to 100 mass% of polyphenylene sulfide resin (A).

  The second invention is a member coated with the polyphenylene sulfide heat-shrinkable tube of the first invention. The member is preferably used for applications of electronic equipment or electrical equipment.

  According to the present invention, by using a phosphorus plasticizer (B) in which the temperature difference T2-T1 is in a predetermined range in the heat-shrinkable tube, the flame retardancy and heat resistance of the polyphenylene sulfide-based heat-shrinkable tube. While maintaining the above, it is possible to impart excellent low temperature shrinkage and to improve the working environment by preventing the plasticizer from volatilizing.

<Polyphenylene sulfide-based heat-shrinkable tube>
The polyphenylene sulfide heat-shrinkable tube of the present invention comprises a resin composition comprising a polyphenylene sulfide resin (A) and a phosphorus plasticizer (B), and may be referred to as a thermogravimetric analyzer (hereinafter referred to as TGA). )), The difference between the temperature T1 at the time of 5% mass reduction and the temperature T2 at the time of 10% mass reduction when heated from 20 ° C. to 600 ° C. at a rate of temperature increase of 10 ° C./min in an air atmosphere. T1 is 10 ° C. or higher and 100 ° C. or lower.

  In the present invention, it is important to use a low-volatile plasticizer that satisfies the above characteristics. If the added plasticizer has high volatility, a large amount of gas is generated during melt extrusion, and the surrounding air is contaminated. In addition, since the plasticizing effect expected when molded into a heat-shrinkable tube cannot be obtained, the shrink finish of the heat-shrinkable tube is deteriorated.

  When the temperature difference T2−T1 is 100 ° C. or more, a large amount of gas is generated during melt extrusion, and the surrounding air is contaminated. Further, since the plasticizer disappears and the plasticizing effect cannot be obtained, the shrink finish of the heat shrinkable tube is deteriorated. Specifically, when the tube is contracted, there is a problem that the end surface of the tube is curled to the inner surface. In addition, when the temperature difference T2-T1 is 10 ° C. or less, the plasticizer does not volatilize and a carbonized layer is easily formed, which may cause eyes and spots, and has an expected plasticizing effect. It is not obtained and the appearance at the time of contraction is deteriorated.

  Further, the polyphenylene sulfide-based heat-shrinkable tube of the present invention is reduced in mass when heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in an air atmosphere by TGA and held at 300 ° C. for 10 minutes. The rate is preferably 0% or more and 5% or less. If the mass reduction rate is 5% or more, a large amount of gas is generated during melt extrusion, which may contaminate the surrounding air. Moreover, there exists a possibility that the plasticizing effect expected when shape | molding to a heat-shrinkable tube may not be acquired.

  In order to satisfy the above-mentioned characteristics of TGA analysis, it is necessary to select a suitable low-volatility phosphorus-based plasticizer (B). For such a suitable phosphorus-based plasticizer (B), It will be described later.

(Polyphenylene sulfide resin (A))
The polyphenylene sulfide resin (A) used in the present invention is a polyphenylene sulfide represented by the following formula (1) (hereinafter sometimes abbreviated as “PPS”) having a repeating unit of 70 mol% or more, preferably 80 mol. % Resin. When the PPS repeating unit is less than 70 mol%, the crystallinity and heat transition temperature of the polyphenylene sulfide resin (A) are lowered, and the flame retardancy and chemical resistance characteristic of the resin composition containing the resin (A) are reduced. Various characteristics such as electrical properties and electrical characteristics may be impaired.

  The polyphenylene sulfide-based resin (A) can contain other copolymerizable units having a sulfide bond as long as the repeating unit is less than 30 mol%, preferably less than 20 mol%. Examples of other copolymerizable repeating units include, for example, a meta bond unit, an ortho bond unit, a trifunctional unit, an ether unit, a ketone unit, a sulfone unit, an aryl unit having a substituent such as an alkyl group, a biphenyl unit, and a terphenylene. Specific examples include units, vinylene units and carbonate units. These units can contain only one type alone or in combination of two or more types. In this case, these structural units may be included in any copolymerization system such as a random type or a block type.

  The structure and molecular weight of the polyphenylene sulfide-based resin (A) are not particularly limited, and it can be used as a polymer having a branched chain or a polymer partially having a crosslinked structure. A (linear type) polymer having a molecular weight of 50,000 or more is preferable.

  The polyphenylene sulfide resin (A) may contain a low molecular weight oligomer. The content of the low molecular weight oligomer is 1.5% by mass or less based on the polyphenylene sulfide resin (A). It is preferable from the viewpoint of maintaining heat resistance and mechanical strength. The molecular weight of the low molecular weight oligomer is in the range of 100 to 2000, and the low molecular weight oligomer contained in the polyphenylene sulfide resin (A) can be removed by washing with a solvent such as diphenyl ether.

The melt viscosity of the polyphenylene sulfide resin (A) is not particularly limited as long as a heat-shrinkable tube satisfying predetermined physical properties can be obtained, but 300 ° C., shear rate 100 sec ⁻¹ , orifice L / D = 10/1 ( mm), which is preferably 100 Pa · s or more, more preferably 200 Pa · s or more, still more preferably 400 Pa · s or more, and preferably 10,000 Pa · s or less, more preferably It is 5,000 Pa · s or less, more preferably 2,000 Pa · s or less. When the apparent viscosity is 100 Pa · s or more, film formation is possible, and when the apparent viscosity is 10,000 Pa · s or less, the load on the extruder during extrusion can be suppressed.

  The production method of the polyphenylene sulfide resin (A) can be a known production method and is not particularly limited. For example, N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) may be used. In general, a method of reacting a dihalogenated aromatic compound such as p-dichlorobenzene with a sodium salt such as sodium sulfide in an aprotic organic solvent such as. In order to adjust the degree of polymerization, it is preferable to add a polymerization aid such as a caustic alkali or a carboxylic acid alkali metal salt and react at a temperature of 230 ° C. to 280 ° C. The pressure in the polymerization system and the polymerization time may be appropriately determined depending on the desired degree of polymerization and the type and amount of polymerization aid used.

  However, in this method, sodium halide is produced as a by-product, and this sodium halide is insoluble in a solvent such as NMP and is thus taken into the resin. After polymerization, the polyphenylene sulfide resin is washed with a large amount of water. However, the sodium halide in the resin cannot be removed sufficiently. Therefore, a method of performing polymerization using lithium salt instead of sodium salt can also be used.

(Phosphorus plasticizer (B))
The heat-shrinkable tube of the present invention is the difference between 5% weight loss temperature T1 and 10% weight loss temperature T2 when heated from 20 ° C. to 600 ° C. at a rate of temperature rise of 10 ° C./min. It is important to use a phosphorus plasticizer (B) such that T2-T1 is 10 ° C. or higher and 100 ° C. or lower. The temperature difference T2-T1 is preferably 10 ° C. or higher and 90 ° C. or lower, more preferably 10 ° C. or higher and 80 ° C. or lower. The disadvantages when outside these temperature ranges are as described above.

  The phosphorus-based plasticizer (B) is heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in an air atmosphere by TGA for the heat-shrinkable tube of the present invention at 300 ° C. for 10 minutes. As described above, it is preferable to use a material having a mass reduction rate of 0% or more and 5% or less when held.

  In consideration of the extrusion temperature of the resin composition in the present invention of 280 ° C. or higher and 320 ° C. or lower, it is preferable to use a phosphorus plasticizer (B) having a boiling point or a thermal decomposition temperature of about 400 ° C. or higher.

  Specific examples of the phosphorus plasticizer (B) that can be used in the present invention include phosphate ester plasticizers. Phosphoric ester plasticizers are preferred because they do not impair the flame retardancy that is characteristic of polyphenylene sulfide resins. It is also desirable from a non-halogen viewpoint.

  Preferable phosphate ester plasticizers include resorcinol bisdi2,6 xylenyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate and the like. By using these phosphate ester plasticizers, the Tg of the resin composition can be lowered without impairing the excellent flame retardancy of the polyphenylene sulfide resin (A). High temperature shrinkability.

  Among the phosphoric ester plasticizers, it is preferable to use resorcinol bisdi-2,6-xylenyl phosphate. The resorcinol bisdi-2,6-xylenyl phosphate is a condensed phosphate ester, has a large molecular weight, and is excellent in compatibility with the polyphenylene sulfide resin (A), under high temperature conditions during extrusion. , Especially stable.

(Resin composition)
The resin composition constituting the polyphenylene sulfide-based heat-shrinkable tube of the present invention comprises the above-described polyphenylene sulfide-based resin (A) and phosphorus-based plasticizer (B), and the polyphenylene sulfide-based resin (A). The phosphorous plasticizer (B) is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, and preferably 15% by mass or less, relative to 100% by mass. Preferably, it is contained at a ratio of 12% by mass or less, more preferably 10% by mass or less. If content of a phosphorus plasticizer (B) is 0.5 mass% or more, a plasticizing effect will be acquired and a low-temperature shrinkability and a crease whitening suppression effect will be acquired. Further, when the content is 15% by mass or less, the melt viscosity is not excessively lowered, and the deterioration of the thickness accuracy can be suppressed.

  As the resin component of the resin composition constituting the heat-shrinkable tube of the present invention, the polyphenylene sulfide resin (A) may be used alone, or may be blended and alloyed with other resins. As a raw material resin for blending and alloying, polyester, liquid crystal polymer, polyamide, polyolefin, polyimide, polyamideimide, polyarylate, polyetherimide, polyetheretherketone, polyethersulfone, polysulfone, polystyrene-based elastomer, Examples thereof include nitrile rubber and acrylic rubber. For example, butadiene copolymer, styrene-isoprene copolymer, butadiene-styrene copolymer (random, block, graft copolymers), isoprene copolymer, chlorobutadiene copolymer, butadiene-acrylonitrile copolymer , Isobutylene copolymer, isobutylene-butadiene copolymer, isobutylene-isoprene copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer. Furthermore, partially modified rubber components can also be used, such as maleic anhydride modified saturated styrene thermoplastic elastomer, partially hydrogenated styrene-butadiene block copolymer, partially hydrogenated styrene-isoprene block copolymer, and the like. Can be mentioned. The proportion of the other resin mixed with the polyphenylene sulfide resin (A) is preferably 0.1% by mass or more, more preferably 2%, based on the resin component in the resin composition (100% by mass). The upper limit is preferably 30% by mass or less, and more preferably 10% by mass or less. By mixing other resins, additional effects such as toughness produced by the other resins can be imparted.

<Method for producing polyphenylene sulfide-based heat-shrinkable tube>
(Preparation of resin composition)
In the resin composition constituting the polyphenylene sulfide-based heat-shrinkable tube of the present invention, each component may be mixed in advance by a mixer such as a tumbler, V-type blender, Banbury mixer, kneading roll, extruder, etc. Directly supply each measured component to the supply port of the extruder for extruding the unstretched tube, or supply the separately measured components to each supply port of the extruder having two or more supply ports, It may be formed by mixing in an extruder.

  Furthermore, a publicly known method can be used as a mixing method of various additives mentioned below including a phosphorus plasticizer (B). For example, a master batch in which various additives are mixed in a suitable base resin such as polyphenylene sulfide resin (A) at a high concentration (typically about 5 to 60% by mass) is prepared separately. A method of adjusting the concentration of the resin used for mixing and a method of mixing various additives directly with the resin used.

  The tube of the present invention is not limited to polyesters such as polyolefin resins, polyamide resins and polycarbonate resins for the purpose of improving and adjusting the molding processability and the physical properties of the tube within a range that does not significantly impair the effects of the present invention. Resins, flame retardants, weathering stabilizers, heat stabilizers, hydrolysis inhibitors, antistatic agents, antiblocking agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, anti-aging agents, hydrochloric acid absorbers, You may add additives, such as antioxidant, a coloring agent, and a pigment, suitably.

  It is important that the resin composition used in the present invention be sufficiently dried before extrusion so that the water content is preferably 0.1% by mass or less, more preferably 0.05% by mass or less. For example, drying can be performed under conditions of 140 ° C. for 3 hours and 120 ° C. for 5 hours, and a method of performing so-called non-drying extrusion in which vacuum venting is performed using the same-direction twin screw extruder is also suitable. Method.

(Formation of unstretched tube)
Next, the heat-shrinkable tube of the present invention is manufactured using the above-described resin composition. The production method is not particularly limited, but it is usually preferable to extrude an unstretched tube using a round die and then stretch it into a heat-shrinkable tube. In addition, a method in which a film extruded / 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. First, the above-mentioned resin composition is heated and melted to a temperature equal to or higher than the melting point by a melt extruder, continuously extruded from a round die, and then forcibly cooled and formed 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 because of high cooling efficiency. The unstretched tube may be continuously supplied to the next stretching step, or once wound into a roll to form an unstretched roll, the unstretched roll is used as a raw material for the next stretching step. May be. From the viewpoint of production efficiency and thermal efficiency, a method of continuously supplying an unstretched tube to the next stretching step is preferable.

(Extension process)
The unstretched tube thus obtained is stretched by being pressurized with compressed gas from the inside of the tube. The stretching method is not particularly limited. For example, while applying pressure by compressed gas from one end of the unstretched tube to the inside of the tube, it is sent out at a constant speed, and then heated by hot water or an infrared heater, etc. In order to regulate the stretching ratio in the direction, stretching 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 draw ratio in the length direction is determined by the ratio between the feed speed of the unstretched tube and the nip roll speed after stretching, and the stretch ratio in the radial direction is determined by the ratio between the unstretched outer diameter and 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.

(Extension conditions)
The stretching conditions are adjusted according to the characteristics of the resin composition to be used, the desired heat shrinkage rate, and the like. Usually, the stretching temperature is not less than the glass transition temperature of the resin composition and not more than 105 ° C, preferably not less than 70 ° C and not more than 100 ° C. It is done in the range.
The polyphenylene sulfide-based heat-shrinkable tube of the present invention is preferably 1.2 to 3.0 times, more preferably 1.3 to 2.5 times, and still more preferably 1.4 to 2.5 times the unstretched tube in the radial direction. 2.0 times, and preferably 1.0 to 2.0 times, more preferably 1.02 to 1.5 times, and even more preferably 1.02 to 1.3 times in the length direction. Are preferred.

  Here, when the draw ratio in the radial direction of the tube is less than 1.2 times, a sufficient amount of shrinkage for coating cannot be obtained. On the other hand, if it exceeds 3 times, the thickness fluctuation tends to increase, and the shrinkage rate tends to decrease due to orientation crystallization. In addition, if the draw ratio in the length direction of the tube exceeds 2.0 times, the amount of shrinkage in the length direction will increase, and the coating position may shift when the electronic parts are coated, or the cut length It is not preferable because it has to be lengthened and leads to cost increase.

<Application of heat-shrinkable tube>
As described above, the polyphenylene sulfide-based heat-shrinkable tube of the present invention can be suitably used for coating a capacitor such as an aluminum electrolytic capacitor, but other uses such as an electric wire (round wire, square wire). It can also be used as a secondary battery such as a dry battery or a lithium ion battery, a steel tube or motor coil end, an electrical device such as a transformer, a small motor, or a fluorescent lamp covering tube for a light bulb, a fluorescent lamp, a facsimile or an image scanner. .

<Characteristics of heat-shrinkable tube>
(Flame retardance)
The heat-shrinkable tube of the present invention has a flame retardancy of VW-1 as evaluated by UL224 Optional VW-1 FlameTest. Therefore, the heat-shrinkable tube according to the present invention can exhibit excellent flame retardancy when formed into a heat-shrinkable member, and can be suitably used, for example, as a covering material for capacitors and batteries. In tubes where VW-1 cannot be obtained, it is difficult to ensure safety as an electrical insulating material, and it is not accepted by the market.

(Thickness of heat-shrinkable tube)
The thickness of the heat-shrinkable tube of the present invention is not particularly limited, but it is preferably 0.05 mm or more and 1.0 mm or less, considering that it is used for coating capacitors, battery members, etc., 0.07 mm or more and 0.0. More preferably, it is 30 mm or less. For example, when the thickness of the heat-shrinkable tube is 0.10 mm, in order to maintain flame retardancy, as described above, the phosphorus-based plasticizer (100% by mass of the polyphenylene sulfide-based resin (A) B) is preferably 0.5% by mass or more and 15% by mass or less. If the proportion of the plasticizer (B) is less than 0.5% by mass, the flame retardancy of the heat-shrinkable tube may be impaired. Conversely, the proportion of the plasticizer (B) is 15% by mass or more. If so, there is a possibility that drip may occur during combustion with the decrease in melt viscosity, and the VW-1 standard cannot be satisfied.

  In addition, although the case where the thickness of the heat-shrinkable tube was 0.10 mm was illustrated above, an appropriate thickness can be selected according to the application of the coating. Even in this case, as described above, by adjusting the amount of the plasticizer (B) added to the polyphenylene sulfide resin (A), the characteristics such as flame retardancy of the polyphenylene sulfide resin (A) are maintained. Thus, a heat-shrinkable tube having excellent low-temperature shrinkability can be obtained. For example, according to the increase in thickness, the amount of the plasticizer added may be reduced as long as the effects of the present invention are not impaired.

(Shrinkability of heat-shrinkable tube)
In the heat-shrinkable tube according to the present invention, the shrinkage in the length direction when immersed in warm water at 100 ° C. for 5 seconds is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. is there. If the shrinkage rate in the length direction is 30% or less, the covering position is difficult to shift when the member is covered, and the cut length can be further shortened. The lower limit of the contraction rate in the length direction in warm water at 100 ° C. is preferably low from the viewpoint of suppressing problems such as the covering position and the cut length, and is preferably about 5% or more. The lower limit of the radial shrinkage when immersed in warm water at 100 ° C. for 5 seconds is preferably 25% or more, more preferably 30% or more, still more preferably 35% or more, and the upper limit is preferably It is 70% or less, more preferably 60% or less, and still more preferably 50% or less. If the shrinkage rate in the radial direction is 25% or more, a sufficient amount of shrinkage can be obtained, and if it is 70% or less, the member can be appropriately coated.

  The heat shrinkage characteristics can be adjusted by appropriately adjusting the amount of the plasticizer (B) added and the tube stretching temperature. For example, when increasing the shrinkage rate in the length direction to the upper limit (30%), increase the ratio of the feed speed of the unstretched tube to the nip roll speed after stretching and decrease it to the lower limit (5%) side. In this case, it can be adjusted by reducing the ratio between the feed speed of the unstretched tube and the nip roll speed after stretching. Also, when increasing the shrinkage rate in the radial direction to the upper limit (70%), increasing the ratio of the diameter of the unstretched tube to the diameter of the tube after stretching and decreasing it to the lower limit (20%) side Can be adjusted by reducing the ratio between the diameter of the unstretched tube and the diameter of the tube after stretching.

  Moreover, since the heat shrink start temperature of the heat shrinkable tube made of polyvinyl chloride is usually around 60 to 80 ° C., it was immersed in warm water at 80 ° C. for 5 seconds from the viewpoint of imparting the same shrinkage characteristics. The heat shrinkage rate at the time is preferably 5% or more, more preferably 10% or more in the radial direction of the tube, and preferably 0 to 5% in the length direction of the tube. By giving the shrinkage characteristics having the same low temperature shrinkage rate as that of the polyvinyl chloride heat-shrinkable tube, it gradually shrinks from a low temperature, and the coating finish in the process of covering the capacitor is improved. It is expected that the coating speed will be increased.

<Method of shrinkage and weight analysis of heat shrinkable tube>
In the present invention, the shrinkage rate of the heat-shrinkable tube was calculated from the following formula by measuring the length and the folding diameter of the heat-shrinkable tube before and after being immersed in warm water at 100 ° C. for 5 seconds.
Shrinkage ratio in length direction [%] = [(length of tube before immersion−length of tube after immersion) / length of tube before immersion] × 100,
-Shrinkage ratio in the radial direction [%] = [(folded diameter of the tube before immersion−folded diameter of the tube after immersion) / folded diameter of the tube before immersion] × 100

  The thermogravimetric analysis (TGA) analysis is about 20 mg to 600 ° C. at a rate of 10 ° C./min in air using a Thermal Analysis System (Perkin Elmer). When the temperature was raised to 5%, the 5% weight loss temperature T1 and the 10% weight loss temperature T2 were measured, and the temperature difference T2-T1 was measured.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following examples.
<Example 1>
As polyphenylene sulfide resin (A), PPS1 (manufactured by Polyplastics, trade name: Fortron 0220C9, apparent viscosity (300 ° C., shear rate 100 sec ⁻¹ ): 510 Pa · s) 92 parts by mass, other than resin (A) As other resins, elastomer 1 (acid-modified SEBS resin (manufactured by Asahi Kasei Chemicals, trade name: Tuftec M1943)) 8 parts by mass, phosphorus plasticizer (B), plasticizer 1 (manufactured by Daihachi Chemical Industry Co., Ltd.) (Product name: Px-200) A resin composition consisting of 10 parts by mass is melted with an extruder set at a cylinder temperature of 300 ° C., and tubular molded through a round die, and a tube having a folding diameter of 57 mm and a thickness of 0.1 mm. Got. The obtained unstretched tube was stretched 1.7 times in the radial direction and 1.1 times in the length direction at a stretching temperature of 90 ° C. using an outer diameter regulating former. The extrusion method and the obtained tube were evaluated by the following methods.

<Example 2>
A heat-shrinkable tube was formed and evaluated in the same manner as in Example 1 except that the mixing ratio of the resin composition was changed as shown in Table 1.

<Comparative Example 1>
As plasticizer, plasticizer 2 (triphenyl phosphate, manufactured by Daihachi Chemical Industry Co., Ltd., trade name: TPP) was used, and the resin composition was formed in the ratio shown in Table 1, and the same as in Example 1. A heat-shrinkable tube was formed and evaluated.

<Comparative example 2>
A heat-shrinkable tube was formed and evaluated in the same manner as in Example 1 except that a resin composition using only PPS1 was formed.

<Evaluation method>
(1) Measurement of temperature difference T2-T1 by TGA About 10 mg of a sample of heat-shrinkable tube is heated from 20 ° C. to 600 ° C. at a rate of 10 ° C./min in the air using Thermal Analysis System (Perkin Elmer). T2-T1 was measured by measuring 5% weight loss temperature T1 and 10% weight loss temperature T2 when the temperature was raised to ° C.

(2) Mass reduction rate when held at 300 ° C. for 10 seconds About 10 mg of a sample of heat-shrinkable tube was heated at a rate of 500 ° C./min in air using a Thermal Analysis System (manufactured by PerkinElmer). The mass reduction rate when heated from 300C to 300C and held at 300C for 10 minutes was measured.

(3) Volatility during extrusion process Collects the volatile gas generated when extruding the resin composition, and whether or not the component contains a plasticizer by GC-MS (gas chromatograph mass spectrometer). Was confirmed and evaluated according to the following criteria.
○: No plasticizer is contained in the volatile gas component.
X: A plasticizer is contained in the volatile gas component.

(4) Shrinkable finish of heat-shrinkable tube Using a hot-air circulating shrink furnace (170 ° C., 30 seconds), a Φ35 mm SUS rod is coated with a heat-shrinkable tube having a folding diameter of 57 mm and a thickness of 0.1 mm. The appearance of the end face of the SUS rod was confirmed.
○: The tube is in close contact with the end surface of the SUS rod without curling the inner surface.
X: The tube is curled on the inner surface, and the tube is not in close contact with the end surface of the SUS rod.

From Table 1, it was found that when the resin composition containing the plasticizer 1 was melt-extruded, the plasticizer 1 was not scattered in the air as a volatile gas (Examples 1 and 2). On the other hand, when the resin composition containing the plasticizer 2 was melt-extruded, the plasticizer 2 was scattered in the air as a volatile gas (Comparative Example 1).
Moreover, the heat-shrinkable tube (Examples 1 and 2) formed from the resin composition containing the plasticizer 1 has good low-temperature shrinkability and can obtain an excellent tube that does not curl to the inner surface of the tube during shrinkage. did it. In contrast, the heat-shrinkable tube (Comparative Example 1) formed from the resin composition containing the plasticizer 2 has a problem that the tube end surface is curled to the inner surface when the tube is contracted. When the curling occurs on the inner surface of the tube, it is not preferable in terms of the finish of a battery, an electronic component, particularly a coated object such as an aluminum electrolytic capacitor.
On the other hand, when no plasticizer was used (Comparative Example 2), the low temperature shrinkability as a heat shrinkable tube could not be obtained.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. The polyphenylene sulfide-based heat-shrinkable tube having such a change, and the tube covered with the tube can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Members should also be understood as being within the scope of the present invention.

  The heat-shrinkable tube of the present invention is excellent in low volatility and shrinkage finish, and can be used as a heat-shrinkable member suitable for coating batteries, electronic components, particularly aluminum electrolytic capacitors.

Claims (5)

A resin composition comprising a polyphenylene sulfide resin (A) and a phosphorus plasticizer (B);
Difference between temperature T1 at 5% mass decrease and temperature T2 at 10% mass decrease when heated from 20 ° C. to 600 ° C. at a temperature increase rate of 10 ° C./min by thermogravimetric analyzer T2-T1 is 10 ° C. or higher and 100 ° C. or lower,
Polyphenylene sulfide heat-shrinkable tube. With a thermogravimetric analyzer, the mass reduction rate when heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in an air atmosphere and held at 300 ° C. for 10 minutes is 0% or more and 5% or less. The polyphenylene sulfide-based heat-shrinkable tube according to claim 1. The polyphenylene sulfide system according to claim 1 or 2, wherein the phosphorus plasticizer (B) is contained in an amount of 0.5 mass% to 15 mass% with respect to 100 mass% of the polyphenylene sulfide resin (A). Heat shrinkable tube. The member coat | covered with the polyphenylene sulfide type heat-shrinkable tube in any one of Claims 1-3. The member of Claim 4 used for the use of an electronic device or an electric device.