JP2011178935A - Heat shrinkable molding comprising polyphenylene sulfide-based resin composition and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat shrinkable molding comprising a polyphenylene sulfide-based resin composition capable of simultaneously satisfying flame retardancy, heat resistance, chemical resistance, electrolytic solution resistance, low-temperature shrinkability and stretching stability. <P>SOLUTION: The heat shrinkable molding is configured by the polyphenylene sulfide-based resin composition having a glass transition temperature Tg obtained by differential scanning calorimetry (DSC) of 50-85°C and a peak temperature difference of ≥80°C, wherein the peak temperature difference is the temperature difference between a crystallization peak temperature Tc measured at a cooling rate of 10°C/min after heating from a crystal melting peak temperature Tm+40°C to Tm+100°C and holding for 1 min in DSC and the crystal melting peak temperature Tm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat-shrinkable molded article comprising a polyphenylene sulfide resin composition and a method for producing the same.

  In recent years, electronic parts such as capacitors have been increased in density due to lighter, thinner and smaller products, and fields with high operating temperatures, such as automobile electrical parts, are rapidly expanding. With such needs, good flame retardancy and heat resistance are also demanded for heat-shrinkable tubes used in capacitor coating applications and the like.

  Conventionally, polyvinyl chloride, polyethylene terephthalate, polyolefin and the like are widely known as materials used in heat-shrinkable tubes.

  Polyvinyl chloride heat-shrinkable tube is excellent in flame retardancy, but has insufficient heat resistance, and could cause environmental problems such as generation of dioxins if it is not treated properly during waste treatment. . On the other hand, a heat-shrinkable tube made of a polyester resin such as polyethylene terephthalate is excellent in heat resistance but has insufficient flame retardancy.

  Also, heat-shrinkable tubes using polyolefin-based resins are treated appropriately during waste treatment, just like polyvinyl chloride heat-shrinkable tubes, because brominated flame retardants are added to impart flame retardancy. Otherwise, environmental problems could occur. In addition, heat-shrinkable tubes using polyolefin-based resins have problems such as complicated steps for manufacturing the tubes because they are subjected to electron beam crosslinking to impart heat resistance.

  In particular, for large-capacity capacitor coating applications, better electrical insulation, chemical resistance, electrolyte resistance, flame resistance, and other properties are required, and the thickness before shrinkage ranges from 0.1 mm to 0.3 mm. The thing of the range of has also appeared.

  Under such circumstances, a polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin is known as a material that simultaneously satisfies flame retardancy and heat resistance. The polyphenylene sulfide resin is an excellent material that satisfies characteristics such as chemical resistance and electrolytic solution resistance in addition to flame retardancy and heat resistance. A heat-shrinkable tube using a polyphenylene sulfide resin composition is known by paying attention to such characteristics (see Patent Document 1 and Patent Document 2).

JP-A-9-157402 International Publication No. WO2008 / 114731

  However, polyphenylene sulfide-based resins are very easily crystallized during cooling after being melt-molded. For this reason, in the method of extruding the polyphenylene sulfide resin composition and cooling it from the outside of the molded body using cold water immediately after coming out of the die, it is possible to sufficiently cool the tubular molded body having a thickness of 0.5 mm or more. There was a problem that the crystallinity was different between the outside and inside of the tube-shaped molded body. Such a tube-shaped molded body having a difference in crystallinity between the outside and the inside has a drawback that it cannot be stably and uniformly stretched even when heated to near the glass transition temperature and compressed air is put inside. is there. Such a problem at the time of production could not be solved by the heat-shrinkable tube made of the polyphenylene sulfide resin composition described in Patent Document 1 to Patent Document 2.

  The present invention has been made in order to solve the above-described problems in the prior art, and the problems include flame retardancy, heat resistance, chemical resistance, electrolytic solution resistance, low temperature shrinkage, and stretching stability at the same time. An object of the present invention is to provide a heat-shrinkable molded article comprising a satisfactory polyphenylene sulfide resin composition.

  In order to solve the above problems, the present inventors have made extensive studies on the polyphenylene sulfide-based resin composition. As a result, the glass transition temperature Tg, the crystal melting peak temperature Tm, and the crystallization peak when gradually cooling after melting. By using a polyphenylene sulfide resin composition in which each temperature Tc exists under predetermined conditions, flame retardancy, heat resistance, chemical resistance, electrolytic solution resistance, low temperature shrinkage, and stretching stability can be satisfied at the same time. As a result, the present invention has been completed.

  That is, the problem of the present invention is that the glass transition temperature Tg obtained by differential scanning calorimetry (DSC) is 50 ° C. or more and 85 ° C. or less, and the DSC is heated from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C. and held for 1 minute. And a heat shrinkage comprising a polyphenylene sulfide resin composition having a temperature difference of 80 ° C. or more between the crystallization peak temperature Tc measured at a temperature drop rate of 10 ° C./min and the crystal melting peak temperature Tm. This is achieved by a molded product.

  The heat-shrinkable molded article of the present invention preferably contains at least one selected from the group consisting of resins other than polyphenylene sulfide resins, elastomers, and plasticizers.

  In the heat-shrinkable molded article of the present invention, the elastomer contained therein is heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA) and held at 300 ° C. for 20 minutes It is preferable that the mass reduction rate is 0% or more and 6% or less.

  In the heat-shrinkable molded article of the present invention, the plasticizer contained therein is heated from 20 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA), and the mass reduction rate becomes 5%. It is preferable that the temperature is 260 ° C. or higher.

  The heat-shrinkable molded article of the present invention can be suitably used for coating an aluminum electrolytic capacitor or the like as long as it has a tube shape.

  When the heat-shrinkable molded article of the present invention has a tube shape, the flame retardancy evaluated by UL224 Optional VW-1 Flame Test is VW-1, considering application to electronic components such as aluminum electrolytic capacitors. Preferably there is.

  In the production of the heat-shrinkable molded article of the present invention, various methods can be used to keep the glass transition temperature Tg, the crystal melting peak temperature Tm, and the crystallization peak temperature Tc within specified ranges. Then, a method of adding a plasticizer to the resin composition, and a method of adjusting the molecular weight of the polyphenylene sulfide resin and providing a thermal history of Tm + 40 ° C. or more and 100 ° C. or less at the time of melt extrusion are preferably used for adjusting Tm and Tc. .

  According to the present invention, there is provided a heat-shrinkable molded article comprising a polyphenylene sulfide-based resin composition having excellent flame retardancy, heat resistance, chemical resistance, electrolytic solution resistance, low-temperature shrinkage, and stretch stability. Can do.

  In particular, when the polyphenylene sulfide-based resin composition contains at least one selected from the group consisting of a resin other than the polyphenylene sulfide-based resin, an elastomer, and a plasticizer, depending on the characteristics of the resin, elastomer, and plasticizer to be included Thus, adhesion between different materials, impact resistance at low temperature, and low temperature shrinkage can be exhibited.

  In addition, the heat-shrinkable molded article of the present invention is such that the elastomer contained therein is heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA) and held at 300 ° C. for 20 minutes Since the mass reduction rate at the time is 0% or more and 6% or less, the decomposition of the resin accompanying the high-temperature extrusion is minimized, and a molded article having a good appearance can be obtained.

  In the heat-shrinkable molded article of the present invention, the plasticizer contained is heated from 20 ° C. at a temperature increase rate of 10 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA), and the mass reduction rate becomes 5%. Since the temperature at the time is 260 ° C. or higher, decomposition of the plasticizer accompanying high-temperature extrusion is minimized, and a molded article having a good appearance can be obtained.

  Moreover, since the flame-retardant property evaluated by UL224 Optional VW-1 Flame Test is VW-1, the heat-shrinkable tube of this invention can be used suitably for the coating | covering of the electronic component by which flame retardance is requested | required. .

  Hereinafter, the heat-shrinkable molded article, heat-shrinkable tube, and member using the tube of the present invention will be described in detail.

<Thermoplastic polyphenylene sulfide resin>
The thermoplastic polyphenylene sulfide (hereinafter may be abbreviated as “PPS”) resin used in the present invention is a resin containing 70 mol% or more, preferably 80 mol% or more of the PPS repeating unit of the following formula (1). is there. If the repeating unit of the PPS is 70 mol% or more, an excessive decrease in the crystallinity of the polymer and the heat transition temperature can be suppressed, and it is a feature of the resin composition containing a PPS resin as a main component. Impairing various properties such as flame retardancy, chemical resistance and electrical properties can be suppressed.

  In the PPS-based resin, as long as it is less than 30 mol%, preferably less than 20 mol% of the repeating unit, other units having a copolymerizable sulfide bond may be contained. Examples of the repeating unit include 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, a terphenylene unit, a vinylene unit, A carbonate unit etc. are mentioned as a specific example, These can be used individually by 1 type independently and combining 2 or more types. In this case, these constitutional units may be any copolymerization system such as random type or block type.

  The PPS resin is preferably a linear / linear (linear type) polymer having a molecular weight of 50,000 or more, but is not limited thereto. Even a polymer having a crosslinked structure can be used.

  The PPS resin may contain a low molecular weight oligomer, but the content of the low molecular weight oligomer is about 1.5% by mass or less based on the total mass in terms of heat deterioration resistance and mechanical strength. To preferred. The molecular weight of the low molecular weight oligomer is in the range of 100 to 2,000, and the low molecular weight oligomer contained in the PPS resin can be removed by washing with a solvent such as diphenyl ether.

  The melt viscosity of the PPS resin is not particularly limited as long as a heat-shrinkable tube can be obtained, but the apparent viscosity measured at 320 ° C., a shear rate of 100 sec-1 and an orifice L / D = 10/1 (mm). 100 Pa · s or more, preferably 200 Pa · s or more, more preferably 400 Pa · s or more, and preferably 10,000 Pa · s or less, and 5,000 Pa · s. It is more preferably s or less, and even more preferably 2,000 Pa · s or less. Film formation is possible if the apparent viscosity is about 100 Pa · s, and if the apparent viscosity is about 10,000 Pa · s or less, the load on the extruder during extrusion can be suppressed.

  The production method of the PPS resin can be a known production method and is not particularly limited. For example, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as “NMP”) and the like. 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 is generally used. In order to adjust the degree of polymerization, it is preferable to add a polymerization aid such as caustic alkali or carboxylic acid alkali metal salt and react at a temperature of 230 ° C. or higher and 280 ° C. or lower. 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 the above 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. Even after the polymerization, the PPS resin is washed with a large amount of water. The sodium halide in the PPS resin cannot be removed sufficiently. Therefore, a method of performing polymerization using lithium salt instead of sodium salt can also be used.

  Examples of commercially available PPS resins include Fortron (manufactured by Polyplastics), DIC-PPS (manufactured by DIC), and Torelina (manufactured by Toray Industries, Inc.).

<Resin and elastomer other than PPS resin>
The PPS resin composition constituting the heat-shrinkable molded article of the present invention may be composed of a PPS resin alone, or may be blended and alloyed with other resins, elastomers, and the like.
Other resins for blending and alloying include polyester, liquid crystal polymer, polyamide, polycarbonate, polyolefin, polystyrene, ABS resin, imide-modified ABS resin, AES resin, polyphenylene ether, copolymer of polyphenylene ether and polystyrene, and / or Alternatively, a mixture, polyimide, polyamideimide, polyarylate, polyetherimide, polyetheretherketone, polyethersulfone, polysulfone and the like can be exemplified. By blending and alloying with these resins, effects such as enhancing the adhesion between different materials between the PPS resin and ink can be obtained.

  The above resin has a mass reduction rate of 0 when heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in a nitrogen atmosphere by a thermogravimetric analyzer (TGA) and held at 300 ° C. for 20 minutes. % Or more and 6% or less, more preferably 0% or more and 4.5% or less. When the mass reduction rate by TGA is within this range, the resin decomposition accompanying high temperature extrusion can be minimized, and a molded article having a good appearance can be obtained.

  On the other hand, examples of elastomers include polyester elastomers, polyamide elastomers, polyurethane elastomers, olefin copolymers, thermoplastic elastomers such as polystyrene elastomers, nitrile rubbers, and acrylic rubbers.

  Polyester elastomers include, for example, aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate as hard segments, polyethers such as polyethylene glycol and polytetramethylene glycol, and aliphatic polyesters such as polyethylene adipate, polybutylene adipate, and polycaprolactone as soft segments. And a block copolymer.

  Examples of the polyamide-based elastomer include block copolymers having nylon 6, nylon 66, nylon 11, nylon 12 or the like as a hard segment and polyether or aliphatic polyester as a soft segment.

  Examples of urethane elastomers include reacting diisocyanates such as 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate and glycols such as ethylene glycol and tetramethylene glycol. Examples of block copolymers include polyurethane obtained as a hard segment, polyether such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, or aliphatic polyester such as polyethylene adipate, polybutylene adipate and polycaprolactone as a soft segment. It is done.

  Examples of olefin elastomers and styrene elastomers include butadiene copolymers, styrene-isoprene copolymers, butadiene-styrene copolymers (random, block, and graft copolymers), isoprene copolymers, Examples include chlorobutadiene copolymer, butadiene-acrylonitrile copolymer, isobutylene copolymer, isobutylene-butadiene copolymer, isobutylene-isoprene copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer. It is done.

  Furthermore, a partially modified rubber component can also be used, for example, a partially hydrogenated styrene-butadiene block copolymer, an acid-modified partially hydrogenated styrene-butadiene block copolymer, a partially hydrogenated styrene-isoprene block copolymer, etc. Is mentioned. Of these, acid-modified partially hydrogenated styrene-butadiene block copolymers are preferred. Acid modification here means that it is modified with an organic acid such as maleic acid, phthalic acid, citric acid, malic acid, adipic acid, and acrylic acid, and particularly modified with maleic acid (for example, Maleic acid modified SEBS) is preferred.

  By blending or alloying the PPS resin and the elastomer, impact resistance of the PPS resin composition can be improved. In the melt molding, an olefin copolymer is particularly preferably used as the elastomer from the viewpoint of being exposed to a high temperature of 310 ° C. or higher and improving the impact resistance at a low temperature. In order to improve the adhesion between these olefinic copolymers and PPS, maleic anhydride groups, epoxy groups, silane groups, etc. can be introduced into the molecular chain of the elastomer as a functional group. Examples include acid graft copolymerized polyolefins, ethylene / acrylic acid / maleic anhydride terpolymers, and the like.

The above-mentioned elastomer is heated from 20 ° C. to 300 ° C. at a temperature rising rate of 500 ° C./min in a nitrogen atmosphere by a thermogravimetric analyzer (TGA), and the mass reduction rate when held at 300 ° C. for 20 minutes is 0% or more % Or less, more preferably 0% or more and 4.5% or less. If the mass reduction rate by TGA is in this range, the decomposition of the elastomer accompanying high temperature extrusion can be minimized, and a molded article having a good appearance can be obtained.
Here, the “mass reduction rate” refers to the percentage of the mass of the elastomer after heating with respect to the total mass of the elastomer before heating.

  Examples of commercially available elastomers include Tuftec M (acid-modified SEBS resin, manufactured by Asahi Kasei Chemicals), Kraton G (acid-modified SEBS resin, manufactured by Kraton Japan), and Epofriend (epoxy / styrene resin, manufactured by Daicel Chemical Industries, Ltd.). ) Bondine (ethylene / acrylic acid / maleic anhydride terpolymer, manufactured by France Arkema).

  The content of the other resin and / or elastomer to be mixed with the PPS resin is preferably 0.1% by mass or more, preferably 100% by mass when the total mass of the PPS resin and the other resin and / or elastomer is 100% by mass. Is 1% by mass or more, more preferably 5% by mass or more, and 35% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less. If the proportion of other resins and / or elastomers mixed with the PPS resin is too small, the effect of addition cannot be expected, and if too large, the characteristics of the PPS resin such as flame retardancy may be impaired.

<Plasticizer>
The PPS resin composition constituting the heat-shrinkable molded article of the present invention preferably contains a plasticizer in order to lower the glass transition temperature Tg of the resin composition and to exhibit low-temperature shrinkage. Examples of the plasticizer used in the present invention include a phthalate ester plasticizer, a tetrahydrophthalate ester plasticizer, a trimellitic acid ester plasticizer, an adipic acid ester plasticizer, a sebacic acid ester plasticizer, and a phosphate ester. Plasticizer, phosphonitrate plasticizer, citrate plasticizer, polyester plasticizer, epoxy plasticizer, lactam plasticizer, sulfonamide plasticizer, glycolic acid plasticizer, paraffin mineral oil, Various known plasticizers such as naphthenic mineral oil, polyolefin and polysiloxane can be used. Among these, those that function as flame retardants, such as phosphonitrate ester plasticizers, are preferred because they do not impair the flame retardancy that is characteristic of PPS resins.

  The plasticizer is heated from 20 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere by a thermogravimetric analyzer (TGA), and the temperature at which the mass reduction rate is 5% (mass is reduced by 5%) is 260. The temperature is preferably at least 270 ° C, and more preferably at least 270 ° C. The upper limit temperature is determined by the type of plasticizer, but is preferably 450 ° C. or lower.

  Preferred examples of the phosphate ester plasticizer in the present invention include aromatic condensed phosphate esters and phosphonitrile acid phenyl esters having higher heat resistance. By using these flame retardant and plasticizer, the glass transition temperature of the resin can be lowered without impairing the excellent flame retardancy of the PPS resin, and as a result, low temperature shrinkage can be imparted to the molded body.

  The addition amount of the plasticizer added to the PPS resin composition used in the present invention is 0.5 parts by mass or more with respect to the total amount of the PPS resin or PPS resin and other resins and / or elastomers, preferably 1 part by mass or more, more preferably 3 parts by mass or more, and 15 parts by mass or less, preferably 10 parts by mass or less, more preferably 7 parts by mass or less. If the addition amount of the plasticizer is 0.5 parts by mass or more, a plasticizing effect can be obtained, and a low temperature shrinkability and a crease whitening suppressing effect can be obtained. Further, when the content is 15 parts by mass or less, it is possible to suppress a decrease in melt viscosity and a deterioration in thickness accuracy.

  Examples of commercially available plasticizers include phosphonitrile acid phenyl ester (trade name: FP-110 manufactured by Fushimi Pharmaceutical Co., Ltd.), 1,3-phenylene bis (di-2,6 xylenyl phosphate) (Daihachi Chemical Industry). Product name: PX-200) and the like.

  The PPS resin composition that constitutes the heat-shrinkable molded article of the present invention can be produced using a normal known production method. For example, PPS resin, or other resins and / or elastomers, plasticizers, and other additives as necessary are premixed to produce a single or twin screw extruder, tumbler, V-type blender, Banbury. A method of supplying to a generally known melt mixer such as a mixer, a kneader, a mixing roll and kneading at a temperature of about 280 ° C. to 450 ° C. or weighing separately to each supply port of an extruder having two or more supply ports And a method of supplying the prepared components.

  In addition, the mixing order of the raw materials is not particularly limited, and the PPS resin to be used is directly mixed with other resins, elastomers, plasticizers, additives, etc., melt kneaded, other resins, elastomers, plasticizers, A method of separately preparing a master batch in which an additive is mixed with a PPS resin at a high concentration (typically about 5 to 60% by mass) and adjusting the concentration to the PPS resin and mixing the master batch , A method in which some raw materials are melt-kneaded by the above-described method and the remaining raw materials are melt-kneaded, or a part of the raw materials are melted and kneaded by a single-screw or twin-screw extruder, and the remaining raw materials are used using a side feeder. Any method may be used such as a method of mixing. Moreover, about a small amount additive component, after kneading | mixing another component by said method etc. and pelletizing, it can also add before shaping | molding and can also be used for shaping | molding.

<Glass Transition Temperature Tg of PPS Resin Composition>
In order for the heat-shrinkable molded article of the present invention to exhibit low-temperature shrinkability, it is important that the glass transition temperature Tg determined by differential scanning calorimetry (DSC) is 50 ° C. or higher and 85 ° C. or lower. Here, if Tg is 85 ° C. or lower, sufficient low temperature shrinkage can be imparted, and if Tg is 50 ° C. or higher, natural shrinkage during storage before use can be suppressed. For these reasons, the glass transition temperature Tg of the heat-shrinkable molded article of the present invention is preferably 53 ° C. or higher, more preferably 55 ° C. or higher, and 83 ° C. or lower, preferably 80 ° C. or lower.

<Crystal melting peak temperature Tm of PPS resin composition>
The heat-shrinkable molded product of the present invention has a melt extrusion temperature of 40 ° C. or higher and 100 ° C. or lower (Tm + 40 ° C. to Tm + 100 ° C.), preferably 40 ° C. or higher and 80 ° C. from the crystal melting peak temperature Tm of the PPS resin composition. The temperature is desirably below (Tm + 40 ° C. to Tm + 80 ° C.), more preferably 43 ° C. to 70 ° C. (Tm + 43 ° C. to Tm + 70 ° C.). If the melt extrusion temperature of the PPS resin composition is lower than Tm + 40 ° C., it may be difficult to sufficiently reduce the crystallinity of the heat-shrinkable molded article. Further, when the melt extrusion temperature is higher than Tm + 100 ° C., the crystallinity of the heat-shrinkable molded body (preferably in a tube shape) is reduced, but a resin, elastomer or plastic other than the PPS resin contained in the PPS resin composition The agent may be susceptible to thermal decomposition.

<The crystallization peak temperature Tc of the PPS resin composition>
In the heat-shrinkable molded article of the present invention, it is most important to control the crystallization peak temperature Tc of the PPS resin composition in the production process. If the crystallization peak temperature Tc is sufficiently low, the heat-shrinkable molded product can be collected in an amorphous state when it is cooled and taken after melt extrusion, and the subsequent stretching step can be performed stably. . When the crystallization peak temperature Tc of the PPS-based resin composition is high, a temperature gradient is generated inside the heat-shrinkable molded body even if it is cooled and taken off after melt extrusion, and gradually cooled. Can be done. As a result, the heat-shrinkable molded body before stretching becomes non-uniformly crystallized, and the stretching process becomes unstable.
The crystallization peak temperature Tc can be measured at a temperature decrease rate of 10 ° C./min after the temperature is raised from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C. and held for 1 minute in differential scanning calorimetry (DSC).

  As a method for controlling the crystallization peak temperature Tc of the PPS resin composition constituting the heat-shrinkable molded article of the present invention, various known methods can be employed. A method for controlling the crystallization peak temperature Tc by terminal modification with an acid metal salt or the like (see, for example, International Publications WO2007 / 129721 and JP2006-199734), and a method of increasing the molecular weight of a PPS resin ( For example, see JP-A-2005-15792), a method of copolymerizing a metaphenylene sulfide unit and a paraphenylene sulfide unit and reducing the crystallization peak temperature Tc as the melting point is lowered. Of reducing the crystallization peak temperature Tc by using a group compound together to form a branched or crosslinked polymer For example, see JP-2007-23263), and the like.

<Significance of temperature difference between Tc and Tm>
In the present invention, if the temperature difference between Tc and Tm of the resin composition is 80 ° C. or more, the molded body can be taken up without proceeding the crystallization of the molded body in the cooling after melt extrusion. The stretching step can be carried out continuously and stably.

  The shape of the heat-shrinkable molded product of the present invention is not particularly limited, and can be any shape such as a flat shape such as a film or a sheet, a tubular shape such as a pipe, or a tubular shape such as a tube. Among these, tube-like shapes used for coating electronic members such as aluminum electrolytic capacitors and various batteries such as nickel metal hydride batteries and lithium ion batteries are preferred.

<The manufacturing method of the heat-shrinkable molded object of this invention>
The heat-shrinkable molded article of the present invention is produced by rapidly cooling a PPS resin composition pellet obtained by melting and extruding a flat die such as a T die or a round die using a cooling roll or water cooling. Can do.

  In the melt extrusion process, various single-screw extruders or twin-screw extruders can be used. From the viewpoint of accuracy of the thickness of the formed film, sheet, or tube, a method of putting pellets in the single-screw extruder is preferable. Used. At this time, by setting the temperature of a part of the cylinder, conduit, and die of the single-screw extruder that is a resin flow path to a temperature range from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C., and giving a thermal history, Crystallization of the heat-shrinkable molded product can be suppressed. The resin flow channel region set in the temperature range from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C. can be arbitrarily set except for the region immediately below and immediately after the hopper, but the PPS resin composition is a PPS resin. In the case of containing a resin other than resin, an elastomer, or a plasticizer, the region of the resin flow path that is as narrow as possible may be set to a temperature range from the crystal melting peak temperature Tm + 43 ° C. to Tm + 70 ° C. preferable.

  By the method as described above, it is possible to easily obtain a thick film, sheet, or tube in which it is difficult to obtain a molded article in an amorphous state only by quenching with a cooling roll or running water.

  When the heat-shrinkable molded article of the present invention is produced as a heat-shrinkable tube, various production methods can be used as long as the pellets made of the composition are melt-extruded under the above temperature conditions. A preferred method is to extrude an unstretched tube using a round die and then stretch it to obtain a seamless 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 to obtain 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 crystal melting peak temperature by a melt extruder, 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. Of these, the method of immersing in low-temperature water is effective because of its 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.

  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, 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 conditions are adjusted depending on the characteristics of the resin composition to be used and the desired heat shrinkage rate.
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.

  In the heat-shrinkable tube of the present invention, the unstretched tube is 1.2 times or more, preferably 1.3 times or more, more preferably 1.4 times or more and 3.0 times or less, preferably 2. 5 times or less, more preferably 2.0 times or less, and 1.0 or more, preferably 1.02 or more to 2.0 or less, preferably 1.5 or less in the length direction. More preferably, it is obtained by stretching at a magnification in the range of 1.3 times or less. Here, if the draw ratio in the radial direction of the heat-shrinkable tube is 1.2 times or more, a shrinkage amount sufficient for coating can be obtained, and if it is 3.0 times or less, the thickness fluctuation tends to increase. It is possible to suppress the decrease in shrinkage due to orientation crystallization. On the other hand, if the stretch ratio in the length direction of the heat-shrinkable tube is 2.0 times or less, the shrinkage amount in the length direction becomes too large, and the coating position shifts when the electronic component is coated. Further, since it is not necessary to increase the cut length, an increase in cost can be suppressed.

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

  The heat-shrinkable tube of the present invention can be suitably used mainly for coating electronic members such as aluminum electrolytic capacitors, and various batteries such as nickel metal hydride batteries and lithium ion batteries. (Round wire, square wire), dry cell, steel tube or motor coil end, transformer, and other electric devices and small motors, or fluorescent tube covering tubes for light bulbs, fluorescent lamps, facsimiles and image scanners.

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

<Raw materials used>
The raw materials used in Examples, Comparative Examples, and Reference Examples of the resin compositions constituting the heat-shrinkable tube used for the following evaluation are shown below.
PPS1: Polyphenylene sulfide resin [manufactured by Polyplastics, trade name: Fortron W300, crystal melting peak temperature Tm: 278 ° C., melt viscosity (310 ° C., shear rate 1200 sec ⁻¹ ): 220 Pa · s]
PPS2: polyphenylene sulfide resin [manufactured by Polyplastics, trade name: Fortron W220A, crystal melting peak temperature Tm: 280 ° C., melt viscosity (310 ° C., shear rate 1200 sec ⁻¹ ): 500 Pa · s]
Elastomer 1: Ethylene / acrylic acid / maleic anhydride terpolymer (manufactured by ARKEMA, France, trade name: Bondine TX8030)
Elastomer 2: Acid-modified styrene = ethylene = butylene = styrene (manufactured by Asahi Kasei Chemical Co., Ltd., trade name: Tuftec M1943)
Phosphoric plasticizer 1: Phosphononitrile acid phenyl ester (trade name: FP-110, manufactured by Fushimi Pharmaceutical Co., Ltd.)
Phosphoric plasticizer 2: condensed phosphate ester (Daihachi Chemical Co., Ltd., trade name: PX-200)

The thermal stability of the elastomer was measured using a thermogravimetric measuring device Q5000IR manufactured by TA Instruments. It heated from 20 degreeC to 300 degreeC with the temperature increase rate of 500 degreeC / min in nitrogen atmosphere, the mass reduction rate when it hold | maintained at 300 degreeC for 20 minutes was measured, and the following references | standards evaluated.
(○) ... Mass reduction rate is 0% or more and 6% or less (x) ... Mass reduction rate is greater than 6%

The thermal stability of the plasticizer was measured using a thermogravimetric measuring device Q5000IR manufactured by TEA Instruments. It heated from 20 degreeC with the temperature increase rate of 10 degree-C / min in nitrogen atmosphere, measured the temperature when a mass reduction | decrease rate will be 5%, and evaluated by the following references | standards.
(○)… The temperature at which the mass reduction rate is 5% is 260 ° C. or more. (×) The temperature at which the mass reduction rate is 5% is less than 260 ° C.

<DSC measurement>
The thermal properties were measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer. During the measurement, dry nitrogen was flowed at 50 ml / min, and the measurement was performed in a nitrogen atmosphere. About 10 mg of the sample was used and measured in an aluminum pan. The DSC chart was measured and recorded by heating the sample at a temperature increase rate of 50 ° C. to 10 ° C./min.

<Appearance>
The appearance of the heat-shrinkable tube obtained in the examples was evaluated according to the following criteria.
(◯) ... The surface of the tube is smooth.
(X) The surface of the tube has a scar shape due to decomposition of the elastomer or plasticizer.

<Flame retardance evaluation>
The flame retardancy of the heat-shrinkable tube was evaluated based on UL224 Optional VW-1 Flame Test.
(◯): VV-1 standard is satisfied.
(X): VW-1 standard is not satisfied.

<Heat resistance>
A 35 mm diameter, 59.5 mm long aluminum electrolytic capacitor was covered with a tube with a folding diameter of 59 mm, a wall thickness of 0.1 mm, and a length of 73 mm in a hot air circulation type shrink furnace at 200 ° C. for 5 seconds, and in a hot air oven at 85 ° C. After aging for 60 minutes in an atmosphere, the film was again exposed to a 200 ° C. atmosphere in a hot air oven for 5 minutes, and the heat resistance was evaluated according to the following criteria.
(○): No swelling occurs (×): Swelling occurs

<Chemical resistance>
The heat-shrinkable tube obtained in tetrahydrofuran (THF) was submerged for 24 hours and evaluated according to the following criteria.
(◯) ... there was no change in appearance.
(×) ... change in appearance.

<Electrolytic resistance>
The heat-shrinkable tube obtained in ethylene glycol (EG) was submerged for 24 hours and evaluated according to the following criteria.
(◯) ... there was no change in appearance.
(×) ... change in appearance.

<Low temperature shrinkage>
The folding diameter of the heat-shrinkable tube before and after being immersed in 90 ° C. hot water for 5 seconds was measured and evaluated according to the following criteria.
(◯) The shrinkage rate was 30% or more.
(X) The shrinkage rate was less than 30%.

<Stretch stability>
The raw tube obtained by melt extrusion and cooling is preheated by passing it through hot water at 90 ° C, and further, the hot air is blown from the outside, compressed air is inserted, and the stretchability when tubular stretching is performed is as follows. Evaluation was made based on the following criteria.
(◯) ... After the compressed air was inserted, stretching was performed continuously without any particular problem.
(X) ... Continuous stretching was impossible, such as rupture after insertion of compressed air.

(Examples 1 and 2, Comparative Examples 1 to 3, and Reference Examples 1 and 2)
The resin composition having the composition described in Table 1 is dissolved in an extruder in which the cylinder temperature is set so that there is a temperature gradient in the temperature range from 290 ° C. to Table 1, and is subjected to tubular molding through a round die. A tube having a diameter of 59 mm and a thickness of 0.3 mm was obtained. The results of evaluating the characteristics of the obtained tube are shown in Table 1.

From Table 1, the heat-shrinkable molded body obtained by melt-extrusion by setting the maximum melting temperature of the cylinder temperature in the temperature range of Tm + 40 ° C. to Tm + 100 ° C. is the temperature difference between the crystallization peak temperature Tc and the crystal melting peak temperature Tm (Tm−Tc). ) Was 80 ° C. or higher, it was excellent in appearance, flame retardancy, heat resistance, chemical resistance, electrolytic solution resistance, low temperature shrinkage, and stretching stability (Examples 1 and 2).
On the other hand, the heat-shrinkable molded article made of the PPS resin composition having Tm-Tc of less than 80 ° C. was inferior in stretching stability (Comparative Example 1). Moreover, the heat-shrinkable molded article made of a PPS resin composition having a Tg exceeding 85 ° C. was inferior in low-temperature shrinkability and stretchability (Comparative Example 2). In addition, the heat-shrinkable molded article that was melt-extruded by setting the maximum melting temperature to 300 ° C., that is, about Tm + 20 ° C. of the resin composition, could not be stably stretched, so the stretching stability was inferior (comparison) Example 3). Moreover, the heat-shrinkable molded body to which an elastomer and a plasticizer with poor heat stability were added had poor appearance (Reference Examples 1 and 2).
From this, it can be seen that the heat-shrinkable molded article of the present invention simultaneously satisfies flame retardancy, heat resistance, chemical resistance, electrolyte resistance, low-temperature shrinkage, and stretching stability.

Claims (9)

The glass transition temperature Tg determined by differential scanning calorimetry (DSC) is 50 ° C. or higher and 85 ° C. or lower. After the temperature is increased from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C. and held in DSC for 1 minute, the temperature decreasing rate is 10 ° C. / A heat-shrinkable molded article comprising a polyphenylene sulfide resin composition having a temperature difference between a crystallization peak temperature Tc measured in minutes and the crystal melting peak temperature Tm of 80 ° C. or more. The heat-shrinkable molded article according to claim 1, wherein the polyphenylene sulfide-based resin composition contains at least one selected from the group consisting of resins other than polyphenylene sulfide-based resins, elastomers, and plasticizers. . The mass loss rate when the elastomer is heated from 20 ° C. to 300 ° C. at a heating rate of 500 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA) and held at 300 ° C. for 20 minutes is 0% or more and 6%. The heat-shrinkable molded article according to claim 2, wherein: The plasticizer is heated from 20 ° C. at a heating rate of 10 ° C./min in a nitrogen atmosphere by thermogravimetric analysis (TGA), and the temperature when the mass reduction rate is 5% is 260 ° C. or more. The heat-shrinkable molded article according to claim 2 or 3. The heat-shrinkable molded article according to any one of claims 1 to 4, which has a tubular shape. The heat-shrinkable tube according to claim 5, wherein the flame retardancy evaluated by UL224 Optional VW-1 Flame Test is VW-1. A member coated with the heat-shrinkable tube according to claim 6. The member of Claim 7 used for the use of an electronic device or an electric device. The glass transition temperature Tg determined by differential scanning calorimetry (DSC) is 50 ° C. or higher and 85 ° C. or lower. After the temperature is increased from the crystal melting peak temperature Tm + 40 ° C. to Tm + 100 ° C. and held in DSC for 1 minute, the temperature decreasing rate is 10 ° C. / A method for producing a heat-shrinkable molded article from a polyphenylene sulfide-based resin composition having a temperature difference between the crystallization peak temperature Tc measured in minutes and the crystal melting peak temperature Tm of 80 ° C. or more, comprising: The process until the melt-extrusion of the resin composition from the die by the extrusion method includes the step of giving a heat history in a temperature range of Tm + 40 ° C. or more and Tm + 100 ° C. or less, the method for producing the heat-shrinkable molded article .