JP2020029954A - tube - Google Patents

Abstract

To provide a tube excellent in flexibility and low out-gas characteristics, and excellent in productivity of a molded article.SOLUTION: Thermoplastic urethane resin having a tensile modulus of elasticity (tensile speed of 200 mm/min) of 3.3 MPa or less and a diffusion coefficent of less than 1.00×10m/s in the form of a resin sheet with thickness of 1.7 mm is used for a tube of this invention. In the thermoplastic urethane resin, it is preferable that the difference between a temperature (°C) at which a storage modulus E' is 1 MPa and a glass-transition temperature (°C) is equal to or higher than 180°C. The glass-transition temperature of the thermoplastic urethane resin is preferably -10°C or lower.SELECTED DRAWING: None

Description

  The present invention relates to a tube using a thermoplastic urethane resin.

  In a clean room in which semiconductor devices are manufactured, it is required to minimize the generation of contaminants such as moisture and chemical substances in order to prevent contamination of silicon wafers. In particular, in a tube through which pure water or clean air blown to a silicon wafer flows, it is extremely important to suppress outgassing.

  Known low-outgas tubes are tubes made of fluororesin or polyester resin. However, tubes made of fluororesin or polyester resin are inferior in flexibility, and inferior in properties (kink resistance) that make it difficult to return to the original shape after breakage or the like. On the other hand, a conventional urethane resin tube having excellent flexibility and kink resistance had a large amount of outgas.

  As a method for reducing the outgas amount of the urethane resin, for example, a method of reducing residual monomers after curing by ultraviolet irradiation by using neopentyl glycol as a polyol component constituting the urethane resin is known (Patent Documents) 1). Further, a method is known in which superheated steam is applied to a flexible polyurethane foam obtained by foaming a polyurethane resin composition to reduce volatile organic compound residues contained in raw materials (see Patent Document 2). .

Japanese Patent No. 5110228 JP 2006-45443 A

  However, with the method disclosed in Patent Document 1, although the residual monomer can be reduced, the reduction of the total outgas amount on the premise of use in a clean room where stricter standards are required is insufficient. Further, the method disclosed in Patent Document 2 requires an additional step of applying superheated steam after the formation of urethane foam, so that the productivity is poor.

  Therefore, an object of the present invention is to provide a thermoplastic urethane resin and a tube which are excellent in flexibility and low outgassing property and are excellent in productivity of a molded product.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, according to a thermoplastic urethane resin having an elastic modulus of a specific value or less and a diffusion coefficient of less than a specific value, flexibility and low outgassing property And excellent productivity of the molded article. The present invention has been completed based on these findings.

That is, according to the present invention, when a resin sheet having a thickness of 1.7 mm is formed, the tensile elastic modulus (tension speed 200 mm / min) is 3.3 MPa or less, and the diffusion coefficient is 1.00 × 10 ⁻¹¹ m ² / s is provided.

  The thermoplastic urethane resin preferably has a difference between the temperature [° C.] at which the storage elastic modulus E ′ is 1 MPa and the glass transition temperature [° C.] of 180 ° C. or more.

  It is preferable that the thermoplastic urethane resin has a glass transition temperature of −10 ° C. or lower.

  The thermoplastic urethane resin contains a structural unit derived from a long-chain polyol, a structural unit derived from a polyisocyanate, and a structural unit derived from a chain extender, the long-chain polyol, the polyisocyanate, and the chain extender It is preferable that the content of structural units derived from components other than the above is 1% by mass or less.

  The long-chain polyol is preferably a polyalkylene glycol, and the polyisocyanate is preferably an aromatic isocyanate.

  The long-chain polyol preferably has a number average molecular weight of 900 to 3,000.

  Further, the present invention provides a tube using the thermoplastic urethane resin.

  The present invention also provides a method for producing a tube using the above-mentioned thermoplastic urethane resin.

Further, the present invention uses a structural unit derived from a long-chain polyol, a structural unit derived from a polyisocyanate, and a thermoplastic urethane resin containing a structural component derived from a chain extender, and a component other than the thermoplastic urethane resin. When the content is 20% by mass or less and the resin sheet has a thickness of 1.7 mm, the tensile elastic modulus (tension speed 200 mm / min) is 3.3 MPa or less, and the diffusion coefficient is 1.00 × 10 ^−. Provide a tube that is less than ¹¹ m ² / s.

  The thermoplastic urethane resin of the present invention has excellent low outgassing properties. For this reason, when a tube using the thermoplastic urethane resin of the present invention is used as a tube used in a clean room, the contamination of the silicon wafer can be extremely low. In addition, the thermoplastic urethane resin of the present invention has excellent flexibility, and therefore, has excellent kink resistance when formed into a tube. Further, since the thermoplastic urethane resin of the present invention has excellent low outgassing properties, it is possible to produce a molded article excellent in low outgassing properties without performing an additional step such as contact with superheated steam, and thus the productivity of molded articles is also low. Excellent.

  The thermoplastic urethane resin of the present invention has a tensile elastic modulus (tension speed of 200 mm / min) of 3.3 MPa or less, preferably 3.0 MPa or less, more preferably 2 or less when formed into a resin sheet having a thickness of 1.7 mm. 0.5 MPa or less, more preferably 2.2 MPa or less. When the tensile elastic modulus is 3.3 MPa or less, excellent flexibility and low outgassing properties are obtained, and the productivity of molded articles is also excellent. When the tensile modulus exceeds 3.3 MPa, the outgas amount is reduced, but the flexibility is impaired, and the kink resistance of the molded product is reduced. The lower limit of the elastic modulus is, for example, 0.5 MPa. When the tensile modulus is 0.5 MPa or more, the total outgas amount is further reduced. The elastic modulus is a value measured at normal temperature.

  The tensile modulus can be measured as follows. First, a thermoplastic urethane resin is heated and pressed at 230 ° C. for 20 seconds to obtain a 1.7 mm thick resin sheet. The conditions of the heating press may be appropriately changed according to the characteristics of the resin. From the resin sheet, a test piece is prepared by punching out a dumbbell-shaped No. 8 die having a parallel portion having a width of 5 mm and specified in JIS K6251. Using the prepared dumbbell-shaped test piece, a tensile test is performed based on JIS K6251 to measure the tensile modulus. The measurement of the tensile modulus can be performed, for example, using a trade name “Autograph AGS-5kNX” (manufactured by Shimadzu Corporation).

The thermoplastic urethane resin of the present invention has a diffusion coefficient of less than 1.00 × 10 ⁻¹¹ m ² / s, preferably 8.00 × 10 ⁻¹² m ² / s or less, more preferably 4.90 × 10 m / s. ^-12 m ² / s or less. When the diffusion coefficient is less than 1.00 × 10 ⁻¹¹ m ² / s, excellent low outgassing properties are obtained. This is presumed to be because the crystallinity of the thermoplastic urethane resin is improved and the free volume is reduced, whereby the movement of gas inside the thermoplastic urethane resin is suppressed, and outgas is hardly discharged to the outside. The lower limit of the diffusion coefficient is 0 m ² / s.

The diffusion coefficient is determined by a differential pressure method based on JIS K7126-1 (2006), a gas permeation curve is prepared for a test piece of a thermoplastic urethane resin using propane gas, and a delay time (θ) is derived from the gas permeation curve. Then, it can be calculated from the equation of diffusion coefficient D [m ² / s] = h ² / 6θ. In the above formula, h indicates the thickness [m] of the test piece, and θ indicates the delay time [s].

  In the thermoplastic urethane resin of the present invention, the difference between the temperature [° C.] at which the storage elastic modulus E ′ becomes 1 MPa and the glass transition temperature [° C.] is preferably 180 ° C. or more, more preferably 200 ° C. or more, and still more preferably. Is 210 ° C. or higher. When the above temperature difference is 180 ° C. or more, both flexibility and low outgassing tend to be excellent. The upper limit of the above temperature difference is, for example, 300 ° C, preferably 270 ° C.

  The temperature at which the storage elastic modulus E 'becomes 1 MPa can be measured by a known or commonly used dynamic viscoelasticity measuring device (DMA). The temperature at which the storage elastic modulus E 'becomes 1 MPa is, for example, 180 to 250C, preferably 180 to 200C. When the temperature at which the storage elastic modulus E ′ becomes 1 MPa is 180 ° C. or more, the heat resistance of the resin is good. When the temperature at which the storage elastic modulus E ′ becomes 1 MPa is 250 ° C. or less, melt molding is relatively easy.

  The above glass transition temperature can be measured by a known or commonly used dynamic viscoelasticity measuring device (DMA). The glass transition temperature is, for example, -80 to 0C, preferably -70 to -10C. When the glass transition temperature is -80 ° C or higher, the heat resistance of the resin is good. When the glass transition temperature is 0 ° C. or lower, flexibility at normal temperature is more excellent.

  The thermoplastic urethane resin of the present invention is preferably obtained by reacting at least a polyisocyanate and a long-chain polyol. That is, the thermoplastic urethane resin of the present invention preferably contains a structural unit derived from a polyisocyanate and a structural unit derived from a long-chain polyol. The outgas generated from the urethane resin is presumed that the outgas remaining inside the thermoplastic urethane resin moves between molecular chains to reach the resin surface, and is released from the resin surface to the outside. When the thermoplastic urethane resin of the present invention has a configuration having a hard phase (hard segment) composed of a structural unit derived from polyisocyanate and a soft phase (soft segment) composed of a structural unit derived from a long-chain polyol, The movement of outgas inside the resin is controlled, and the outgas amount can be easily controlled while having excellent flexibility.

  The polyisocyanate is not particularly limited as long as it is a compound having at least two isocyanate groups in a molecule. Examples of the polyisocyanate include an aliphatic polyisocyanate, an alicyclic polyisocyanate, an aromatic polyisocyanate, and an araliphatic polyisocyanate. As the polyisocyanate, only one kind may be used, or two or more kinds may be used.

  Examples of the aliphatic polyisocyanate include 1,3-trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,2-propylene diisocyanate, 2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, 3-methyl-1,5-pentamethylene diisocyanate, 2,4,4-trimethyl And aliphatic diisocyanates such as -1,6-hexamethylene diisocyanate and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate.

  Examples of the alicyclic polyisocyanate include 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate). , 4,4'-methylenebis (cyclohexylisocyanate), methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) Alicyclic diisocyanates such as cyclohexane and norbornane diisocyanate;

  Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthylene-1,4-diisocyanate, and naphthylene-1,5-diisocyanate 4,4'-diphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2,2 'diphenylpropane-4, Aromatic diisocyanates such as 4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, and 4,4'-diphenylpropane diisocyanate, and the like. .

  Examples of the araliphatic polyisocyanate include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, ω, ω′-diisocyanate-1,4-diethylbenzene, and 1,3-bis (1-isocyanate-1). And aromatic diisocyanates such as 1,4-bis (1-isocyanate-1-methylethyl) benzene and 1,3-bis (α, α-dimethylisocyanatomethyl) benzene.

  As the polyisocyanate, a dimer or trimer of an aliphatic polyisocyanate, an alicyclic polyisocyanate, an aromatic polyisocyanate, or an araliphatic polyisocyanate, a reaction product or a polymer (for example, dimer of diphenylmethane diisocyanate) And trimers, reaction products of trimethylolpropane with tolylene diisocyanate, reaction products of trimethylolpropane with hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, etc.) Can be used.

  As the polyisocyanate, an aromatic polyisocyanate is preferable, and an aromatic diisocyanate is more preferable. When an aromatic polyisocyanate (particularly, an aromatic diisocyanate) is used, it is presumed that the movement of outgas is suppressed in a portion that becomes a hard segment in the urethane resin, and the total outgas amount is easily reduced. Among the aromatic diisocyanates, 4,4'-diphenylmethane diisocyanate is particularly preferred.

  Examples of the long-chain polyol include polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, polyacryl polyol and the like. As the long-chain polyol, only one kind may be used, or two or more kinds may be used.

  Examples of the polyether polyol include polyalkylene ether glycols such as polyethylene ether glycol, polypropylene ether glycol, and polytetramethylene ether glycol (PTMG), and a plurality of alkylene oxides as monomer components such as an ethylene oxide-propylene oxide copolymer. (Alkylene oxide-other alkylene oxide) copolymers.

  As the polyester polyol, for example, a condensation polymer of a polyhydric alcohol and a polycarboxylic acid; a ring-opening polymer of a cyclic ester (lactone); a polyhydric alcohol, a polycarboxylic acid, and a cyclic ester are used. Reactants and the like. In the condensation polymer of polyhydric alcohol and polycarboxylic acid, examples of polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, , 4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4- Diethyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), cyclohexanedimethanols (1,4-cyclohexane Methanol and the like), bisphenols (bisphenol A, etc.), sugar alcohols (xylitol and sorbitol) and the like. Examples of the polycarboxylic acid include aliphatic dicarboxylic acids such as malonic acid, maleic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid and dodecandioic acid; 1,4-cyclohexanedicarboxylic acid And alicyclic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid and trimellitic acid. In the ring-opening polymer of the cyclic ester, examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, ε-caprolactone, and the like. In the reaction product of the three types of components, the above-mentioned compounds and the like can be used as the polyhydric alcohol, polycarboxylic acid, and cyclic ester.

  Examples of the polycarbonate polyol include a reaction product of a polyhydric alcohol and phosgene, chloroformate, dialkyl carbonate, or diaryl carbonate; and a ring-opening polymer of a cyclic carbonate (such as an alkylene carbonate). Specifically, in the reaction product of a polyhydric alcohol and phosgene, as the polyhydric alcohol, the above-mentioned polyhydric alcohols (for example, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, Neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, etc.). In the ring-opened polymer of the cyclic carbonate, examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate, and the like. The polycarbonate polyol may be a compound having a carbonate bond in the molecule and a terminal having a hydroxyl group, and may have an ester bond together with the carbonate bond. Representative examples of polycarbonate polyols include polyhexamethylene carbonate diol, diols obtained by ring-opening addition polymerization of lactone to polyhexamethylene carbonate diol, and cocondensates of polyhexamethylene carbonate diol with polyester diol or polyether diol. And the like.

  The polyolefin polyol is a polyol containing an olefin as a component of a skeleton (or main chain) of a polymer or a copolymer and having at least two hydroxy groups in a molecule (particularly at a terminal). The olefin may be an olefin having a carbon-carbon double bond at a terminal (for example, an α-olefin such as ethylene or propylene), or an olefin having a carbon-carbon double bond at a site other than the terminal. (For example, isobutene and the like), and may be a diene (for example, butadiene and isoprene). Representative examples of polyolefin polyols include butadiene homopolymers, butadiene such as isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, and butadiene-n-octadecyl acrylate copolymer. Alternatively, an isoprene-based polymer obtained by modifying the terminal with a hydroxyl group may be used.

The polyacryl polyol is a polyol containing (meth) acrylate as a component of a skeleton (or main chain) of a polymer or a copolymer and having at least two hydroxyl groups in a molecule (particularly at a terminal). Examples of the (meth) acrylate include an alkyl (meth) acrylate [eg, a C _1-20 alkyl (meth) acrylate].

As the long-chain polyol, a polyether polyol is preferable, and a polyalkylene glycol is more preferable, and a poly C _2-6 alkylene glycol is more preferable. When a polyether polyol is used, it is easy to control the amount of outgas that moves in a portion that becomes a soft segment in the urethane resin. Among the polyether polyols, polytetramethylene ether glycol is particularly preferred.

  The number average molecular weight of the long-chain polyol is preferably from 500 to 10,000, more preferably from 600 to 6000, and still more preferably from 900 to 3,000. When the number average molecular weight is 500 or more, the number of cross-linking points with the polyisocyanate in the thermoplastic urethane resin becomes appropriate, and the flexibility is more excellent. When the number average molecular weight is 10,000 or less, the reactivity with polyisocyanate is improved, so that the residual polyol tends to be reduced, and the total outgas amount is further reduced. The number average molecular weight is a number average molecular weight in terms of standard polytetrahydrofuran, measured by gel permeation chromatography (GPC).

  The thermoplastic urethane resin of the present invention is preferably obtained by reacting with a polyisocyanate and a long-chain polyol using a chain extender. That is, the thermoplastic urethane resin of the present invention preferably contains a structural unit derived from a chain extender. As the chain extender, only one kind may be used, or two or more kinds may be used.

  As the chain extender, known or commonly used chain extenders used for producing a thermoplastic urethane resin can be used. Examples of the chain extender include, but are not particularly limited to, low molecular weight polyols and polyamines. The molecular weight of the chain extender is, for example, less than 500, preferably 300 or less.

  Examples of the chain extender include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,2-pentane. Diols such as diol, 2,3-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; Diamines such as methylene diamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and 4,4'-methylenebis-2-chloroaniline. Among these, diols are preferred, and 1,4-butanediol is particularly preferred.

  The thermoplastic urethane resin of the present invention has a ratio of the number of moles of the isocyanate group of the polyisocyanate to the number of moles of the isocyanate-reactive group (hydroxyl group, amino group, etc.) of the long-chain polyol and the chain extender [NCO / isocyanate reaction] Is preferably 0.9 to 1.3, more preferably 0.95 to 1.1, and still more preferably 1.0 to 1.1. That is, in the thermoplastic urethane resin of the present invention, the ratio of the number of moles of the structural part derived from the isocyanate group to the number of moles of the structural part derived from the isocyanate-reactive group is preferably within the above range. When the molar ratio is 0.9 or more (especially 1.0 or more), the isocyanate group is sufficiently incorporated into the thermoplastic urethane resin with respect to the isocyanate-reactive group, so that the structural unit derived from polyisocyanate It is presumed that the movement of outgas in the molecule is suppressed by the hard segment. It is also assumed that the amount of the residual long-chain polyol and the chain extender not taken into the thermoplastic urethane resin is reduced. For these reasons, the total outgas amount tends to decrease. When the molar ratio is 1.3 or less (especially 1.1 or less), residual polyisocyanate not taken into the thermoplastic urethane resin is reduced, and the total outgas amount tends to be reduced.

  The ratio of the number of moles of the structural units derived from the long-chain polyol to the number of moles of the structural units derived from the chain extender [long-chain polyol / chain extender] is set so that the tensile elastic modulus of the thermoplastic urethane resin falls within a specific range. From the viewpoint of reducing the total amount of outgas, it is, for example, 0.05 to 10, preferably 0.1 to 2, more preferably 0.2 to 0.5, and particularly preferably 0.2 to 0.4.

  It is preferable that the thermoplastic urethane resin of the present invention does not substantially contain constituent units derived from other components (components other than the polyisocyanate, the long-chain polyol, and the chain extender). In addition, in this specification, substantially not including means not actively adding except impurities contained in the raw material, and may be, for example, 1% by mass or less.

The thermoplastic urethane resin of the present invention is preferably composed of a structural unit derived from an aromatic polyisocyanate, a structural unit derived from a polyether polyol, and a structural unit derived from a chain extender, among other components. It is preferable that the composition does not substantially include a structural unit derived from (other polyisocyanate and other long-chain polyol). In particular, a structural unit derived from an aromatic diisocyanate (particularly, 4,4′-diphenylmethane diisocyanate) and a structural unit derived from a polyalkylene glycol (preferably poly C _2-6 alkylene glycol, particularly preferably polytetramethylene glycol) Consisting of a structural unit derived from a diol (particularly 1,4-butanediol) as a chain extender, a structural unit derived from another component (another polyisocyanate, another polyol, or another chain extender) is substantially It is preferably not included.

  The thermoplastic urethane resin of the present invention has a weight average molecular weight Mw of usually 5,000 to 1,000,000, and can be molded by a general thermoplastic resin molding machine such as extrusion molding, injection molding, and hot press molding. Can be molded.

The thermoplastic urethane resin of the present invention preferably has an outgas amount of phenols of 1000 μg / m ² or less in terms of hexadecane when a 1.7 mm × 2 mm × 50 mm test piece is heated at 30 ° C. for 60 minutes. preferably 800 [mu] g / m ^2, more preferably not more than 700 [mu] g / m ^2. The outgassing amount can be measured using known or commonly used gas chromatography. The outgas generated from the thermoplastic urethane resin contains unreacted polyol, polyisocyanate, a chain extender, and additives such as an antioxidant and an ultraviolet absorber.

  The molded article obtained from the thermoplastic urethane resin of the present invention is excellent in flexibility and low outgassing property. For this reason, belts such as flat belts and V-belts, tubes, hoses, suction pads, vibration-isolating dampers, vibration-isolating joints, shock absorbers, casters, packing, soles for soles, switches, valves, valves, filters, rolls, Rollers (discharge rollers, paper feed rollers, etc.), clips, films, sheets, tires, casters, mats, gloves, adhesive plasters, robes, skins, bags, instrument panel snow chains, ski boots, spring covers, pumps, physical functional materials (Artificial heart and the like) are particularly useful.

  Among them, the thermoplastic urethane resin of the present invention is excellent in flexibility and low outgassing property, and from the viewpoint of further excellent kink resistance of the molded article, as a molded article using the thermoplastic urethane resin of the present invention, a tube is preferable. A tube in a clean room is more preferable, and a tube in a clean room of a semiconductor manufacturing factory is particularly preferable. Particularly, it is preferable to use a cooling water piping tube, a cooling antifreeze piping tube, a clean dry air piping, and a nitrogen gas piping in a clean room of a semiconductor manufacturing plant. Note that a tube using the thermoplastic urethane resin of the present invention may be referred to as a “tube of the present invention”.

  The tube of the present invention is a tube using the thermoplastic urethane resin of the present invention. The tube of the present invention can be manufactured using the thermoplastic urethane resin of the present invention. The tube of the present invention may contain components other than the thermoplastic urethane resin of the present invention. The other components include antioxidants, ultraviolet absorbers, plasticizers, stabilizers, release agents, surfactants, antistatic agents, conductive materials, coloring agents (pigments, dyes), flame retardants, foaming agents, Examples include a lubricant, a lubricant, a filler, a crosslinking agent, a solvent, a developing solution, a bulking agent, a wax, an oil, a grease, a processing aid, a processing agent, a reinforcing material, a filler, an antiblocking agent, and an antiaging agent. As the other components, only one kind may be used, or two or more kinds may be used.

  Since the thermoplastic urethane resin of the present invention has excellent flexibility, the tube of the present invention requires a minimum amount of other components for imparting flexibility, such as a plasticizer or a flame retardant that can function as a plasticizer. Limit. Further, since the plasticizer and the flame retardant can generate outgas, the tube of the present invention is excellent in flexibility and extremely excellent in low outgassing property by minimizing the amount of use.

  The content of the thermoplastic urethane resin of the present invention in the tube of the present invention is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass, based on 100% by mass of the tube of the present invention. The content is more preferably at least 95% by mass, particularly preferably at least 99% by mass. When the content is 50% by mass or more, flexibility and low outgassing property are excellent.

  The content of components other than the thermoplastic urethane resin of the present invention in the tube of the present invention is preferably less than 50% by mass, more preferably less than 20% by mass, and still more preferably 100% by mass of the tube of the present invention. It is less than 10% by weight, more preferably less than 5% by weight, particularly preferably less than 1% by weight. When the content is less than 50% by mass, flexibility and low outgassing property are excellent.

  The tube of the present invention preferably has a tensile elastic modulus (tension speed of 200 mm / min) of 0.5 to 3.3 MPa, more preferably 0.6 to 3 MPa, when formed into a resin sheet having a thickness of 1.7 mm. 0.0 MPa. When the tensile elastic modulus is 0.5 MPa or more, it is more excellent in low outgassing property. When the tensile elastic modulus is 3.3 MPa or less, flexibility is excellent and kink resistance is more excellent. The tensile modulus of the tube can be measured in the same manner as the measurement of the tensile modulus of the thermoplastic urethane resin, except that the resin sheet is sampled from the tube as a test piece.

In the tube of the present invention, when a 1.7 mm × 2 mm × 50 mm test piece is heated at 30 ° C. for 60 minutes, the outgassing amount of phenols is preferably 1000 μg / m ² or less in terms of hexadecane, more preferably 800 μg. / M ² or less, more preferably 700 μg / m ² or less. The outgassing amount can be measured using known or commonly used gas chromatography. In addition, as the outgas generated from the tube, those exemplified as the outgas that can be contained in the above-mentioned thermoplastic urethane resin can be mentioned.

  The tube of the present invention uses, in particular, a thermoplastic urethane resin containing a constituent unit derived from a long-chain polyol, a constituent unit derived from a polyisocyanate, and a constituent component derived from a chain extender, and the thermoplastic urethane resin of the present invention. It is preferable that the content of the other components is 20% by mass or less, and the tensile elastic modulus (tension speed 200 mm / min) of the resin sheet having a thickness of 1.7 mm is 0.5 to 3.3 MPa.

  The tube of the present invention is obtained by kneading a resin composition containing the thermoplastic urethane resin of the present invention and other components as necessary, and then extruding, injection molding, blow molding, calender molding, press molding, and injection molding. It can be manufactured by a known method such as a mold or a molding method for cans.

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

Example 1
In a reaction vessel equipped with a stirrer and a thermometer, polytetramethylene glycol (PTMG) (trade name “PTMG2000”, manufactured by Mitsubishi Chemical Corporation) and 1,4-butanediol (1,4-BD) were placed in Table 1 Were uniformly mixed at the molar ratios shown in Table 1. After the obtained mixture was heated to 100 ° C., the molar ratio of 4,4′-diphenylmethane diisocyanate (MDI) to the molar ratio shown in Table 1 (the number of moles relative to the total number of moles of PTMG and the number of moles of 1,4-butanediol) was used. ), And a urethanization reaction was carried out. After the MDI was charged, the mixture was stirred for 5 minutes and poured into a vat to solidify. The obtained solid was aged in an electric furnace at 100 ° C. for 48 hours, cooled, and then crushed to obtain a flake-like thermoplastic urethane resin.

Examples 2 to 4, Comparative Examples 1 to 3
A thermoplastic urethane resin was obtained in the same manner as in Example 1 except that the kind of long-chain polyol and the molar ratio of polyisocyanate were changed as shown in Table 1. The raw materials shown in the table are as follows.
PTMG850: trade name “PTMG850”, manufactured by Mitsubishi Chemical Corporation, number average molecular weight 850
PTMG1000: trade name “PTMG1000”, manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000
PTMG1500: trade name "PTMG1500", manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1500
PTMG2000: trade name "PTMG2000", manufactured by Mitsubishi Chemical Corporation, number average molecular weight 2000
1,4-BD: 1,4-butanediol 1,6-HD: 1,6-hexanediol MDI: 4,4′-diphenylmethane diisocyanate HDI: 1,6-hexamethylene diisocyanate

  The following evaluation was performed about the thermoplastic urethane resin obtained by the Example and the comparative example. Table 1 shows the results. In addition, the unit of the compounding amount of the long-chain polyol, the chain extender, and the polyisocyanate shown in Table 1 is a relative mole.

(1) Tensile modulus The thermoplastic urethane resins obtained in Examples and Comparative Examples were heated and pressed at 230 ° C. to obtain a 1.7 mm thick resin sheet. Next, a dumbbell-shaped test piece was prepared from the obtained resin sheet by punching out a dumbbell-shaped No. 8 shape described in JIS K6251 with a width of 5 mm at the parallel portion. Using the prepared dumbbell-shaped test piece, a tensile test was performed using a trade name “Autograph AGS-5kNX” (manufactured by Shimadzu Corporation) at 23 ° C., a mark line distance of 10 mm, and a tensile speed of 200 mm / min. The tensile modulus was measured.

(2) Amount of Outgas A test piece was prepared by punching the resin sheet prepared in the above evaluation of the tensile modulus into a shape of 1.7 mm × 2 mm × 50 mm. The obtained test piece was heated at 30 ° C. for 1 hour, the generated gas was cold-trapped at −30 ° C., and the trapped gas component was injected by a heat desorption method and measured by gas chromatography. And the outgas amount of phenols was extracted. Helium was used as the carrier gas, and DB-1 (1.0 μm, 0.32 mmφ × 60 m) was used for the column. The column temperature was 40 ° C. (2 min.) → 10 ° C. (1 min.) → 250 ° C. (10 min.). Was changed. The column pressure was 80 kPa, and the ion source temperature was 200 ° C.

(3) Diffusion Coefficient The thermoplastic urethane resins obtained in Examples and Comparative Examples were heated and pressed at 230 ° C. to obtain a resin sheet having a thickness h of 0.4 mm. Next, using the obtained resin sheet, a gas permeation curve was prepared by a differential pressure method with reference to JIS K7126-1 (2006). Specifically, the obtained resin sheet was set on a gas permeability tester equipped with a pressure sensor, and the high-pressure cell was pressurized to 100 kPa using propane gas, and the low-pressure cell from the high-pressure cell through the resin sheet over time. Gas was passed through the cell. Then, the elapsed time was plotted on the horizontal axis and the pressure of the low-pressure side cell was plotted on the vertical axis to create a gas permeation curve. From the slope of steady-state portion of the resulting gas permeability curve, a delay time θ derives [s], to calculate the diffusion coefficient D from equation of the diffusion coefficient ^{D [m 2 / s] =} h 2/6.

(4) Temperature at which storage elastic modulus E 'is 1 MPa A test piece was prepared by punching out a 1.7 mm x 5 mm x 50 mm shape from the resin sheet prepared in the above evaluation of tensile modulus. Using a dynamic viscoelasticity measuring device (DMA), the obtained test piece was heated at a rate of 3 ° C./min. The storage elastic modulus E ′ was measured under the measurement conditions of a frequency of 1 Hz and a temperature range of −130 to 250 ° C., and the temperature at which the storage elastic modulus E ′ became 1 MPa was read.

(5) Glass transition temperature In the above evaluation of the storage elastic modulus measurement, the temperature at the peak top of the loss tangent tanD was defined as the glass transition temperature.

As shown in Table 1, the thermoplastic urethane resins of Examples 1 to 4 have a tensile modulus of 3.3 MPa or less, a diffusion coefficient of less than 1.00 × 10 ⁻¹¹ m ² / s, and flexibility. And low outgassing properties. In addition, since the thermoplastic urethane resin is excellent in low outgassing property, when manufacturing a molded article using the thermoplastic urethane resin, a step of applying superheated steam to reduce the amount of outgas is not required, and the molded article is not required. Excellent productivity. On the other hand, when the tensile modulus exceeds 3.3 MPa or the diffusion coefficient is 1.00 × 10 ⁻¹¹ m ² / s or more (Comparative Examples 1 to 3), the outgas amount becomes 800 μg / m ² or more. Or the flexibility was insufficient.

Claims (7)

Thermoplastic having a tensile elastic modulus (tension speed of 200 mm / min) of 3.3 MPa or less and a diffusion coefficient of less than 1.00 × 10 ⁻¹¹ m ² / s when a resin sheet having a thickness of 1.7 mm is formed. Tube made of urethane resin.   2. The tube according to claim 1, wherein a difference between a temperature [° C.] at which the storage elastic modulus E ′ of the thermoplastic urethane resin is 1 MPa and a glass transition temperature [° C.] is 180 ° C. or more.   The tube according to claim 1, wherein the glass transition temperature of the thermoplastic urethane resin is −10 ° C. or lower.   The thermoplastic urethane resin, a structural unit derived from a long-chain polyol, a structural unit derived from a polyisocyanate, and a structural unit derived from a chain extender, the long-chain polyol, the polyisocyanate, and the chain extender The tube according to any one of claims 1 to 3, wherein the content of a constituent unit derived from a component other than the above is 1% by mass or less.   The tube according to claim 4, wherein the long-chain polyol is a polyalkylene glycol, and the polyisocyanate is an aromatic isocyanate.   The tube according to claim 4 or 5, wherein the long-chain polyol has a number average molecular weight of 900 to 3000. Using a thermoplastic urethane resin containing a constituent unit derived from a long-chain polyol, a constituent unit derived from a polyisocyanate, and a constituent component derived from a chain extender, the content of components other than the thermoplastic urethane resin is 20% by mass. And a tensile elastic modulus (tension speed 200 mm / min) of 3.3 MPa or less and a diffusion coefficient of less than 1.00 × 10 ⁻¹¹ m ² / s when a resin sheet having a thickness of 1.7 mm is used. Is a tube.