JP7110064B2 - tube - Google Patents

Description

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

2. Description of the Related Art In a clean room where semiconductor devices are manufactured, it is required to prevent generation of contaminants such as moisture and chemical substances as much as possible in order to prevent contamination of silicon wafers. In particular, suppression of outgassing is extremely important in tubes for circulating pure water and clean air to be sprayed onto silicon wafers.

Fluorocarbon resin and polyester resin tubes are known as low outgassing tubes. However, the fluororesin and polyester resin tubes are inferior in flexibility, and are inferior in properties (kink resistance) in which they are difficult to return to their original shape after being broken or the like. On the other hand, conventional urethane resin tubes, which are excellent in flexibility and kink resistance, generate a large amount of outgassing.

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

Japanese Patent No. 5110228 JP-A-2006-45443

However, although the method disclosed in Patent Document 1 can reduce residual monomers, it is insufficient to reduce the total amount of outgassing on the premise of use in a clean room where stricter standards are required. In addition, the method disclosed in Patent Document 2 requires an additional step of applying superheated steam after forming the urethane foam, resulting in poor productivity.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a thermoplastic urethane resin and a tube which are excellent in flexibility and low outgassing properties and which are excellent in the productivity of molded articles.

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

That is, in the present invention, a resin sheet having a thickness of 1.7 mm has a tensile elastic modulus (tensile speed of 200 mm/min) of 3.3 MPa or less and a diffusion coefficient of 1.00 × 10 ^-11 m ² /. A thermoplastic urethane resin is provided that has less than s.

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

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

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

The number average molecular weight of the long chain polyol is preferably 900-3000.

The present invention also provides a tube using the thermoplastic urethane resin.

The present invention also provides a method of manufacturing a tube using the thermoplastic urethane resin.

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

The thermoplastic urethane resin of the present invention is excellent in low outgassing properties. Therefore, when a tube using the thermoplastic urethane resin of the present invention is used as a tube for use in a clean room, contamination of silicon wafers can be kept to an extremely low level. Moreover, since the thermoplastic urethane resin of the present invention is excellent in flexibility, it is excellent in kink resistance when made into a tube. In addition, since the thermoplastic urethane resin of the present invention is excellent in low outgassing properties, it is possible to produce molded articles with excellent low outgassing properties without performing additional steps such as contact with superheated steam. Excellent.

The thermoplastic urethane resin of the present invention has a tensile modulus of elasticity (tensile speed of 200 mm/min) of 3.3 MPa or less, preferably 3.0 MPa or less, more preferably 2 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, the flexibility and low outgassing property are excellent, and the productivity of the molded product is also excellent. If the tensile modulus exceeds 3.3 MPa, although the amount of outgas is reduced, the flexibility is impaired and the kink resistance of the molded product is reduced. Further, 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 amount of outgassing is further reduced. The elastic modulus is a value measured at room temperature.

The tensile modulus can be measured as follows. First, a thermoplastic urethane resin is hot-pressed at 230° C. for 20 seconds to obtain a resin sheet with a thickness of 1.7 mm. The conditions for hot pressing may be changed as appropriate according to the properties of the resin. From this resin sheet, a dumbbell-shaped No. 8 shape defined by JIS K6251 with a width of 5 mm in the parallel portion is punched out to prepare a test piece. Using the prepared dumbbell-shaped test piece, a tensile test is performed based on JIS K6251 to measure the tensile modulus. The tensile modulus can be measured, 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 2 /s or less. ⁻¹² m ² /s or less. When the diffusion coefficient is less than 1.00×10 ⁻¹¹ m ² /s, the low outgassing property is excellent. It is presumed that this is because the thermoplastic urethane resin has improved crystallinity and a smaller free volume, which suppresses the movement of gas inside the thermoplastic urethane resin and makes it difficult for outgas to be discharged to the outside. The lower limit of the diffusion coefficient is 0 m ² /s.

The above diffusion coefficient is obtained by creating a gas permeation curve using propane gas for a thermoplastic urethane resin test piece by the differential pressure method based on JIS K7126-1 (2006), and deriving the lag time (θ) from the gas permeation curve. and can be calculated from the equation of diffusion coefficient D[m ² /s]=h ² /6θ. In the above formula, h is the thickness [m] of the test piece, and θ is 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 above 210°C. When the temperature difference is 180° C. or more, there is a tendency to be more excellent in both flexibility and low outgassing properties. The upper limit of the above temperature difference is, for example, 300°C, preferably 270°C.

The temperature at which the storage 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 modulus E' becomes 1 MPa is, for example, 180 to 250°C, preferably 180 to 200°C. When the temperature at which the storage elastic modulus E′ becomes 1 MPa is 180° C. or higher, 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 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 0°C, preferably -70 to -10°C. 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, the flexibility at room temperature is more excellent.

The thermoplastic urethane resin of the present invention is preferably obtained by reacting at least polyisocyanate with long-chain polyol. That is, the thermoplastic urethane resin of the present invention preferably contains structural units derived from polyisocyanate and structural units derived from long-chain polyol. The outgassing generated from the urethane resin is presumed to be that the outgassing remaining inside the thermoplastic urethane resin moves between the molecular chains, reaches the resin surface, and is released from the resin surface to the outside. Then, when the thermoplastic urethane resin of the present invention is configured to have a hard phase (hard segment) composed of structural units derived from polyisocyanate and a soft phase (soft segment) composed of structural units derived from long-chain polyol, By controlling the movement of outgassing inside the resin, it is possible to easily control the amount of outgassing while having excellent flexibility.

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

Examples of aliphatic polyisocyanates include 1,3-trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1, 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 Aliphatic diisocyanates such as -1,6-hexamethylene diisocyanate and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate.

Alicyclic polyisocyanates include, for example, 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) , 4,4′-methylenebis(cyclohexyl isocyanate), 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 are included.

Examples of aromatic polyisocyanates 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, 4,4'-diphenylpropane diisocyanate;

Examples of araliphatic polyisocyanates include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3-bis(1-isocyanate-1 -methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, 1,3-bis(α,α-dimethylisocyanatemethyl)benzene, and the like.

In addition, as polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, dimer or trimer of araliphatic polyisocyanate, reaction product or polymer (for example, dimer of diphenylmethane diisocyanate trimers, reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, etc.) can be used.

Among the polyisocyanates, aromatic polyisocyanates are preferred, and aromatic diisocyanates are more preferred. It is presumed that the use of aromatic polyisocyanate (especially aromatic diisocyanate) suppresses the movement of outgassing in the hard segment portion of the urethane resin, and the total amount of outgassing tends to decrease. Among aromatic diisocyanates, 4,4'-diphenylmethane diisocyanate is particularly preferred.

Examples of the long-chain polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and polyacrylic polyols. Only one type of the long-chain polyol may be used, or two or more types may be used.

Examples of polyether polyols include polyalkylene ether glycols such as polyethylene ether glycol, polypropylene ether glycol, and polytetramethylene ether glycol (PTMG), as well as ethylene oxide-propylene oxide copolymers containing multiple alkylene oxides as monomer components. (alkylene oxide-other alkylene oxide) copolymers containing

Polyester polyols include, for example, polyhydric alcohol and polycarboxylic acid condensation polymer; ring-opening polymer of cyclic ester (lactone); polyhydric alcohol, polycarboxylic acid, and cyclic ester. reaction products and the like. Examples of the polyhydric alcohol in the condensation polymer of polyhydric alcohol and polycarboxylic acid include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1 ,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 (1,4-cyclohexanediol, etc.), cyclohexanedimethanols (1,4-cyclohexanedimethanol, etc.), bisphenols (bisphenol A, etc.), sugar alcohols (xylitol, sorbitol, etc.), and the like. Examples of polyvalent carboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; 1,4-cyclohexanedicarboxylic acid; alicyclic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and aromatic dicarboxylic acids such as trimellitic acid. Examples of cyclic esters in the ring-opening polymer of cyclic esters include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone. As the polyhydric alcohol, polyhydric carboxylic acid, and cyclic ester in the reaction product of the three components, the above-described ones can be used.

Polycarbonate polyols include, for example, reaction products of polyhydric alcohols with phosgene, chloroformates, dialkyl carbonates, or diaryl carbonates; ring-opening polymers of cyclic carbonates (alkylene carbonates, etc.); Specifically, in the reaction product of a polyhydric alcohol and phosgene, the polyhydric alcohol includes the polyhydric alcohols described above (e.g., ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, etc.). Examples of the alkylene carbonate in the ring-opening polymer of the cyclic carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate. The polycarbonate polyol may be a compound having a carbonate bond in the molecule and a terminal hydroxyl group, and may have an ester bond as well as a carbonate bond. Typical examples of polycarbonate polyols include polyhexamethylene carbonate diol, diol obtained by ring-opening addition polymerization of lactone to polyhexamethylene carbonate diol, cocondensate of polyhexamethylene carbonate diol and polyester diol or polyether diol. etc.

A polyolefin polyol is a polyol having an olefin as a component of the backbone (or main chain) of a polymer or copolymer and having at least two hydroxy groups in the molecule (especially at the end). The olefin may be an olefin having a carbon-carbon double bond at the terminal (e.g., α-olefin such as ethylene, propylene, etc.), or an olefin having a carbon-carbon double bond at a site other than the terminal. (eg, isobutene, etc.), or dienes (eg, butadiene, isoprene, etc.). Representative examples of polyolefin polyols include butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer, and the like. Alternatively, an isoprene-based polymer whose terminal is modified with a hydroxyl group can be used.

A polyacrylic polyol is a polyol having (meth)acrylate as a component of the skeleton (or main chain) of a polymer or copolymer and having at least two hydroxyl groups in the molecule (especially at the terminal). (Meth)acrylates include (meth)acrylic acid alkyl esters [eg, (meth)acrylic acid C _1-20 alkyl esters, etc.].

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

The number average molecular weight of the long-chain polyol is preferably 500-10,000, more preferably 600-6,000, still more preferably 900-3,000. When the number average molecular weight is 500 or more, the number of cross-linking points with polyisocyanate in the thermoplastic urethane resin becomes appropriate, and the flexibility is excellent. When the number average molecular weight is 10,000 or less, the reactivity with polyisocyanate is improved, so the amount of residual polyol tends to decrease, and the total amount of outgassing is further reduced. The above number average molecular weight is the 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 a polyisocyanate, a long-chain polyol, and a chain extender. That is, the thermoplastic urethane resin of the present invention preferably contains structural units derived from a chain extender. Only one kind of the chain extender may be used, or two or more kinds thereof may be used.

As the chain extender, known or commonly used chain extenders used in the production of thermoplastic urethane resins 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 diols, 2,3-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol; Examples include diamines such as methylenediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis-2-chloroaniline and the like. Among these, diols are preferred, and 1,4-butanediol is particularly preferred.

The thermoplastic urethane resin of the present invention is a ratio of the number of moles of isocyanate groups in polyisocyanate to the number of moles of isocyanate-reactive groups (hydroxyl groups, amino groups, etc.) possessed by long-chain polyols and chain extenders [NCO/isocyanate reaction is preferably 0.9 to 1.3, more preferably 0.95 to 1.1, 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 groups are sufficiently incorporated into the thermoplastic urethane resin with respect to the isocyanate-reactive groups. It is presumed that the movement of outgassing in the molecule is suppressed by the hard segment. In addition, it is presumed that residual long-chain polyols and chain extenders that have not been incorporated into the thermoplastic urethane resin are reduced. For these reasons, the total amount of outgas tends to decrease. When the molar ratio is 1.3 or less (especially 1.1 or less), the amount of residual polyisocyanate that has not been incorporated into the thermoplastic urethane resin tends to decrease, resulting in a decrease in the total amount of outgassing.

The ratio of the number of moles of 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 modulus of the thermoplastic urethane resin is within a specific range. And from the viewpoint of reducing the total amount of outgassing, 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.

The thermoplastic urethane resin of the present invention preferably does not substantially contain structural units derived from other components (components other than polyisocyanate, long-chain polyol, and chain extender). In this specification, "substantially free" means that impurities contained in the raw material are not actively added, and may be, for example, 1% by mass or less.

The thermoplastic urethane resin of the present invention preferably comprises structural units derived from an aromatic polyisocyanate, structural units derived from a polyether polyol, and structural units derived from a chain extender. (Other polyisocyanates and other long-chain polyols) are preferably substantially free of constituent units. In particular, structural units derived from aromatic diisocyanate (especially 4,4′-diphenylmethane diisocyanate) and structural units derived from polyalkylene glycol (preferably polyC _2-6 alkylene glycol, particularly preferably polytetramethylene glycol) Consists of structural units derived from a diol (especially 1,4-butanediol) as a chain extender, and substantially structural units derived from other components (other polyisocyanates, other polyols, and other chain extenders) 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 general thermoplastic resin molding machines such as extrusion molding, injection molding, and hot press molding. Can be molded.

The thermoplastic urethane resin of the present invention preferably has an outgassing amount of phenols of 1000 μg/m ² or less in terms of hexadecane when a test piece of 1.7 mm×2 mm×50 mm is heated at 30° C. for 60 minutes. It is preferably 800 μg/m ² or less, more preferably 700 μg/m ² or less. The amount of outgas can be measured using a known or commonly used gas chromatography. The outgas generated from the thermoplastic urethane resin includes unreacted polyols, polyisocyanates, chain extenders, and additives such as antioxidants and ultraviolet absorbers.

Molded articles obtained from the thermoplastic urethane resin of the present invention are excellent in flexibility and low outgassing properties. For this reason, belts such as flat belts and V-belts, tubes, hoses, suction pads, anti-vibration dampers, anti-vibration joints, shock absorbers, casters, packing, shoe soles, switches, valves, valves, filters, rolls, Rollers (paper ejection rollers, paper feed rollers, etc.), clips, films, sheets, tires, casters, mats, gloves, bandages, robes, skins, bags, instrument panel snow chains, ski boots, spring covers, pumps, body functional materials It is particularly useful as a member of (an artificial heart, etc.).

Among them, from the viewpoint that the thermoplastic urethane resin of the present invention is excellent in flexibility and low outgassing property and that the molded article is excellent in kink resistance, a tube is preferable as the molded article using the thermoplastic urethane resin of the present invention. More preferably, it is a tube in a clean room, particularly preferably a tube in a clean room of a semiconductor manufacturing factory. In particular, it is preferable to use a cooling water piping tube, a cooling antifreeze liquid piping tube, a clean dry air piping, and a nitrogen gas piping in a clean room of a semiconductor manufacturing factory. In addition, the tube using the thermoplastic urethane resin of the present invention may be referred to as the "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. Other components include antioxidants, ultraviolet absorbers, plasticizers, stabilizers, release agents, surfactants, antistatic agents, conductive materials, coloring agents (pigments, dyes), flame retardants, foaming agents, Lubricants, lubricants, fillers, cross-linking agents, solvents, developing liquids, extenders, waxes, oils, greases, processing aids, processing agents, reinforcing materials, fillers, anti-blocking agents, anti-aging agents and the like. Only one kind of the other components may be used, or two or more kinds thereof may be used.

Since the thermoplastic urethane resin of the present invention is excellent in flexibility, the tube of the present invention uses a minimum amount of other components for imparting flexibility, such as plasticizers and flame retardants that can function as plasticizers. can be limited. In addition, since plasticizers and flame retardants can generate outgassing, the tube of the present invention is excellent in flexibility and extremely excellent in low outgassing properties by minimizing the amount used.

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 with respect to 100% by mass of the tube of the present invention. Above, more preferably 95% by mass or more, particularly preferably 99% by mass or more. When the content is 50% by mass or more, the flexibility and the low outgassing properties 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 less than 20% by mass relative to 100% by mass of the tube of the present invention. It is less than 10% by mass, more preferably less than 5% by mass, and particularly preferably less than 1% by mass. When the content is less than 50% by mass, flexibility and low outgassing properties are excellent.

The tube of the present invention preferably has a tensile elastic modulus (tensile rate of 200 mm/min) of 0.5 to 3.3 MPa, more preferably 0.6 to 3, when made into a resin sheet having a thickness of 1.7 mm. .0 MPa. When the tensile elastic modulus is 0.5 MPa or more, the outgassing property is excellent. When the tensile elastic modulus is 3.3 MPa or less, the flexibility and the kink resistance are more excellent. The tensile elastic modulus of the tube can be measured in the same manner as the tensile elastic modulus of the thermoplastic urethane resin described above, except that a resin sheet is taken from the tube as a test piece.

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

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

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

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited only to these examples.

Example 1
Polytetramethylene glycol (PTMG) (trade name “PTMG2000”, manufactured by Mitsubishi Chemical Corporation) and 1,4-butanediol (1,4-BD) were added to a reaction vessel equipped with a stirrer and a thermometer. were uniformly mixed at the molar ratio shown in . After heating the resulting mixture to 100° C., 4,4′-diphenylmethane diisocyanate (MDI) was added in the molar ratio shown in Table 1 (the number of moles relative to the sum of the number of moles of PTMG and the number of moles of 1,4-butanediol. ratio), and the urethanization reaction was carried out. After the MDI was added and stirred for 5 minutes, it was poured onto a vat and solidified. The resulting solid was aged in an electric furnace at 100° C. for 48 hours, cooled, and pulverized to obtain flaky thermoplastic urethane resin.

Examples 2-4, Comparative Examples 1-3
A thermoplastic urethane resin was obtained in the same manner as in Example 1 except that the type of long-chain polyol and the molar ratio of polyisocyanate were changed as shown in Table 1. In addition, 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 thermoplastic urethane resins obtained in Examples and Comparative Examples were evaluated as follows. 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 relative mol.

(1) Tensile Modulus The thermoplastic urethane resins obtained in Examples and Comparative Examples were hot-pressed at 230° C. to obtain resin sheets with a thickness of 1.7 mm. Next, the obtained resin sheet was punched into a dumbbell-shaped No. 8 shape according to JIS K6251 having a width of 5 mm in the parallel portion to prepare a dumbbell-shaped test piece. Using the prepared dumbbell-shaped test piece, a tensile test was performed using a product name "Autograph AGS-5kNX" (manufactured by Shimadzu Corporation) under the conditions of 23 ° C., a marked line distance of 10 mm, and a tensile speed of 200 mm / min. Tensile modulus was measured.

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

(3) Diffusion Coefficient Thermoplastic urethane resins obtained in Examples and Comparative Examples were hot-pressed at 230° C. to obtain resin sheets with a thickness h of 0.4 mm. Next, using the obtained resin sheet, a gas permeation curve was created by a differential pressure method with reference to JIS K7126-1 (2006). Specifically, the obtained resin sheet is set in a gas permeability tester with a pressure sensor, the high-pressure side cell is pressurized to 100 kPa using propane gas, and over time, from the high-pressure side cell to the low pressure side through the resin sheet. 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. The lag time θ [s] was derived from the slope of the steady state portion of the obtained gas permeation curve, and the diffusion coefficient D was calculated from the equation: diffusion coefficient D [m ² /s]=h ² /6.

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

(5) Glass transition temperature In the evaluation of the storage modulus measurement, the temperature at the peak top of the loss tangent tanD was taken 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 excellent in both low outgassing properties. In addition, since the thermoplastic urethane resin has excellent low outgassing properties, when manufacturing molded products using the thermoplastic urethane resin, there is no need to apply superheated steam to reduce the amount of outgassing. 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 is 800 μg/m ² or more. or insufficient flexibility.

Claims (7)

A tensile modulus (tensile 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 made into a resin sheet having a thickness of 1.7 mm,
Containing a structural unit derived from a polyisocyanate, a structural unit derived from a long-chain polyol, and a structural unit derived from a chain extender,
The ratio of the number of moles of isocyanate groups in the polyisocyanate to the number of moles of isocyanate-reactive groups possessed by the long-chain polyol and the chain extender [isocyanate group/isocyanate-reactive group] is 0.9 to 1.3. can be,
A thermoplastic urethane resin is used in which the ratio of the number of moles of 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 0.05 to 10 . tube. The tube according to claim 1, wherein the difference between the temperature [°C] at which the storage elastic modulus E' of the thermoplastic urethane resin becomes 1 MPa and the glass transition temperature [°C] is 180°C or more. 3. The tube according to claim 1, wherein the thermoplastic urethane resin has a glass transition temperature of -10° C. or lower. The tube according to any one of claims 1 to 3, wherein the content of structural units derived from components other than the long-chain polyol, the polyisocyanate, and the chain extender is 1% by mass or less. A tube according to any preceding claim, wherein the long chain polyol is a polyalkylene glycol and the polyisocyanate is an aromatic isocyanate. The tube according to any one of claims 1 to 5, wherein the long-chain polyol has a number average molecular weight of 900-3000. 7. The tube according to any one of 1 to 6, wherein the content of components other than the thermoplastic urethane resin is 20% by mass or less.