JP2008106188A - Method for producing electron beam-crosslinkable thermoplastic polyurethane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam-crosslinkable thermoplastic polyurethane excellent in insulating property and resistance to water, useful as a wire-coating material, in order to solve problems of conventional thermoplastic polyurethane wherein they are not suitable for use as the wire-coating material because they are inferior in insulating property and resistance to water. <P>SOLUTION: The problems on insulating property and the resistance to water, resistance to alkali, etc., of a conventional electron beam-crosslinkable thermoplastic polyurethane can be solved by using a polybutadiene polyol containing at least 50% of 1, 2-vinyl units. The mechanical property of the electron beam-crosslinkable thermoplastic polyurethane is enhanced by irradiating the resultant thermoplastic polyurethane with an electron beam, and the wire-coating material and a high performance film, etc., with the prescribed performance can be provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing an electron beam cross-linked thermoplastic polyurethane that is excellent in insulation, water resistance, heat resistance, solvent resistance, and alkali resistance and is useful for a coating material for electric wires, a high performance film, and the like.

Wire covering materials and films are used in a wide range of fields, and are used in various places, so a wide range of physical properties is required. Polyester polyol-based thermoplastic polyurethane, which is currently the mainstream, has a high balance in certain fields, but has a poor balance in that it cannot satisfy the required performance in other fields.
The thermoplastic polyurethane composed of 1,2-vinyl bond-containing polybutadiene polyol used in the present invention is a resin having a wide range of high performance, plasticity and rubberiness, and can be easily used by a general-purpose processing machine. Since it can be molded, it is used for various industrial products.

However, a thermoplastic polyurethane using a polybutadiene containing a 1,2-vinyl body has been generally known. For example, a method has been proposed in which 1,2-polybutadiene and an existing thermoplastic resin are kneaded with a roll, press-molded, and then irradiated with an electron beam (Patent Document 1). However, the method disclosed in Patent Document 1 has a problem that it takes time and effort to mold because 1,2-polybutadiene is kneaded into a once molded thermoplastic resin and then press molded. It was. Moreover, since the content of 1,2-polybutadiene is 1 to 30 parts by weight, there are problems such as inferior insulation and water resistance.
Furthermore, in the method of producing a conductive roller by introducing polybutadiene into the polyurethane molecule, a technique for obtaining a highly durable roll by irradiating the surface of the roller with an electron beam and crosslinking it has also been proposed ( Patent Document 2). However, in the method disclosed in Patent Document 2, since polybutadiene having a low 1,2-vinyl content in the polybutadiene polyol is used, problems such as low solvent resistance and insulation occur. In addition, since the nominal average functional group number is 2 or more, the molded composition cannot have thermoplasticity, and deviates from the object of the present invention.
JP 2002-348479 A Japanese Patent Laid-Open No. 2001-82451

As described above, the conventional thermoplastic polyurethane is inferior in performance such as insulation and water resistance, and therefore is not suitable for use as a wire coating material. Accordingly, an object of the present invention is to obtain an electron beam cross-linked thermoplastic polyurethane which is excellent in insulation and water resistance and is particularly useful as a wire covering material.

In order to achieve the above object, the present inventors conducted sincere research on electron beam cross-linked thermoplastic polyurethane, and as a result, by using a polybutadiene polyol containing a 1,2-vinyl body having an unsaturated bond, the insulating property is improved. Thus, the present inventors have found that the water resistance, alkali resistance and the like can be solved, and have completed the present invention. Furthermore, by irradiating the obtained thermoplastic polyurethane with an electron beam, the mechanical properties can be improved, and it becomes possible to obtain a coating material for electric wires, a high-performance film, and the like having the above characteristics.

That is, the present invention is the following I to VII.
I. A polybutadiene polyol (A) in which the microstructure of the butadiene unit in the polybutadiene polyol contains 50% or more of a 1,2-vinyl body, a glycol having 4 to 15 carbon atoms having a side chain alkyl group as a chain extender (B), and A method for producing a thermoplastic polyurethane capable of obtaining high physical properties by crosslinking an electron beam crosslinked thermoplastic polyurethane obtained from an organic polyisocyanate (C) by irradiating an electron beam of 50 to 3,000 keV.
II. (A) is a polybutadiene polyol having a number average molecular weight of 500 to 5,000, the fine structure of the butadiene unit in the polybutadiene polyol is 50 mol% or more of the 1,2-vinyl body, and the nominal average functional group number is 1. The manufacturing method according to I above, which is 8 or more and less than 2.0.
III. The production method of the above I or II, wherein (B) is 2-ethyl-1,3-hexanediol.
IV. The production method of the above I or II, wherein (B) is 2-butyl-2-ethyl-propanediol.
V. The manufacturing method as described in any one of said I-IV whose organic diisocyanate (C) is diphenylmethane diisocyanate.
VI. A coating material for electric wires, which is a resin obtained by the production method according to any one of the above items I to V and is excellent in mechanical strength, water resistance, and insulation.
VII. A high-performance film, which is a resin obtained by the production method according to any one of the above items I to V and is excellent in mechanical strength, water resistance, and insulation.

For the first time, the present invention makes it possible to produce a thermoplastic polyurethane that is excellent in insulation, water resistance, solvent resistance, heat resistance, etc. and that also maintains mechanical strength. In particular, the thermoplastic polyurethane of the present invention is excellent in insulation, water resistance, solvent resistance, heat resistance, and alkali resistance, and thus is useful as a coating material for electric wires and a high performance film.

  The 1,2-vinyl body-containing polybutadiene polyol (A) used in the present invention may have a 1,2-vinyl body content of 50% or more, preferably a 1,2-vinyl body content of 50% or more. Any polybutadiene polyol may be used as long as it has a number average molecular weight of 500 to 5,000 and a nominal average functional group number of 1.80 or more and less than 2.0. Among these, those having a number average molecular weight of 800 to 3,000, a 1,2-bond content of 55% or more, and an average nominal average functional group number of 1.85 or more and less than 2.00 are preferable. Particularly preferable are a number average molecular weight of 1,000 to 2,500, a 1,2-bond content of 60% or more, and a nominal average functional group number of 1.9 or more and less than 2.0.

  The thermoplastic polyurethane obtained by the present invention has a number average molecular weight of 30,000 to 100,000, preferably 40,000 to 80,000. When the molecular weight is larger than 100,000, fish eyes are generated and the flowability during molding is deteriorated. On the other hand, if the molecular weight is less than 30,000, the processability is deteriorated and the physical properties are also lowered. Therefore, in order to obtain the molecular weight within the above range, the 1,2-polybutadiene polyol used in the present invention is preferably within the above range, and when the nominal average functional group number is less than 1.8, it does not become a high molecular weight body. The desired resin cannot be obtained and the desired physical properties are not reached. In the case of 2.0 or more, the thermoplasticity cannot be obtained, and in order to obtain the thermoplasticity, the molecular weight becomes low, and the same adverse effect as that of less than 1.8 occurs.

  Examples of the glycol (B) having 4 to 10 carbon atoms having a side chain alkyl group in the present invention include dipropylene glycol, 2-ethyl-1,3-hexanediol, and 2-ethyl-2-butylpropanediol. 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-octanediol, 2-butyl-octanediol, 2-methyl-nonanediol, 2-butylnonanediol, 2-methyldecanediol, etc. Can be mentioned. Two or more of these glycols may be used in combination. Among these, 2-ethyl-1,3-hexanediol and 2-ethyl-2-butylpropanediol are preferable, and 2-ethyl-1,3-hexanediol is particularly preferable.

The chain extender used in the present invention is preferably a glycol having 4 to 25 carbon atoms having a side chain alkyl group as described above. A glycol having no side chain alkyl group has poor compatibility with 1,2-polybutadiene polyol, and a resin having high mechanical properties cannot be obtained. Defects such as liquid separation occur. On the other hand, when the number of carbon atoms is 20 or more, the moldability is deteriorated and the mechanical strength cannot be maintained, which causes problems such as deterioration of physical properties.
For glycols, diamines and amino alcohols having a number average molecular weight of less than 500, such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, ethylenediamine, hexamethylenediamine and monoethanolamine, which do not have a side chain alkyl group Although it can be used by a method using a solvent, removal of the solvent is necessary, which is not preferable as a synthesis method.

  As the organic polyisocyanate (A) in the present invention, those conventionally used can be used. Such organic polyisocyanates include, for example, aromatic polyisocyanates having 6 to 20 carbon atoms [1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate ( TDI), 2,4′- and / or 4,4′-diphenylmethane diisocyanate (MDI), etc.]; aliphatic polyisocyanates having 2 to 18 carbon atoms [ethylene diisocyanate, hexamethylene diisocyanate, etc.]; 4-15 carbon atoms Alicyclic polyisocyanates [xylene diisocyanate (XDI), α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI), etc.]; araliphatic polyisocyanates having 8 to 15 carbon atoms; and these two The above mixture is mentioned. Among these, aromatic polyisocyanates having 6 to 20 carbon atoms are preferable, and 2,4- and / or 2,6-tolylene diisocyanate (TDI), 2, 4′- and / or 4, 4 ′ are more preferable. -Diphenylmethane diisocyanate.

In producing an electron beam cross-linked thermoplastic polyurethane, an equivalent ratio (x / A) of 1,2-vinyl-containing polybutadiene polyol (A) and glycol (B) having 4 to 15 carbon atoms having a side chain alkyl group Is preferably 0.5 to 5, and more preferably 1 to 5. If x / A is less than 0.5, the mechanical strength is insufficient, and if x / A is more than 5, the moldability and workability are liable to deteriorate.
The equivalent ratio (NCO / OH) of the organic polyisocyanate (C) and the hydroxyl group-containing component ((A) + (B)) is preferably 0.8 to 1.3. When the equivalence ratio is less than 0.8, the mechanical strength becomes insufficient, and when it exceeds 1.3, there is a problem that appearance defects such as fish eyes are likely to occur in the resulting composition.

  There is no limitation in particular as a manufacturing method of an electron beam bridge type thermoplastic polyurethane pellet, and it can manufacture by a well-known method. For example, a method of measuring, mixing and stirring two liquids of a mixture of a 1,2-vinyl-containing polybutadiene polyol (A) and a chain extender (B) and an organic diisocyanate (A), and quantifying the above raw materials A method of measuring with a pump and mixing vigorously and then pouring onto a vat and further reacting at a temperature of 50 to 200 ° C., preferably 60 to 160 ° C., 100 to 250 ° C., preferably 120 to 250 ° C. The above raw material is supplied to an extruder, and the raw material is kneaded and transported in the extruder. The method of extruding the produced TPU from a die, charging all the raw materials into a kneader, 100 to 250 ° C., preferably 120 to 230 ° C. It can be produced by a method of reacting at ° C. After production, it is cut using a strand cut or the like to obtain TPU pellets. Further, in order to complete the reaction, it is possible to return the resin to the above-described reactor again or to perform aging.

During the production of TPU pellets, the use of a so-called urethanization catalyst is not particularly limited,
It is preferable to use it because it has advantages such as shortening of reaction time and completion of reaction. As the catalyst, any of the commonly used urethanization catalysts can be used. For example, bismuth, lead, tin, iron, antimony, uranium, cadmium, cobalt, thorium, aluminum, mercury, zinc, nickel, cerium, molybdenum 1 type, or 2 or more types of mixtures among organic compounds, inorganic compounds, etc., such as vanadium, copper, manganese, zirconium, and calcium. Preferred catalysts are organometallic compounds, particularly preferred are dialkyltin compounds. Typical organotin catalysts include, for example, stannous octoate, stannous oleate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin mercaptopropionate, dibutyltin dodecyl mercaptide, dioctyltin. Examples include dilaurate. The amount of catalyst to be used is determined by the properties of other raw materials, reaction conditions, desired reaction time, etc., and is not particularly limited. In general, the catalyst is 3 mass of the total mass of the reaction mixture. % Or less, preferably 2% by mass or less.

The present invention can further use an additive. As additives, lubricants, hydrolysis inhibitors, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, fillers, reinforcing fibers and the like can be used as necessary.

The molded article of the electron beam cross-linked thermoplastic polyurethane of the present invention can be produced by the following method. As a specific molding method of the above-mentioned electron beam cross-linked thermoplastic polyurethane pellets, the above-mentioned TPU pellets can be formed into a film of 0.03 to 5 mm by press molding, injection molding, blow molding, T-die film molding, inflation molding, etc. Or a sheet-like molding is obtained. In any case, the heating temperature of the sheet is preferably 60 to 250 ° C.
The molded article of the electron beam cross-linked thermoplastic polyurethane obtained by the above method is then cured by irradiation with an electron beam. When irradiated with an electron beam, a three-dimensional crosslinked structure is formed by radical polymerization of the vinyl group of 1,2-polybutadiene, and the molded product can be further cured. The electron beam is permeable to the synthetic resin, and the degree of transmission depends on the thickness of the molded product and the kinetic energy of the electron beam. When the energy of the electron beam is adjusted so that it can be uniformly transmitted in the thickness direction according to the irradiation thickness, a molded product having a uniform degree of crosslinking in the thickness direction can be obtained.

  The energy of the electron beam is 50 to 3,000 keV, preferably 300 to 2,000 keV with respect to the above molded product, but if it is smaller than 50 keV, the proportion of electrons captured and absorbed in the surface layer portion is relatively The number of electron beams that pass through the sheet is reduced, the internal cross-linking is delayed as compared with the surface layer portion, and the cross-linking degree is different, which is not preferable. On the other hand, if it is greater than 3,000 keV, the degree of cross-linking becomes too large and it becomes hard, so that the tensile strength is large, but the elasticity, elasticity and elongation are small, which is not preferable.

  In this case, the irradiation amount of the electron beam is preferably 1 to 100 Mrad (corresponding to 10 to 1,000 kGy in the SI unit system), more preferably 1 to 50 Mrad. If it is less than 1 Mrad, the degree of crosslinking of 1,2-polybutadiene is small and the tensile strength of the sheet is also small, which is not preferable. If it exceeds 100 Mrad, the degree of cross-linking becomes too large and it becomes hard, so that the tensile strength is large, but the elasticity and elongation are small, which is not preferable.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, “%” means “% by mass”.

(Production Example 1)
A temperature-adjustable mixing tank is charged with 19.52 kg of polybutadiene polyol, Krasol LBH2000, 3.04 kg of 2-ethyl-1,3-hexanediol (EHD), and 1.5 g of dioctyltin dilaurate (DOTDL) and mixed uniformly. The temperature was adjusted to 70 ° C. This liquid mixture is sent to the head tank, where the temperature is adjusted to 85 ° C. The temperature near the hopper of the twin-screw extruder was adjusted to 190 ° C., intermediate temperature: 200 ° C., tip temperature: 190 ° C., and the mixed solution was 313.5 g / min and MDI was 106.3 g from the hopper port. The raw material was continuously supplied under the conditions of / min, and the molten resin was discharged from the strand die, cooled and solidified, and then the strand was cut. Next, the mixture was aged at 25 ° C. for 3 days to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 25 kg / hour. What processed the obtained pellet into the film of thickness 100 micrometers is set to "PU-1."

(Production Example 2)
The PU-1 was cured by irradiating an electron beam with an electron beam irradiation device under the conditions of an acceleration voltage of 165 kV, an irradiation dose of 10 Mrad, and an oxygen concentration of 800 ppm or less. Let the obtained film be PU-1 '.

(Production Example 3)
A temperature-adjustable mixing tank was charged with 16.01 kg of polybutadieneol, Krasol LBH 2000, 4.49 kg of octanediol, and 1.5 g of dioctyltin dilaurate, and uniformly mixed to adjust the temperature to 70 ° C. This liquid mixture is sent to the head tank, where the temperature is adjusted to 85 ° C. The temperature near the hopper of the twin screw extruder: 190 ° C., intermediate temperature: 200 ° C., tip temperature: 190 ° C. The temperature of the mixture is 284.7 g / min and MDI is 136 g / min from the hopper port. The raw material was continuously supplied under the conditions described above, the molten resin was discharged from the strand die, and the strand was cut after cooling and solidification. Next, the mixture was aged at 25 ° C. for 3 days to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 25 kg / hour. The obtained pellets processed into a film having a thickness of 100 μm are referred to as “PU-2”.

(Production Example 4)
The PU-2 was cured by irradiation with an electron beam under the conditions of an acceleration voltage of 165 kV, an irradiation dose of 10 Mrad, and an oxygen concentration of 800 ppm or less. Let the obtained film be PU-2 '.

(Production Example 5)
A temperature-adjustable mixing tank is charged with polybutadieneol, Krasol LBH 2000, 17.60 kg, 2-butyl-2-ethyl-propanediol (BEPD), 4.06 kg, and dioctyltin dilaurate, 1.5 g. The temperature was adjusted to 70 ° C. This liquid mixture is sent to the head tank, where the temperature is adjusted to 85 ° C. The temperature near the hopper of the twin screw extruder: 190 ° C., intermediate temperature: 200 ° C., tip temperature: 190 ° C. The temperature of the mixture is 300.8 g / min and MDI is 118.1 g from the hopper port. The raw material was continuously supplied under the conditions of / min, and the molten resin was discharged from the strand die, cooled and solidified, and then the strand was cut. Next, the mixture was aged at 25 ° C. for 3 days to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 25 kg / hour.
The obtained pellets processed into a film having a thickness of 100 μm are referred to as “PU-3”.

(Production Example 6)
PU-3 Electron Beam Crosslinking Method PU-3 was cured by irradiating an electron beam with an electron beam irradiation device under the conditions of an acceleration voltage of 165 kV, an irradiation dose of 10 Mrad, and an oxygen concentration of 800 ppm or less. Let the obtained film be PU-3 '.

(Production Example 7)
A temperature-adjustable mixing tank is charged with 19.54 kg of polybutadieneol C, 2.96 kg of 2-ethyl-1,3-hexanediol (EHD), and 1.5 g of dioctyltin dilaurate, and uniformly mixed to 70 ° C. The temperature was adjusted. This liquid mixture is sent to the head tank, where the temperature is adjusted to 85 ° C. The temperature near the hopper of the twin screw extruder: 190 ° C., intermediate temperature: 200 ° C., tip temperature: 190 ° C. The temperature of the mixed solution is 312.4 g / min and MDI is 107.3 g from the hopper port. The raw material was continuously supplied under the conditions of / min, and the molten resin was discharged from the strand die, cooled and solidified, and then the strand was cut. Next, the mixture was aged at 25 ° C. for 3 days to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 25 kg / hour.
A product obtained by processing the obtained pellets into a film having a thickness of 100 μm is referred to as “PU-4”.

(Production Example 8)
PU-4 Electron Beam Crosslinking Method The PU-4 was cured by irradiating an electron beam with an electron beam irradiation device under the conditions of an acceleration voltage of 165 kV, an irradiation dose of 10 Mrad, and an oxygen concentration of 800 ppm or less. Let the obtained film be PU-4 '.

(Production Example 9)
Method of synthesizing PU-5 A temperature-adjustable mixing tank was charged with 22.38 kg of polyol A, 2.52 kg of 1,4-BD, and 1.5 g of octyltin dilaurate (DOTDL), and mixed uniformly to 60 ° C. The temperature was adjusted. This liquid mixture is sent to the head tank, where the temperature is adjusted to 85 ° C. The temperature near the hopper of the twin-screw extruder is 180 ° C., the intermediate temperature is 190 ° C., the tip temperature is 200 ° C., and the mixed solution is 358.8 g / min and MDI is 141.2 g from the hopper port. The raw material was continuously supplied under the conditions of / min, and the molten resin was discharged from the strand die, cooled and solidified, and then the strand was cut. Subsequently, it was dehydrated and dried to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 30 kg / hour.
A product obtained by processing the obtained pellets into a film having a thickness of 100 μm is referred to as “PU-5”.

(Production Example 10)
Method for synthesizing PU-6 A temperature-adjustable mixing tank was charged with 21.42 kg of polyol B, 3.48 kg of 1,4-BD, and 1.5 g of octyltin dilaurate (DOTDL), and uniformly mixed at 80 ° C. The temperature was adjusted. This liquid mixture is sent to the head tank, where the temperature is adjusted to 90 ° C. The temperature near the hopper of the twin screw extruder: 190 ° C., intermediate temperature: 200 ° C., tip temperature: 200 ° C. The temperature of the mixture is 260 g / min and the MDI is 156.7 g / min from the hopper port. The raw material was continuously supplied under the conditions described above, the molten resin was discharged from the strand die, and the strand was cut after cooling and solidification. Subsequently, it was dehydrated and dried to obtain thermoplastic polyurethane resin pellets. The resin feed amount is 25 kg / hour.
What processed the obtained pellet into the film of thickness 100 micrometers is set to "PU-6."

(Production Example 11)
1950 g of Polybd R-45HT and 312.5 g of 2-ethyl-1,3-hexanediol were charged into a temperature-adjustable mixing tank, and the mixture was uniformly mixed and the temperature was adjusted to 80 ° C. To this vessel, 759.5 g of MDI was added, stirred and mixed at high speed, cast into a vat, and reacted at 80 ° C. for 12 hours. The reaction product was pulverized and pelletized, but could not be pelletized because it did not melt. The nominal average functional group number of the polybutadiene polyol (Polybd R-45HT) used in this production example is 2.3, which is outside the scope of the present invention.

Examples 1-4, Comparative Examples 1-4
For the thermoplastic polyurethane resins PU-1 to PU4 and PU-1 ′ to PU-4 ′ obtained in Production Examples 1 to 8, mechanical properties, gel fraction, and softening point were measured. The results are listed in Table 1.

From the results shown in Table 1, the softening point and the gel fraction are dramatically improved. Moreover, it can be confirmed that the mechanical properties are also improved as compared with those before electron beam crosslinking.

Examples 5-7, Comparative Examples 5-6
For the thermoplastic polyurethane resins PU-1 ′ to PU-4 ′ obtained in Production Examples 2, 4, 6, and 8, and PU-5 and PU-6 obtained in Production Examples 9 and 10, hardness, machine Physical properties, volume resistivity, water absorption, and softening point were measured. The results are listed in Table 2. About Examples 5-7, the measurement result of Examples 1-3 was also described collectively.

  From the results shown in Table 2, the resin of the present invention subjected to electron beam cross-linking has better volume resistivity and softening point than other general resins. Also, the mechanical properties are comparable to other resins.

The raw materials used in Production Examples 1 to 11 are as follows.
(Polybutadiene polyol)
Krasol LBH2000: 1,4-cis / 1,4-trans / 1,2-vinyl = 10-15% by mass / 20-25% by mass / 60-70% by mass, functional group number = 1.9, number average molecular weight = 2000 Polybutadiene polyol, Polybd R-45HT manufactured by SARTOMER: 1,4-cis / 1,4-trans / 1,2-vinyl = 20% by mass / 60% by mass / 20% by mass, functional group number = 2.3, hydroxyl group Value = 46.6 mg KOH / g, polybutadiene polyol having a number average molecular weight = 2800, polybutadiene polyol C manufactured by Idemitsu Co., Ltd .: 1,4-cis / 1,4-trans / 1,2-vinyl = 0 mass% / 90 mass% / 10% by mass, number of functional groups = 1.8, hydroxyl value = 35 to 55 mgKOH / g, number average molecular weight = 2000 Real (polyol)
Polyol A: Polyester polyol polyol B having a number average molecular weight of 2,000 obtained from 1,4-butanediol and adipic acid B: Polytetramethylene glycol, PTG-1000SN, manufactured by Hodogaya Chemical Co., Ltd. (chain extender)
2-ethyl-1,3-hexanediol (EHD): octanediol, 2-butyl-2-ethyl-propanediol (BEPD) manufactured by Kyowa Hakko Chemical Co., Ltd .: DMH, 1,4-BD manufactured by Chisso Corporation 1,4-butanediol, manufactured by Mitsubishi Chemical Corporation (isocyanate)
MDI: 4,4′-diphenylmethane diisocyanate (Millionate MT, manufactured by Nippon Polyurethane Industry Co., Ltd.)
(resin)
TPU: Thermoplastic polyurethane resin

  The evaluation experiment results shown in Tables 1 and 2 were conducted according to the following measurement methods.

(Softening point)
The film was punched into a JIS K-6251, No. 2 type test piece, applied with a load of 500 gf / cm @ 2, mounted in a drier, heated at a heating rate of 5 DEG C./min, and the elongation of the film tripled. The temperature was taken as the softening point.

(Tensile test, modulus, elongation, tear test)
Measurement was performed according to JIS K6251.

(Gel fraction)
Extraction was performed in methyl ethyl ketone (MEK) at 130 ° C. for 5 hours, and the gel fraction was calculated by the following formula.
Gel fraction (%) = (mass after extraction / mass before extraction) × 100

(Water absorption test)
Measurement was performed according to JIS K7209.

(Volume resistivity)
Measurement was performed according to JIS K6911.

(Hardness test)
Measurement was performed according to JIS K6253.

The molded product thus produced is excellent in water resistance, flexibility and insulation, and is useful not only as a coating material for electric wires but also for various film applications.

Claims (7)

A polybutadiene polyol (A) in which the microstructure of the butadiene unit in the polybutadiene polyol contains 50% or more of a 1,2-vinyl body, a glycol having 4 to 15 carbon atoms having a side chain alkyl group as a chain extender (B), and A method for producing a thermoplastic polyurethane capable of obtaining high physical properties by crosslinking an electron beam crosslinked thermoplastic polyurethane resin obtained from an organic polyisocyanate (C) by irradiation with an electron beam of 50 to 3,000 keV. (A) is a polybutadiene polyol having a number average molecular weight of 500 to 5,000, the fine structure of the butadiene unit in the polybutadiene polyol is 50 mol% or more of the 1,2-vinyl body, and the nominal average functional group number is 1. The production method according to claim 1, which is 8 or more and less than 2.0. The method according to claim 1 or 2, wherein (B) is 2-ethyl-1,3-hexanediol. The process according to claim 1 or 2, wherein (B) is 2-butyl-2-ethyl-propanediol. The method according to any one of claims 1 to 4, wherein the organic diisocyanate (C) is diphenylmethane diisocyanate. It is resin obtained from the manufacturing method in any one of Claims 1-5, Comprising: It is excellent in mechanical strength, water resistance, and insulation, The coating material for electric wires characterized by the above-mentioned. A high-performance film obtained by the manufacturing method according to claim 1, wherein the high-performance film is excellent in mechanical strength, water resistance, and insulation.