JPH0349284B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention polymerizes a polyester diol containing 3-methyl-1,5-pentanediol as a glycol component, an organic diisocyanate, and a chain extender. , relates to a method for continuously producing homogeneous thermoplastic polyester polyurethane with improved heat resistance and thermal decomposition resistance. Conventional technology Thermoplastic polyurethane has long been attracting attention as an alternative material to rubber and plastics because it has many features such as high elasticity, excellent abrasion resistance, and excellent oil resistance, and normal plastic molding processing methods can be applied to it. It has come to be used in large quantities as a molding material in a wide range of applications. As thermoplastic polyurethane, polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, etc. are known, but among these polyurethanes, polyester polyurethane is preferably used from the viewpoint of its hydrolysis resistance and low temperature properties. It is being Examples of polyester polyurethanes include polyester diols containing 1,4-butanediol (hereinafter sometimes abbreviated as BD polyester diol), polyester diols such as polycaprolactone diol (CL polyester diol), organic diisocyanates, and Polyurethanes containing chain extenders are known. In addition, polyester diol (hereinafter sometimes abbreviated as MPD polyester diol) containing 3-methyl-1,5-pentanediol as a glycol component is a polyurethane that has better hydrolysis resistance and low-temperature properties than the polyurethane mentioned above. Polyurethane obtained using
(Refer to Publication No. 48-101496). The manufacturing method of these polyurethanes is carried out by mixing raw materials and polymerizing them.
It is known that in order to produce homogeneous polyurethane, it is preferable to mix raw materials in a molten state and polymerize. Although some general literature states that the polymerization temperature at this time is preferably in the range of 150 to 250°C, it is usually kept as low as possible within the range of 200°C or less, taking into account the thermal decomposition of the raw materials, especially the organic diisocyanate. A lower temperature is selected. For example, the polymerization temperature described in JP-A-48-101496 mentioned above is at most 160°C. Problems to be Solved by the Invention However, since the thermoplastic polyurethane obtained by the above manufacturing method has a large temperature dependence of melt viscosity, it is difficult to mold it in the same manner as other general-purpose thermoplastic resins. The drawback was that there was a high rate of defective products. Furthermore, since molding is carried out at high temperatures, if polyurethane with good thermal stability is not used, defects may occur in the physical properties and appearance of the molded product due to thermal deterioration during the molding process and decomposition within the molding machine.
Another drawback was that it was difficult to perform long-term processing. This is because the molding temperature and the thermal decomposition temperature of polyurethane are close to each other. In order to avoid this thermal decomposition, if the softening point of the polyurethane is set low so that it can be molded at a relatively low temperature, the heat deformation resistance temperature of the thermoplastic polyurethane inevitably decreases, which is undesirable. This is the reason why thermoplastic polyurethane is said to have poor moldability. In order to produce a thermoplastic polyester polyurethane with particularly excellent moldability, thermal decomposition resistance, and heat resistance, the present inventors have conducted various studies on the production conditions for the production, and have found that a thermoplastic polyurethane that is fully satisfactory. I couldn't get it. That is, for example, BD polyester diol or
I tried manufacturing polyurethane from CL polyester diol and diisocyanate using a conventional method, but
The melt viscosity of the polyurethane had a large temperature dependence, it did not have sufficient moldability, and it did not have sufficient thermal decomposition resistance. In addition, MPD polyester diol, 4,4'-diphenylmethane diisocyanate and 1,4-
A mixture of butanediol was poured onto a hot plate at 160°C, aged, and then crushed to prepare polyurethane (flake), but the melt viscosity of this polyurethane has a large temperature dependence, and the moldability was improved as a result. It wasn't something. Furthermore, even when other examples were repeated and when the example described in JP-A-47-34494 was repeated, a polyurethane that was fully satisfactory in terms of moldability could not be obtained. In view of the problems of the prior art described above, the present inventors have created a homogeneous thermoplastic polyester polyurethane that has improved not only hydrolysis resistance and low-temperature properties, but also moldability, heat resistance, and thermal decomposition resistance. With the aim of providing a method, the present invention has been completed after extensive research. Means for Solving the Problems According to the present invention, the above object is achieved by polymerizing a polymeric diol, an organic diisocyanate, and a chain extender to continuously produce a thermoplastic polyurethane. Methyl-1,5-
Using a polyester diol (a) with an average molecular weight of 1,000 to 5,000 obtained by polycondensing pentanediol and dicarboxylic acid, () the diisocyanate (b) to the polyester diol (a) according to the general formula 0.001M+0.5< R＜0.0023M＋4.6
[] [Here, M represents the average molecular weight of the polyester diol (a), and R represents the molar ratio of the organic diisocyanate (b) to the polyester diol (a)], and ( ) The temperature during polymerization was Tp℃ [After mixing the raw materials with the same composition as the raw material composition of the polyurethane to be obtained using the batch charging method, the temperature was 150℃, 160℃, 170℃
and 5 after polymerization for 15 minutes each at a temperature of 180 °C.
Four DSC curves were obtained by subjecting the polyurethane obtained by cooling at a cooling rate of °C/min to differential scanning calorimetry (DSC).
Obtained when heating at a heating rate of 10℃/min.
This is achieved by a method for producing thermoplastic polyurethane, which is characterized in that the temperature is the highest temperature (°C) showing the top of the highest endothermic peak of the DSC curve) or higher. The polymeric diol used in the present invention is 3-
A polyester diol (MPD polyester diol) obtained by polycondensation using methyl-1,5-pentanediol and dicarboxylic acid as essential components, and in the present invention, 3-methyl
The use of 1,5-pentanediol is essential. Although other manufacturing conditions are essential in the present invention, the use of a polyester diol containing the diol as a glycol component improves hydrolysis resistance, low-temperature properties, moldability, heat resistance, and heat decomposition resistance. polyurethane can be obtained. Even if the polymerization is carried out under the production conditions of the present invention except for using, for example, BD polyester diol or CL polyester diol instead of the MPD polyester diol, the urethane bonds will decompose if the resulting polyurethane is left in a high temperature atmosphere. Not only does this occur, but the temperature dependence of the melt viscosity is large, resulting in poor moldability. When producing the above MPD polyester diol, 3-methyl-1,5 is used as the glycol component.
- Although it is desirable to use pentanediol alone, a mixed glycol containing this diol as a main component may also be used. Examples of glycols used in combination include ethylene glycol, butanediol, hexanediol, propylene glycol,
Examples include neopentyl glycol, diethylene glycol, nonanediol, and the like. These glycols may be used not only alone but also in combination of two or more. The amount of 3-methyl-1,5-pentanediol used in the mixed glycol is 30% by weight or more, preferably 45% by weight based on the mixed glycol.
It is preferably at least 60% by weight, more preferably at least 60% by weight. In addition, the dicarboxylic acid for producing the above MPD polyester diol has an oxygen number of 4 to 12.
Aliphatic dicarboxylic acids or aromatic dicarboxylic acids having 8 to 12 carbon atoms are preferred, and specific examples thereof include succinic acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid, and terephthalic acid. Among them, adipic acid or azelaic acid is preferably used. The above MPD-based polyester diol can be produced by a method similar to the known method used in the production of polyethylene terephthalate or polybutylene terephthalate, that is, transesterification or direct esterification followed by melt polycondensation reaction (see above). (Refer to Japanese Patent Application Laid-open No. 101496/1983). In the present invention, the average molecular weight of the MPD polyester diol is 1000 to 5000, preferably 1500 to 5000.
Must be within the range of 4000. If the average molecular weight is too small, the temperature dependence of the melt viscosity of the obtained polyurethane will be small, but the heat resistance,
Low-temperature properties deteriorate significantly. On the other hand, if the average molecular weight is too large, the obtained polyurethane will have good low-temperature properties, but the temperature dependence of the melt viscosity will be large and the moldability will be reduced. Examples of the organic diisocyanate used in the present invention include diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6
- Aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and hexamethylene Examples include aliphatic or alicyclic diisocyanates such as diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. These diisocyanates may be used alone or in combination of two or more. In the present invention, the usage ratio of MPD polyester diol (a) and organic diisocyanate (b) is as follows:
The molecular weight of polyester diol (a) is represented by M,
It is important to use a molar ratio of organic diisocyanate to MPD polyester diol (a) that satisfies the general formula 0.001M+0.5<R<0.0023M+4.6, expressed as R, along with other manufacturing conditions. be. If R is less than 0.001M+0.5, heat resistance will be poor, and if R is 0.0023M+4.6 or more, heat resistance will be good, but low temperature properties and moldability will be poor. The chain extenders used in the present invention include commonly used chain extenders in the polyurethane industry, i.e., compounds with a molecular weight of 400 or more having at least two active hydrogen atoms capable of reacting with isocyanate groups, such as ethylene glycol. , butanediol, propylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol, bis(β-hydroxy Diols such as ethyl) terephthalate and xylene glycol, water,
Examples include hydrazine, ethylene diamine, propylene diamine, xylylene diamine, isophorone diamine, piperazine, phenylene diamine, tolylene diamine, adipic acid dihydrazide, isophthalic acid dihydrazide, and the like. These compounds may be used alone or in combination of two or more. The most preferred chain extender is butanediol,
1,4-bis(β-hydroxyethoxy)benzene. The amount of these chain extenders used is logically determined by R-
Although the amount may be 1, the actual amount is R-1 plus several mol% of R-1. In addition, R is as defined above here. In the production method of the present invention, in addition to using the above specific MPD polyester diol as the polymer diol and using the polyester diol and organic diisocyanate in a specific ratio, the temperature during polymerization is set to Tp. (℃) (Tp as defined above) or higher, preferably Tp+5
(°C) or higher. By doing so, a homogeneous thermoplastic polyurethane is obtained which has improved not only hydrolysis resistance and low-temperature properties, but also moldability, heat resistance and thermal decomposition resistance.
On the other hand, if the temperature during polymerization is low, the melt viscosity of the resulting polyurethane will have a large temperature dependence, and the moldability will not be improved at all. The temperature dependence of the produced melt viscosity changes extremely depending on the polymerization temperature, but this effect is small when, for example, BD polyester diol or CL polyester diol is used as the polymer diol, and the present invention using MPD polyester diol It is unique to In addition, when determining Tp in the above, the polymerization performed during the preparation of polyurethane to determine Tp, that is, the polymerization by a batch charging method of raw materials having the same composition as the raw materials for the polyurethane to be obtained (hereinafter referred to as prepolymerization) 150℃ as the temperature when
Select one temperature (α) from among 160°C, 170°C and 180°C (i.e., a relatively low temperature at which melt polymerization is possible), and evaluate the resulting polyurethane.
The temperature T〓 ₁ (°C) indicating the peak of the highest endothermic peak of the polyurethane is determined from the DSC curve, and the temperature T〓 ₁ can be regarded as Tp in some cases.
Depending on the average molecular weight of the MPD polyester diol and the ratio of the polyester diol to the organic diisocyanate, that is, the R value, the resulting polyurethane at a certain prepolymerization temperature (α) may vary.
T ₁ may be lower than T〓 ₁ or T〓 ₁ of a polyurethane produced by polymerization at a polymerization temperature (β or γ) 10° C. or 20° C. lower than the polymerization temperature. In addition,
If the prepolymerization temperature is 190° C., the above-mentioned reversal of the polymerization temperature and the T ₁ of the produced polyurethane does not occur. Furthermore, although it is preferable that the increments of the prepolymerization temperature be small, if the increments are 10°C, even if Tp is the highest temperature among the obtained T ₁ , it is practically the same as the true Tp, and there is no problem. There isn't. Therefore, the above method for determining Tp is extremely convenient and rational. The temperature during polymerization is preferably a temperature at which polyurethane decomposes considerably, for example, 260° C. or lower. Preferred specific examples of the production method of the present invention include the following method. That is, the MPD polyester diol, the chain extender, and the organic diisocyanate are continuously fed by a metering pump into an extruder in which at least one part is set at Tp°C or above, and then extruded into a strand or sheet. be. In this method,
The MPD polyester diol and the chain extender may be supplied in the form of a mixture, or the MPD polyester diol and the organic diisocyanate may be used in the form of a prepolymer before or after supply. As the extruder, it is recommended to use a multi-screw extruder, typically a self-cleaning twin-screw extruder, from the viewpoint of uniformity of the polyurethane produced. The thermoplastic polyurethane obtained by the production method of the present invention has excellent hydrolysis resistance and low-temperature properties, and is significantly improved in moldability, heat resistance, and heat decomposition resistance. In particularly favorable cases, the activation energy (Ea) of the apparent melt flow of the produced polyurethane becomes small, and the general formula (250−44N)({η}−1.1)+45<Ea<(250−44N)({η }−1.1)+70 [] (However, in the formula, N represents the percentage of the weight of nitrogen atoms relative to the weight of polyurethane. Also, {η} is 30
The logarithmic viscosity measured in dimethylformamide at a concentration of 0.5 g/100 ml at °C is less than or equal to 1.1)
It is within the range expressed by . The thermoplastic polyurethane obtained by the production method of the present invention has particularly excellent moldability and heat decomposition resistance, so it can be easily molded using commonly used injection molding machines, extrusion molding machines, blow molding machines, etc. Taking advantage of its hydrolysis resistance, low-temperature properties, and heat resistance, it is used in sheets, films, tube hoses, roll gears, packing materials, vibration-proofing materials, belt laminate products, automobile parts, sporting goods, etc. It is also understood that it can be dissolved in a solvent and used as a treatment agent for artificial leather or fibers, as an adhesive, etc., but can also be used for a variety of other applications known in the art or to be developed in the future. be done. Examples Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the Examples and Comparative Examples, the temperature dependence of the melt flow characteristics of polyurethane was measured using a Koka-type flow tester (for example, a Koka-type flow tester manufactured by Shimadzu Corporation).
CFT-500 type) using heating method (hold 185℃ x
5min, heating rate 5℃/min, die diameter x length =
Measure the viscosity at 0.5mmφ×5mml, load 20Kg),
Activation energy Ea (Kcal/
Evaluated in moles). The apparent activation energy Ea (Kcal/mole) of the melt flow can be calculated by plotting the logarithm of the flow rate ratio, which has a correlation with the absolute temperature, against the reciprocal of the absolute temperature, finding its slope K, and calculating it as follows: Calculated by the formula. Ea=-2.303R・K (Here, R is the gas constant (1.987cal/deg・mole)
In addition, the logarithmic viscosity {η} is 0.5 g/dm in DMF solution at 30°C.
Measured at a concentration of 100ml. Regarding low-temperature properties, a 100μ film was prepared by pressing the obtained polyurethane pellets at 250℃ for 2 minutes (10Kg/cm ² ), and a dynamic viscoelasticity automatic measuring device (manufactured by Toyo Baldwin Co., Ltd.) was used. Evaluation was made by measuring the main dispersion peak temperature (T _a ) using the rheovibron model DOV-) (110 Hz). Regarding heat resistance, it was prepared using the same method as above.
Punch out a 100μ film into a tanzak shape and JISK
Tensile strength (T _B ¹²⁰ ,
T _B ²⁰ ) and its strength retention rate [T _B ¹²⁰ /T _B ²⁰
×100 (%)] was also evaluated. Further, the hydrolysis resistance of polyurethane was evaluated by a young angle test. Jingle test is 70
A polyurethane film with a thickness of 50μ was left for 28 days at 95% relative humidity at a temperature of 95% relative humidity, and the tensile strength retention of the film before and after the jungle test was evaluated. Thermal decomposition resistance was measured using a differential scanning calorimeter (Rigaku Denki Co., Ltd.)
The evaluation was made by measuring the thermal weight loss rate when 10 mg of polyurethane was left for 5 hours at 230° C. under a nitrogen atmosphere using TG-BSC (manufactured by TG-BSC). The raw materials used in each table in Examples and Comparative Examples are shown with abbreviations, and the relationship between the abbreviations and compounds is as follows (Table 1).

[Table] Example 1 (Measurement of Tp) 100 c.c. kneader with rotation speed set at 40 rpm (Brabender Plastograph manufactured by Brabender)
PMPA, MDI and BD (chain extender)
A total of 90g of PMPA/MDI/BD was prepared using the one-shot method at a molar ratio of 1/5/4.
Polymerization was carried out at temperatures of 150°C, 160°C, 170°C and 180°C, respectively. After the obtained polyurethane was left at room temperature for one week, it was subjected to a differential scanning calorimeter (Model DSC-2C manufactured by Perkin-Elmer) to obtain a DSC curve. T′p of the polyurethane produced at each polymerization temperature is the second
As shown in the table, the Tp of this polyurethane is 209
℃.

[Table] (Manufacture of polyurethane) Made of PMPA and BD with an average molecular weight of 2000 at 30℃
MDI heated to 50°C and melted to 50°C
and the molar ratio of PMPA/MDI/BD used is 1/5/
4 was continuously charged into a twin-screw extruder rotating in the same direction using a metering pump, and continuous melt polymerization was performed. At this time, the inside of the extruder was divided into three zones: a front section, a middle section, and a rear section, and the temperature of the middle section was set to 230° C., which was higher than Tp. This temperature was defined as the melt polymerization temperature. The polyurethane produced was continuously extruded into water in the form of a strand, and then formed into pellets using a pelletizer. The obtained polyurethane was examined for its apparent activation energy (Ea) of melt flow, heat resistance, low temperature properties, hydrolysis resistance, and thermal decomposition resistance. The results are shown in Table 3. Examples 2 to 7 and Comparative Examples 1 to 10 (Measurement of Tp) Using the raw materials shown in Table 3 and the composition ratios shown in the same table, polyurethane was prepared in the same manner as in Example 1, and the Tp was I asked for it. The results are shown in Table 3. (Manufacture of polyurethane) Polyurethane (pellets) were produced in the same manner as in Example 1, except that the raw materials shown in Table 3 were used in the composition ratios shown in the table, and the polymerization temperature was set to Tp as shown in the table. ) was manufactured. Table 3 shows the physical properties of each polyurethane produced.

【table】

[Table] As is clear from Table 3, polyurethane obtained by polymerizing PMPA as a polymeric diol at a temperature above Tp can be obtained by polymerizing under the same conditions except that the polymerization temperature is below Tp. The apparent activation energy of melt flow is about half that of polyurethane, and it has excellent moldability (see Example 1 and Comparative Example 1). However, PMPA
If the molar ratio R of MDI to R is not within the range of the value shown by the general formula [], the heat resistance of the polyurethane produced will be extremely poor (Comparative Example 2), or the apparent activation energy of the melt flow will be extremely large (Comparative Example 3). Furthermore, if the average molecular weight of PMPA is small, the resulting polyurethane will have poor heat resistance and poor low-temperature properties (Comparative Example 4). The apparent activation energy is significantly large (Comparative Example 5), whereas PMPA has a molecular weight of 1000~
If it is within the range of 5000, the above two drawbacks are improved (Examples 1 to 4), and even if PCL is used as the polymer diol and polymerized at a temperature higher than Tp, the resulting polyurethane The apparent activation energy of the melt flow does not become very small (Comparative Example 8). Effects of the Invention By the method of the present invention, a thermoplastic polyurethane can be obtained which has improved not only hydrolysis resistance and low-temperature properties but also moldability, heat resistance, and thermal decomposition resistance.

Claims (1)

[Scope of Claims] 1. In the continuous production of thermoplastic polyurethane by polymerizing a polymeric diol, an organic diisocyanate, and a chain extender, () 3-methyl- as the polymeric diol;
Using a polyester diol (a) having an average molecular weight of 1,000 to 5,000 obtained by polycondensing 1,5-pentanediol and dicarboxylic acid, () adding the organic diisocyanate (b) to the polyester diol (a), Formula 0.001M+0.5<R<0.0023M+4.6
[] [Here, M represents the average molecular weight of the polyester diol (a), and R represents the molar ratio of the organic diisocyanate (b) to the polyester diol (a).] The temperature during polymerization is Tp℃ [However, Tp is 150℃, 160℃,
Four DSC curves (formed It means the highest temperature (℃) that shows the top of the highest endothermic peak of the DSC curve obtained when polyurethane is heated at a rate of 10℃/min.]
A method for producing thermoplastic polyurethane, characterized by the above. 2 Polyester diol (a) is 3-methyl-1,
The method according to claim 1, which is a polymeric diol obtained by polycondensing 5-pentanediol and an aliphatic dicarboxylic acid having 4 to 12 carbon atoms. 3. The production method according to claim 2, wherein the aliphatic dicarboxylic acid is adipic acid or azelaic acid. 4 The average molecular weight of polyester diol (a) is 1500
4,000. 5. The manufacturing method according to claim 1, wherein the polymerization is continuous melt polymerization using a multi-screw extruder, and any part of the extruder is at a temperature of Tp (° C.) or higher.