JPH06100654A - Thermoplastic polyurethane and its production - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic polyurethane excellent in low temperature properties, melt flow and mechanical strengths by copolymerizing a specified functional polymer with a polyol, a polyisocyanate the a chain extender in a specified weight ratio. CONSTITUTION:3-50 pts.wt. functional polymer having a number-average molecular weight of 1000-100000, comprising 0-90 mol % structural units of formula I and 100-10 mol % total of structural units of formulas II and III, and having at least 0.6, on the average per molecule, structural units of formula IV is copolymerized with 97-50pts. a polyol, a polyisocyanate (e. g. hexamethylene diisocyanate) and a chain extender (e. g. ethylene glycol), to produce a thermoplastic polyurethane. In the formulas, R<1>, R<2> and R<4> are each H or methyl; and R<3> is ethyl or isopropyl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyurethane having excellent cold resistance and fluidity when melted, and a method for producing the same.

[0002]

2. Description of the Related Art Polyurethane generally consists of a soft segment formed by a reaction between a polyol and a polyisocyanate and a hard segment formed by a reaction between a chain extender and a polyisocyanate. A polyurethane containing a polyester polyol or a polyether polyol as a polyol is
Footwear such as sports shoes, various hoses and tubes,
It is widely used for various applications such as interior and exterior parts of automobiles.

Among the polyurethanes having polyester polyol or polyether polyol as the polyol, thermoplastic polyurethane is superior to other thermoplastic elastomers in abrasion resistance, high strength, oil resistance and the like, but also in cold resistance. It is inferior and has a high melt viscosity at the time of molding, that is, poor fluidity at the time of melting.

To solve these drawbacks, it has been proposed to add a plasticizer and raise the molding temperature.
Changes in physical properties over time due to plastic bleeding, etc.
In reality, there are many problems such as the mold being heavily contaminated and the thermoplastic polyurethane being deteriorated when the molding temperature is raised.

Further, a polyurethane using a polyolefin polyol having a hydroxyl group in the molecule as a part of a polyol component (JP-A-4-136016) or a polyolefin polyol having a dihydroxyl group at one end as a part of a polyol component. A polyurethane to be used (JP-A-4-175329) and the like have been proposed, and it is known that a polyurethane excellent in cold resistance and hydrolysis resistance can be obtained.

However, according to the method described in JP-A-4-136016, the fluidity of the resulting polyurethane when melted is insufficient, and the fluidity may rather deteriorate depending on the hydroxyl group concentration in the polyolefin polyol. ,
Not preferable.

In the method described in JP-A-4-175329, the production of a polyolefin polyol having a dihydroxyl group at one end is relatively complicated, and
The fluidity of the obtained polyurethane when melted is also insufficient, which is not preferable.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic polyurethane excellent in cold resistance and fluidity at the time of melting while maintaining the excellent mechanical properties of thermoplastic polyurethane.

[0009]

According to the present inventor, the above-mentioned object is obtained by formulating the structural unit represented by the formula 1 from 0 to 90 mol% and the formula 2
The total amount of the structural units represented by the formula 4 and the structural units represented by the formula 3 is 100 to 10 mol%, and the average number of the structural units represented by the formula 4 is 0.6 or more per molecule at one end of the molecular chain. Number average molecular weight of 1,000 to 100,
000 functional group-containing polymers can be achieved by the thermoplastic polyurethane obtained by copolymerizing the functional group-containing polymer, the polyol, the polyisocyanate, and the chain extender in a ratio of 3 to 50 parts based on 100 parts in total. Heading out, the present invention has been completed.

[0010]

[Chemical 17] (In the formula, R ¹ represents a hydrogen atom or a methyl group.)

[0011]

[Chemical 18] (In the formula, R ² represents a hydrogen atom or a methyl group.)

[0012]

[Chemical 19] (In the formula, R ³ represents an ethyl group or an isopropyl group.)

[0013]

[Chemical 20] (In the formula, R ⁴ represents a hydrogen atom or a methyl group.) The present invention is described in detail below.

First, the structural unit forming the basic skeleton of the functional group-containing polymer used in the present invention is represented by the above formulas 1, 2 and 3. These structural units are composed of, for example, a hydrogenated product (hydrogenated product) of a diene portion of a copolymer such as styrene, α-methylstyrene, butadiene, and isoprene.
For example, in Formula 1, the structural unit when R ¹ is a hydrogen atom corresponds to a styrene polymer, and when R ¹ is a methyl group in Formula 1, the structural unit corresponds to an α-methylstyrene polymer. Where R ² is a hydrogen atom and R ³ is an ethyl group in Formula 3, the structural unit corresponds to a hydrogenated product of a butadiene polymer, R ² is a methyl group in Formula 2, and R ³ is an isopropyl group in Formula 3. And the structural unit corresponds to the hydrogenated product of the isoprene polymer. The functional group-containing polymer may include both of the structural units represented by Formulas 1, 2, and 3 as its basic skeleton, and in this case, these structural arrangements may be arbitrary.

One end of the molecular chain of the functional group-containing polymer is represented by formula 4. For example, when R ⁴ is a hydrogen atom, this structure corresponds to a functional group-containing polymer obtained by reacting one end of the molecular chain with ethylene oxide. Further, when R ⁴ is a methyl group, it corresponds to a functional group-containing polymer obtained by reacting propylene oxide on one end of the molecular chain.

Further, in the functional group-containing polymer used in the present invention, the ratio of the structural unit represented by the formula 1 should not exceed 90 mol%. When the structural unit represented by the formula 1 exceeds 90 mol%, the fluidity of the resulting thermoplastic polyurethane during melting and the cold resistance are insufficient, which is not preferable.

Further, the functional group-containing polymer must have an average of 0.6 or more structural units represented by the formula 4 per molecule. When the content of this structural unit is less than 0.6 on average per molecule, the blocking efficiency of the functional group-containing polymer with the polyol, polyisocyanate and chain extender is reduced, and the mechanical strength of the resulting thermoplastic polyurethane is reduced. It deteriorates and is not preferable.

The molecular weight of the functional group-containing polymer is 1,000.
It must be in the range of 100,000. When the molecular weight is less than 1,000, the mechanical strength of the resulting thermoplastic polyurethane is lowered and the effect of imparting cold resistance is also small, which is not preferable. On the other hand, when the molecular weight is more than 100,000, the effect of improving the fluidity at the time of melting the thermoplastic polyurethane is small and not preferable.

Further, in the present invention, the functional group-containing polymer is 3 to 3 parts with respect to the total amount of the functional group-containing polymer, polyol, polyisocyanate and chain extender being 100 parts.
It is necessary to copolymerize at a ratio of 50 parts. When the amount of the functional group-containing polymer added is less than 3 parts, the resulting thermoplastic polyurethane is not preferable because the cold resistance and the fluidity at the time of melting are not sufficiently improved. When the amount of the functional group-containing polymer added is more than 50 parts, the resulting thermoplastic polyurethane has a large decrease in mechanical properties, which is not preferable. Such a functional group-containing polymer can be obtained by the following method.

For example, it can be obtained by hydrogenating a diene portion of a copolymer of an aromatic vinyl compound having a hydroxyl group at one end of a molecular chain and a conjugated diene.

A living polymer is produced by anionically polymerizing an aromatic vinyl monomer and a conjugated diene monomer with butyllithium as a polymerization initiator, and the polymerization active end thereof is treated with ethylene oxide to form a hydroxyl group at one end of the molecular chain. To obtain a polymer having The obtained polymer is hydrogenated by a known method to obtain a hydrogenated product of a diene portion of a copolymer of an aromatic vinyl compound having a hydroxyl group at one end of a molecular chain and a conjugated diene.

For the hydrogenation reaction, for example, a method of carrying out catalytic hydrogenation using a Ziegler type homogeneous catalyst or a solid heterogeneous catalyst is adopted.

The polyol used in the present invention includes a saturated aliphatic glycol having 2 to 9 carbon atoms and 4 carbon atoms.
Polyester polyols obtained by condensation with saturated aliphatic dicarboxylic acid or aromatic dicarboxylic acid of 10 to 10 and condensation of alkylene oxide having 2 to 4 carbon atoms, condensation of alkylene oxide and alkylene glycol, ring-opening polymerization of tetrahydrofuran In addition to the polyether polyols obtained by the above, dihydroxy polyester amides, dihydroxy polyacetals and the like can be used.

The polyisocyanate used in the present invention is a known aliphatic, alicyclic or aromatic organic polyisocyanate containing two or more isocyanate groups in the molecule, particularly hexamethylene diisocyanate.
Isophorone diisocyanate (IPDI), 4,4'-
Dicyclohexylmethane diisocyanate, 4,4'-
Diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, toluylene diisocyanate (TDI), 1,5-naphthylene diisocyanate,
Diisocyanates such as xylylene diisocyanate,
Trimethylolpropane or 3 per mol of glycerin
Examples thereof include triisocyanate to which TDI of a mole is added. Of these, MDI is particularly preferable.

Further, as the chain extender used in the present invention, ethylene glycol, saturated aliphatic glycol having 2 to 9 carbon atoms such as 1,4-butanediol (BD), and 1,4-xylylene glycol, Examples thereof include aromatic glycols such as phenylene bis- (β-hydroxyethyl ether). Of these, BD is particularly preferable.

Regarding the operation method for obtaining the thermoplastic polyurethane of the present invention, a thermoplastic polyurethane prepolymer is produced from the above-mentioned polyol, polyisocyanate and chain extender, and then a functional group-containing polymer is added to react. And a method of advancing the reaction by adding the functional group-containing polymer together with the polyol, polyisocyanate and chain extender at the initial stage of the reaction. In the reaction, various extruders, kneaders and the like can be used, and it is particularly preferable to use a twin-screw extruder.

In the thermoplastic polyurethane obtained in the present invention, if necessary, a lubricant, carbon black, organic and inorganic dyes, pigments, flame retardants, clay, calcium carbonate, fillers such as glass fiber, a plasticizer, Antioxidants and antioxidants can be optionally added.

The thermoplastic polyurethane obtained by the present invention is excellent in cold resistance and fluidity at the time of melting while maintaining abrasion resistance, high strength and oil resistance.
Useful for rolls, gears, belts, hoses, tubes, packing, etc.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

The compounds used in Examples and Comparative Examples are shown by abbreviations, and the relationship between the abbreviations and compounds is as shown in Table 1.

[0031]

[Table 1] Reference Example 1 (Synthesis of Functional Group-Containing Polymer A) After producing a living polymer by anionically polymerizing an isoprene monomer in n-hexane using n-butyllithium as an initiator, 1 is added to a polymerization active terminal.
By adding 0-fold mole of ethylene oxide, polyisoprene (I) having a hydroxyl group at one end of the molecular chain was obtained.

Next, the obtained polyisoprene (I) was dissolved in n-heptane in a pressure resistant reactor equipped with a stirrer, Raney nickel catalyst was added, and the mixture was reacted at 150 ° C. under a hydrogen pressure of 35 kg / cm ^2. It was After removing the Raney nickel catalyst by filtration, the filtrate was concentrated and dried under reduced pressure,
A hydrogenated product of polyisoprene (A) having a hydroxyl group at one end of the molecular chain was obtained.

Since the hydroxyl value determined by the acetylation method and the molecular weight (Mn) determined by the osmometer are 20,000, the functional group-containing polymer A has a molecular weight of 0.
It had 93 hydroxyl groups. The structural unit obtained by measurement of the NMR spectrum was 91 mol% of the structural unit represented by Formula 2 (R ² is a methyl group) and 9 mol% of the structural unit represented by Formula 3 (R ³ is an isopropyl group). there were.

Reference Example 2 (Synthesis of Functional Group-Containing Polymer B) A styrene monomer was subjected to anionic polymerization in cyclohexane using n-butyllithium as an initiator, and then an isoprene monomer was added to produce a living block polymer, followed by polymerization. A polystyrene-polyisoprene block polymer (II) having a hydroxyl group at one end of the molecular chain was obtained by adding 10 times mol of ethylene oxide to the active end.

Next, the obtained polystyrene-polyisoprene block polymer (II) was dissolved in cyclohexane in a pressure-resistant reaction vessel equipped with a stirrer, and Raney nickel catalyst was added thereto, and the mixture was stirred under a hydrogen pressure of 35 kg / cm ² for 15 minutes.
The reaction was carried out at 0 ° C. After removing the Raney nickel catalyst by filtration, the filtrate was concentrated and dried under reduced pressure to obtain a hydrogenated product of polystyrene-polyisoprene block polymer (functional group-containing polymer B). The Mn of the styrene block obtained from GPC was 10,000, the charge ratio, NM
Styrene / isoprene calculated from both R is 25/7
It was 5 (mol / mol).

From the hydroxyl value and the molecular weight (40,000) determined by the acetylation method, the functional group-containing polymer B had 0.89 hydroxyl groups per molecule. The structural unit obtained by measurement of the NMR spectrum is 25 mol% of the structural unit represented by Formula 1 (R ¹ is a hydrogen atom), 67 mol% of the structural unit represented by Formula 2 (R ² is a methyl group), 8 mol% of the structural unit represented by Formula 3 (R ³ is an isopropyl group)
Met.

Reference Example 3 (Synthesis of Functional Group-Containing Polymer C) A hydroxyl group-containing polyisoprene (M was obtained by radical polymerization with hydrogen peroxide in an autoclave having an internal volume of 1 liter.
n = 3,800, OH number = 32.9 mg / g, average number of hydroxyl groups per molecule = 2.22) 100 g, reduced nickel 10 g (nickel loading 35%, carrier; diatomaceous earth), and cyclohexane as reaction solvent After charging 200 g and purging the inside of the system with purified nitrogen gas, the temperature was raised to 150 ° C. over 30 minutes.

At the time when a steady state of 150 ° C. was reached, high-purity hydrogen gas was supplied to the autoclave, and the system internal pressure was set to 50 kg.
The hydrogenation reaction was carried out while maintaining / cm ² . After the reaction, the hydrogenated product was taken out, the catalyst was removed by filtration, and the solvent was further distilled off to obtain a hydroxyl group-containing hydrogenated polyisobrene (functional group-containing polymer C).

Reference Example 4 (Synthesis of Functional Group-Containing Polymer D) 400 g of n-heptane and 22 g of s-butyllithium were charged into a pressure-resistant reaction vessel equipped with a stirrer and a dropping funnel, and 50
The temperature was raised to 0 ° C., 600 g of isoprene was continuously added dropwise from the dropping funnel, and a polymerization reaction was carried out for 4 hours. Then, the reaction vessel was cooled with dry ice / methanol, and the reaction was carried out for 1 hour while blowing carbon dioxide gas from the lower portion of the reaction vessel to convert the end of the molecular chain into COOLi. The reaction solution was treated with 1N-hydrochloric acid, washed with water and methanol, and dried under reduced pressure at 70 ° C. for 24 hours to obtain polyisoprene (I) having a carboxyl group at one end.

600 g of polyisoprene (I) was dissolved in 720 g of n-heptane and charged into a pressure-resistant reaction vessel equipped with a stirrer, 60 g of a nickel catalyst supported on diatomaceous earth was added, and the mixture was heated at 150 ° C. under a hydrogen pressure of 15 kg / cm ^2. The reaction was carried out for 6 hours. The reaction product was diluted with n-heptane, the catalyst was filtered off, and the filtrate was concentrated and dried under reduced pressure to obtain a hydrogenated product of polyisoprene having a carboxyl group at one end (II).
The hydrogenation rate determined by iodine value measurement was 92.0%.

Furthermore, 600 g of hydrogenated product of polyisoprene (II) was added to toluene 720 in a pressure resistant reactor equipped with a stirrer.
It was dissolved in g and charged, tetra-n-butylammonium bromide (6 g) and glycidol (17.8 g) were added, and the mixture was added at 90 ° C. to 1
The reaction was allowed for 0 hours. The reaction vessel was purified by reprecipitation with toluene / acetone and dried under reduced pressure at 80 ° C. for 24 hours to obtain a hydrogenated product of polyisoprene having a dihydroxyl group at one end (functional group-containing polymer D). The number average molecular weight by GPC was 24,300, and the number of hydroxyl groups per molecule determined from the hydroxyl value was 1.94.

Example 1 90 g of PBA as a polyol, 46 g of MDI as a polyisocyanate, and 12.2 g of BD as a chain extender.
Was charged into a kneader (content volume 150 ml) heated to 100 ° C., the rotation speed was increased from 40 rpm to 100 rpm,
The internal temperature was raised from 100 ° C to 200 ° C. After reaching the temperature of 200 ° C. and mixing for 10 minutes, 10 g of the functional group-containing polymer A produced in Reference Example 1 was added as a functional group-containing polymer, and the mixing was continued for another 10 minutes, and then the compound was quickly taken out under a nitrogen stream. . The compound was aged under a nitrogen stream at 80 ° C for 12 hours, then 220 ° C, 1
Various physical properties are summarized in Table 2 using a thermoplastic polyurethane sheet obtained by press molding at 00 kg / cm ² for 5 minutes.
In Table 2, the cold resistance of the thermoplastic polyurethane sheet is
A test piece with a thickness of about 500 μm was prepared, and t was measured by Rheovibron DDV-III (11 Hz) manufactured by Orientec Co., Ltd.
The an an δ was measured, and the lower the peak temperature, the better.

Example 2 80 g of PBA as a polyol, 42 g of MDI as a polyisocyanate, and 10.8 of BD as a chain extender.
g, various reactions were performed in the same manner as in Example 1 except that 20 g of the functional group-containing polymer A was used, and after aging, various physical properties of the obtained thermoplastic polyurethane sheet are summarized in Table 2.

Example 3 90 g of PBA as a polyol, 46 g of MDI as a polyisocyanate, and 12.2 of BD as a chain extender.
10 g of the functional group-containing polymer B was charged into a kneader (internal volume: 150 ml) heated to 100 ° C., and the rotation speed was 4
Increase the internal temperature from 100 ℃ to 2 by increasing the rpm from 100rpm.
Raised to 00 ° C. After reaching 200 ° C. and mixing for 15 minutes, the compound was quickly taken out under a nitrogen stream. Table 2 shows the physical properties of the thermoplastic polyurethane sheet obtained by aging the compound under a nitrogen stream at 80 ° C for 12 hours and then press-molding at 220 ° C at 100 kg / cm ² for 5 minutes.

Example 4 80 g of PBA as a polyol, 42 g of MDI as a polyisocyanate, and 10.8 of BD as a chain extender.
The reaction was carried out in the same manner as in Example 3 except that 20 g of the functional group-containing polymer B was used, and various physical properties of the thermoplastic polyurethane sheet obtained after carding are summarized in Table 2.

Comparative Example 1 Various physical properties of the thermoplastic polyurethane sheet obtained after the reaction and aging were carried out in the same manner as in Example 1 except that the functional group-containing polymer was not added. As shown in the results shown in Table 2, although the thermoplastic polyurethane to which the functional group-containing polymer is not added has good mechanical strength,
It can be seen that the melt viscosity is high and the cold resistance is poor.

Comparative Example 2 Various physical properties of the thermoplastic polyurethane sheet obtained after the reaction and aging were carried out in the same manner as in Example 3 except that the functional group-containing polymer was not added. As shown in the results shown in Table 2, although the thermoplastic polyurethane to which the functional group-containing polymer is not added has good mechanical strength,
It can be seen that the melt viscosity is high and the cold resistance is poor.

Comparative Example 3 30.0 g of a functional group-containing polymer C as a polyol,
PBA120.0g, MDI as polyisocyanate
Of 51.6 g and BD of 12.4 g as a chain extender were used, the reaction was carried out in the same manner as in Example 3, and after aging,
Table 2 shows the physical properties of the resulting thermoplastic polyurethane sheet. As shown in the results shown in Table 2, the thermoplastic polyurethane to which the hydrogenated polyisoprene having a hydroxyl group is added has a high melt viscosity, although it has excellent cold resistance.

Comparative Example 4 30.0 g of a functional group-containing polymer D as a polyol,
PBA120.0g, MDI as polyisocyanate
Of 45.9 g and BD of 11.0 g as a chain extender were used, the reaction was carried out in the same manner as in Example 3, and after aging,
Table 2 shows the physical properties of the resulting thermoplastic polyurethane sheet. From the results shown in Table 2, it can be seen that the thermoplastic polyurethane to which the hydrogenated polyisoprene having a dihydroxy group at one end is added has an excellent cold resistance but an insufficient decrease in melt viscosity.

[0050]

[Table 2]

[0051]

INDUSTRIAL APPLICABILITY The present invention provides a thermoplastic polyurethane excellent in cold resistance and fluidity when melted while maintaining the excellent mechanical properties of the thermoplastic polyurethane.

Claims (4)

[Claims] 1. A structural unit of the formula 1, 0 to 90 mol%.
And the structural unit represented by the formula 2 and the structural unit represented by the formula 3 are combined in an amount of 100 to 10 mol%, and the structural unit represented by the formula 4 is averaged to one end of the molecular chain of 0 per molecule. A number average molecular weight of 1,000 or more having 6 or more
A thermoplastic polyurethane obtained by copolymerizing 0,000 functional group-containing polymer in a proportion of 3 to 50 parts with respect to a total amount of 100 parts of the functional group-containing polymer, polyol, polyisocyanate and chain extender. [Chemical 1] (In the formula, R ¹ represents a hydrogen atom or a methyl group.) (In the formula, R ² represents a hydrogen atom or a methyl group.) (In the formula, R ³ represents an ethyl group or an isopropyl group.) (In the formula, R ⁴ represents a hydrogen atom or a methyl group.) 2. The compound is composed of 0 to 90 mol% of the structural unit represented by the formula 1, 100 to 10 mol% of the structural unit represented by the formula 2 and the structural unit represented by the formula 3,
A number average molecular weight of 1,000 or more having an average of 0.6 or more structural units represented by Formula 4 per molecule at one end of the molecular chain
100,000 functional group-containing polymer, 3 to 50 parts of the total amount of the functional group-containing polymer, the polyol, the polyisocyanate and the chain extender are copolymerized, and a thermoplastic polyurethane characterized by the above-mentioned. Manufacturing method. [Chemical 5] (In the formula, R ¹ represents a hydrogen atom or a methyl group.) (In the formula, R ² represents a hydrogen atom or a methyl group.) (In the formula, R ³ represents an ethyl group or an isopropyl group.) (In the formula, R ⁴ represents a hydrogen atom or a methyl group.) 3. A thermoplastic polyurethane prepolymer is prepared from a polyol, a polyisocyanate and a chain extender, and then the structural unit represented by the formula 1 is 0 to 90 mol%.
It is composed of 100 to 10 mol% of the structural unit represented by the formula 2 and the structural unit represented by the formula 3, and the average molecular weight of the structural unit represented by the formula 4 is 0.6 at one end of the molecular chain. Number average molecular weight of 1,000 or more
A method for producing a thermoplastic polyurethane, which comprises adding 50,000 functional group-containing polymers and introducing them into the main chain of the prepolymer. [Chemical 9] (In the formula, R ¹ represents a hydrogen atom or a methyl group.) (In the formula, R ² represents a hydrogen atom or a methyl group.) (In the formula, R ³ represents an ethyl group or an isopropyl group.) (In the formula, R ⁴ represents a hydrogen atom or a methyl group.) 4. Consists of 0 to 90 mol% of the structural unit represented by the formula 1, 100 to 10 mol% of the structural unit represented by the formula 2 and the structural unit represented by the formula 3,
A number average molecular weight of 1,000 or more having an average of 0.6 or more structural units represented by Formula 4 per molecule at one end of the molecular chain
100,000 functional group-containing polymer is used as a polyol,
A method for producing a thermoplastic polyurethane, which comprises adding together with a polyisocyanate and a chain extender at the initial stage of the reaction. [Chemical 13] (In the formula, R ¹ represents a hydrogen atom or a methyl group.) (In the formula, R ² represents a hydrogen atom or a methyl group.) (In the formula, R ³ represents an ethyl group or an isopropyl group.) (In the formula, R ⁴ represents a hydrogen atom or a methyl group.)