JPH0797428A - Production of polyurethane - Google Patents

Abstract

PURPOSE:To produce a polyurethane excellent in hydrolysis resistance and low-temperature resistance and also in mechanical properties such as strengths and elongation by reacting a polyisocyanate with a specified polyester polyol. CONSTITUTION:A polyurethane is produced by reacting a polyisocyanate with a polyol and optionally a chain extender and/or other components. The polyol comprises a polyester polyol having a number-average molecular weight of 500-10000, mainly consisting of polycarboxylic acid units mainly consisting of dicarboxylic acid units represented bythe formula and low-molecular-weight polyol units mainly consisting of aliphatic or alicyclic low-molecular-weight diol units. The dicarboxylic acid unit of the formula is derived from 2- methyl-1,9-nonane-diol. At most 50mol% of the polyester polyol used in the polyurethane may be replaced by other polycarboxylic acid units.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polyurethane. More specifically, the present invention relates to a method for producing a polyurethane which is excellent in hydrolysis resistance and cold resistance, and also in mechanical properties such as strength and elongation, which is extremely useful for a wide variety of applications.

[0002]

2. Description of the Related Art Polyurethanes have hitherto been produced by reacting polyols such as polyester polyols and polyether polyols with polyisocyanates and, if necessary, a chain extender composed of a low molecular weight compound having an active hydrogen atom. . Of these, those using polyester polyol as the polyol component are inferior in hydrolysis resistance,
As a result, the surface becomes sticky in a relatively short time, or cracks are generated, which considerably limits the use.

Polyurethanes using polyether polyols instead of polyester polyols are excellent in hydrolysis resistance, but on the other hand, they have very poor light resistance.
Furthermore, it is inferior to polyurethane using polyester polyol in mechanical properties, abrasion resistance, and oil / solvent resistance.

As the polyol component, for example, 1,6
-When a polycarbonate polyol having excellent hydrolysis resistance such as hexanediol polycarbonate is used, the above-mentioned drawbacks caused when a polyether polyol is used are improved, but the polycarbonate polyol is extremely expensive, and Poor cold resistance.

On the other hand, as a polyester polyurethane having relatively good hydrolysis resistance, a polyester polyurethane using a polycaprolactone polyol or a polyester polyol obtained from 1,6-hexanediol and neopentyl glycol or adipic acid is conventionally used. Although known, these polyester-based polyurethanes are still not sufficiently satisfactory in hydrolysis resistance.

Further, in the case of polyester-based polyurethane, reducing the ester group concentration in the polyester portion is effective in improving the hydrolysis resistance of the polyester-based polyurethane, and therefore, it is obtained from glycol or dicarboxylic acid having a large number of carbon atoms. It is preferred to use polyester polyols to make polyurethanes.
However, even in this case, the hydrolysis resistance of polyurethane is improved, but the crystallization tendency is large, and when left in a low temperature atmosphere, the cold resistance represented by bending resistance, flexibility, etc.
The low temperature characteristics are significantly reduced.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is a polyurethane which is excellent in hydrolysis resistance and cold resistance, has good mechanical properties, and can be effectively used in a wide variety of applications. Is to provide.

[0008]

As a result of the research conducted by the present inventors based on the above-mentioned object, the use of a polyester polyol having a 2-methylnonanedioic acid unit as a polycarboxylic acid unit results in the result. The new polyester-based polyurethane is extremely excellent in hydrolysis resistance,
Moreover, they have found that they have very good cold resistance and also have excellent mechanical properties such as strength and elongation, and completed the present invention.

That is, the present invention relates to a polyisocyanate, a polyol, and optionally a chain extender and / or
Alternatively, in the method of producing a polyurethane by reacting other components, as the above-mentioned polyol, the following formula (I);

[0010]

[Chemical 2] A polyester polyol having a number average molecular weight of 500 to 10,000 mainly composed of a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by and a low molecular polyol unit mainly composed of an aliphatic or alicyclic low molecular diol unit is used. And a method for producing a polyurethane.

In the present invention, the "polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by the formula (I)" is at least 50 mol% or more, preferably 60% by mole of the polycarboxylic acid unit constituting the polyester polyol. ~ 1
00 mol% is a dicarboxylic acid unit of formula (I), ie 2
-Means to consist of methylnonanedioic acid units. When the proportion of the dicarboxylic acid unit of the formula (I) is less than 50 mol%, the resulting polyester polyurethane has poor hydrolysis resistance, cold resistance and mechanical properties. Here, 2-methylnonanedioic acid constituting the dicarboxylic acid unit of the formula (I) can be produced, for example, from 2-methyl-1,9-nonanediol by a known method.

As described above, the polyester polyol used for polyurethane may contain other polycarboxylic acid units as long as the content is 50 mol% or less. As the other polycarboxylic acid units, the following formula ( II);

[0013]

[Chemical 3] [In the formula, R ¹ is a divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms (excluding 1-methylheptamethylene group),
Represents a saturated alicyclic hydrocarbon group or aromatic hydrocarbon group]
The dicarboxylic acid unit represented by is preferable. Specific examples of such a dicarboxylic acid unit include a unit of a saturated aliphatic dicarboxylic acid such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, and a saturated alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid. And a unit of an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid or isophthalic acid. Among them, in order to obtain a polyurethane excellent in hydrolysis resistance, low temperature characteristics and flexibility, adipic acid, azelaic acid,
Saturated aliphatic dicarboxylic acid units such as sebacic acid are particularly preferred because they do not significantly reduce their performance. The polycarboxylic acid unit to be coexistent with the dicarboxylic acid unit of the formula (I) may be one type or two or more types. If necessary, a trifunctional or higher polycarboxylic acid unit may be contained as long as it is a small amount.

In the present invention, the "low-molecular-weight polyol unit having an aliphatic or alicyclic low-molecular-weight diol unit as a main component" means at least 50 mol% or more, preferably at least 50 mol% of the low-molecular-weight polyol unit constituting the polyester polyol. Means that 70 to 100 mol% is composed of an aliphatic or alicyclic low-molecular diol unit. When the proportion of the low-molecular diol unit is less than 50 mol%,
Hydrolysis resistance of the resulting polyester-based polyurethane,
Cold resistance and mechanical properties are reduced.

The aliphatic or alicyclic low molecular weight diol unit is represented by the following formula (III);

[0016]

[Chemical 4] (In the formula, R ² represents a divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms or a saturated alicyclic hydrocarbon group), and a low-molecular diol unit is preferable.

Examples of the diol unit represented by the formula (III) include ethylene glycol, propylene glycol,
1,4-butanediol, 1,5-pentanediol,
Neopentyl glycol, 1,6-hexanediol,
3-methyl-1,5-pentanediol, 2-methyl-
1,8-octanediol, 1,9-nonanediol,
Examples of the unit include a saturated aliphatic low-molecular diol such as 2-methyl-1,9-nonanediol and 1,10-decanediol, and a saturated alicyclic low-molecular diol such as cyclohexanedimethanol and cyclohexanediol. These low molecular diol units may be used alone or in combination of two or more. If necessary, the low-molecular diol unit may further have a small amount of a unit composed of a trifunctional or higher-functional low-molecular polyol such as triol.

The method for producing the above polyester polyol used in the present invention is not particularly limited, and known polyester condensation means can be applied. For example, 2-methylnonanedioic acid or a dicarboxylic acid mixture containing the same and an aliphatic or alicyclic low-molecular diol are charged at a desired ratio,
A polyester polyol can be produced by carrying out an esterification or transesterification reaction, and further subjecting the obtained reaction product to a polycondensation reaction in the presence of a polycondensation catalyst at high temperature and under vacuum.

The above-mentioned polyester polyol used in the present invention must have a number average molecular weight of 500 to 10,000, and if the number average molecular weight is less than 500, the resulting polyurethane will have poor low temperature properties. When it is larger than 10,000, the mechanical performance of polyurethane becomes poor. The number average molecular weight of the polyester polyol is preferably 700 to 6000.

In the present invention, as the polyol to be reacted with the polyisocyanate, in addition to the above-mentioned polyester polyol containing a dicarboxylic acid unit of the formula (I) and an aliphatic or alicyclic low-molecular diol unit, a small amount (usually all Other polyols such as polyether polyol and polycarbonate polyol may be used as long as they are 40% by weight or less based on the polyol.

In the present invention, as the polyisocyanate, any of the polyisocyanates conventionally used in the production of polyurethane can be used. Examples of polyisocyanates include 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, 1,5-naphthylene diisocyanate, 3,
Aromatic diisocyanates such as 3'-dichloro-4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, toluylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, etc. Examples thereof include aliphatic or alicyclic diisocyanates, and these polyisocyanates may be used alone or in combination of two or more kinds. If necessary, triisocyanate or higher polyisocyanate such as triisocyanate can be used, in which case a thermosetting polyurethane is formed.

Furthermore, in the present invention, a chain extender can be used if necessary. As the chain extender, it is preferable to use a low molecular weight compound having two or more active hydrogen atoms,
Examples of the low molecular compound include ethylene glycol,
1,4-butanediol, 1,6-hexanediol,
1,4-bis (β-hydroxyethoxy) benzene,
1,4-cyclohexanediol, bis (β-hydroxyethyl) terephthalate, diols such as xylylene glycol, water, hydrazine, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine, phenylenediamine, tolylenediamine, adipine Examples thereof include acid dihydrazide and isophthalic acid dihydrazide. These compounds may be used alone or in combination of two or more kinds. The amount of the chain extender used is not particularly limited and can be appropriately selected according to the hardness to be imparted to the target polyurethane, and the like.
Usually, the amount is preferably about 10 mol or less, particularly about 0.2 to 6 mol.
It is preferable to use it in a molar ratio.

Further, in the present invention, a catalyst, a reaction accelerator, a foaming agent, which are usually used in the production of polyurethane,
Any components such as an internal release agent, a filler, a reinforcing agent, a dye / pigment, a stabilizer and the like can be used if necessary.

In the production of polyurethane, based on the total amount of active hydrogen atoms contained in the polyester polyol, the chain extender and other components, the isocyanate group equivalent is about 0.9 to about 1 equivalent of the active hydrogen atoms. 1.
It is preferable to use the polyisocyanate so as to have a ratio of 5, especially about 1. As a method for producing polyurethane, any known urethanization reaction technique can be used, and both the prepolymer method and the one-shot method can be used.

To give an example of the method for producing the polyurethane of the present invention, a polyester polyol and a low molecular weight compound having an active hydrogen atom are mixed and heated to 40 to 100 ° C., and then the active hydrogen atom and the isocyanate in the mixture are mixed. A method for producing a polyurethane by adding polyisocyanate in an amount such that the molar ratio of the group becomes 1: 1 to 1: 1.5 and stirring for a short time and then heating to, for example, 50 to 160 ° C., polyester polyol, active hydrogen Method for producing polyurethane by kneading a mixture of atom-containing low molecular weight compound and polyisocyanate at high temperature (for example, 180 to 260 ° C.), polyester polyol, active hydrogen atom-containing low molecular weight compound in extruder such as multi-screw extruder And polyisocyanate etc. are continuously supplied at high temperature (eg 180 to 260 ° C.) Method for producing polyurethane and continue melt polymerization, the polyester polyol, although the active hydrogen atom-containing low molecular compound and a method for performing a polyurethane-forming reaction by the polyisocyanate in an organic solvent, not of course limited to these methods.

In particular, when the above method is used, dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, toluene, methyl ethyl ketone, ethyl acetate, isopropanol, ethyl cellosolve and the like can be used as the organic solvent.
These solvents may be used alone or in combination of two or more. When carrying out the production reaction of polyurethane in an organic solvent, it is convenient to produce a polyurethane having a high molecular weight by setting the concentration in the range of 10 to 40% by weight.

Although the molecular weight and viscosity of the resulting polyurethane differ depending on the type and molecular weight of the polyester polyol, polyisocyanate and chain extender used, and the ratio of their use, 0.5 g / dl of dimethylformamide is used for polyurethane. The polyurethane is produced in such a manner that the logarithmic viscosity of the solution is 0.5 to 2.0 g / dl when measured at 30 ° C. from the viewpoint of mechanical performance and hydrolysis resistance of the obtained polyurethane. preferable. However, the present invention is not limited to this, and polyurethanes having various molecular weights and viscosities can be produced.

The polyurethane produced according to the present invention is
Extremely excellent in hydrolysis resistance and cold resistance,
It has excellent mechanical properties such as strength and elongation, so it can be used for seats, films, rolls, gears, solid tires, belts, hoses, tubes, packing materials, vibration-proof materials, shoe soles,
It can be effectively used for a wide variety of applications such as sports shoes, machine parts, automobile parts, sports goods, elastic fibers, artificial leather, fiber treatment agents, adhesives, caulking agents, binders and paints. Hereinafter, the present invention will be specifically described with reference to Examples and the like, but the present invention is not limited thereto.

[0029]

EXAMPLES In the following Examples, Comparative Examples and Reference Examples, the number average molecular weight of polyester polyol and the logarithmic viscosity of polyurethane were measured, and the mechanical properties of polyurethane (breaking strength and breaking elongation), hydrolysis resistance and Evaluation of cold resistance was performed according to the following method.

Measurement of number average molecular weight : Calculated by the hydroxyl value of polyester diol. Measurement of logarithmic viscosity : Polyurethane was dissolved in dimethylformamide to a concentration of 0.5 g / dl, and the logarithmic viscosity of the solution at 30 ° C was measured.

Evaluation of mechanical performance : The mechanical performance was evaluated according to the method defined in JIS K7311. That is, a polyurethane film having a thickness of 100 μm was prepared, a dumbbell-shaped test piece was prepared from this film, and the breaking strength and the breaking elongation were measured at a pulling speed of 30 cm / minute using this.
The mechanical performance was evaluated by these.

Evaluation of hydrolysis resistance : A polyurethane film having a thickness of 100 μm was formed, and the film was 70
The film was allowed to stand for 28 days at 95 ° C. and 95% relative humidity, the rupture strength of the film was measured before and after the test, and the strength retention rate (%) after the standing with respect to the strength before the standing was determined and evaluated.

Evaluation of cold resistance : A polyurethane film having a thickness of 100 μm was formed, the dynamic viscoelasticity of a test piece prepared from this film was measured at a frequency of 11 Hz, and the temperature at which the dynamic loss elastic modulus E ″ peaked. (Tα) was determined, and thereby the cold resistance was evaluated.

Reference Example 1 [Production of Polyester Polyol] 1,100 g of 1,4-butanediol and 1880 g of 2-methylnonanedioic acid were charged in a reactor, and the mixture was heated under normal pressure at 210 g.
The esterification reaction was carried out while distilling the water generated at ° C out of the system. When about 250 g of water was distilled, 120 mg of tetraisopropyl titanate was added, and 200-100 m
The reaction was continued while reducing the pressure to mHg. When the acid value reached 1.0, the degree of vacuum was gradually raised by a vacuum pump to complete the reaction. As a result, the hydroxyl value was 56.2 and the acid value was 0.
A polyester diol having 10 and a number average molecular weight of 2000 (polyester polyol A) was obtained.

Reference Examples 2 to 6 Reference Example 1 except that the dicarboxylic acids and low molecular weight diols shown in Table 1 below were used.
An esterification reaction and a polycondensation reaction were carried out in the same manner as in 1. to obtain the corresponding polyester diols (polyester polyols B to F).

In Table 1, dicarboxylic acids and low molecular weight diols are indicated by the following abbreviations. MNA: 2-methylnonanedioic acid ADA: adipic acid SBA: sebacic acid BD: 1,4-butanediol MPD: 3-methyl-1,5-pentanediol ND: 1,9-nonanediol

[0037]

[Table 1]

<< Examples 1 to 4 and Comparative Examples 1 to 3 >> Polyester polyols A to F obtained in Reference Examples 1 to 6 and polycaprolactone diol (polyester polyol G: number average molecular weight 2000) were prepared. Each polyurethane was produced by the following method.
That is, 0.02 of each of polyester polyols A to G
Mol (40 g) and 1,4-butanediol (0.06 mol) (5.4 g) were placed in a three-necked flask and kept at 80 ° C., and 4,4′-diphenylmethane diisocyanate (0.04 mol) was added thereto.
After adding 08 mol (20 g) and stirring for 30 seconds, 23
Transferred to Labo Plastomill kept at 0 ° C. and mixed for 5 minutes. Then, it was aged at 80 ° C. for 12 hours to obtain polyurethane. The inherent viscosity of each polyurethane was measured by the method described above. Each of the polyurethanes obtained above was hot-pressed at 240 ° C. to prepare a film having a thickness of 100 μm, and the mechanical performance, hydrolysis resistance and cold resistance were evaluated by using the film according to the method described above. The results are shown in Table 2 below.

[0039]

[Table 2]

From the results in Table 2 above, a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by the formula (I) (that is, a 2-methylnonanedioic acid unit) and an aliphatic or alicyclic low-molecular diol unit Examples 1 to 1 of the present invention using polyester polyols A to D consisting of
4 was compared with Comparative Example 1 in which the polyester polyol E containing a polycarboxylic acid unit composed of an adipic acid unit without a 2-methylnonanedioic acid unit was used, cold resistance of the resulting polyurethane was Although the polyurethanes of Examples 1 to 4 and Comparative Example 1 are about the same, it is understood that the polyurethanes obtained in Examples 1 to 4 are particularly excellent in hydrolysis resistance and have good mechanical performance.

The polyurethane of Comparative Example 2 obtained by using the polyester polyol F containing a sebacic acid unit as a polycarboxylic acid unit has hydrolysis resistance of Examples 1 to 4.
Although almost the same as the polyurethane of Example 1,
It can be seen that cold resistance and elongation at break are extremely inferior to the polyurethane of No. 4. In addition, from the results of Table 2,
In the case of Comparative Example 3 in which polycaprolactone diol was used as the polyester polyol, the mechanical properties and cold resistance of the obtained polyurethane were almost the same as those of Examples 1 to 4, but the hydrolysis resistance was extremely poor. You can see that

[0042]

EFFECT OF THE INVENTION According to the method of the present invention, a polyurethane of good quality, which is excellent in hydrolysis resistance and cold resistance as well as in mechanical properties such as strength and elongation, is well balanced in various performances. The polyurethane can be effectively used in various wide applications.

Claims (1)

[Claims] 1. In a method for producing a polyurethane by reacting a polyisocyanate, a polyol, and optionally a chain extender and / or other components, as the above-mentioned polyol, the following formula (I): A polyester polyol having a number average molecular weight of 500 to 10,000 mainly composed of a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by and a low molecular polyol unit mainly composed of an aliphatic or alicyclic low molecular diol unit is used. A method for producing a polyurethane, comprising: