JP3310413B2 - Method for producing polyurethane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 excellent in mechanical properties such as strength and elongation and is extremely useful for various kinds of applications.

[0002]

2. Description of the Related Art Conventionally, polyurethanes have been produced by reacting polyols such as polyester polyols and polyether polyols with polyisocyanates and, if necessary, chain extenders comprising low molecular weight compounds having active hydrogen atoms. . Among them, those using a polyester polyol as the polyol component are inferior in hydrolysis resistance,
As a result, the surface becomes tacky in a relatively short time or cracks or the like occur, which considerably limits the use.

[0003] Polyurethanes using polyether polyols instead of polyester polyols are excellent in hydrolysis resistance, but are very poor in light resistance.
Further, they are inferior to polyurethanes using polyester polyols in mechanical properties, abrasion resistance, oil resistance and solvent resistance.

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

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

In the case of a 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 is therefore obtained from glycols and dicarboxylic acids having a large number of carbon atoms. Preferably, polyurethanes are produced using polyester polyols.
However, even in this case, although the hydrolysis resistance of the polyurethane is improved, the tendency of crystallization is large, and when left in a low-temperature atmosphere, the cold resistance typified by flex resistance and flexibility, etc.
The low-temperature characteristics are significantly reduced.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyurethane which is excellent in hydrolysis resistance and cold resistance, has good mechanical performance, and can be effectively used for a wide range of applications. It is to provide.

[0008]

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

That is, the present invention provides a polyisocyanate, a polyol, and if necessary, a chain extender and / or
Alternatively, in the method for producing a polyurethane by reacting other components, the polyol represented by the following formula (I):

[0010]

Embedded image Use of a polyester polyol having a number average molecular weight of 500 to 10,000 mainly consisting of a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by and a low molecular weight polyol unit mainly composed of an aliphatic or alicyclic low molecular weight diol unit. And a method for producing a polyurethane.

In the present invention, "a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by the formula (I)" refers to at least 50 mol%, preferably 60 mol% or more of a polycarboxylic acid unit constituting a polyester polyol. ~ 1
00 mol% is a dicarboxylic acid unit of the formula (I), that is, 2
-It is composed of methyl nonanedioic acid units. When the proportion of the dicarboxylic acid unit of the formula (I) is less than 50 mol%, the hydrolysis resistance, cold resistance and mechanical properties of the obtained polyester-based polyurethane are reduced. Here, 2-methylnonane diacid 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 the polyurethane can contain another polycarboxylic acid unit as long as it is 50 mol% or less. II);

[0013]

Embedded image [Wherein, R ¹ is a divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms (excluding a 1-methylheptamethylene group),
Represents a saturated alicyclic hydrocarbon group or an aromatic hydrocarbon group]
The dicarboxylic acid unit represented by is preferred. Specific examples of such dicarboxylic acid units include units of saturated aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and saturated alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. And units of an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid and isophthalic acid. Among them, in order to obtain a polyurethane having excellent hydrolysis resistance, low-temperature properties and flexibility, adipic acid, azelaic acid,
Units of a saturated aliphatic dicarboxylic acid such as sebacic acid are particularly preferred because they do not significantly reduce their performance. The polycarboxylic acid unit coexisting with the dicarboxylic acid unit of the formula (I) may be one type or two or more types. Further, if the amount is small, a polycarboxylic acid unit having three or more functionalities may be contained as needed.

In the present invention, the term "low-molecular-weight polyol unit mainly composed of an aliphatic or alicyclic low-molecular-weight diol unit" 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 weight diol unit is less than 50 mol%,
Hydrolysis resistance of the resulting polyester polyurethane,
Cold resistance and mechanical properties are reduced.

The aliphatic or alicyclic low molecular weight diol unit includes the following formula (III):

[0016]

Embedded image (Wherein, R ² represents a divalent saturated aliphatic hydrocarbon group or a saturated alicyclic hydrocarbon group having 2 to 20 carbon atoms).

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 include units composed of a saturated aliphatic low molecular weight diol such as 2-methyl-1,9-nonanediol and 1,10-decanediol, and a saturated alicyclic low molecular weight diol such as cyclohexanedimethanol and cyclohexanediol. These low molecular weight diol units may be used alone or in combination of two or more. If necessary, the low-molecular-weight diol unit may further have a small amount of a unit composed of a trifunctional or higher-functional low-molecular-weight polyol such as triol.

The method for producing the polyester polyol used in the present invention is not particularly limited, and any 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 conducting an esterification or transesterification reaction and further subjecting the resulting reaction product to a polycondensation reaction under high temperature and vacuum in the presence of a polycondensation catalyst.

The polyester polyol used in the present invention needs to have a number average molecular weight of 500 to 10000. If the number average molecular weight is smaller than 500, the obtained polyurethane has poor low-temperature properties. If it is larger than 10,000, the mechanical performance of the polyurethane becomes poor. The number average molecular weight of the polyester polyol is preferably from 700 to 6000.

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

In the present invention, any of the polyisocyanates conventionally used for producing polyurethane can be used as the polyisocyanate. Examples of polyisocyanates include 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, 1,5-naphthylene diisocyanate,
Aromatic diisocyanates such as 3'-dichloro-4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, toluylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane 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. If necessary, a polyisocyanate having three or more functionalities such as triisocyanate can be used, and in this case, a thermosetting polyurethane is formed.

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

In the present invention, a catalyst, a reaction accelerator, a foaming agent,
Arbitrary components such as an internal release agent, a filler, a reinforcing agent, a dye and a pigment, and a stabilizer can be used as needed.

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

As 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 of adding a polyisocyanate in an amount such that the molar ratio of groups becomes 1: 1 to 1: 1.5, stirring the mixture for a short time, and then heating the mixture to, for example, 50 to 160 ° C. to produce a polyurethane, polyester polyol, active hydrogen A method for producing a polyurethane by kneading a mixture of an atom-containing low-molecular compound and a polyisocyanate at a high temperature (for example, 180 to 260 ° C.), a polyester polyol and an active hydrogen atom-containing low-molecular compound in an extruder such as a multi-screw extruder. And polyisocyanate are continuously supplied at a high temperature (for example, 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 the production reaction of the polyurethane is carried out in an organic solvent, it is convenient to carry out the reaction in a concentration range of 10 to 40% by weight since a polyurethane having a high molecular weight can be produced.

The molecular weight and viscosity of the obtained polyurethane vary depending on the type and molecular weight of the polyester polyol, polyisocyanate, and chain extender used, and the proportions of them, but the polyurethane is prepared by adding 0.5 g / dl of dimethylformamide. The production of the polyurethane in such a manner that the logarithmic viscosity measured at 30 ° C. as a solution is 0.5 to 2.0 g / dl is preferred in view of the 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 comprises
With extremely excellent hydrolysis resistance and cold resistance,
Because it is also excellent in mechanical performance such as strength and elongation, sheets, films, rolls, gears, solid tires, belts, hoses, tubes, packing materials, vibration isolating materials, shoe soles,
It can be effectively used in a wide variety of applications such as sports shoes, machine parts, automobile parts, sporting goods, elastic fibers, artificial leather, fiber treatment agents, adhesives, caulks, binders, and paints. Hereinafter, the present invention will be described specifically 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 (rupture strength and elongation at break), hydrolysis resistance and The evaluation of cold resistance was performed according to the following method.

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

Evaluation of mechanical performance : Evaluated according to the method specified 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 tensile speed of 30 cm / min using this film.
These were used to evaluate the mechanical performance.

Evaluation of hydrolysis resistance : A polyurethane film having a thickness of 100 μm was formed.
The film was left standing for 28 days at 95 ° C. and a relative humidity of 95%, the breaking strength of the film before and after the film was measured, and the strength retention ratio (%) after standing against the strength before leaving was evaluated.

Evaluation of cold resistance : A polyurethane film having a thickness of 100 μm was formed, and 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 into a reactor and placed under a normal pressure under a pressure of 210 g.
The esterification reaction was carried out while distilling off the water produced at a temperature of outside the system. When about 250 g of water was distilled, 120 mg of tetraisopropyl titanate was added, and 200 to 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 increased by a vacuum pump to complete the reaction. As a result, a hydroxyl value of 56.2 and an acid value of 0.
A polyester diol having 10 and a number average molecular weight of 2,000 (polyester polyol A) was obtained.

Reference Examples 2 to 6 Reference Examples 1 to 6 were conducted except that 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 Example 1 to obtain corresponding polyester diols (polyester polyols BF).

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 1-4 and Comparative Examples 1-3 Each of the polyester polyols AF obtained in Reference Examples 1-6 and polycaprolactone diol (hereinafter referred to as polyester polyol G: number average molecular weight 2000) was used. Each polyurethane was produced by the following method.
That is, 0.02 of each of the polyester polyols A to G was used.
Mol (40 g) and 0.06 mol (5.4 g) of 1,4-butanediol were kept in a three-necked flask at 80 ° C., and 4,4′-diphenylmethane diisocyanate was added to 0.1 mol.
After adding 08 mol (20 g) and stirring for 30 seconds, 23
The mixture was transferred to a Labo Plastomill maintained at 0 ° C and mixed for 5 minutes. Thereafter, the mixture was aged at 80 ° C. for 12 hours to obtain a polyurethane. The logarithmic viscosity of each polyurethane was measured by the method described above. Each of the polyurethanes obtained above was hot-pressed at 240 ° C. to produce a film having a thickness of 100 μm, and the mechanical performance, hydrolysis resistance and cold resistance were evaluated using the film by the above-mentioned methods. The results are shown in Table 2 below.

[0039]

[Table 2]

From the results in Table 2 above, it can be seen that 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 4 of the present invention using polyester polyols A to D consisting of
4 and Comparative Example 1 using a polyester polyol E containing a polycarboxylic acid unit consisting of an adipic acid unit without containing a 2-methylnonanedioic acid unit, the cold resistance of the obtained polyurethane was measured. Although the polyurethanes of Examples 1 to 4 and Comparative Example 1 are almost the same, it can be seen that the polyurethanes obtained in Examples 1 to 4 are particularly excellent in hydrolysis resistance and also have good mechanical performance.

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

[0042]

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

Claims (1)

(57) [Claims] 1. A method for producing a polyurethane by reacting a polyisocyanate, a polyol and, if necessary, a chain extender and / or other components, wherein the polyol is represented by the following formula (I): Use of a polyester polyol having a number average molecular weight of 500 to 10,000 mainly consisting of a polycarboxylic acid unit mainly composed of a dicarboxylic acid unit represented by and a low molecular weight polyol unit mainly composed of an aliphatic or alicyclic low molecular weight diol unit. A method for producing a polyurethane.