JP2844466B2 - Method for producing polyurethane - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polyurethane.

More specifically, the present invention relates to a process for producing a polyurethane obtained by reacting an organic diisocyanate compound with a low-melting polycarbonate diol compound which is liquid or easily melted at room temperature and has excellent workability.

[Prior Art] Polyurethane resins are used in many fields such as foams, adhesives, fibers such as spandex, elastomers and paints, and the main raw materials are diisocyanate compounds and polyol compounds.

Examples of the polyol compound include polyether polyols such as polypropylene glycol and polytetramethylene glycol, polyester polyols derived from dihydric carboxylic acids such as adipic acid and polyhydric alcohols, and lactones obtained by reacting with alcohols. Polylactone polyols and the like are used, and are properly used for various applications according to the required performance.

However, since the polyether polyol has an ether bond, a urethane resin produced using the polyether polyol has a disadvantage that heat resistance and weather resistance are poor.

On the other hand, since polyester polyols and polylactone polyols have ester bonds, urethane resins produced using them have the disadvantage that they have poor water resistance.

In order to obtain a new urethane resin overcoming these drawbacks, it has been proposed to use a polyol having a carbonate bond in the molecular structure as a raw material.

At present, the most widely used polycarbonate polyol, that is, a polyol having a carbonate bond in the molecular structure, has 1, as shown in the following formula (I) in the molecular structure.
It has 6-hexanediol as a basic skeleton.

Polycarbonate diol having a 1,6-hexanediol structure in the basic skeleton is a polyurethane resin obtained by using it, mechanical strength, heat resistance, moisture resistance, etc., are very well-balanced, It also has the advantage of being easily manufactured industrially.

[Problems to be Solved by the Invention] However, since the polycarbonate diol having the 1,6-hexanediol structure in the basic skeleton has crystallinity, the polyurethane resin obtained by using the polycarbonate diol is There is a disadvantage that the low-temperature characteristics are inferior.

On the other hand, a polyether polyol-based polyurethane having excellent low-temperature properties has a problem of lacking heat resistance.

The present inventors have found that a polycarbonate diol-based polyurethane having excellent mechanical strength and wet heat resistance and improved low-temperature characteristics can be synthesized by solving these problems, and arrived at the present invention.

[Constitution of the Invention] That is, the present invention provides a method for producing a polyurethane by reacting an organic diisocyanate compound with a compound having two or more active hydrogens in a molecule, wherein the compound having active hydrogen used is phosgene or A polycarbonate diol obtained by reacting an aliphatic diol with one selected from the group consisting of bischloroformate, alkylene carbonate, diaryl carbonate, and dialkyl carbonate, wherein the aliphatic diol has a molecular weight of 300 to 2,000. Methylene glycol and / or polypropylene glycol 20 to 80% by weight Polyhydric alcohol having 20 or less carbon atoms (however, molecular weight 300
(Excluding polytetramethylene glycol and polypropylene glycol of about 2000) at a ratio of 80 to 20% by weight.

First, phosgene and bischloroformate are compounds that are one component of the polycarbonate diol used in the polyurethane production method of the present invention.

Examples of the alkylene carbonate include ethylene carbonate, 1,2-propylene carbonate, and 1,2-butylene carbonate.

Examples of the diaryl carbonate include diphenyl carbonate and dinaphthyl carbonate.

Examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate. Each of these can be reacted with a diol compound described below to form a polycarbonate diol by a known method.

As the compound corresponding to the method for producing a polyurethane of the present invention, it is essential to use polytetramethylene glycol and / or polypropylene glycol having a molecular weight of 300 to 2,000.

If the molecular weight is 300 or less, the characteristics of polytetramethylene glycol and / or polypropylene glycol cannot be sufficiently exhibited, and the low-temperature characteristics of the resulting carbonate diol cannot be improved.

Also, when polytetramethylene glycol and / or polypropylene glycol having a molecular weight of 2,000 or more are used, the molecular weight of the carbonate diol to be obtained is at least the minimum in order to obtain the characteristics of carbonate diol.
4000 to 5000.

The polyol having such a molecular weight is substantially meaningless as a urethane raw material.

The above polytetramethylene glycol and / or polypropylene glycol are reacted by charging at least one selected from polyhydric alcohols having 20 or less carbon atoms in 20 to 80% by weight in a proportion of 80 to 20% by weight. Let it.

The following can be used as the polyhydric alcohol having 20 or less carbon atoms.

Ethylene glycol, 1,2-propanediol, 1,3-
Butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, hydroxypivalic acid ester of neopentyl glycol, 2-methylpentanediol, 3-methylpentanediol, 2,2,4-trimethyl-1,6 -Hexanediol, 3,3,5-trimethyl-
1,6-hexanediol and 2,3,5-trimethylpentanediol.

If the content of polytetramethylene glycol and / or polypropylene glycol is less than 20% by weight, the obtained polycarbonate diol has poor low-temperature properties,
The desired performance of the present invention cannot be obtained.

When the content of polytetramethylene glycol and / or polypropylene glycol is more than 80% by weight, there is no point in using a polyhydric alcohol having 20 or less carbon atoms, and the feature of a carbonate bond is lost. Mechanical strength etc. cannot be obtained in the polyurethane produced.

As the dialkyl carbonate used in the present invention, dimethyl carbonate and diethyl carbonate are preferable.

Even if a compound having more than 20 carbon atoms is used, an industrially preferable polycarbonate diol cannot be obtained.

The reaction for obtaining a polycarbonate diol using an alkyl carbonate in the present invention is represented by the following general formula.

(R is an alkyl group, R 'is a residue of a polyether polyol or a residue of a polyhydric alcohol having 20 or less carbon atoms) In the present invention, when phosgene is used as a compound requiring a dehydrochlorination step, polycarbonate diol is used. The reaction obtained is represented by the following general formula.

In the present invention, when bischloroformate is used as a compound requiring a dehydrochlorination step, a reaction for obtaining a polycarbonate diol is represented by the following general formula.

At this time, the two diol compounds used as the raw materials are randomly incorporated into the molecule by a carbonate bond.

If one is HO-R ¹ -OH and the other is HO-R ² -OH Are randomly present in the molecule.

Crystallinity is broken by the polyether chains being randomly bonded by the carbonate bond, and the resulting carbonate diol exhibits low-temperature characteristics.

Then, another reaction is to react polytetramethylene glycol and / or polypropylene glycol having a molecular weight of 300 to 2000 with 20 to 80% by weight of a polyhydric alcohol having a carbon number of 20 or less with an aliphatic diol having a mixture of 80 to 20% by weight. In the case where dialkyl carbonate is used as a raw material, the situation of the reaction procedure and the like will be described in detail.

For the reaction, a catalyst usually used in transesterification can be used.

For example, metals such as lithium, sodium, potassium, rupidium, cesium, magnesium, calcium, strontium, barium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic and cerium and alkoxides thereof.

Examples of other suitable catalysts include carbonates of alkali and alkaline earth metals, zinc borate, zinc oxide, lead silicate, lead arsenate, lead carbonate, antimony trioxide, germanium dioxide, cerium trioxide, And aluminum isopropoxide.

Particularly useful and preferred catalysts are magnesium organic acids,
Organic metal compounds such as metal salts of calcium, cerium, barium, zinc, tin, titanium and the like.

The amount of catalyst used is 0.0001% to 1.0% of the total weight of starting materials
Is appropriate.

 Preferably it is 0.001-0.2%.

 The reaction temperature is preferably about 80C to 220C.

In the early stage of the reaction, the reaction is carried out at a temperature near the boiling point of the dialkyl carbonate. As the reaction proceeds, the temperature is gradually increased and the reaction further proceeds.

An apparatus capable of separating the produced diol compound and the raw material dialkyl carbonate is usually a reactor equipped with a distillation tower, in which the reaction is carried out while refluxing the dialkyl carbonate, and the alcohol produced as the reaction proceeds is distilled off.

In the case where the dialkyl carbonate is partly azeotropically dissipated together with the alcohol distilled off at this time, it is better to allow for this dissipated amount when the raw materials are measured and charged.

According to the above reaction formula, the theoretical molar ratio of the diol compound (n + 1) to the molar ratio of the dialkyl carbonate is n, but in practice, the molar ratio of the dialkyl carbonate / diol compound is preferably 1.1 to 1.3 of the theoretical molar ratio. .

The reaction can be carried out at normal pressure, but can be carried out under reduced pressure, for example, at 1 mmHg to 200 mmHg in the latter half of the reaction to speed up the progress of the reaction.

The molecular weight of the polycarbonate diol in the present invention can be adjusted by changing the reaction molar ratio of the raw material diol compound to dialkyl carbonate, dialkylene carbonate and the like.

That is, the molecular weight can be controlled by adjusting n in the above formula.

The organic diisocyanate compounds that can be used include the following.

That is, 2,4 tolylene diisocyanate, 2,6 tolylene diisocyanate, 4,4 'diphenylmethane diisocyanate, tolidine diisocyanate, xylene diisocyanate, hydrogenated 4,4' diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4 'dicyclohexyl Examples thereof include methane diisocyanate, 1,5 naphthalene diisocyanate, carbodiimide-modified MDI, and xylylene diisocyanate, and one or more kinds can be used.

At this time, a chain extender may be allowed to coexist with the above mixture, if necessary.

The chain extender is a low molecular weight compound having active hydrogen, and specific examples thereof include the following.

Ethylene glycol, propylene glycol, 1,4-butylene glycol, 2-methylpropanediol, neopentyl glycol, pentanediol, 1,6-hexanediol, ethylenediamine, propylenediamine, hydrazine, isophoronediamine, metaphenylenediamine, 4,4 '-Diaminodiphenylmethane, diaminodiphenylsulfone, 3,3'-dicro-4,4'-diaminodiphenylmethane and the like.

In the present invention, a polyurethane is produced by reacting a polyol with an excess of organic diisocyanate to produce a prepolymer having terminal isocyanate groups, and then reacting a chain extender such as diol or diamine to form a polyurethane. Any method such as a polymer method or a one-shot method in which all components are added simultaneously to form a polyurethane can be used.

These reactions can be carried out without solvent or in a solvent.

It is preferable to use an inert solvent. Specific examples include toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, dimethylformamide, and tetrahydrofuran.

Further, in the urethanization reaction, a urethanization catalyst can be used.

For example, organic tin compounds such as tin octylate and dibutyltin dilaurate, or tertiary amines such as N-methylmorpholine and triethylamine are exemplified.

In the polycarbonate diol-based polyurethane obtained by the production method of the present invention, the aliphatic diol in the polycarbonate diol is 20 to 80% by weight of polytetramethylene glycol and / or polypropylene glycol having a molecular weight of 300 to 2000. Polyhydric alcohol having 20 or less carbon atoms. It can be confirmed that at least one type of tear selected from the above is used in a combination of 80 to 20% by weight.

[Effects of the Invention] The polyurethane obtained from the polycarbonate diol thus obtained has a good balance of low-temperature properties, mechanical strength, wet heat resistance, etc., and includes elastomers, adhesives, binders for magnetic tapes, spandex, etc. It can be widely used for various industrial applications.

 Hereinafter, the present invention will be described with reference to examples.

[Synthesis Example 1] 620 g (6.89 mol) of dimethyl carbonate was placed in a 2 round bottom flask equipped with a stirrer and a thermometer 10-stage plate distillation column.
740 g (6.27 mol) of 1,6-hexanediol, polytetramethylene glycol having a molecular weight of 830 (PTMG80 manufactured by Mitsubishi Chemical Corporation)
0) 640 g (0.77 mol) and tetrabutyl titanate 0.30 g as a catalyst were charged, and the reaction was carried out under normal pressure under boiling dimethyl carbonate to distill off methanol distilled off.

The temperature of the reaction vessel gradually increased and reached 200 ° C., and when the distillation of methanol almost disappeared, the pressure reduction operation was started, and unreacted substances were distilled off under a reduced pressure of final 20 mmHg to obtain a reaction product. .

The obtained polycarbonate diol was a paste having an OH value of 55.2 and a melting point of about 30 ° C.

[Synthesis Example-2] Instead of 640 g (0.77 mol) of polytetramethylene glycol having a molecular weight of 830 (PTMG800 manufactured by Mitsubishi Kasei), a molecular weight of 750 was used.
Synthesis Example 1 except that 640 g (0.853 mol) of polypropylene glycol (Sanix PP750 manufactured by Sanyo Chemical Industries, Ltd.) was used.
And the following results were obtained.

The obtained polycarbonate diol was a viscous liquid having an OH value of 57.1.

[Synthesis Example 3] The same results as in Synthesis Example 1 were obtained except that 740 g (6.27 mol) of 3-methylpentanediol was used instead of 1,6-hexanediol, and the following results were obtained.

The obtained polycarbonate diol was a viscous liquid having an OH value of 55.2.

[Synthesis Example-4] 1,4-butanediol instead of 1,6-hexanediol
The same procedure as in Synthesis Example 1 was carried out except that 990 g (11 mol) was used, and the following results were obtained.

The obtained polycarbonate diol has an OH value of 56.5 melting point.
It was a paste at 30 ° C.

[Synthesis Example-5] The following results were obtained in the same manner as in Synthesis Example 1, except that 3-methylpentanediol was used in a mixture at a molar ratio of 2/1 instead of 1,6-hexanediol alone. I got

The obtained polycarbonate diol was a viscous liquid having an OH value of 55.8.

[Synthesis Example-6] 640 g (0.98) of polytetramethylene glycol having a molecular weight of 650 (PTMG650 manufactured by Mitsubishi Kasei) instead of polytetramethylene glycol having a molecular weight of 830 (PTMG800 manufactured by Mitsubishi Kasei)
Mol), and the following results were obtained in the same manner as in Synthesis Example 1.

The obtained polycarbonate diol was a viscous liquid having an OH value of 57.2.

(Comparative Synthesis Example)

As a diol compound using the same apparatus as in Synthesis Example-1
Polycarbonate diol was similarly obtained using 1,6-hexanediol at 100%.

[Examples 1 to 6, Comparative Example] Using the polycarbonate diols obtained in Synthesis Examples 1 to 6 and Comparative Synthesis Example as raw materials, a polyurethane was synthesized under the following reaction conditions, and a film thickness of 150 μm was obtained from the polyurethane.
Was prepared and the physical properties were evaluated.

[Polyurethane reaction conditions]

(1) Compounding polyol 100 parts 1.4BG 8.3 parts MDI 35.6 parts Solvent (DMF) 267.3 parts Note) Polyol (Mw2000) /1.4BG/MDI NCO / OH = 1.03 1.4BG / polyol = 2.0 (2) Cooking schedule Parts, 8.3 parts of 1.4BG and 144 parts of solvent are charged into a reactor and heated to 60 ° C.

 Next, add 35.6 parts of MDI and further raise the temperature.

When the temperature in the reactor reaches 80 ° C., the temperature is maintained for several hours.

 Then, the temperature inside the reactor is removed until it reaches 60 ° C.

When the temperature reaches 60 ° C., 123.3 parts of a solvent is added and the mixture is aged at the same temperature.

(3) Properties of polyurethane NV (%) = 35 VIS (cp / 25 ° C) = 60-80,000 Solvent = DMF (4) Preparation of film A polyurethane solution is coated on a release paper and forced dried.

Finished film thickness (μ) = 150 (5) Physical property measurement JIS No. 3 dumbbell punching measuring machine Shimadzu Autograph Table 1 shows the results.

As shown in Table 1, the polyurethane of the present invention has excellent low-temperature properties.

Continuation of front page (56) References JP-A-1-252629 (JP, A) JP-A-2-175721 (JP, A) JP-A 64-1724 (JP, A) JP-A 64-1182 (JP, A) JP-A-62-187725 (JP, A) JP-A-57-190015 (JP, A) JP-A-56-145948 (JP, A) JP-A-49-48789 (JP, A) U.S. Pat. (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08G 18/00-18/87 C08G 64/00-64/42 CA (STN)

Claims (1)

(57) [Claims] 1. An organic diisocyanate compound and 2
In producing a polyurethane by reacting with a compound having two or more active hydrogens, the compound having active hydrogen used is selected from the group consisting of phosgene or bischloroformate, alkylene carbonate, diaryl carbonate, and dialkyl carbonate. A polycarbonate diol obtained by reacting a kind with an aliphatic diol, wherein the aliphatic diol is 20 to 80% by weight of polytetramethylene glycol and / or polypropylene glycol having a molecular weight of 300 to 2,000, and a polyhydric alcohol having 20 or less carbon atoms. (However, molecular weight 300
(Excluding polytetramethylene glycol and polypropylene glycol of about 2000) in a ratio of 80 to 20% by weight.