JPH01254724A - Production of polyurethane - Google Patents

Abstract

PURPOSE:To obtain the title polymer of high molecular weight, suitable for mechanical and instrumental parts, coatings, adhesives, etc., by reaction between a polyisocyanate and a polyol dehydration-treated by azeotropic distillation. CONSTITUTION:(A) a polyol having the two or more hydroxyl group such as ethylene glycol or polyesterpolyol (e.g., a synthesized product from glycerin and malonic acid) is mixed with an organic solvent (e.g., toluene) capable of forming an azeotropic mixture with water followed by heating to carry out azeotropic distillation. (B) Thence, a polyisocyanate having in the molecule two or more isocyanate groups (e.g., hexamethylene diisocyanate) is added to carry out reaction, thus obtaining the objective polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing polyurethane useful as various mechanical equipment parts, paints, adhesives, and the like.

(Prior art and problems to be solved by the invention) Polyurethane is produced by reacting a polyol containing at least two hydroxyl groups in the molecule with a polyisocyanate having at least two isocyanate groups in the molecule. . At this time, there are a solution method that uses an organic solvent and a non-solution method that does not use an organic solvent.

The most important thing to be careful about when manufacturing polyurethane is the contamination of water. In the case of polyurethane foam production, moisture is added in a controlled manner; otherwise, moisture contamination causes a decrease in the molecular weight of polyurethane.
It is essential to remove water by drying the solvent and degassing the raw material by heating and vacuuming. However, when the present inventors synthesized polyurethane using highly hygroscopic polyols such as ethylene glycol and polypropylene glycol, and polyols with high molecular weight and high viscosity as raw materials, these polyols were degassed by heating and vacuum. However, the molecular weight of the polyurethane obtained was low, and a polyurethane with a sufficiently high molecular weight could not be obtained.

(Means for Solving the Problems) The present inventors aimed to obtain a polyurethane with a sufficiently large molecular weight even when used as a raw material for the above-mentioned highly hygroscopic polyol or highly viscous polyol. Continuing the intensive research. As a result, the inventors discovered that the above objects can be achieved by using a polyol that has been dehydrated by azeotropic distillation, and have completed the present invention.

That is, the present invention provides a method for producing polyurethane from a polyol having at least two hydroxyl groups in the molecule and a polyisocyanate having at least two isocyanate groups in the molecule, in which the polyol is subjected to dehydration treatment by azeotropic distillation. This is a method for producing polyurethane, which is characterized by using a polyol produced by

The polyol having at least two or more hydroxyl groups in the molecule used in the present invention is not particularly limited, and any generally known polyol can be used. Examples of polyols that can be suitably used include the following compounds.

(1) Polyether polyol (2) Polyester polyol (3) Polymer polyol (4) Specific examples of polyols higher than polygetatsuene polyols are as follows.

(1) Polyether polyol ethylene glycol, diethylene glycol, propylene glycol, 1,4-butylene glycol, glycerin, hexanetriol, trimethylolpropane, pentaerythritol, sorbitol, sucrose, dipropylene glycol, dihydroxydiphenylpronoyan, dihydroxydiphenylmethane, Dihydroxydiphenyl ether, dihydroxydiphenyl ether, dihydroxybiphenyl, hydroquinone, resorcinol,
Naphthalene diol, aminophenol, aminonaphthol, methyljetanolamine, ethyl diisoglonolamine, triethanolamine, ethylenediamine, hexamethylenediamine, bis(p-aminocyclohexyl)methane, tolylenediamine, diphenylmethanediamine, etc. It is a polyether polyol obtained by addition and ring-opening polymerization of one or more of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc.

(2) Polyester polyols ethylene glycol, diethylene glycol, propylene glycol, digloglene glycol, trimethylene glycol, 1,3-butylene glycol, 1#4-butylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, decamethylene glycol, bisphenol A
1 bisphenol F, p-xylylene glycol, 1,
4-cyclohexanediol, 1,4-cyclohexane dimetatool, glycerin, trimethylolpropane,
One or more of hexanetriol, intererythritol, malonic acid, maleic acid, succinic acid,
Polyester polyols made from one or more of adipic acid, glutaric acid, pimelic acid, sebacic acid, oxalic acid, phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, etc., or gloviolactone , butyrolactone, caprolactone, and other cyclic esters are ring-opening polymerized.

(3) Polymer polyol These include polyols obtained by graft polymerizing ethylenically unsaturated compounds such as acrylonitrile, styrene, and methyl methacrylate to the above polyether polyols and polyester polyols.

(4) Polybutadiene polyols These include 1,2-polybutadiene polyol, 1,4-polybutadiene polyol, polychloroprene polyol, butadiene-acrylonitrile copolymer polyol, and the like.

Among the polyols mentioned above, the effects of the production method of the present invention are particularly remarkable on polyols that are structurally highly hygroscopic, have a high molecular weight, and have a high viscosity. Specifically, it is effective for BoIJ ether polyols and polyester polyols having a molecular weight of 1000 or more, and particularly for polythiyl polyols.

Next, the polyisocyanate having at least two or more isocyanate groups in the molecule is not particularly limited, and any generally known polyisocyanate can be used. Examples of polyisocyanates that can be suitably used include the following compounds.

For example, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate,
Naphthalene diisocyanate, dimethylbiphenylene diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, polymethylene polyphenylisocyanate, and modified products of these isocyanates.

The greatest feature of the present invention is that, prior to carrying out the urethanization reaction using the above-mentioned polyol and polyisocyanate,
The point is that the polyol is dehydrated by azeotropic distillation.

For the azeotropic distillation, any known method may be used without any restriction. Specifically, this is a method in which a mixture of an organic solvent and a polyol that forms an azeotrope with water is distilled, and an azeotrope of water and the organic solvent is distilled out. If an increase in the viscosity of the system is undesirable, or if the urethanization reaction is directly carried out by the ordinary solution method, it is desirable to remove only water. An example of a method that can be suitably used is a method using a moisture metering receiver. That is, when the polyol and organic solvent system is heated, a mixture of the organic solvent and water is distilled off in gaseous form. By passing this mixed gas through a moisture metering receiver equipped with an Allene, the moisture is condensed and separated, and only the organic solvent returns to the original system. As a result, only water is removed from the system.

Here, the conditions required for the organic solvent are (&) the ability to form a minimum azeotrope with water, (b) no or very low compatibility with water, and (c) ) It is inert to polyols, (dJ boiling point is lower than the boiling point of the polyol used, and more preferably (e) it is inert to urethanization reaction.The above conditions are satisfied, Examples of suitable solvents include the following: chlorine, benzene, toluene,
Aromatic solvents such as xylene, ethylbenzene, chlorobenzene: octane, hexane, pentane, hegetane,
Aliphatic hydrocarbon solvents such as cyclohexane; and chlorine solvents such as carbon tetrachloride. Among these organic solvents, aromatic solvents are most suitable from the viewpoint of solubility of polyol.

When mixing an organic solvent and a polyol, there is no particular restriction on the mixing pressure, and it is possible to add the organic solvent to the polyol, add heboriol to the organic solvent, or add it in portions.
Either method is applicable.

Regarding the composition ratio, it is necessary to add an organic solvent so that the ratio of water contained in the polyol to the organic bath agent is less than the ratio of water in the azeotropic mixture composition, and the stirring capacity of the equipment It is necessary to add it to the appropriate viscosity. Therefore, the suitable value varies depending on the type of organic solvent, the type of polyol, and the molecular weight, but in general, organic bath agent: polyol = 0.5:1 to 20:1 (volume ratio), and it is more preferable. is 1:1 to 10:1.

When heating a system of polyol and organic solvent to perform azeotropic distillation,
- Stir the system inside the membrane.

The time required for azeotropic distillation varies depending on the type, composition ratio, and water content of the polyol and organic solvent, but
It takes about 30 minutes to 5 hours.

- The larger the amount of organic solvent refluxed into the membrane, the faster the process will be completed.

After completion of the azeotropic distillation, a urethanization reaction is carried out, and when carried out by a solution method, the polyisocyanate may be added as is to the system of the polyol and organic solvent. In addition, when carrying out by a non-solution method, the organic solvent may be distilled off while heating and stirring, and then the polyisocyanate is added, or the organic solvent may be distilled off after the polyisocyanate compound is added.

In the method for producing polyurethane of the present invention, there are no particular restrictions on the urethanization reaction, and generally known urethanization reaction conditions can be used as they are. That is, the amount of polyisocyanate used is such that the amount of isocyanate groups contained therein is in an equivalent ratio of 0.4 to 1.4, preferably 0.8 to 1.2, to the total amount of hydroxyl groups contained in the polyol. It is preferable to select the equivalent ratio. On the other hand, in order to obtain a higher molecular weight in order to improve physical properties, it is preferable to bring this equivalent ratio as close to 1 as possible. At this time, if water is present in the system, it is difficult to bring the equivalent ratio close to 1, and reproducibility is also difficult, causing variations in the physical properties of the obtained polyurethane.

Catalysts that may be used as necessary in the method for producing polyurethane of the present invention include amine catalysts such as triethylamine, triethylenediamine, N,N'-dimethylpiperazine, and N-ethylformoline; metal catalysts such as dibutyltin. Tin-based catalysts such as dilaurate, tin octoate, dimethyltin dichloride, trimethyltin hydroxide, triglytin acetate, dibutyltin diacetate and dibutyltin sulfide; iron-based catalysts such as iron acetylacetate and iron benzoate; nickel acetylacetonate, Nickel Octo:! 1--
)+1nickel/4' lumitate and other nickel-based catalysts; manganese-based catalysts such as manganese acetylacetonate and manganese-2-ethylhexanoate; lead-based catalysts such as lead-2-ethylhexanoate and lead oleate, etc. Any conventionally known catalyst can be used. Among the above catalysts,
Particularly preferred are amine catalysts and tin catalysts. In the present invention.

The amount of these catalysts to be used is preferably 0.001 to 5.0 parts by weight, particularly preferably 0.01 to 3.0 parts by weight, based on 100 parts by weight of the total amount of polyol. Known conditions such as reaction temperature and time are used.

(Actions and Effects of the Invention) A feature of the present invention is that, prior to carrying out the valethanization reaction using a polyol and a polyisocyanate, the polyol is
It forms a minimum azeotropic mixture with water and performs azeotropic distillation in an organic solvent that is inert to polyols. This allows polyols to be used as structurally highly hygroscopic, high molecular weight, and highly viscous polyols. It can also be easily dehydrated by heating and stirring the organic solvent to reflux. By dehydrating the polyol, side reactions such as the amination reaction of isocyanate groups, the formation of urea bonds, and the Viillet reaction are suppressed during the urethanization reaction, and as will be explained in detail in the examples below, the formation of The result is an increase in the molecular weight of the polyurethane.

Therefore, the method for producing polyurethane of the present invention is an excellent method for increasing the total number of polyurethane polymer chains and forming them regularly, and is particularly suitable for producing flexible polyurethane elastomers using high molecular weight polyether polyols. This is a suitable manufacturing method.

EXAMPLES The present invention will be explained in more detail by way of examples.

Example 1 Polypropylene glycol (number average molecular weight 2.600)
26 g (0,020 equivalent Jl) was placed in a 500 cc three-necked flask equipped with an Alene water meter and a dropping funnel, and 300 cc of benzene was added thereto and magnetically stirred. This was heated to reflux the benzene. As the reflux progressed, water was separated in the water quantitative receiver, and after about 4 hours, no further separation of water was observed. Next, from the dropping funnel, hexamethylene diisocyanate)
(1,51i, 0.018 eq.) and benzene 10 ce
The solution was added dropwise into the heated and stirred system. After 1 hour, add 0.02.1 di-n-butyltin dilaurate.
: 10 cet of benzene was added.

After 4 hours, heating and stirring were stopped, and benzene was removed from the contents in the flask using an evaporator. The polyurethane produced was a highly viscous, colorless and transparent liquid, and its molecular weight was determined to be 57,000 by polyurethane chromatography using tetrahydrofuran as a solvent.

Example 2゜Poly(oxypropylene)Jsu(oxyethylene)glycol, (propylene oxide/ethylene oxide-5
0150% random copolymer, diol type, molecular weight 13.600) 27.2i 4.00
Air stirring was performed. This was heated to reflux the benzene. As the reflux progressed, water was separated in the water quantitative receiver, and after about 4 hours, no further separation of water was observed.

Next, hexamethylene diisocyanate) 0.312. F
A solution of 10 cc of benzene and 10 cc of benzene was added to the heated and stirred system. After 1 hour, 0.029"f of di-n-butyltin dilaurate was added.

After heating and stirring the entire system for 4 hours, the reaction was stopped. By removing benzene with an evaporator, a highly viscous colorless transparent liquid polyurethane was obtained. Tetrahydro 7
The molecular weight Fi determined by chromatography using all run solvents was 67.600.

Example 3 Poly(oxypropylene) poly(oxyethylene) glycol, (propylene oxide/ethylene oxide-5
0150,:177 dumb copolymer, diol type,
Molecular weight 13,600) 50 g (7,35X10'
As a result of carrying out the same operations as in Example 2, except for using 200 cc of benzene and 0.853 g (9,80 x 10 activity) of benzene (9,80 x 10 activity), a highly viscous transparent liquid was obtained. A polyurethane was obtained.The molecular weight was measured in the same manner as in the above example and found to be 76.0.
It was 00.

Example 4゜Poly(oxypropylene)&su(oxyethylene)glycol (7”propylene oxide/ethylene oxide-5
0150, random copolymer, diol type, molecular weight 13,600) was placed in a 500 cc three-necked flask equipped with a moisture meter with an Allene, and 250 cci of benzene was added thereto, followed by magnetic stirring. As the reflux progressed, water was separated in the water quantitative receiver, and after about 3 hours, no new separation of water was observed.Next, hexamethylene diisocyanate 0.427.!9 (5, 08X10 ik
) and 10 cc of benzene were added to the system, which was heated and stirred. After heating and stirring the entire system for 4 hours, the reaction was stopped.

By removing benzene with an evaporator, a highly viscous colorless transparent liquid polyurethane was obtained.

The total molecular weight was measured in the same manner as in the above example, and the result was 44.
It was 000.

Example 5 Poly 1-ropylene glycol (several thousand q molecules i, 2.600
) 529 (0,040 equivalents) was placed in a 500 cc three-necked flask equipped with a water metering receiver with an Allene and a dropping funnel, and all 300 cc of benzene was added thereto, followed by magnetic stirring. This was heated to reflux the benzene. As the reflux progresses, water is separated in the water quantitative receiver,
After 1 hour and 20 minutes, no new water equinoxes were observed. Next, from the dropping funnel, tolylene diisocyanate)
A solution of 3.4.9 (0,040 equivalents) and 10 cc of benzene was dropped into the heated and stirred system. continue,
0.061 i of di-n-butyltin dilaurate and 10 cc of benzene were added. After 7 hours, heating and stirring were stopped, and benzene was removed from the contents in the flask using an evaporator. The produced polyurethane is a highly viscous colorless transparent liquid, and its molecular weight is 48 as determined by chromatography using tetrahydrofuran as a solvent.
,600.

Comparative Example 1 Poly(oxypropylene) poly(oxyethylene) glycol (propylene oxide/ethylene oxide = 50
150. About 200 g of random copolymer, diol type, molecular weight 13,600) was placed in a beaker, and about 501 molecular sieves were added thereto. This at 50℃/
1 Preliminary drying was performed using Hg for 15 hours. Dry poly(oxypropylene) poly(oxyethylene) glycol 27.211 (4,00X 10-3 equivalents),
300 cc of benzene, which had been previously dehydrated and dried, and 0.0 cc of sheen-n-butyltin dilaurate.
02N was added. After thoroughly mixing these with magnetic stirring under a nitrogen stream, hexamethylene diynecyanate) 0
．． 269L (3,2X10-t!/k) and benzene 50
cc (solution D was added. Then, the mixture was heated and stirred to reflux the benzene. After refluxing the benzene for 6 hours, the reaction was stopped and benzene was removed from the system using an enogu borator. The polyurethane produced was The molecular weight was measured by Dal permeation chromatography using tetrahydrofuran as a solvent and found to be 23.400.

Example 6. Comparative Example 2 As a polyol, a nol type compound as shown in Table 1 was mixed with the organic solvent listed in Table 1, and the mixture was prepared as shown in Table 1 using the same apparatus as in Example 2. Dehydration and drying treatment is carried out under suitable conditions.9.

Next, polyisocyanate compounds and catalysts as shown in Table 1-3 were added to each system, and reactions were carried out under the conditions shown in Table-3.

After the reaction, the organic solvent was distilled off from each system under reduced pressure. The molecular weight of the obtained polyurethane was determined by Dal permeation chromatography using tetrahydrofuran as a solvent. The results are shown in Table-4.

In addition, as a comparative example, polyols shown in Table 2 were subjected to dehydration treatment by heat defoaming under the conditions also listed in Table 2. Next, from each dehydrated sample, 0.02 equivalent, except for Comparative Example 2-3, 0.004
An equivalent amount was placed in a 500 cc flask, and an organic solvent that had been previously dehydrated and dried as shown in Table 3 was added thereto under a nitrogen stream.

Stirring was performed. A polyisocyanate compound and a catalyst as shown in Table 3 were added to this, and a reaction was carried out under the conditions as shown in Table 3. Post-reaction treatments were carried out in the same manner as in the above examples. The molecular weight of the produced polyurethane was also measured in the same manner as in the above example, and is shown in Table 4.

Claims (1)

[Claims] In a method for producing polyurethane from a polyol having at least two or more hydroxyl groups in the molecule and a polyisocyanate having at least two or more isocyanate groups in the molecule, a polyol that has been dehydrated by azeotropic distillation is used as the polyol. A method for producing polyurethane characterized by: