JPH11302245A - Production of monoisocyanate compound and composition for polyurethane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a monoisocyanate compound useful for directly converting a natural trifunctional polyol such as castor oil or lesquerella oil to a bifunctional polyol and having high safety and obtain a composition for polyurethane having low viscosity and good workability in production of polyurethane and capable of providing a cured product excellent in hue and free from surface tackiness. SOLUTION: This method for producing a monoisocyanate compound comprises reacting a diisocyanate having <=300 molecular weight with a monohydroxy compound equivalent or less to the diisocyanate and then removing excess diisocyanate by vacuum distillation. This polyurethane composition contains a reaction product of a monoisocyanate compound with at least one kind of vegetable oil selected from castor oil and lesquerella oil as a polyol component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an intermediate material for polyurethane, which is useful for paints, adhesives, sealing agents, flooring materials, structural materials, clothing materials, cushioning materials, sealing materials for electronic parts, and the like. It relates to a composition for polyurethane using the same. More specifically, the present invention relates to a method for producing a monoisocyanate compound suitable for modifying castor oil and resquella oil, and a polyurethane composition using the same to provide a cured product having low viscosity, excellent workability and no stickiness.

[0002]

2. Description of the Related Art Castor oil and resquella oil are triglycerides of fatty acids containing a monohydroxy unsaturated carboxylic acid having 18 or 20 carbon atoms as a main component, and are used as trifunctional polyols. However, bifunctional raw materials are generally mainly used to obtain a strong polyurethane cured product. Against this background, studies have been made to change castor oil and resquella oil into bifunctional groups. JP-B-63-22216 proposes that a transesterification product of castor oil and a natural fat / oil substantially free of hydroxyl groups is used as a part of the polyol. But,
The cured polyurethane from the transesterified polyol had surface stickiness, and the amount of addition was limited. In Japanese Patent Publication No. 60-28842, castor oil 1
Monoisocyanate (R-NCO, wherein R is a monovalent aromatic, aliphatic, or alicyclic residue) compound 0.3 to
A polyurethane resin composition using a modified castor oil reacted with 0.8 mol has been proposed. However, monoisocyanates represented by phenyl isocyanate have not been put to practical use because of their high toxicity.

[0003]

An object of the present invention is to provide a method for producing a highly safe monoisocyanate compound, and a low viscosity, excellent workability and excellent hue from castor oil or resquella oil. The object of the present invention is to provide a composition for polyurethane having no stickiness on the surface of a cured product.

[0004]

Means for Solving the Problems The present inventors have made intensive studies mainly on various isocyanate compounds, polyols and natural fats and oils such as castor oil, and have reached the present invention. That is,
The present invention provides: 1. A method for purifying a monoisocyanate compound, which comprises reacting a dihydroxy isocyanate having a molecular weight of 300 or less with a monohydroxy compound having an equivalent weight or less, and then removing excess diisocyanate by distillation under reduced pressure. The present invention relates to a composition for polyurethane, comprising as a polyol component a reaction product of the monoisocyanate compound obtained in the preceding section and at least one vegetable oil such as castor oil or rescue oil.

The diisocyanates having a molecular weight of 300 or less include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, tetramethyl xylylene diisocyanate, methyl cyclohexane diisocyanate, dimethyl cyclohexane diisocyanate, cyclohexane dimethyl isocyanate, Diphenylmethane diisocyanate and the like can be used. Preferably, the molecular weight is 200 or less, particularly preferably tolylene diisocyanate, 1,5-naphthalenediisocyanate,
Isophorone diisocyanate, hexamethylene diisocyanate and the like are preferred because they are easy to handle and can be obtained industrially.

As the monohydroxy compound, any organic compound having a primary or secondary hydroxyl group can be used. For example, alcohols such as methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, benzyl alcohol, octanol, 2-ethylhexanol, nonanol, decanol and dodecanol, and those containing an ether or ester bond can also be used. For example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, oxyethylene oxypropylene copolymer, oxybutylene oligomer and co-oligomer,
Monoalkoxides and monoesters such as butanediol, nonanediol and decanediol. Further, as another hydroxy compound, phenol, cresol, naphthol, cumylphenol and the like can be used. When a hydroxy compound having a long chain and particularly having many ether bonds is used, a monoisocyanate compound suitable for low-hardness polyurethane can be obtained. When a hydroxy compound having a ring structure is used, it can be made suitable for polyurethane for high hardness.

The reaction between a diisocyanate and a monohydroxy compound is carried out as follows. It is desirable that the monohydroxy compound be dried in advance. Drying can be performed by a known method such as distillation, adsorption, and aeration of dry nitrogen gas. Charge the diisocyanate in excess of the equivalent,
The monohydroxy compound is slowly added with stirring under a dry inert gas atmosphere. The temperature at this time is 20 to 10
Keep at 0 ° C. Next, 100 ~ 150 after the end of fever
Aging at about 1 hour. Next, when excess diisocyanate is recovered by distillation under reduced pressure, a monoisocyanate compound is obtained in the bottom. Isocyanate group in preparation /
The hydroxy group ratio is preferably 2 or more, and more preferably 3 to 10. Further, the distillation temperature for recovering excess diisocyanate is preferably 100 to 200 ° C. at the pot temperature. In the bottom, a monoisocyanate compound in which one of the isocyanate groups of the diisocyanate is urethane-bonded to a monohydroxy compound is a main component, and in addition, monoisocyanate in a form in which these are dimerized by an allohanate bond is also generated. If the isocyanate group / hydroxy group ratio is smaller than the above range, it is not preferable because two diisocyanate groups are both urethanized. The fraction obtained by distillation is diisocyanate,
Can be reused as is. However, if this ratio is larger than the above range, the energy loss increases, which is not preferable.

Next, the reaction of the above monoisocyanate compound with castor oil, resquella oil, or a mixed oil thereof will be described. These charging ratios are determined so that the average number of hydroxyl groups is usually two. The reaction proceeds by heating and stirring at about 60 to 200 ° C. for about 1 to 8 hours in a dry inert gas atmosphere. A catalyst is not particularly required, but a known urethane-promoting catalyst may be added in advance, in which case the reaction conditions can be relaxed. The progress of the reaction can be monitored by hydroxyl value, isocyanate concentration, infrared spectrum, GPC and the like.

The polyurethane composition of the present invention may contain another polyol component in addition to the above components. For example, a hydroxy-terminated polybutadiene, a hydrogenated product thereof, or an alkylene oxide or /
And one or more known polyols such as adducts of lactones and polyester polyols.

In the polyurethane composition of the present invention, a polyisocyanate is an essential component together with these polyols. As the polyisocyanates, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like and modified products thereof are used. The amount of the polyisocyanate used is determined based on the stoichiometric amount.
The mixed solution is sent to a required place by a method such as casting, coating, spraying, pouring, or spraying, and is cured by heating or ambient temperature.

The composition of the present invention may contain known additives such as a urethane-promoting catalyst, a foaming agent, a surfactant, and a plasticizer. In addition, asphalt, coal tar, petroleum resin, and by-product residue in the production of phenols such as phenol, cresol, and resorcin may be mixed for the purpose of improving waterproofness and corrosion resistance and reducing costs. Further, talc, clay, silica, alumina, calcium carbonate, iron oxide, titanium oxide, carbon black, glass and the like may be further contained as fillers and pigments.

Uses of the composition of the present invention include paints, adhesives,
It covers a wide range of industries including sealing agents, flooring materials, synthetic tatami materials, bumpers, structural materials, clothing materials, footwear materials, cushioning materials, electronic component sealing materials, and insulating materials.

[0013]

The embodiments of the present invention will be described with reference to the following Examples, but it should not be construed that the invention is limited thereto. Acid value in the examples,
The hydroxyl value was measured by the standard oil and fat analysis test method established by the Japan Oil Chemical Association. In each case, the unit is mg-KOH / g. The hue was measured by the Gardner method, the isocyanate content was measured by JIS K1603, and the viscosity at 25 ° C. was measured by an E-type viscometer. The physical properties of the polyurethane were evaluated as follows.

<Method for Evaluating Physical Properties of Polyurethane> (a) Compatibility: Polyol and polyisocyanate (carbodiimide-modified diphenylmethane diisocyanate: MDI-LL, manufactured by Mitsui Chemicals) are mixed at an NCO / OH ratio of 1.05 (mol / mol). The sample was allowed to stand at room temperature under reduced pressure, and the following judgment was made. ：: uniform transparent, ×: non-uniform separation (b) Curing The mixture of (a) was mixed with a mold for hardness measurement (a petri dish made of polymethylpentene) and a mold for tensile strength test (a constricted part made of high-density polyethylene: inner diameter 5 mm, length 10 mm) , Copper chuck parts: inner diameter 7 mm, length 30 mm)
The composition was cured by heating at 5 ° C. for 5 hours, and the following tests were performed. (C) Curability: Curing status after 3 hours at 100 ° C.
It was determined as follows. ：: solid (hardened), △: semi-solid, ×: liquid (d) Hardness: JISK-2215 (e) Tensile strength: Fix the upper part of the tensile strength test piece, fix the plastic tank at the lower part, and add 1 kg of water to this / Min. The load when the test piece was cut was divided by the initial area of the neck portion of the test piece to obtain the tensile strength. (F) Surface stickiness: The stickiness of the cured product surface at room temperature was examined to determine the presence or absence of stickiness.

Example 1 2,4-Tolylene diisocyanate (manufactured by Tokyo Kasei, 19.2% isocyanate concentration) was placed in a 500 ml multi-necked flask equipped with a stirrer, thermometer, dropping funnel, nitrogen blowing tube, distillation tube and condenser. 279 g (1.6 mol) of 2-ethylhexyl alcohol 26 dried under a nitrogen atmosphere with stirring.
g (0.2 mol) are added dropwise over 40 minutes. The exotherm extinguishes the temperature from room temperature to 40 ° C. When the exotherm subsides, heat and heat at 100 ° C. for 1 hour to complete the reaction. Then, the pressure was reduced, and the unreacted raw material was recovered under the conditions of a pressure of 13 mmHg and a pot temperature of 160 ° C. until no distillate was found. Collection amount 2
40 g, the isocyanate concentration of this recovered liquid is 19.1%
, Indicating that it can be reused as it is.
In addition, 60 g of a slightly yellow transparent liquid was obtained as a bottom residue. Isocyanate concentration 12.1%, hue 1, viscosity 3480 cp
Met. From GPC analysis and isocyanate concentration of this product, the following composition was found. RO-CO-NH-Ar-N = C = O 82.2% O = C = N-Ar-N = C = O 0.7% Others 0.3% Here, the Ar group represents a tolylene group, and the R group represents a 2-ethylhexyl group.

Example 2 61 g of the monoisocyanate compound of Example 1 was placed in a 500 ml four-necked flask, heated to 80 ° C., and 93 g of purified castor oil (manufactured by Toyokuni Oil) was added dropwise with stirring over 30 minutes. did. Thereafter, the mixture was heated and stirred at 100 to 150 ° C. for 3 hours to complete the reaction, and 125 g of an oily substance was obtained. Acid value 0.4, hydroxyl value 82.8, hue 3.5, viscosity 1058
It was 0 cp. From the GPC comparison before and after the reaction, it was confirmed that the monoisocyanate compound almost reacted and disappeared. From these results, it was found that this was a polyol having an average number of functional groups of 2.

Example 3 16.94 g of the polyol obtained in Example 2 and 3.78 g of polyisocyanate (MDI-LL, manufactured by Mitsui Chemicals, isocyanate concentration: 29.1%) were mixed, and defoamed under reduced pressure. Injected. Next, it was heated and cured in a 100 ° C. constant temperature bath for 5 hours, and the physical properties were examined. Table 1 shows the results.

Reference Example 1 252 g of castor oil and rapeseed oil 93 were placed in the same apparatus as in Example 1.
g, and dried under reduced pressure while blowing nitrogen with stirring. Next, 20 ml of tetrahydrofuran and 1 ml of a 28% sodium methylate methanol solution were added, and the mixture was heated at 80 ° C. for 2 hours at room temperature.
And react for 1 hour. The reaction was terminated by neutralization with an equivalent amount of phosphoric acid, and 337 g of a liquid material was obtained by removing clay and distilling off the light fraction.
I got Hydroxyl value 120, acid value 0.8, viscosity 261c
p, hue 1.5.

Comparative Example 1 The polyol of Reference Example 1 was cured in the same manner as in Example 3, and the physical properties of the cured product were examined. The results are shown in Table 1. The surface of the cured product had stickiness and low tensile strength.

[0020]

According to the method for producing a monoisocyanate compound of the present invention, a highly safe monoisocyanate can be obtained. By using this for the modification of castor oil or resquella oil, the viscosity is low. Provided is a polyurethane composition which can reduce the working speed and can be formed into a cured product without surface stickiness.

Claims (2)

[Claims] 1. A method for producing a monoisocyanate compound, which comprises reacting a diisocyanate having a molecular weight of 300 or less with a monohydroxy compound having an equivalent weight or less and removing excess diisocyanate by distillation under reduced pressure. 2. A polyurethane composition comprising, as a polyol component, a reaction product of the monoisocyanate compound obtained in claim 1 and at least one vegetable oil such as castor oil or rescue oil.