JP2569659B2 - Method for emulsifying isocyanate compound - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for emulsifying an isocyanate compound, and more specifically, it is possible to emulsify an isocyanate compound at any time by using a specific emulsifier that is stable to isocyanate groups. The present invention relates to a method for obtaining an emulsion of an isocyanate compound having good stability.

[Prior art and its problems] Isocyanate compounds are basic raw materials in the urethane industry and are used in all industrial fields, but most of them are used in non-aqueous systems. However, in recent years, the desire to use isocyanate compounds in aqueous systems has increased due to the demand for stability and the expansion of the range of applications, and their use in aqueous systems has been studied as an adhesive or a crosslinking agent, and in the production of aqueous urethane resins. Significant amounts of isocyanate compounds have already been used in aqueous systems in the wood bonding field.

However, isocyanate compounds generally do not dissolve in water, and therefore, it is necessary to emulsify the isocyanate compound for use in an aqueous system. Therefore, it is advantageous if the isocyanate compound can be emulsified. Since the isocyanate compound is a substance which is unstable in water, it is desirable that it can be emulsified in a short time and with a simple operation, and it is difficult to use emulsification as a practical problem if a special operation or equipment is required for emulsification. .

The simplest emulsification method is a method in which an emulsifier is added and mixed to the isocyanate compound as needed to give self-emulsifying properties, and then water is added to emulsify the mixture, or the mixture is poured into water and stirred and emulsified. For this purpose, the emulsifier must have a sufficient emulsifying ability. In addition, the emulsifier itself must be stable and easy to handle, easily dissolved in the isocyanate compound, have good stability, and must be resistant to isocyanate groups. It is active and does not deteriorate or reduce the emulsifying property of the isocyanate compound over time.If it is used as a cross-linking agent, it has good compatibility with other resins and chemicals used in combination. Required.

From the above viewpoints, conventionally used emulsifiers are hardly applicable to emulsification of isocyanate compounds. This is because ordinary anionic emulsifiers and cationic emulsifiers are generally solid, do not dissolve in the isocyanate compound, and the liquid type also contains a large amount of water or contains an alcohol. Can not be used to react with. Also,
Nonionic emulsifiers include liquid types with low water content,
Although they have good solubility with isocyanate compounds, they all have a hydroxyl group in a hydrophilic group, and thus react with an isocyanate group to lose emulsifying ability.

For the method of emulsifying isocyanate compounds, refer to
No. 7472 discloses the use of an adduct of polyoxyethylene monoalkyl ether and polyisocyanate, which has at least one isocyanate group, as an emulsifier, but this emulsifier has an active isocyanate group. Therefore, the stability itself is poor, and the isocyanate group loses its effect as an emulsifier due to a moisture absorption reaction. For this reason, this emulsifier is not handled independently in this form, and in practice, the polyoxyethylene monoalkyl ether is added to the isocyanate compound to be emulsified and reacted as specified in the specification. The emulsifier is used to produce the emulsifier. As described above, in the above-mentioned method, it is necessary to add a polyoxyethylene monoalkyl ether to an isocyanate compound to be emulsified in advance and react it, and it is not possible to impart emulsifiability merely by adding and mixing when necessary.

As a similar method, JP-B-61-43396 discloses that a compound having a polyoxyethylene chain at both ends and a polyoxypropylene glycol at both ends is added to a polyisocyanate compound and reacted therewith. Just like adding and mixing, emulsifiability cannot be obtained.

Therefore, in these methods, when the isocyanate compound is used by emulsification, it is necessary to carry out an emulsion modification reaction on the isocyanate compound to be used in advance, and to prepare a sufficient amount of the isocyanate compound. However, there is a drawback that the mobility of emulsifying and using a necessary amount of the compound is poor.

Furthermore, in these methods, the isocyanate compound to be emulsified has a relatively low molecular weight and a monomeric isocyanate compound has a good emulsifying effect, but glycols, triols or polyester polyols, polyols such as polyether polyols and polyisocyanate compounds are used. Polyisocyanates having a relatively high molecular weight and a high urethane bond content, such as so-called adduct-type polyisocyanates and isocyanate prepolymers, which have been reacted with the same, have the disadvantage that the emulsifying effect is poor and it is difficult to impart emulsifying properties. doing.

Further, when an isocyanate compound provided with emulsifying properties is used in an aqueous system, the isocyanate group inherently has reactivity with water, so that the emulsified isocyanate compound gradually reacts with water and loses its activity. Although this is essentially unavoidable, delaying the reaction with water as much as possible and maintaining a long pot life are important issues in actual use, and the emulsifiers used will benefit from this. However, the conventional method is unsatisfactory in this respect, and an emulsification method for obtaining an emulsion of an isocyanate compound having a longer pot life is required.

[Means for Solving the Problems] The present invention has been made in view of the conventional circumstances as described above, and the present inventors have developed a range from low molecular weight isocyanate compounds to high molecular weight isocyanate prepolymers. As a result of intensive research, to obtain a stable and easy-to-handle emulsifier and emulsification method, which can easily emulsify these by simply adding and mixing, and obtain an emulsion with a long pot life, It has been found that this is possible by using certain emulsifiers of the present invention and has reached the present invention.

That is, the present invention provides a compound represented by the general formula: (Where R is an alkyl group having 1 to 3 carbon atoms, X is a residue of a polyisocyanate compound, Y is a higher alcohol having 8 or more carbon atoms, a hydroxyl group-containing fatty acid ester having 8 or more carbon atoms of a fatty acid, and a molecular weight of 200 to 1000. Is a residue after any of the polyoxypropylene monoalkyl ethers has reacted with the isocyanate group, n is an integer of 5-35, and l, m, p and q are positive integers.) A method for emulsifying an isocyanate compound, characterized in that one or a mixture of two or more of the above compounds is used as an emulsifier for the isocyanate compound.

Here, the isocyanate compound refers to all generally known organic isocyanate compounds, and can be used arbitrarily. Examples thereof include monoisocyanates such as phenyl isocyanate, tolyl isocyanate, butylphenyl isocyanate, cyclohexyl isocyanate, lauryl isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate and their nuclear water additives, 2,4- and 2, Diisocyanates such as 6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 1,5-naphthylene diisocyanate, 2,4,
Buret-type polyisocyanate derived from triisocyanates such as 6-triisocyanate toluene, 2,4,4'-triisocyanate diphenyl ether, tri (isocyanatephenyl) methane, 3 moles of hexamethylene diisocyanate and 1 mole of water, Isocyanurate-type polyisocyanate formed by trimerization of diisocyanates as described above, diphenylmethane-
Polymethylene polyphenyl polyisocyanate by-produced in the production of 4,4'-diisocyanate, and adduct-type polyisocyanate obtained by adding the above-mentioned polyisocyanate to glycols, triols or polyester polyols, polyether polyols, etc. And polyisocyanates such as isocyanate prepolymers,
And mixtures thereof.

On the other hand, a general formula as an emulsifier; Or a general formula; (Wherein R, X, Y, n, l, m, p and q have the same meanings as described above). Both compounds [I] and [II] are compounds having a hydrophilic group. It is synthesized by linking an oxyethylene mono-lower alkyl ether and a hydroxyl group-containing compound having an aliphatic group or an alkoxypolyoxypropylene chain as a hydrophobic group with a polyisocyanate compound.

The alkyl group (R) of the polyoxyethylene monoalkyl ether is a methyl, ethyl or propyl group, and an alkyl group larger than this is not preferable because the effect as a hydrophilic group is reduced. The most preferred alkyl group is a methyl group.

If n, which is the number of repeating units of polyoxyethylene, is less than 5, the effect as a hydrophilic group is low, and if it exceeds 35, solidification is likely to occur due to an increase in crystallinity, which is not preferable in terms of stability and handling. A more preferred n number is 8 to 25.

X is a residue of a polyisocyanate compound. As the polyisocyanate compound forming X, the above-mentioned diisocyanates, triisocyanates and other polyisocyanate compounds in the isocyanate compound can all be used. However, an adduct-type polyisocyanate, an isocyanate prepolymer, or the like having an excessively large molecule is not suitable, and the molecular weight is preferably 600 or less.

Y is a residue of a hydroxyl group-containing compound that forms a hydrophobic group. Examples of the higher alcohol having 8 or more carbon atoms as the hydrophobic group-forming compound include octanol, decyl alcohol, lauryl alcohol, oleyl alcohol,
Isostearyl alcohol, so-called synthetic higher alcohols obtained by oxo reaction of olefin, liquid phase oxidation of paraffin, and the like, and mixtures thereof, and the like. An alcohol having less than 8 carbon atoms is not preferable because the effect as a hydrophobic group is poor and a good emulsifying effect cannot be obtained.

Examples of the hydroxyl group-containing fatty acid ester having 8 or more carbon atoms of the fatty acid include monoglycol esters such as lauric acid, isomyristic acid, isopalmitic acid, isostearic acid, oleic acid, etc. Examples thereof include fatty acid partial ester compounds of polyhydric alcohols such as tate, and alkyl esters such as butyl and 2-ethylhexyl ricinoleate, and triglycerides. Castor oil containing glycinol as a main component can be used as triglyceride ricinoleate. A hydroxyl group-containing fatty acid ester having less than 8 carbon atoms in the fatty acid is not preferred because the effect as a hydrophobic group is inferior.

Further, since polyoxypropylene monoalkyl ether forms a hydrophobic group, it must be insoluble in water. For this reason, the alkyl group is preferably a compound having 4 or more carbon atoms, such as butyl ether and 2-ethylhexyl ether. preferable. The molecular weight is preferably 200 to 1000, and 200
If it is less than 1,000, the effect as a hydrophobic group is weak, while if it exceeds 1,000, the molecular weight of the emulsifier becomes too large, which is not preferable.

Each of the hydrophobic group-forming compounds listed above has a melting point of 35.
It is preferable that the temperature is not higher than ° C. If the temperature exceeds 35 ° C., the resulting emulsifier tends to cause poor solubility in isocyanate compounds and precipitation at low temperatures. These hydrophobic group-forming compounds can be used as a mixture of two or more compounds.

m and l are derived from the number of functional groups of the polyisocyanate compound and the hydrophobic group-forming compound used. Since one isocyanate group of the polyisocyanate bonds to the hydroxyl group of the hydrophobic group-forming compound, m is (the number of isocyanate groups of the polyisocyanate compound) -1, that is, 1 for diisocyanates and 2 for triisocyanates, Also, 1 is a number equal to the number of hydroxyl groups of the hydrophobic group-forming compound because all hydroxyl groups of the hydrophobic group-forming compound are reacted with the isocyanate group.

p and q are both 1 or more because the polyisocyanate compound links at least one polyoxyethylene monoalkyl ether and the hydrophobic group-forming compound, and the sum thereof is equal to the number of functional groups of the polyisocyanate compound. .

Examples of the above emulsifiers include, for example, the following.

CH ₃ O (CH ₂ CH ₂ O) ₁₅ CONH (CH ₂ ) ₆ NHCOOC ₁₅ H ₃₁ It is recognized that more preferable emulsifiability can be obtained by selecting the same type of polyisocyanate compound as the isocyanate compound to be emulsified for use in preparing these emulsifiers. This is considered to be because the polyisocyanate compound serving as a linking agent in the structure of the emulsifier also acts as a hydrophobic group, which helps to improve the affinity of the entire hydrophobic group with the isocyanate compound to be emulsified.

In addition, since the polyisocyanate compound as the linking agent in the emulsifier also acts as a hydrophobic group, the proportion of the total hydrophobic groups can be easily increased. Is more useful mainly for introducing a hydrophilic group.

The emulsifier used in the method of the present invention is a nonionic emulsifier, and by adjusting the content of polyoxyethylene mono-lower alkyl ether, an emulsifier having a wide range of HLB can be synthesized. When an isocyanate compound is used by emulsifying it in water, it is generally used as an O / W emulsion, and among these emulsifiers, those having an HLB of about 8 to 16 are most widely used. Also, depending on the application,
When an O-type emulsion is to be obtained, it can be applied by designing and using an emulsifier having a lower HLB. As described above, various emulsifiers can be designed according to the use and purpose.

As a method for synthesizing an emulsifier, a polyoxyethylene mono-lower alkyl ether is added to a polyisocyanate compound and reacted, and then a polyoxyethylene mono-lower alkyl ether is added or reacted, or a polyoxyethylene mono-lower alkyl ether is added to the polyisocyanate compound. After the reaction, the reaction can be carried out by any of the methods of reacting a hydrophobic group-forming compound. However, the hydrophobic group-forming compound may have poor compatibility with the polyisocyanate compound or the polyoxyethylene mono-lower alkyl ether in some cases. In such a case, a method in which the compound is first reacted like a method gives a good result. Even in the case of poor compatibility, it can be completely homogenized by the reaction. In some cases, a method of using an appropriate organic solvent and distilling it after completion of the reaction may be employed. The reaction is carried out at a temperature between normal temperature and 100 ° C.

The emulsifier of the present invention obtained as described above is an almost transparent oily liquid and is extremely stable. Further, depending on the composition, it may be jellyed at a low temperature, but is well dissolved in the isocyanate compound. Further, since the compound is inert to the isocyanate group, the isocyanate compound to which the compound is added is stable for a long period of time.

The emulsifier used for the emulsification of the isocyanate compound may be used in any amount depending on the purpose. In general, the use of 5 to 20% of the isocyanate compound to be emulsified can sufficiently achieve the purpose. As a general emulsification method, by adding and mixing the emulsifier in advance with the isocyanate compound to be emulsified, the isocyanate compound can have self-emulsifiability in water. That is, the isocyanate compound thus prepared can be easily emulsified by adding it to water or, when using it as a cross-linking agent, to a base aqueous polymer or the like and stirring. Further, emulsification can also be carried out by a so-called phase inversion emulsification method in which water is added little by little to the emulsifying isocyanate compound. This method is relatively simple and a good emulsion can be obtained. In some cases, it is also possible to add an isocyanate compound to water containing the emulsifier and carry out mechanical emulsification by vigorous shear stirring, and an arbitrary method is adopted depending on the intended situation.

Further, the isocyanate compound to be emulsified can be easily emulsified by the above-mentioned method even with a relatively high molecular weight isocyanate prepolymer which has conventionally been difficult to emulsify. Further, the emulsion of the isocyanate compound obtained by the method of the present invention in this manner,
It is noted that it has a significantly longer pot life compared to that by the conventional method. Although the reason for this is not clear, it is considered that the surface of the emulsion particles of the isocyanate compound is covered by the hydrophobic group of the emulsifier, thereby delaying the contact reaction with water.

The fact that a long pot life of this isocyanate emulsion can be obtained is one of the major features of the present invention.

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. In the following description, all parts and percentages are by weight unless otherwise specified.

Production Example 1 (Synthesis of emulsifier) 178 parts of isophorone diisocyanate was added to 200 parts of a synthetic isoalkyl alcohol having a hydroxyl value of 225, and reacted at 90 ° C for 3 hours. The NCO content of the reaction system was 8.9%, and the reaction almost proceeded as intended. Then, 480 parts of polyoxyethylene monomethyl ether having a hydroxyl value of 93.5 were added, and 90
The reaction was performed at a temperature of 3 ° C. for 3 hours. The reaction product was a slightly yellow oily liquid which was almost transparently soluble in water. This is designated as emulsifier A.

Production Example 2 (same as above) A crude product having an isocyanate equivalent of 135 and an average number of functional groups of 2.7
4,4'-diphenylmethane diisocyanate (hereinafter referred to as crude M
187 parts of oleic acid monoglyceride having a hydroxyl value of 300 was added to 365 parts of DI), reacted at 60 ° C. for 2 hours, and polyoxyethylene monomethyl ether having an average molecular weight of 560 was added to 9 parts.
52 parts were added, and the mixture was further reacted at 70 ° C. for 3 hours. The reaction product was a reddish-brown transparent viscous liquid which was slightly turbid but well soluble in water. This is designated as emulsifier B.

Production Example 3 (same as above) Average molecular weight in 200 parts of 2,4-tolylene diisocyanate
643 parts of polyoxyethylene monomethyl ether of 560 to 60
The mixture was added over about 2 hours while maintaining at ℃, and after further reacting for 2 hours, 308 parts of oleyl alcohol was added and reacted at 70 ° C. for 3 hours. The reaction product is a clear yellow oily liquid,
It was transparently soluble in water. This is designated as emulsifier C.

Production Example 4 (same as above) Crude MD having an average number of functional groups of 2.7 and an isocyanate equivalent of 135
I While maintaining 100 parts at 60 ° C., 266 parts of polyoxyethylene monoethyl ether having an average molecular weight of 600 was added in about 2 hours, and after further reacting for 3 hours, Diadol 135 (manufactured by Mitsubishi Chemical Industry Co., Ltd.) Synthetic higher alcohol, hydroxyl value 260) 6
4 parts were added and reacted at 70 ° C. for 3 hours to obtain an emulsifier. This emulsifier was a reddish brown transparent viscous liquid and was well soluble in water. This is designated as emulsifier D.

Production Example 5 (same as above) 174 parts of 2,4-tolylene diisocyanate had an average molecular weight of
405 of polyoxypropylene monohexyl ether 405
After reacting at 70 ° C. for 3 hours, 862 parts of polyoxyethylene monomethyl ether having a hydroxyl value of 65.1 was further added, and the mixture was reacted at the same temperature for 3 hours. The reaction product was a pale yellow transparent oily liquid that was well soluble in water. This is designated as emulsifier E.

Example 1 Coronate EH (product of Nippon Polyurethane Industry Co., Ltd.) which is a trimerized polyisocyanate of hexamethylene diisocyanate was used in an amount equivalent to 8.5% of emulsifier A (the content of polyoxyethylene monomethyl ether was 4.75%.
) And stirred and mixed well. 6 parts of water is added to 50 parts of this mixture, and the mixture is immediately stirred to form a white O / W type creamy emulsion. After sufficient stirring, 44 parts of water was further added for dilution to obtain a polyisocyanate emulsion having a solid content of 50%. At room temperature (about 20 ° C)
It was stable without separation even after standing for 16 hours, and the isocyanate content retained the initial 90%.

For comparison, the same polyoxyethylene monomethyl ether as used for emulsifier A was used in an amount of 4.75%, and the other operations were performed in the same manner as described above. In this case, the polyisocyanate could not be emulsified. After mixing with polyoxyethylene monomethyl ether, the mixture was kept at 70 ° C. for 4 hours and reacted with polyoxyethylene monomethyl ether to form a good emulsion. However, this emulsion started foaming after 4 hours and precipitated. Produce things,
After 6 hours, the isocyanate content was almost zero.

Examples 2 to 4 and Comparative Examples 1 to 2 As shown in Table 1 below, emulsifiers were added to polyisocyanate to PAPI 135 (manufactured by MD Chemical Co., Ltd.) as crude MDI and mixed well. After homogenization, 1.5 volumes of water were added to each mixture with vigorous stirring. The emulsified state of the polyisocyanate is as shown in Table 1, and the emulsifier of the present invention showed good emulsifiability and emulsion stability.

For comparison, the same table also shows a case where emulsification was carried out in the same manner as above using commercially available emulsifiers such as polyoxyethylene nonylphenyl ether and polyoxyethylene monomethyl ether.

Example 5 To 200 parts of PAPI 135 was added 50 parts of polyoxypropylene triol having an average molecular weight of 3045 obtained by reacting glycerin with propylene oxide, and reacted at 70 ° C. for 3 hours to obtain a polyisocyanate prepolymer. Emulsifier B
Was added to the prepolymer at 8%, and the mixture was thoroughly stirred and mixed. 5 parts of water was added to 50 parts of this mixture, and the mixture was stirred and immediately turned into a white-brown paste-like emulsion. When 95 parts of water was further added with stirring, an almost white good emulsion was obtained. The emulsion was stable without separation or coagulation after 20 hours and the isocyanate content retained about 50% of its initial value.

Example 6 3 mol of 2,4-tolylene diisocyanate and hydroxyl value of 4
Emulsifier C (5 parts) was added to 60 parts of a 75% toluene solution of adduct-type polyisocyanate derived from 1 mol of 25 polyoxypropylene triol, and the mixture was thoroughly stirred and uniformly mixed. Next, 80 parts of water was added to the mixture, and the mixture was vigorously stirred (3000 rotations, 1 minute) with a homomixer to obtain a good white emulsion. This emulsion was stable without any change after 3 hours.

For comparison, the same procedure as above was performed except that 2.8 parts of polyoxyethylene monomethyl ether having an average molecular weight of 560 (an amount corresponding to the content of polyoxyethylene monomethyl ether in 5 parts of emulsifier C) was used as an emulsifier. In this case, emulsification was not possible, and no emulsion was obtained. Further, the emulsifiability was poor even after the mixture containing polyoxyethylene monomethyl ether was kept at 70 ° C. for 3 hours to sufficiently react the polyoxyethylene monomethyl ether with the isocyanate.

Examples 7 and 8, Comparative Examples 3 and 4 Coronate MR-200 (Nippon Polyurethane Industry Co., Ltd.)
And crude MDI) were mixed with an emulsifier as shown in Table 2 below, and sufficiently stirred and mixed to prepare an emulsifiable polyisocyanate. After blending, polyoxyethylene monomethyl ether for comparison was allowed to react at 70 ° C. for 3 hours.
Next, when 30 parts of these emulsifiable polyisocyanates were added with 3 parts of water and stirred, all of them became white-brown creamy emulsions. After sufficiently stirring, the mixture was diluted with 50 parts of water to obtain an emulsion. The shelf stability of this emulsion is as shown in Table 2, and a clearly long pot life was observed in the method of the present invention. Further, the isocyanate content at the time of coagulation maintained about 80% of the initial value.

Examples 9 to 14 As shown in Table 3 below, various polyisocyanates and emulsifiers were combined and mixed well to prepare emulsifiable polyisocyanates. These polyisocyanates were added to a colloid-dispersed aqueous urethane resin Hydran HW-311 (a product of Dainippon Ink and Chemicals, Inc.) and stirred vigorously to examine the dispersibility of the polyisocyanate in the aqueous resin. The results are as shown in Table 4. In each case, a good emulsion was formed and the stability was also good.

Also, the resin containing the emulsifying polyisocyanate was spread on a glass plate and dried at 120 ° C. for 10 minutes.
All of the polyisocyanates added formed a cured film that was not dissolved in methyl ethyl ketone. The same was true 6 hours after the addition of the polyisocyanate.

Example 15 Polyoxypropylene triol having an average molecular weight of 3000
Of an isocyanate prepolymer obtained by reacting 100 parts and a mixed polyol of 100 parts of polyoxypropylene glycol having an average molecular weight of 2000 with 31.5 parts of tolylene diisocyanate (2,4- / 2,6- = 80/20). 80% toluene solution
To 289 parts, 320 parts of water containing 7% of emulsifier E was added and stirred and mixed. Next, when this mixture was processed in a colloid mill, a good emulsion was obtained. This isocyanate prepolymer emulsion was useful in a method of adding a diamine thereto to obtain a polyurethane emulsion.

Claims (1)

(57) [Claims] 1. The following general formula: (Where R is an alkyl group having 1 to 3 carbon atoms, X is a residue of a polyisocyanate compound, Y is a higher alcohol having 8 or more carbon atoms, a hydroxyl group-containing fatty acid ester having 8 or more carbon atoms of a fatty acid, and a molecular weight of 200 to 1000. Is a residue after any of the polyoxypropylene monoalkyl ethers is reacted with the isocyanate group, n is an integer of 5-35, and l, m, p and q are positive integers. A method for emulsifying an isocyanate compound, comprising using one or a mixture of two or more of the compounds to be used as an emulsifier for an isocyanate compound.