JP2775291B2 - Aqueous block polyisocyanate composition and thermosetting aqueous composition containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aqueous blocked polyisocyanate composition containing a novel water-soluble blocked polyisocyanate and a thermosetting aqueous composition containing the same.

Specifically, the aqueous blocked polyisocyanate composition of the present invention is a composition containing a water-soluble blocked polyisocyanate in which a specific polyisocyanate is blocked with a specific blocking agent, and thus has excellent stability in water, It is characterized in that the blocking agent does not remain in the cured resin and the isocyanate group can be easily regenerated at a relatively low temperature.

(Prior Art) A so-called polyurethane-based resin obtained by reacting a polyisocyanate compound having two or more isocyanate groups in one molecule with a compound having two or more active hydrogens in one molecule is available. Due to its excellent performance such as flexibility, abrasion resistance, chemical resistance, and weather resistance, it is applied in a wide range of fields such as paints, coatings, films, elastomers, foams, casting materials, and fiber treatment materials.

On the other hand, since the isocyanate group has high reactivity with the compound having active hydrogen and it is difficult to suppress the reaction, the chemical reaction of the polyisocyanate compound with the isocyanate group reacted with a blocking agent (also referred to as a protecting agent or a masking agent). Conventionally, a method is known in which an isocyanate group is regenerated and used by an appropriate treatment such as heating or addition of a catalyst when a reaction of the isocyanate group is required. I have.

The blocked polyisocyanate compound is often used in an organic solvent system, but recently, due to social demands such as depollution and resource saving, there is a high tendency to use the blocked polyisocyanate compound with water as a solvent, and Water-soluble or water-affinity (hereinafter referred to as "water-based") water-based block polyisocyanate compounds using bisulfites or acid-neutralized dialkylaminoalkanols as blocking agents have been used as crosslinkers and fiber treatment agents for water-based paints. ing.

(Problems to be Solved by the Invention) Conventionally, bisulfite is known as a blocking agent for obtaining an aqueous blocked polyisocyanate compound (Japanese Patent Application Laid-Open No. 50-140557). Because it is insoluble, there are restrictions on the types of polyisocyanate compounds that can be used as blocking agents,
The obtained blocked polyisocyanate compound has poor stability in water.

In addition, there is a problem that the bisulfite used as a blocking agent remains in the cured resin and has various adverse effects.

Further, an aqueous block polyisocyanate compound in which a polyisocyanate compound is blocked with a dialkylaminoalkanol, a tertiary nitrogen atom derived from the dialkylaminoalkanol is neutralized with an acid, and the resultant is water-soluble, is also known.

However, when this water-based blocked polyisocyanate compound is used as a cross-linking agent for water-based paints and the like, the blocking agent is dissociated to cause a cross-linking reaction.
Since the above high temperature is required, there is a problem that the material of the object to be coated is limited and energy is disadvantageous.

An object of the present invention is to solve the above-mentioned problems of the prior art water-soluble blocked polyisocyanate, that is, excellent in stability in water, and easily regenerate isocyanate groups at a relatively low temperature by a simple treatment such as heating, A water-soluble blocked polyisocyanate capable of reacting with an active hydrogen-containing compound is obtained, and an aqueous block polyisocyanate composition containing the same and water and a thermosetting resin composition containing the composition and the active hydrogen-containing compound can be provided. In addition, it can be used as an aqueous crosslinking agent.

(Means for solving the problem) As a result of various studies on the above problems, the present inventors have found that a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule as a heat dissociable blocking agent for blocking a polyisocyanate compound. The present inventors have found that an organic acid salt, an inorganic acid salt or a quaternary ammonium salt of an organic compound having a group can effectively work in an aqueous system even at a relatively low temperature, and have completed the present invention.

That is, the present invention provides a polyisocyanate containing an isocyanurate ring or a buret group in which at least a part of an isocyanate group (—NCO) is blocked with a heat-dissociable blocking agent, and at least one of the blocking agents is contained in one molecule. Has a tertiary nitrogen atom (R ¹ R ² R ³ N, pyridine type, quinoline type) and a phenolic hydroxyl group (Ar—OH);
At least a part of the quaternary nitrogen atom has at least one selected from an organic acid salt, an inorganic acid salt and a quaternary ammonium salt.
Provided is an aqueous blocked polyisocyanate composition comprising a seeded water-soluble blocked polyisocyanate and water.

(Here, R ¹ , R ² , and R ³ represent a monovalent organic group other than hydrogen, Ar
-Represents an aromatic ring residue or an aromatic hetero residue. In addition, the molar ratio of the phenolic hydroxyl group (Ar-OH group) in the blocking agent to the isocyanate group (-NCO group) in the polyisocyanate (the ratio of OH group / NCO group) is 0.1 to 1.5.
Is also characteristic. Further, at least one kind of organic acid salt, inorganic acid salt or quaternary ammonium salt added to at least a part of the tertiary nitrogen atom in the blocking agent constituting the water-soluble blocked polyisocyanate. Is also characterized in that it is 10 to 200 equivalent% per equivalent of tertiary nitrogen atom, and also provides a thermosetting aqueous composition containing an active hydrogen-containing compound and the composition described in any of the above. I do.

 Hereinafter, the present invention will be described in detail.

(I) Blocking method, etc .: (A) Blocking agent of the present invention: The compound having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule used as the blocking agent of the present invention includes 2- Hydroxypyridine compounds such as hydroxypyridine and 3-hydroxypyridine; hydroxyquinoline compounds such as 8-hydroxyquinoline and 2-hydroxyquinoline; and formula (1): (In the formula, n is an integer of 1 to 5, L is an integer of 0 to 4, R is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R ¹ and R ² are an alkyl group having 1 to 4 carbon atoms. And the like.

Here, in the general formula (1), n is an integer of 1 to 5, but is preferably 1. L is an integer of 0 to 4, preferably 1.

R is hydrogen or methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl,
A tert-butyl group and the like are mentioned, and hydrogen is preferable.

Examples of the alkyl group having 1 to 4 carbon atoms for R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, and an n-butyl group, and a methyl group is preferable.

Specific examples of the compound of the general formula (1) include, for example, 2-
(Dimethylaminophenyl) phenol, 4- (dimethylaminomethyl) phenol, 2,4-bis (dimethylaminomethyl) phenol, 2,6-bis (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylamino) Methyl) phenol, 2- (dimethylamino) phenol, 4- (dimethylamino) phenol and the like.

Among the above compounds having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule, preferred are:
2- (dimethylaminomethyl) phenol, 8-hydroxyquinoline, 2-hydroxypyridine, 2,6-bis (dimethylaminomethyl) phenol, and 2,4,6-tris (dimethylaminomethyl) phenol, which are particularly preferable. Is 2- (dimethylaminomethyl) phenol.

JP-B-53-15960 describes an epoxy resin curing agent obtained by mixing and reacting dimethylaminomethylphenols and a compound having an isocyanate group, but the description is merely for use as an epoxy resin curing agent. No mention is made of the use of an aqueous blocked polyisocyanate compound by reacting with an organic acid, an inorganic acid or a quaternizing agent.

(B) Solubilizing agent: 1) At least a part of the tertiary nitrogen atom contained in these blocking agents is an organic acid salt, an inorganic acid salt or a quaternary nitrogen atom.
In order to make it a quaternary ammonium salt, it is necessary to treat it with a solubilizer.

Examples of the solubilizer include organic acids such as formic acid, acetic acid, lactic acid, propionic acid, oxalic acid, and p-toluenesulfonic acid; inorganic acids such as hydrochloric acid, sulfuric acid, boric acid, and phosphoric acid; or methyl chloride, methyl bromide, and benzyl chloride. And quaternizing agents such as dialkyl sulfates such as dimethyl sulfate and diethyl sulfate.

Of these, acetic acid, hydrochloric acid, alkyl halides (quaternizing agents) and the like are preferred.

(C) Other blocking agent: In addition to the blocking agent having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule, another blocking agent is used as a blocking agent for the polyisocyanate compound. It is also possible to use them together.

Other blocking agents that can be used include, for example, oximes such as methyl ethyl ketoxime, acetoxime and cyclohexanone oxime; phenols such as phenol, p-chlorophenol and p-nitrophenol; lactams such as ε-caprolactam and γ-butyrolactam. And active methylene compounds such as methyl acetoacetate, acetylacetone and diethyl malonate.

(Ii) Polyisocyanate component: Examples of the polyisocyanate applicable to the present invention include all known diisocyanates such as hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, and xylylene diisocyanate. Polyisocyanates such as polymethylene polyphenylisocyanate; isocyanate prepolymers containing free isocyanate groups produced from various polyols and polyisocyanate compounds; and polyisocyanate containing a isocyanurate ring and containing burette groups But is not limited to only the exemplified polyisocyanates. .

In particular, the use of modified isocyanates such as polyisocyanates containing an isocyanurate ring and polyisocyanates containing a burette group is preferred.

(Iii) Water-soluble blocked polyisocyanate: 1) As a method for producing the water-soluble blocked polyisocyanate of the present invention, the following two methods are generally used.

That is, by reacting a blocked polyisocyanate compound in which isocyanate groups are blocked with a compound having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule with an organic acid, an inorganic acid or a quaternizing agent, A method of forming a blocked polyisocyanate.

A compound having at least a part of a tertiary nitrogen atom in a compound having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule by using a compound in which at least a part of a tertiary nitrogen atom is salted with an organic acid, an inorganic acid or a quaternizing agent, A method of blocking an isocyanate to obtain a water-soluble blocked polyisocyanate.

Either of the above two methods can be selected, but a normal method is used.

(Iv) Reaction of the blocking agent of the present invention with a polyisocyanate: 1) Ratio of OH group / NCO group: In the reaction of a compound having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule with a polyisocyanate. A molar ratio (OH group / OH group / phenolic hydroxyl group (Ar-OH group) in a compound having a tertiary nitrogen atom and a phenolic hydroxyl group in one molecule) to an isocyanate group (-NCO group) in a polyisocyanate compound; NCO group ratio)
Is usually selected in the range of 0.1 to 1.5 (claim 2).

However, when this ratio is smaller than 1, other blocking agents as described above are used in combination so that a water-soluble blocked polyisocyanate having no free isocyanate group is finally obtained.

2) Reaction temperature: The reaction temperature is usually 0 to 150 ° C, preferably 30 to 90 ° C.

3) Solvent: For this reaction, if necessary, a solvent such as acetone,
Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; amide solvents such as dimethylformamide; ethyl acetate, butyl acetate, ethyl cellosolve acetate;
Ester solvents such as butyl cellosolve acetate; hydrocarbon solvents such as toluene, xylene and cyclohexane;
And / or in the presence of a mixture of two or more of these solvents, and / or 4) a urethanization catalyst: The urethanization catalyst is, for example, an organotin compound such as stannous octylate, dibutyltin dilaurate; or an organic compound such as lead oleate. The reaction may be carried out in the presence of a catalyst such as a lead compound; an organic zinc compound such as zinc diacetylacetonate; and an amine compound such as triethylamine and triethylenediamine.

5) The progress of this reaction can be checked by measuring the free isocyanate content in the system over time, for example using IR.

(V) Water-solubilization of the blocked polyisocyanate: 1) To solubilize the thus-obtained block polyisocyanate, an organic acid, an inorganic acid or a quaternizing agent is reacted to form a salt thereof.

2) The amount of the organic acid, inorganic acid or quaternizing agent used in this reaction is generally not less than the amount required for water-solubilization. For example, in one molecule which acts as a blocking agent in a blocked polyisocyanate Is usually 10 to 200 equivalent%, preferably 50 to 120 equivalent% with respect to 1 equivalent of the tertiary nitrogen atom derived from the compound having a tertiary nitrogen atom and a phenolic hydroxyl group. .

3) The reaction between the blocked polyisocyanate and an organic acid, an inorganic acid or a quaternizing agent is carried out in the presence of water and / or an organic solvent if necessary.

Examples of the organic solvent include ethanol, acetone, methyl ethyl ketone, ethyl cellosolve, dimethylformamide and the like.

Further, the reaction can be performed at any of normal temperature and heating.

(Vi) Water-soluble blocked polyisocyanate: 1) Chemical structure: The water-soluble blocked polyisocyanate of the present invention has the following chemical structure.

[Where Q Is an organic acid anion residue, an inorganic acid residue or
Quaternary such as halogen anion and dialkyl sulfate anion
Agent anion, X Is a monovalent anion; n is an integer of 1 to 5; L is an integer of 0 to 4; R is a monovalent organic group other than hydrogen;¹, R^TwoIs an alkyl group having 1 to 4 carbon atoms, R^ThreeIs hydrogen or an alkyl group having 1 to 4 carbon atoms
You. 2) Properties: Water-soluble blocked polyisocyanate thus obtained
Has excellent water solubility and can be applied at relatively low temperatures.
To regenerate the isocyanate group by heat, an aqueous frame
Useful as a crosslinking agent.

The reactivity of the blocked polyisocyanate can be controlled by appropriately selecting an organic acid, an inorganic acid, or a quaternizing agent for salt formation.

3) Uses and the like: The use and use of the aqueous block polyisocyanate composition containing the water-soluble blocked polyisocyanate and water of the present invention can be considered in a wide range. It is used as a synthetic leather treating agent, a water-based cross-linkable paint, a water-based cross-linkable adhesive, a pyrolytic surfactant, and the like.

For example, an active hydrogen-containing compound and a water-soluble blocked polyisocyanate of the present invention are mixed in an aqueous system to form a thermosetting aqueous composition, the isocyanate is regenerated by a treatment such as heating, and then the active hydrogen-containing compound is reacted. The present invention can be used in various fields such as the following (claim 4).

(Examples) Hereinafter, the present invention will be specifically described based on examples, comparative examples, and application examples, but these do not limit the scope of the present invention.

 However, parts and% are based on weight.

(A) Production of water-soluble blocked polyisocyanate: (Example 1) Isocyanurate-type polyisocyanate compound of hexamethylene diisocyanate [Duranate TPA-100
(Solid content 100%; manufactured by Asahi Kasei Corporation)] To a solution obtained by adding 42 parts of acetone to 200 parts, 2- (dimethylaminomethyl) was added.
After adding 175 parts of phenol so as to keep the reaction temperature in the range of 40 to 50 ° C., the reaction was carried out at 40 to 50 ° C. for 3 hours, and it was confirmed by IR measurement that the free isocyanate group was substantially eliminated.

Next, 70 parts of acetic acid is added and mixed at 30 ° C. for 30 minutes. Then, 730 parts of deionized water is added, and a pale yellow transparent block polyisocyanate aqueous solution (A-1) having a resin content of 40% is added.
I got

(Example 2) 70 parts of acetic acid was changed to 118 parts of a 35% hydrochloric acid aqueous solution, and 730 of deionized water was used.
The reaction was carried out in the same manner as in Example 1 except that 613 parts of deionized water was used, to obtain a pale yellow transparent blocked polyisocyanate aqueous solution (A-2) having a resin content of 40%.

(Example 3) 70 parts of acetic acid was converted to 134 parts of an aqueous 85% phosphoric acid solution, and 730 of deionized water was used.
The reaction was carried out in the same manner as in Example 1 except that 776 parts of deionized water was used to obtain a pale yellow-brown transparent block polyisocyanate aqueous solution (A-3) having a resin content of 40%.

(Example 4) A burette group-containing polyisocyanate compound of hexamethylene diisocyanate [Duranate 24A-100 (solid content: 100%; manufactured by Asahi Kasei Corporation)] was mixed with 200 parts of acetone.
After adding 88 parts of 2- (dimethylaminomethyl) phenol and 51 parts of methyl ethyl ketoxime so as to keep the reaction temperature in the range of 40 to 50 ° C.,
The reaction was carried out at a temperature of 3 ° C. for 3 hours, and it was confirmed by IR measurement that the free isocyanate groups were substantially eliminated.

Next, 35 parts of acetic acid was added, and the mixture was mixed at 30 ° C. for 30 minutes. Then, 1500 parts of deionized water was added to obtain a pale yellow transparent block polyisocyanate aqueous solution having a resin content of 20%.

Example 5 Reference Example Hexamethylene diisocyanate isocyanurate-type polyisocyanate compound [Duranate TPA-100
(Solid content 100%; manufactured by Asahi Kasei Kogyo Co., Ltd.)] To a solution obtained by adding 42 parts of acetone to 200 parts, 3-hydroxypyridine 110
The reaction was carried out at 60 to 70 ° C. for 10 hours, and it was confirmed by IR measurement that the free isocyanate groups had substantially disappeared.

Next, 70 parts of acetic acid was added, and the mixture was mixed at 30 ° C. for 30 minutes. Then, 890 parts of deionized water was added to obtain a white and uniform aqueous dispersion having a resin content of 30%.

(Comparative Example 1) In the synthesis operation of Example 1, when deionized water was added so that the resin content was 40% without adding acetic acid, an aqueous solution or a uniform aqueous dispersion could not be obtained. The resin precipitated as a white paste.

Comparative Example 2 Example 1 except that 175 parts of 2- (dimethylaminomethyl) phenol was changed to 97 parts of dimethylaminoethanol.
The reaction was carried out in the same manner as described above to obtain a colorless and transparent blocked polyisocyanate aqueous solution (R-1) having a resin content of 40%.

(B) Production of thermosetting aqueous composition: (Examples 6 to 8, Comparative Example 3) As an active hydrogen-containing compound, polyvinyl alcohol (PV
(A, average polymerization degree: 500, saponification degree: 88%) Deionized water (80 parts) was added to 20 parts to prepare a PVA aqueous solution having a solid content of 20%.
To 100 parts of this 20% PVA aqueous solution, 10 parts of the aqueous solution of the blocked polyisocyanate of Example 1, Example 2, Example 3 or Comparative Example 2 was blended as a crosslinking agent, thereby preparing four types of aqueous solutions.

These aqueous solutions were applied on a glass plate using an applicator, and then heat-treated at the temperatures shown in Table 1 for 30 minutes each. The obtained coating film was immersed in deionized water, allowed to stand at 20 ° C. for 24 hours, and further treated with hot water at 90 ° C. for 1 hour. Subsequently, by performing drying, by measuring the residual weight ratio of the obtained dried coating film, various aqueous block polyisocyanate compounds and
The degree of crosslinking with PVA was evaluated. Table 1 shows the results.

(Effects of the Invention) The water-soluble blocked polyisocyanate of the present invention: not only has water-soluble performance but also has excellent stability in water.

As shown in Comparative Example 2, relatively low temperature (for example, 120 to 180 ° C.) as compared with aqueous blocked polyisocyanate using dialkylaminoalkanol as a blocking agent
Can easily regenerate the isocyanate group.

 The blocking agent does not remain in the cured resin.

By appropriately selecting an organic acid, an inorganic acid or a quaternizing agent for forming a soluble salt, the reactivity as a blocked polyisocyanate can also be controlled.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification symbol FI C08G 18/80 C08G 18/80 (58) Fields investigated (Int.Cl. ⁶ , DB name) C07C 275/62 C07C 265/14 C08G 18/80 CA (STN)

Claims (4)

(57) [Claims] An isocyanate group (-NCO) of a polyisocyanate containing an isocyanurate ring or a burette group.
At least part of is blocked with a thermodissociable blocking agent,
At least one of the blocking agents has a tertiary nitrogen atom (R ¹ R ² R ³ N, pyridine type, quinoline type) and a phenolic hydroxyl group (Ar-OH) in one molecule, And a water-soluble blocked polyisocyanate in which at least one selected from an organic acid salt, an inorganic acid salt or a quaternary ammonium salt is added to at least a part of the tertiary nitrogen atom, and water. A water-based blocked polyisocyanate composition characterized by the following. (Here, R ¹ , R ² , and R ³ represent a monovalent organic group other than hydrogen, Ar
-Represents an aromatic residue or an aromatic heterocyclic residue. ) The molar ratio of the phenolic hydroxyl group (Ar-OH group) in the blocking agent to the isocyanate group (-NCO group) in the polyisocyanate (ratio of OH group / NCO group)
The aqueous blocked polyisocyanate composition according to claim 1, wherein the composition is 0.1 to 1.5. 3. An organic acid salt, an inorganic acid salt or a quaternary ammonium salt added to at least a part of a tertiary nitrogen atom in the blocking agent constituting the water-soluble blocked polyisocyanate. 3. The aqueous blocked polyisocyanate composition according to claim 1, wherein the amount of the seed is 10 to 200 equivalent% per equivalent of tertiary nitrogen atom. 4. A thermosetting aqueous composition comprising an active hydrogen-containing compound and the composition according to claim 1.