JPH0827249A - Aqueous block polyisocyanate composition and aqueous coating compound composition containing the same - Google Patents

Abstract

PURPOSE:To obtain the subject composition useful as a coating compound, a binder, etc., having excellent water dispersibility, weather resistance, chemical resistance, chipping resistance, etc., by adding a prescribed compound to a polyisocyanate containing an isocyanurate bond. CONSTITUTION:This composition comprises a block polyisocyanate which is obtained by adding (B) a compound of the formula (R is a 1-4C alkyl; (n) is 4-30) to (A) an aliphatic or alicyclic polyisocyanate containing an isocyanate bond and has the addition ratio of >=22.5 pts.wt. of the component B to 100 pts.wt. of the component A, has 3-70 pts.wt. of NCO content and its free NCO groups are blocked with a thermally dissociative blocking agent. The composition has 2-20wt.% of effective NCO concentration. The component A is preferably modified with a hydroxyl compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel non-yellowing aqueous block polyisocyanate composition having excellent weather resistance, chemical resistance, chipping resistance and the like, and an aqueous coating composition containing the same.

[0002]

2. Description of the Related Art In recent years, water-based paints have been attracting attention from the viewpoints of global environment, safety and hygiene. From building exteriors to industrial products, it has come to be used for industrial paints such as food cans and coil coatings. Furthermore, there are many proposals for one-part paints for automobiles that require high quality such as weather resistance, chemical resistance, and impact resistance, and JP-A-56-157358.
Issue, JP-A-63-175079, JP-A-63-1
Aqueous paints are disclosed in, for example, No. 93968. Most of the curing agents used here are alkyl etherified melamines.

Further, a coating film obtained from a urethane-based coating material which is crosslinked with isocyanate has excellent abrasion resistance, chemical resistance, and stain resistance, and, in addition, it has an aliphatic or fat content as an isocyanate component. By using a non-yellowing polyisocyanate prepared from a cyclic diisocyanate as a raw material, the weather resistance is further excellent, and the demand thereof is increasing. Therefore, water-based urethane paints capable of crosslinking with isocyanate are being actively developed. When a one-component type is required for line paints, the isocyanate group of polyisocyanate is usually masked with a heat dissociative blocking agent and used as a block polyisocyanate.

As a technique for making block polyisocyanate aqueous, for example, in JP-A-52-59657, a surfactant is used to make block polyisocyanate aqueous. Japanese Unexamined Patent Publication (Kokai) No. 56-151753 uses a polyethylene oxide containing a higher fatty acid having 7 to 26 carbon atoms and blocks the isocyanate group of the polyisocyanate with sodium bisulfite to make the block polyisocyanate aqueous. It is possible. In these techniques, it has been desired to improve the physical properties of the coating film, such as surfactants and blocking agents remaining in the coating film after the coating film is formed, and the components thereof are eluted.

Therefore, a technique of reacting polyisocyanate with a specific polyoxyethylene which is a hydrophilic group to prevent elution of a hydrophilic component and making it aqueous by using a high-speed stirring group is disclosed in JP-A-61-31422. It is disclosed. However, with this technology, the water-solubilization of the block based on polyisocyanate having a heat-resistant isocyanurate structure is insufficient, and since special equipment such as a high-speed stirrer is required, the water-hydration technology is improved. Was desired.

A technique for making such a block of polyisocyanate having a heat-resistant isocyanurate structure water-soluble is disclosed in JP-A-62-151419 and JP-A-2-
It is disclosed in Japanese Patent No. 3465. JP-A-62-151
No. 419 discloses that polyoxyethylene group is added to a part of polyisocyanate, and polyethylene glycol,
A water-soluble polymer compound such as a copolymer of ethylene oxide and propylene oxide is mixed. The physical properties of the coating film may be deteriorated due to the addition of the water-soluble polymer compound, and its improvement has been desired. In JP-A-2-3465, hydrophilicity is imparted by hydroxycarboxylic acid to make it aqueous, but the hydrated block polyisocyanate is anionic, and its stability is hindered by the ionic state of the coating material. There were cases.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a nonionic type aqueous composition of a block polyisocyanate obtained from a non-yellowing polyisocyanate having an isocyanurate structure, and an aqueous coating composition using the same. The task is to do.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been completed by discovering that the above-mentioned problems can be solved by using a non-yellowing type block polyisocyanate having an isocyanurate structure, which is obtained by hydrating it under specific conditions. . That is, according to the present invention, a compound represented by the general formula (1) is added to an aliphatic and / or alicyclic polyisocyanate having an isocyanurate bond, and the addition ratio is (1) 100 parts by weight of the polyisocyanate. 22.5 parts by weight or more, and (2) 3% or more and 70% or less of the isocyanate group of the polyisocyanate, and the free isocyanate group is blocked with a heat dissociable blocking agent. Is a block polyisocyanate, and the effective isocyanate concentration of the block polyisocyanate is from 2 to 20% by weight, which is an aqueous block polyisocyanate composition. Furthermore,

[0009]

Embedded image

The above-mentioned aqueous block polyisocyanate composition in which the aliphatic and / or alicyclic polyisocyanate is modified with a hydroxy compound. More specifically, the heat dissociative blocking agent is an oxime compound, an active methylene compound, an acid amide compound, the above-mentioned aqueous block isocyanate composition, the above aqueous block polyisocyanate composition and the above aqueous block isocyanate composition. An aqueous block polyisocyanate composition containing 500 parts by weight or less of a solvent-type block polyisocyanate composition with respect to 100 parts by weight, and using these, a water-affinitive polyol and the above aqueous block polyisocyanate composition. The present invention proposes an aqueous coating composition containing

As the aliphatic or alicyclic polyisocyanate having an isocyanurate bond of the present invention, it is preferable to use an aliphatic or alicyclic diisocyanate. The aliphatic diisocyanate preferably has 4 to 30 carbon atoms, and the alicyclic diisocyanate preferably has 8 to 30 carbon atoms. For example, 1,4-tetramethylene diisocyanate and 1,5 -Pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,
2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate, 1-isocyanate-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate),
1,3-bis (isocyanatomethyl) -cyclohexane, 4,4′-dicyclohexylmethane diisocyanate and the like can be mentioned. Among them, 1,6-hexamethylene diisocyanate (hereinafter referred to as HMDI) and isophorone diisocyanate (hereinafter referred to as IPDI) are preferable from the viewpoint of weather resistance and industrial availability, and even when used alone, You may use together.

The modified product is modified with a hydroxyl compound when an isocyanurate-type aliphatic or alicyclic polyisocyanate obtained by using the aliphatic or alicyclic diisocyanate is produced. Examples of the hydroxyl compound include monohydroxy compounds such as methanol, ethanol, isopropanol and phenol, ethylene glycol, propylene glycol, 1,3-butanediol, pentanediol, hexanediol, cyclohexanediol, neopentyl glycol, 2,
There are dihydroxyl compounds such as 2,4-trimethyl 1,3-pentanediol. These may be used alone or in combination of two or more.

The aliphatic / alicyclic diisocyanate and the hydroxyl compound are 50 to 200 ° C., preferably 50 to 150.
React at ℃. At this time, a solvent may be used, but a solvent inert to isocyanate should be used. This conversion reaction can be performed after the isocyanurate-forming reaction, but is preferably performed before the isocyanurate-forming reaction.

A catalyst is usually used for the isocyanurate-forming reaction. Generally, the catalyst used here is preferably basic, for example, tetramethylammonium, a tetraalkylammonium hydroxide such as tetraethylammonium or an organic weak acid salt, trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium. , Hydroxyalkylammonium hydroxide such as triethylhydroxyethylammonium, organic weak acid salts, alkylcarboxylic acid potassium salts such as acetic acid and caproic acid, alkali metal salts such as sodium, metal alcoholates such as sodium and potassium, hexamethyldisilazane, etc. And aminosilyl group-containing compounds. The catalyst concentration is usually selected from the range of 10 ppm to 1.0% with respect to the isocyanate compound.

The reaction may or may not use a solvent. If a solvent is used, a solvent inert to the isocyanate group should be used. The reaction temperature is usually 20-
The temperature is 160 ° C, preferably 40 to 130 ° C. Although the end point of the reaction varies depending on the hydroxyl compound used, it is carried out so that the yield is generally 10% or more and 75% or less.

When the reaction reaches the target yield, the catalyst is deactivated by, for example, sulfonic acid, phosphoric acid, phosphoric acid ester or the like to stop the reaction. If the unreacted diisocyanate and the solvent are removed, an isocyanurate-type aliphatic / alicyclic polyisocyanate having an isocyanurate structure can be obtained.

Next, the obtained isocyanurate-type aliphatic / alicyclic polyisocyanate is reacted with the compound of the general formula (1) and added.

[0018]

Embedded image

R in the general formula (1) has 1 to 4 carbon atoms. When it is 5 or more, the water-solubilizing ability is hindered, which is not preferable.
Preferred are methyl and ethyl groups having 1 and 2 carbon atoms. More preferably, it is methyl having 1 carbon atom. In the general formula (1), n is 4 to 30. When it is 3 or less, the water-solubilizing ability is insufficient, and when it exceeds 30, the coating film physical properties are adversely affected. It is preferably 5 to 20.

3% to 70% of the isocyanate group of the aliphatic / alicyclic polyisocyanate is represented by the general formula (1).
To react with the compound shown by. If it is less than 3%, the water-solubilizing ability is insufficient and the water dispersibility is poor. If it exceeds 70%, the physical properties of the coating film are adversely affected when it is used as a paint. It is preferably 4% or more and 50% or less. In this case, the weight ratio of the polyisocyanate to the compound represented by the general formula (1) is 100: 2.
It is 2.5 or more, preferably 100 to 22.5 to 150, and more preferably 100 to 22.5 to 100.

When the reaction is carried out, a solvent may be used. The solvent in this case should be inert to the isocyanate. You may use tin, such as dibutyl tin dilaurate, organic metal salts, such as zinc and lead, and a tertiary amine as a catalyst. The reaction temperature may be 30 to 120 ° C.,
Considering productivity and side reactions, 50 ° C to 100 ° C is preferable. The reaction between the polyisocyanate and the compound represented by the general formula (1) may precede or follow the blocking reaction below.

The resulting isocyanate group of the aliphatic / alicyclic polyisocyanate to which the compound represented by the general formula (1) is added is blocked with a heat dissociative blocking agent. Examples of the heat dissociative blocking agent used include phenol-based, alcohol-based, active methylene-based, mercaptan-based, acid amide-based, acid imide-based, imidazole-based, urea-based, oxime-based, amine-based imine-based and the like. These may be used alone or in combination. More specific blocking agents are shown below. (1) Phenol-based; phenol, cresol, ethylphenol, butylphenol, etc. (2) Alcohol-based; ethylene glycol, benzyl alcohol, methanol, ethanol, etc. (3) Active methylene-based; dimethyl malonate, diethyl malonate, acetoacetic acid Methyl, ethyl acetoacetate, acetylacetone, etc. (4) Mercaptan type; butyl mercaptan, dodecyl mercaptan, etc. (5) Acid amide type; acetanilide, acetic acid amide, ε-
Caprolactam, δ-valerolactam, γ-butyrolactam, etc. (6) Acid imide type; succinimide, maleic imide, etc. (7) Imidazole type; imidazole, 2-methylimidazole, etc. (7) Urea type; urea, Thiourea, ethylene urea, etc. (8) oxime type; formaldoxime, acetoaldoxime, methylethylketoxime, cyclohexanone oxime, etc. (10) carbamic acid type; phenyl N-phenylcarbamate, etc., (11) amine type; diphenylamine , Aniline, carbazole, etc. (12) imine type; ethyleneimine, polyethyleneimine, etc., acid amide compounds such as ε-caprolactam, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc. Active meth Emissions-based compound, acetoxime, oxime compounds such as methyl ethyl ketoxime are preferred. More preferred are active methylene compounds and oxime compounds.

The blocking reaction can be carried out with or without the presence of a solvent. When using a solvent, it is necessary to use a solvent which is inactive to the isocyanate group. In the blocking reaction, an organic metal salt of tin, zinc, lead or the like, a tertiary amine or the like may be used as a catalyst. The reaction can be generally carried out at -20 to 150 ° C, preferably 0 to 100 ° C. If it exceeds 100 ° C, a side reaction may occur. On the other hand, if the temperature is too low, the reaction rate becomes slow, which is disadvantageous. It is preferred that substantially all the isocyanate groups are blocked.

The effective isocyanate concentration per resin component of the obtained aqueous block polyisocyanate of the present invention is 2
~ 20% by weight. The effective isocyanate concentration means the concentration of the isocyanate group blocked by the heat dissociative blocking agent. When the effective isocyanate concentration is out of the above range, it is difficult to obtain a suitable cross-linking density, and it is difficult to obtain good coating film physical properties.

The thus-prepared aqueous block polyisocyanate composition can also be used as a mixture with a solvent-type block polyisocyanate having no water-solubilizing ability.
The solvent-type block polyisocyanate is one in which a free isocyanate group is blocked with a heat dissociative blocking agent, and particularly, all the portions represented by the general formula (1) of the aqueous block polyisocyanate composition are thermally dissociated. A block polyisocyanate substituted with a sex blocking agent is used.

Surprisingly, the aqueous block polyisocyanate composition thus obtained, even when mixed with solvent-based block polyisocyanate, usually
The use amount of the compound represented by the general formula (1) necessary for making it aqueous can be achieved in a smaller amount. In this case, the mixing weight ratio of the aqueous block polyisocyanate and the solvent type block polyisocyanate is 100 to 0 to 1000, preferably 0 to 500.

The aqueous block polyisocyanate thus prepared is mixed with a water-affinitive polyol to form an aqueous coating composition. The water-affinity polyol used in the present invention can be used without particular limitation as long as it is usually used for water-based paints, and it does not have ionicity even if it is anionic, cationic or zwitterionic. It may be one. Alkyd type, polyester type, epoxy type, fluorine type, acrylic type and the like. Resin component hydroxyl value is 10 to 300, number average molecular weight 2,000 to 50,000
And is dissolved or dispersed in a dispersion medium containing water as a main component. When the resin component has a hydroxyl value of less than 10, the density of urethane crosslinks due to the reaction with the isocyanate component decreases, and the physical properties of the present invention cannot be achieved. The crosslink density increases, and the mechanical properties of the coating film deteriorate, which is not preferable. As the soluble type polyol, there is disclosed in JP-A-63-295680.
JP, JP-A-63-175059, JP-A-62.
The manufacturing method thereof is disclosed in Japanese Patent Laid-Open No. 216671 and Japanese Patent Laid-Open No. 2-191692. As a dispersion type polyol, a method for producing the same is disclosed in Japanese Patent Application Laid-Open No. 56-157358. As a fluoropolyol which is a fluorocopolymer having a hydroxyl group, JP-A-57-3 is known.
The manufacturing method is disclosed in Japanese Patent No. 4107, Japanese Patent Application Laid-Open No. 61-231044, Japanese Patent Application Laid-Open No. 3-37252, and the like. The present invention is disclosed in JP-A-63-295680.
JP-A-63-175059, JP-A-56-157
In the water-based coating composition of the present invention disclosed in Japanese Patent No. 358, etc., the equivalent ratio of the isocyanate group blocked with the heat dissociable blocking agent and the hydroxyl group of the water-affinity polyol is usually 0.5 to 2.5: 1. However, when a melamine-based curing agent is used in combination as the curing agent, the ratio is usually 0.1 to 1.5: 1.

Hexamethoxymethylol melamine and methyl butyl etherified melamine are typical examples of the melamine type curing agent. Usually, a water-soluble paint is prepared by mixing a water-affinity polyol, a curing agent, an additive, etc., adding a medium containing water as a main component, and adjusting the paint viscosity according to the coating method.

The thus-prepared water-based paint is applied to metals, plastics, etc. by spray coating, roll coating, shower coating, dip coating, etc., and is also useful as a chipping-resistant coating, a precoat metal coating, and the like. Further, if necessary, an antioxidant, an ultraviolet absorber, a pigment, a metal powder pigment such as aluminum, a crosslinking accelerator such as an organometallic compound such as dibutyltin dilaurate, a leveling agent, and the like may be added.

The water-based block isocyanate of the present invention is useful as an inorganic material such as ink, adhesive, fiber, film and ceramic, modifier for paper, wood and the like, surface treatment agent and binder, in addition to paint.

[0031]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples. The evaluation was performed according to the following. [Evaluation of water dispersibility] 10 parts of an aqueous block polyisocyanate (resin content: 75%) and 100 parts of ion-exchanged water were mixed, allowed to stand for one day, and then visually observed. The state in which the resin was not dispersed at all was evaluated as X, the state in which the resin was dispersed was set as Δ, and the state in which the resin was uniformly dispersed was evaluated as O. [Gel Fraction] When the cured coating film was immersed in acetone at 20 ° C. for 24 hours, the value of the undissolved part weight was 5 before the immersion.
Less than 0% was evaluated as x, 50 or more and less than 85% as Δ, and 85% or more as o. [Coating film haze value] A coating film having a film thickness of 30 μm coated on a transparent glass plate having a thickness of 1 m / m was measured by a direct reading haze computer HGM-2DP of Suga Test Instruments Co., Ltd. to have a value of 1.0. Less than was evaluated as ◯ and 1.0 or more was evaluated as x.

[0032]

Example 1 (Production of Aqueous Block Polyisocyanate) A polyisocyanate compound having an isocyanurate structure using HMDI as a raw material was placed in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser (Asahi Kasei Corporation. ) Trade name: Duranate TPA) 100 parts, propylene glycol monomethyl ether acetate 55 parts, polyethylene glycol monomethyl ether (average molecular weight 750)
30 parts were charged and kept at 70 ° C. for 4 hours under a nitrogen atmosphere. Then, the temperature of the reaction solution was lowered to 50 ° C., and 47 parts of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured, and it was confirmed that the absorption of the isocyanate group disappeared. The resulting aqueous block polyisocyanate had a resin solid content of 75% and an effective isocyanate concentration per resin of 12.3%. The water dispersibility of this aqueous block polyisocyanate composition was evaluated according to the above-mentioned evaluation method, and the result was good (◯). Table 1 shows the evaluation results.

[0033]

Examples 2 to 4 and Comparative Examples 1 and 2 The procedure of Example 1 was repeated except for the facts shown in Table 1. The results are shown in Table 1.

[0034]

Example 5 (Production of urethane-modified aqueous block polyisocyanate) 100 parts of HMDI and 1,3-butanediol were placed in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser.
0.8 parts was charged, and 2 hours at a liquid temperature of 80 ° C under a nitrogen atmosphere.
Held After adjusting the liquid temperature to 60 ° C., 0.02 g of tetramethylammonium capryate, which is an isocyanurate-forming reaction catalyst, was added in portions. When the isocyanate concentration in the reaction solution reached 42%, 0.02 g of phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HMDI was removed with a thin film evaporator. The urethane-modified polyisocyanate product obtained has a viscosity of 2300 mPas /
The isocyanate concentration was 25 ° C. and 21.0%.

100 parts of the obtained urethane-modified polyisocyanate, 53 parts of propylene glycol monomethyl ether acetate, and 30 parts of polyethylene glycol monomethyl ether (average molecular weight 350) were charged and kept at 70 ° C. for 4 hours under a nitrogen atmosphere. Then, the temperature of the reaction solution was lowered to 50 ° C., and 38 parts of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured, and it was confirmed that the absorption of the isocyanate group disappeared. The resulting aqueous block polyisocyanate has a resin solid content of 75%,
The effective isocyanate concentration per resin was 10.5%. Table 1 shows the evaluation results of this aqueous block polyisocyanate.

[0036]

Examples 6 and 7 (mixed system of aqueous and solvent-type block polyisocyanate) Solvent-type block polyisocyanate (duranate TPA-B) which is a block of polyisocyanate having an isocyanurate structure using HMDI as a raw material A 75% resin content solution of the propylene glycol monomethyl ether acetate solvent in Example 1 was mixed with the aqueous block polyisocyanate compositions obtained in Examples 1 and 2, and the water dispersibility was evaluated. Table 2 shows the results.

[0037]

[Examples 8 to 11] Water-soluble acrylic polyol neutralized with dimethylethanolamine (Arolone 76, trade name of Nippon Shokubai Co., Ltd., hydroxyl value of resin component 64 mgKOH / g)
And the aqueous block polyisocyanate compositions obtained in Examples 1 to 7 in which the equivalent ratio of isocyanate group / hydroxyl group was 1 /
1. A 10 wt% propylene glycol monomethyl ether acetate solution of dibutyltin dilaurate was mixed so that dibutyltin dilaurate was 0.5 wt% with respect to the coating solid content. By further adding water, the viscosity of the coating material becomes Ford Cup No. 4 was adjusted to 30 seconds. This paint was applied with an applicator and cured at 140 ° C. for 20 minutes. The coating film evaluation results are shown in Table 3.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

The aqueous block polyisocyanate composition of the present invention is excellent in water dispersibility, and the aqueous coating composition using the same is excellent in weather resistance, chemical resistance and chipping resistance. And, it is possible to achieve the water-based conversion of the solvent-based isocyanate cross-linked urethane paint. Further, it is possible to provide an aqueous block polyisocyanate composition which is also useful as a modifier and a binder.

Claims (5)

[Claims] 1. An aliphatic and / or alicyclic polyisocyanate having an isocyanurate bond is represented by the general formula (1):
The compound shown by is added, and the addition ratio is (1) 22.5 parts by weight or more based on 100 parts by weight of the polyisocyanate, and (2) 3% or more of the isocyanate group of the polyisocyanate. It is 70% or less, and the free isocyanate group is a block polyisocyanate blocked with a heat dissociative blocking agent, and the effective isocyanate concentration of the block polyisocyanate is 2 to 20% by weight. Aqueous block polyisocyanate composition characterized. Embedded image 2. The aliphatic and / or alicyclic polyisocyanate is modified with a hydroxy compound.
Aqueous block polyisocyanate composition of. 3. The aqueous block polyisocyanate composition according to claim 1, wherein the heat dissociative blocking agent is an oxime compound, an active methylene compound, or an acid amide compound. 4. An aqueous block polyisocyanate composition according to any one of claims 1 to 3, and 500 parts by weight or less of a solvent-type block polyisocyanate per 100 parts by weight of the aqueous block polyisocyanate composition. An aqueous block polyisocyanate composition comprising: 5. An aqueous coating composition comprising a water-affinity polyol and the aqueous block polyisocyanate composition according to any one of claims 1 to 4.