JP2001294643A - Self-emulsifiable polyisocyanate and water-based coating material produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a self-emulsifiable polyisocyanate having a sufficient pot life in a state dispersed in water and giving a coating film having sufficient crosslinking density when used as a curing agent for coating material and provide a water-based coating material produced by using the polyisocyanate. SOLUTION: The objective self-emulsifiable polyisocyanate is produced by reacting (A) a polyether monool comprising a block copolymer expressed by formula (1) (R is a 1-5C alkyl; and (m) and (n) are each an integer of >=1) and having the oxypropylene content higher than the oxyethylene content and optionally (B) an aliphatic compound containing active hydrogen group and other than the compound (A) with (C) an aliphatic and/or alicyclic polyisocyanate. The water-based coating material contains the self-emulsifiable polyisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a self-emulsifying polyisocyanate. More specifically, the present invention relates to a self-emulsifiable polyisocyanate in which isocyanate groups can be present for a long time after being dispersed in water.

[0002]

2. Description of the Related Art Paints, adhesives, coatings and the like containing a large amount of organic solvents have adverse effects on human bodies, safety and health problems such as explosion and fire, and pollution problems such as air pollution. Therefore, in order to improve these problems, aqueous systems have been actively developed in recent years. Conventionally, a water-soluble polymer solution or an aqueous emulsion has been used.However, in an aqueous one-component system, since a required physical property cannot be often expressed, a crosslinking agent is generally used for improving weather resistance and adhesiveness. . There are various crosslinking systems, and self-emulsifying polyisocyanates are widely used as crosslinking agents. Examples of conventional self-emulsifying polyisocyanates include JP-A-61-291613 and JP-A-5-22.
There are those described in, for example, Japanese Patent Publication No. 2150 and the like, in which a hydrophilic surfactant is introduced into polyisocyanate. Japanese Patent Application Laid-Open No. H10-195172 describes a self-emulsifying polyisocyanate in which a hydrophilic surfactant and a hydrophobic chain are introduced. Also, Japanese Unexamined Patent Publication No.
JP-183753 discloses an isocyanate composition obtained by reacting an organic polyisocyanate with a compound having a polyoxyethylene group and a polyoxypropylene group.

However, Japanese Unexamined Patent Publication No. 61-291613
In JP-A-5-222150 and the like, the hydrophilic surfactant specifically described is an alkoxy polyethylene glycol. When such a self-emulsifiable polyisocyanate is dispersed in water, reduction of isocyanate groups due to reaction between isocyanate groups and water occurs,
There is a problem that a sufficient pot life (usable time) cannot be secured. In JP-A-10-195172, since a hydrophobic chain is introduced in addition to a hydrophilic surfactant, the isocyanate content of the self-emulsifying polyisocyanate becomes small. It is difficult to obtain a coating film having a high crosslinking density. Further, in JP-A-57-183753, the pot life of the aqueous dispersion of polyisocyanate is still insufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating film having a sufficient pot life when dispersed in water and having a sufficient crosslink density when used as a curing agent for paints. To provide a self-emulsifying polyisocyanate and an aqueous paint using the same.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a self-emulsifying polyisocyanate obtained by using a specific modifying agent solves the above-mentioned problems, and complete the present invention. Reached.

That is, the present invention provides the following (1) to (4)
It is shown in. (1) A block copolymer represented by the formula (1), wherein the polyether monool (A) has a higher oxypropylene group content than the oxyethylene group content, and an aliphatic and / or alicyclic polyisocyanate. A self-emulsifiable polyisocyanate, which is obtained by reacting (C).

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(2) a block copolymer represented by the formula (1), wherein the polyether monool (A) has a higher oxypropylene group content than the oxyethylene group content;
And compounds having an aliphatic active hydrogen group other than (A) (B)
And an aliphatic and / or alicyclic polyisocyanate (C)
And a self-emulsifiable polyisocyanate obtained by reacting

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(3) The self-emulsifiable polyisocyanate according to the above (1) or (2), wherein (C) is an isocyanurate-modified polyisocyanate using hexamethylene diisocyanate.

(4) An aqueous paint comprising the self-emulsifiable polyisocyanate of any of the above (1) to (3) and an aqueous resin.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a block copolymer represented by the following formula (1), wherein the polyether monool (A) has a larger oxypropylene group content than a oxyethylene group content by mass. , And an aliphatic active hydrogen group-containing compound (B) other than (A) used as necessary
And an organic polyisocyanate (C).

[0011]

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In the case of (A), when R is a group having 6 or more carbon atoms, the dispersibility of the resulting polyisocyanate in water tends to decrease. When the number of oxyethylene groups is larger than that of oxypropylene groups, the pot life when the obtained polyisocyanate is dispersed in water tends to be short.

The preferred number average molecular weight of (A) is 800 to
It is 5,000 or more, preferably 1,000 to 3,000. When the number average molecular weight is less than the lower limit, the obtained polyisocyanate is difficult to disperse in water. On the other hand, when the ratio exceeds the upper limit, the viscosity of the obtained polyisocyanate is increased, and the workability in the step of dispersing in water is likely to be reduced.

(A) is obtained by a known method. First, a poly (oxyethylene) monol is produced by subjecting ethylene oxide to a ring-opening addition reaction using a monol compound as an initiator. Subsequently, it is obtained by subjecting propylene oxide to a ring-opening addition reaction.

As the monol used for the initiator,
Examples thereof include aliphatic monoalcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, and t-butanol. Preferred in the present invention are methanol and ethanol.

In the present invention, an aliphatic active hydrogen group-containing compound (B) other than (A) can be used if necessary. (B) includes methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, pentanol, hexanol, heptanol, octanol,
-Low molecular weight monols such as ethylhexanol, benzyl alcohol, cyclohexanol and alkylene glycol monoalkyl ether; low molecular weight first monoamines such as ethylamine, butylamine and aniline; low molecular weight second monoamines such as diethylamine, dibutylamine and methylaniline.
Monoamines, active hydrogen group-containing polyesters, active hydrogen group-containing polyethers whose repeating units are oxyalkylene groups having 3 or more carbon atoms, active hydrogen group-containing polycarbonates, active hydrogen group-containing polyolefins, hydroxy higher fatty acids having 6 or more carbon atoms and The ester etc. are mentioned. Preferred in the present invention are monols.

The aliphatic and / or alicyclic polyisocyanate (C) used in the present invention is a modified aliphatic diisocyanate and / or alicyclic diisocyanate, and isocyanurate group, uretdione group, biuret group, It has one of allophanate groups.
Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, and cyclohexyl diisocyanate. These diisocyanates may be used as a mixture of two or more kinds. Further, urethane-modified, urea-modified, carbodiimide-modified, and uretonimine-modified diisocyanates can also be suitably used. (C) which is preferable in the present invention is hexamethylene diisocyanate or an isocyanurate-modified polyisocyanate using hexamethylene diisocyanate.

When (C) is an aromatic polyisocyanate, the pot life tends to be short when the obtained polyisocyanate is dispersed in water. Further, for example, when the self-emulsifiable polyisocyanate of the present invention is used as a curing agent for a coating material, the use of an aromatic polyisocyanate causes yellowing of the coating film, so that the appearance of the coating film tends to be impaired.

The reaction temperature of the reaction between (A) and (C) is from 30 to 120 ° C, preferably from 40 to 100 ° C. The aliphatic active hydrogen group-containing compound (B) other than (A) used as necessary may be reacted at the same time as (A) or may be reacted at a different time. During the reaction, a urethanization catalyst such as dibutyltin dilaurate or triethylenediamine may be added as necessary.

After completion of the reaction, a pigment, a dye,
Dispersion stabilizers, viscosity modifiers, leveling agents, anti-gelling agents, light stabilizers, antioxidants, ultraviolet absorbers, heat resistance improvers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents,
Reinforcing materials, catalysts, thixotropic agents and the like can be added.

In the self-emulsifying polyisocyanate of the present invention, the amount of (A) introduced is (A) :( C) = 1: 100-80: 100, based on the mass ratio of (A) to (C).
Preferably (A) :( C) = 1.5: 100-70: 1
00. When (B) is used, the preferred amount of (B) to be introduced is based on the mass ratio of (B) and (C).
(B) :( C) = 1: 100-80: 100, preferably (B) :( C) = 1: 100-70: 100.

When the amount of (A) introduced is less than the lower limit, the water dispersibility of the modified polyisocyanate tends to deteriorate. Conversely, if the upper limit is exceeded, the isocyanate content will decrease as a result, so that when used as a curing agent, the physical properties of the cured product tend to decrease.

The self-emulsifying polyisocyanate of the present invention has an average number of functional groups of 2 to 5, preferably 2.1 to 4.9. If the average number of functional groups is too low, the strength and durability of the cured product are likely to decrease. If the average number of functional groups is too high,
Since the (number average) molecular weight is too large, the viscosity is increased and the workability (dispersion in water) is likely to be reduced.

The self-emulsifying polyisocyanate of the present invention has an isocyanate content of 10 to 20% by mass, preferably 10.5 to 19.5% by mass. If the isocyanate content is too small, the crosslinked density is low, and the strength and durability of the cured product are likely to decrease. If the isocyanate content is too large, the amount of the isocyanurate group or (A) introduced into the polyisocyanate is small, so that the durability of the cured product is reduced and the dispersibility of the polyisocyanate in water is easily reduced.

The free diisocyanate content of the self-emulsifying polyisocyanate of the present invention is 1% or less, preferably 0.9% or less. If the free diisocyanate content is too high, the pot life after dispersion in water is shortened, and the problem of odor tends to occur.

The aqueous coating composition of the present invention comprises the above-mentioned self-emulsifying polyisocyanate and an aqueous resin.

Examples of the aqueous resin having an active hydrogen group include polyvinyl alcohol, polyethylene oxide, a water-soluble ethylene-vinyl acetate copolymer, a water-soluble acrylic resin,
Water-soluble epoxy resin, water-soluble cellulose derivative, water-soluble polyester, water-soluble lignin derivative, water-soluble fluororesin, water-soluble resin such as water-soluble silicone resin, latex,
What is described as an emulsion, for example, rubber-based latex such as styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, chloroprene latex, polybutadiene latex, polyacrylate Latex, polyvinylidene chloride latex, polybutadiene latex, or those obtained by carboxyl modification of these latex, and the like,
Also, polyvinyl chloride emulsion, urethane acrylic emulsion, silicone acrylic emulsion, vinyl acetate acrylic emulsion, polyurethane emulsion,
Acrylic emulsion and the like can be mentioned. In addition, fluorine emulsions having excellent weather resistance and stain resistance are poor in solvent resistance due to non-crosslinking, but by using the self-emulsifying polyisocyanate of the present invention, weather resistance, stain resistance and solvent resistance are improved. Etc. can be further improved.

Even when the aqueous resin does not contain active hydrogen groups capable of reacting with isocyanate groups or contains only a small amount thereof, the self-emulsifiable polyisocyanate eventually reacts with water in the aqueous resin. As a result, a polyurea compound is formed, and a hard and tough coating film is formed, so that weather resistance is improved. Further, since the isocyanate group reacts with an active hydrogen group existing on the surface of the adherend, the adhesion is also improved. But,
When using an aqueous resin containing a large amount of active hydrogen groups that can react with isocyanate groups at room temperature, the active hydrogen groups in the polymer and the isocyanate groups of the self-emulsifiable polyisocyanate react to form a crosslinked structure, Weatherability,
The solvent resistance and the like are further improved. In addition, when baking at a high temperature, the self-emulsifying type polyisocyanate containing a uretdione group dissociates the uretdione group and generates an isocyanate group, so the addition effect is remarkable as compared with the case of using at normal temperature. Appears in Therefore, the aqueous resin more preferably contains an active hydrogen group capable of reacting with an isocyanate group.

The method of using the self-emulsifying type polyisocyanate of the present invention as an aqueous coating includes adding the self-emulsifying type polyisocyanate as it is to an aqueous resin, dispersing the self-emulsifying type polyisocyanate in water once, or dissolving it in a solvent commonly used in the urethane industry. Method. A preferred method is to disperse a self-emulsifying polyisocyanate in water and then blend this dispersion with an aqueous resin, or blend an aqueous resin with the dispersion.

In the water-based coating composition of the present invention, the mixing ratio of the water-based resin and the self-emulsifying polyisocyanate is expressed by mass ratio: water resin (solid content) / self-emulsifying polyisocyanate = 10
0 / 0.5 to 100/100, preferably 100/1 to
100/80.

Further, the self-emulsifying polyisocyanate of the present invention, which is dispersed in water, can be used as it is in an aqueous paint.

In this case, the mixing ratio of water and the self-emulsifying polyisocyanate is expressed by mass ratio, water / self-emulsifying polyisocyanate = 100/1 to 100/100, preferably 10/100.
0/10 to 100/100. This dispersion becomes a paint (coating agent) or adhesive with very good adhesion because the isocyanate groups which are present relatively stably even after being dispersed in water react with the active hydrogen present on the surface of the substrate. . In addition, a considerable amount of time has passed since the aqueous dispersion, and the aqueous dispersion after the isocyanate groups have disappeared also has a particle size of 0.1 to 0.1%.
A film mainly composed of a urea compound, which is stable as an emulsion state of about 0.3 μm and is obtained by drying it at room temperature or under heat, is hard and tough, and therefore has a film or sheet form or various bases. It can be used as a coating agent for materials. When importance is attached to the adhesion to the base material, it is desirable to use in a state where the isocyanate group is present.

The self-emulsifying type polyisocyanate of the present invention is used as an aqueous adhesive, an organic solvent type paint or adhesive, a sealing material, an ink, a fiber / glass fiber treating agent, and a sizing agent, in addition to the aqueous coating. can do.
As the effect of addition, excellent adhesion compared to conventional ones,
A cured or treated product having durability can be obtained.

[0034]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In Examples and Comparative Examples,
“%” Means “% by mass”.

Synthesis Example [Production of Isocyanurate-Modified Polyisocyanate] A reactor equipped with a stirrer, a thermometer, a nitrogen sealed tube, and a cooler having a capacity of 500 ml: 300 g of HDI (hexamethylene diisocyanate) and 1,3- After 2.8 g of butanediol was charged, the inside of the reactor was replaced with nitrogen, and the mixture was heated to a reaction temperature of 80 ° C. with stirring and reacted at the same temperature for 2 hours. The measured isocyanate content of the reaction solution was 48.6%. Next, 0.06 g of potassium caprate was used as a catalyst, and phenol 0.3 was used as a cocatalyst.
g was added and an isocyanurate-forming reaction was performed at 60 ° C. for 6 hours. 0.042 g of phosphoric acid was added to this reaction solution as a terminator.
After stirring at the reaction temperature for 1 hour, free HDI was
At 1.3 ° C. by thin film distillation.
An isocyanurate-modified polyisocyanate NCO-1 was obtained. NCO-1 is a pale yellow transparent liquid, isocyanate content of 21.3%, viscosity at 25 ° C. of 1,500 mPa · s,
The free HDI content was 0.3%, and the average number of functional groups was 3.8.

[Production of self-emulsifying type polyisocyanate] Example 1 Capacity: 1,000 ml incorporating the same apparatus as in the synthesis example
L reactor was charged with 601 g of NCO-1 and 399 g of monol (1) and reacted at 70 ° C. for 3 hours to obtain self-emulsifying polyisocyanate A. The viscosity at 25 ° C. of the polyisocyanate A is 2,720 mPa
-The s and isocyanate group content was 11.1%.

Examples 2 to 4 and Comparative Examples 1 and 2 Self-emulsifying polyisocyanates BF were obtained in the same manner as in Example 1 using the raw materials shown in Table 1. Table 1 shows the results.

[0038]

[Table 1]

In Examples 1 to 4, Comparative Examples 1 and 2, and Table 1. Monool (1): methoxypolyethylene glycol having a number average molecular weight of 400 to which propylene oxide has been added. Total number average molecular weight = 1,100. Monool (2): methoxypolyethylene glycol having a number average molecular weight of 400 to which propylene oxide has been added Total number average molecular weight = 1,400 Monool (3): methoxypolyethylene glycol having a number average molecular weight of 700 and propylene oxide The total number average molecular weight = 1,700 monool (4): methoxy polyethylene glycol The total number average molecular weight = 400 monol (5): ricinoleic acid methyl ester

Examples 7 to 12 and Comparative Examples 3 and 4 The obtained self-emulsifying polyisocyanates A to H were evaluated by the following tests. Table 2 shows the results. [Water dispersibility test method] Capacity: In a 2,000 ml container,
900 g of water and 100 g of a self-emulsifiable polyisocyanate are blended, and a homomixer is used for 30 seconds at a high speed (2,000 per minute).
(0 times), and the state of the aqueous dispersion was visually evaluated. [Measurement of pot life] The sample prepared in the water dispersibility test was stored as it was at 25 ° C., and the isocyanate content was measured every hour after dispersing. The time when the isocyanate content became 0 was defined as the pot life time. [Coating physical properties] In a 300 ml container, 100 g of the following acrylic emulsion and 10 self-emulsifying polyisocyanates were added.
g for 30 seconds with a homomixer (2,000 rpm)
(0 times) to prepare the clear coating. This clear paint is applied to an aluminum plate with an applicator,
After coating to a thickness of μm, the coating was cured at 50 ° C. for 20 hours to obtain a coated sample. The solvent resistance of this coating sample was evaluated. Solvent resistance: Xylene was impregnated into absorbent cotton, and this was rubbed on the coating film. ：: No change in appearance at 200 times. Δ: The coating film surface fogged after 100 cycles. ×: The coating film is broken after 50 times or less.

[Synthesis of Aqueous Acrylic Emulsion] Capacity with stirrer, thermometer, nitrogen sealed tube, cooler: 2,
170 g of ion-exchanged water, 4 g of Lebenol WZ (anionic emulsifier, manufactured by Kao) and 1 g of Neugen EA-170 (nonionic emulsifier, manufactured by Daiichi Kogyo Seiyaku) were charged into a 000 ml reactor, and heated to 80 ° C. Next, 300 g of methyl methacrylate and 180 g of butyl acrylate
g, 4 g of acrylic acid, 5 g of diacetone acrylamide, 330 g of ion-exchanged water, Neugen EA-170
Was added dropwise over 3 hours while maintaining the temperature in the reaction solution at 80 ° C., and then reacted at 80 ° C. for 3 hours. After completion of the reaction, the reaction mixture is cooled to room temperature, and pH is adjusted with a 25% aqueous ammonia solution.
8 to obtain an aqueous acrylic emulsion having a solid content of 49.5%.

[0042]

[Table 2]

As can be seen from Table 2, the self-emulsifying polyisocyanate of the present invention had improved pot life after dispersion in water, and when used as a curing agent for aqueous paints, the physical properties of the coating film were good.

[0044]

As described above, the self-emulsifiable polyisocyanate of the present invention is modified with a compound having a hydrophilic segment and a hydrophobic segment in the same molecule, and thus has a pot life after water dispersion. Is long. Further, since a sufficient isocyanate content can be secured, when used as a curing agent for an aqueous paint, the coating film showed good physical properties. The self-emulsifying type polyisocyanate of the present invention can be applied to water-based paints, water-based adhesives, water-based coating agents, sealants, inks, fiber / glass fiber treatment agents, sizing agents, and the like. Further, the present invention can be applied to a conventional organic solvent system.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/02 C09D 5/02 175/08 175/08 201/00 201/00 F-term (Reference) 4J034 BA02 BA03 BA06 BA08 CA02 CA13 CA17 CA22 CB01 CC02 CD04 CD05 DA01 DB01 DE02 DF02 DG03 DG04 DG09 HA07 HA08 HA14 HB05 HB06 HB08 HB09 HC03 HC06 HC12 HC22 HC35 HC46 HC52 HC54 HC61 HC64 HC71 HC73 JA01 RA07 RA17 4J0251 BA021 BA021 BA021 CA062 CA071 CA072 CB051 CB052 CC041 CC042 CD021 CD022 CD081 CD082 CD091 CD092 CE021 CE022 CF031 CF032 CF071 CF072 CG001 CG002 CG161 CG162 CJ031 CJ032 CJ181 CJ182 DB001 DB002 DD001 03 DG023 DG021 DG021

Claims (4)

[Claims] 1. A block copolymer represented by the formula (1), wherein the polyether monool (A) has a higher oxypropylene group content than the oxyethylene group content, and an aliphatic and / or alicyclic group A self-emulsifiable polyisocyanate obtained by reacting with a polyisocyanate (C). Embedded image 2. A block copolymer represented by the formula (1), wherein the polyether monool (A) has a higher oxypropylene group content than the oxyethylene group content, and an aliphatic system other than (A). An active hydrogen group-containing compound (B);
A self-emulsifiable polyisocyanate obtained by reacting an aliphatic and / or alicyclic polyisocyanate (C). Embedded image 3. The self-emulsifiable polyisocyanate according to claim 1, wherein (C) is an isocyanurate-modified polyisocyanate using hexamethylene diisocyanate. 4. An aqueous coating comprising the self-emulsifying polyisocyanate according to claim 1 and an aqueous resin.