JPH04198210A - Production of new aqueous acrylic/urethane dispersion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel and useful method for producing aqueous acrylic-urethane dispersions. More specifically, it has extremely good compatibility obtained through a reaction with a compound having both a blocked isocyanate group and an active isocyanate group, and also has excellent weather resistance of acrylic resin and strength and flexibility of polyurethane resin. This invention relates to a method for producing a specific one-component acrylic-urethane aqueous liquid separation having mechanical properties such as.

The aqueous acrylic-urethane dispersion obtained by the method of the present invention is extremely useful as a treatment agent for fibers and synthetic leather products, an adhesive, a coating, a vehicle for paint or ink, etc., among others.

(Conventional technology) In recent years, there has been increasing interest in water-based resins as an alternative to conventional organic solvent-based resins from the perspective of pollution control and environmental pollution control. Among these, water-based polyurethane resins have From the mechanical properties, for example,
In addition to being used as a treatment agent for artificial leather and fibers, such as those listed in Japanese Patent Application Laid-Open No. 1983-11938 and Fibers, 27.481 (1975), it can also be used as a treatment agent for PVC base materials or plastics. It has been used in a wide range of fields such as film adhesives.

However, it is still insufficient in terms of weather resistance, and acrylic resins still have an advantage in this field.

For solvent-based systems, two-component acrylic resins with hydroxyl groups and polyisocyanate as a crosslinking agent are used.
Urethane resins are well known, and paints with very good properties have been obtained.

On the other hand, in aqueous systems, it is difficult to use polyisocyanates, and acrylic resins and polyurethane resins are not compatible, so it is necessary to combine the excellent mechanical properties of polyurethane resins with the weather resistance of acrylic resins. Although such aqueous acrylic-urethane dispersions have been promising, the reality is that good ones have not yet been obtained.

(Problems to be Solved by the Invention) As described above, as long as conventional techniques are followed, it is difficult to obtain an extremely practical - wave-shaped acrylic-urethane aqueous dispersion, and therefore, acrylic resin and polyurethane resin It can be said that the current need in the industry is for an aqueous acrylic-urethane dispersion that has good compatibility with the polyurethane resins and has both the excellent mechanical properties of polyurethane resins and the weather resistance of acrylic resins.

Therefore, the present inventor's basic aim is to improve the compatibility between acrylic resin and polyurethane resin, and also to achieve both the excellent mechanical properties of polyurethane resin and the weather resistance of acrylic resin. I started my research with all my heart.

Therefore, the problem to be solved by the present invention is to create an extremely practical acrylic material that has both the weather resistance of an acrylic resin and the flexibility and strength of a polyurethane resin. An object of the present invention is to provide an aqueous urethane dispersion.

(Means for Solving the Problems) Therefore, the present inventors set their sights on the problems to be solved by the invention as described above, and developed an acrylic resin that solves and overcomes the various problems described above in the prior art. About a corrugated acrylic-urethane resin that combines good weather resistance and the excellent mechanical properties of a polyurethane resin,
As a result of extensive research, we have completed the present invention.

That is, the present invention is based on carrying out chain elongation by deblocking in an aqueous dispersion of an acrylic resin containing blocked isocyanate groups. First, one molecule is added to an acrylic resin solution having a hydroxyl value in the range of 5 to 200. A prepolymer having at least one active isocyanate group and a blocked isocyanate group is mixed in the acrylic resin, and the hydroxyl groups in the acrylic resin are reacted with the isocyanate groups in the prepolymer to form a block isocyanate-containing acrylic resin. Aqueous acrylic-urethane is produced by a unique method of forming a solution, then adding water to form a stable dispersion, and then extending the chain in the aqueous dispersion using an amino group-containing compound. The technical idea can be summarized as providing a new method for producing a dispersion liquid.

The acrylic resin solution having a hydroxyl value within the above range of 5-200 used in carrying out the method of the present invention may contain, for example, hydroxyl ethyl acrylate, hydroxypropyl acrylate, methacrylate as a hydroxyl group-containing monomer. monomers such as hydroxyethyl acid or hydroxypropyl methacrylate; or monoacrylic acid or monomethacrylic acid of polyglycols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol or ethylene oxide or propylene oxide adducts of bisphenol A. monomers such as esters; other polymerizable vinyl monomers copolymerized with these monomers, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, (meth)acrylate; ) (meth)acrylic esters such as lauryl acrylate; α- or β-unsaturated amides such as acrylamide, methacrylamide, n-methylacrylamide; α such as axolonitrile and methacrylonitrile;
- or β-unsaturated nitriles; styrene derivatives such as styrene, α-methylstyrene, vinyltoluene;
Vinyl esters such as vinyl acetate and vinyl propionate; vinyl halides such as vinyl chloride, vinylidene chloride, and other fluorine-containing monomers; or one or more monomers of conjugated dienes such as butadiene. It can be obtained by copolymerizing.

The hydroxyl value of the hydroxyl group-containing acrylic resin solution obtained in this manner must be within the range of 5 to 200 per resin solid content.

When the hydroxyl value of the acrylic resin solution is lower than 5,
This is not preferable because the subsequent reaction with the active isocyanate group is not sufficiently carried out, resulting in poor compatibility of the acrylic-urethane resin finally obtained. In addition, if the hydroxyl value of the acrylic resin solution becomes too high, exceeding 200, it is not preferable because it tends to gel due to the subsequent reaction with active isocyanate groups. Preferably 20
~180.

Further, in the hydroxyl group-containing acrylic resin solution used in the present invention, a carboxyl group-containing monomer may be used for the purpose of improving the stability of the final dispersion of the aqueous acrylic-urethane resin dispersion.

Particularly representative examples of such carboxyl group-containing monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid.

The amount of the carboxyl group-containing monomer used is preferably 5% by weight or less based on the total monomers. If the amount of this carboxyl group-containing monomer used exceeds 5% by weight, the final acrylic - The water resistance of the urethane resin coating film tends to decrease, which is not preferable.

In the present invention, the thus obtained 5-20
A prepolymer having both at least one active isocyanate group and a blocked isocyanate group in one molecule is mixed into an acrylic resin solution having a hydroxyl value in the range of 0, and the hydroxyl groups in the acrylic resin and the prepolymer are mixed. isocyanate group.

Here, as the prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule, for example, a polyisocyanate compound having two or more isocyanate groups in one molecule is used. Those obtained by blocking at least one of them using an isocyanate group blocking agent can be used.

Examples of particularly representative organic isocyanate compounds having two or more isocyanate groups in one molecule include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and m-phenylene diisocyanate. , p-phenylene diisocyanate, 4. 4'-diphenylmethane diisocyanate,
2. 4'-diphenylmethane diisocyanate, courtesy
2'-diphenylmethane diisocyanate, 3,3°-
dimethyl-4,4'-biphenylene diisocyanate,
3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3. 3'-dichloro-4,4'
-biphenylene diisocyanate, 1゜5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1
, 6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, l,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate,
Examples include lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 3,3°-dimethyl-4,4'-dicyclohexylmethane diisocyanate.

mata, ethylene glycol, propylene glycol, 1
, 3-propanediol, 1,4-butanediol, 1
, 5-bentanediol, 3-methyl-1,5-bentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, molecular weight 200~
6,00 polyethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol,
1,4-Cyclohexane dimetatool, bisphenol A1 hydrogenated bisphenol A5 low molecular weight polyhydroxy compounds such as glycerin, trimethylolpropane, sorbitol or pentaerythritol,
Also preferred are prepolymers obtained by reacting an organic isocyanate compound in excess of the stoichiometric amount.

In the present invention, those obtained by blocking some of these isocyanate groups with a blocking agent can also be used.

As such isocyanate blocking agents, conventionally known ones can be used, but some of the most representative ones are formaldoxime, acetaldoxime, propionaldoxime, butyraldo boshin, benzaldo. oxime, acetophenone oxime,
Oximes such as methyl ethyl ketoxime and cyclohexanone oxime; phenols such as phenol, ortho-chlorophenol and meta-cresol; lactams such as epsilon-caprolactam; or compounds such as diethyl malonate.

Particularly preferred are oximes represented by methyl ethyl ketoxime.

Usually, the preparation of the prepolymer having at least one active isocyanate group and blocked isocyanate group in one molecule used in the present invention is as follows:
This can be done by dropping an isocyanate blocking agent into an organic isocyanate compound having two or more isocyanate groups in one molecule. The preparation of partially blocked prepolymers can also be carried out with so-called isocyanate groups, such as dioxane, acetone, methyl ethyl ketone, acetonitrile, ethyl acetate, tetrahydrofuran, toluene or xylene, in order to ensure a homogeneous reaction. Active organic solvents are used.

Usually 20-100% based on the solid content of the prepolymer
(% by weight) is used.

If the amount of organic solvent is less than 20% based on the solid content of the prepolymer, the viscosity of the prepolymer solution tends to become too high, making water dispersion difficult, which is not preferred. On the other hand, when the amount of organic solvent is more than 100% based on the solid content of the prepolymer, water dispersibility is no longer improved even if the amount of organic solvent is increased further;
Since the amount of solvent removed increases, it is rather uneconomical.

Next, in the present invention, a prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule is added to the previously obtained acrylic resin solution having a hydroxyl value within the range of 5 to 200. and,
The hydroxyl groups in the acrylic resin are reacted with the isocyanate groups in the prepolymer. In this case, the isocyanate groups that are active against the hydroxyl value of the acrylic resin are usually used in less than stoichiometric amounts.

If the amount of active isocyanate groups is large relative to the hydroxyl value of this acrylic resin, it tends to gel, which is undesirable, and usually OH/active NC0 = 110.2 to 1
It is carried out within a certain range.

The thus obtained blocked isocyanate-containing acrylic resin solution is then turned into a stable dispersion by adding water thereto.

In this case, a polyamine compound is used in combination in the present invention.

Typical examples of such polyamine compounds used in the present invention include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine,
Thank you 5-dimethylpiperazine, isophoronediamine, 4
．． 4'-dicyclohexylmethanediamine, 3,3'
Diamines such as -dimethyl-4,4'-dicyclohexylmethanediamine and 1,4-cyclohexylmethanediamine; polyamines such as diethylenetriamine, dipropylenetriamine, and triethylenetetramine; and hydrazines, and these may be used alone. Of course, they may be used or two or more types may be used in combination.

In addition to these polyamines, derivatives having an amine terminal group, which are obtained by reacting the above polyamines with a less than stoichiometric amount of a polyepoxide compound, can also be preferably used. can.

In the present invention, the thus obtained blocked isocyanate-containing acrylic resin solution is prepared by adding polyamines and then dispersing it in water to prepare an aqueous dispersion, or by dispersing it in water before adding polyamines. After that, polyamines are added to prepare an aqueous dispersion, and this aqueous dispersion is then heated to dissociate the blocking agent, and the regenerated isocyanate groups are reacted with the polyamines, such as those excavated from the earth. By doing so, the desired novel acrylic-urethane aqueous dispersion is produced.

In this case, the water dispersion method is such that the acrylic-urethane polymer containing blocked isocyanate groups forms a sufficient amount of salts such as carboxyl groups or sulfonic acid groups to form a stable aqueous dispersion. In the case of a polymer that can contain such groups, a soda-free polyurethane aqueous dispersion can be obtained by converting the carboxyl group or sulfonic acid group into a salt form, and in the case of a polymer that does not contain such groups, HLB is Nonionic emulsifiers such as polyoxyethylene nonylphenol ether yaphorioxyethylene-oxypropylene block copolymer 16-18; or known and commonly used surfactants such as anionic emulsifiers such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate. An aqueous polyurethane dispersion can be obtained by carrying out phase inversion emulsification using a colloid mill or by carrying out mechanical emulsification using a colloid mill or the like.

In carrying out the method of the present invention, the amount of polyamines used is such that the ratio of the equivalent of blocked isocyanato groups to the equivalent of polyamine is NCo/NH=1. 2
/1-0. 3, preferably within the range of 1.0-0.5.

The equivalence ratio of N CO/N H is 1. If it is larger than 2, the molecular weight of the urethane portion inevitably becomes small, which deteriorates the mechanical properties of the resulting acrylic-urethane resin, which is not preferable.

On the other hand, the NCO/NH ratio is 0. If it is smaller than 3, most of the isocyanate groups regenerated by dissociation of the blocking agent are consumed in reaction with the surrounding water, so that the resulting acrylic-urethane resin This is not preferable because it results in a decrease in the mechanical properties of the material.

In addition, the conditions for dissociating the blocked isocyanate group are as follows:
It varies depending on the type of blocking agent, but usually 40-9
This is achieved by stirring for 2-10 hours at 0°C.

In carrying out the supplementary injection of the present invention, the amount of water used to water-disperse the blocked isocyanate group-containing acrylic resin solution is not particularly limited, but the weight percentage of the polyurethane polymer finally obtained However, after this water dispersion, it is preferable that the amount is about 20 to 40%.

After the deblocking reaction is completed, it is important to azeotrope the aqueous acrylic-urethane dispersion with water under reduced pressure in order to remove the organic solvent and the generated blocking agent contained in the aqueous acrylic-urethane dispersion.

The aqueous acrylic-urethane dispersion obtained by the method of the present invention has excellent adhesion to the surface of metals, especially inorganic compounds, and also has excellent weather resistance and mechanical properties.

In addition, it can be applied by spray painting, roll coating, etc., and a good coating film can be obtained.

Therefore, the acrylic-urethane aqueous dispersion obtained by the method of the present invention is different from the conventional acrylic aqueous dispersion.
It can be used in many applications that could never be applied.

This includes vehicles for ink, automotive paint, and household paint, as well as glass, plastic, textiles, paper,
It can be used in a wide range of applications, such as coating leather, wood or metal; thin film coating on fibers and textiles; surface coating for fur; and as various adhesives.

(Example) Next, the present invention will be specifically explained using Examples and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified.

Example 1 500 parts of methyl ethyl ketone is added to a four-hole flask equipped with a thermometer, a stirrer, and a reflux condenser, stirring is started while nitrogen gas is flowing, and the mixture is heated to 80°C. To this, 10 parts of a mixture of a polymerizable unsaturated bond-containing compound prepared by mixing 170 parts of n-butyl acrylate, 130 parts of methyl methacrylate, 100 parts of styrene, and 100 parts of hydrobovine diethyl methacrylate; and tert-butyl hydroperoxide were injected dropwise into the flask from a separate dropping funnel over a period of 3 hours, and the same temperature was maintained for 6 hours after the completion of the dropwise addition to continue the copolymerization reaction and complete the copolymerization reaction. I let it happen. The OH value at this time was 86.3 (per solid content).

Next, 52.4 parts of a compound in which one isocyanate group of tolylene diisocyanate was blocked with methyl ethyl ketoxime was added, and the mixture was heated at 80° C. for 2 hours to cause the active isocyanate group to react with the OH group of the acrylic resin.

After that, 1 of isophorone diamine was added to the thus obtained acrylic resin solution containing blocked isocyanate groups.
Add 6.2 parts and stir to make a homogeneous solution, then add polyoxyethylene-polyoxyprobiene block polymer (ethylene content = 80%, molecule M = 12.0
00) was mixed with 750 parts of an aqueous solution, and then passed through a colloid mill to prepare an emulsion.

Next, the obtained emulsion was maintained at 80° C. for 2 hours with stirring, and then the methyl ethyl ketone and the dissociated blocking agent were distilled off under reduced pressure until the nonvolatile content was 44.5% and the pH was adjusted to A target aqueous acrylic-urethane dispersion having a temperature of 7.5°C and a viscosity of 250 cps at 25°C was obtained.

The aqueous acrylic-urethane dispersion obtained here formed a film with extremely good gloss and transparency, and had excellent chemical resistance and water resistance, as well as good weather resistance. .

Example 2 Add 500 parts of methyl ethyl ketone to the same apparatus as in Example 1, start stirring while flowing nitrogen gas, and stir at 80°.
Heat to C. A mixture of polymerizable unsaturated bond-containing compounds prepared by mixing 200 parts of n-butyl methacrylate, 100 parts of methyl methacrylate, 150 parts of hydroxypropyl methacrylate, and 50 parts of methacrylic acid, and 10 parts of tert- Butyl hydroperoxide was injected dropwise into the flask from a separate dropping funnel over a period of 3 hours, and even after the dropwise addition was completed, the same temperature was maintained for 6 hours to continue the copolymerization reaction and complete the copolymerization reaction. I finished it. The OH value at this time was 116.9 (per solid content).

2 in a prepolymer in which 3 moles of tolylene diisocyanate were added to 1 mole of trimethylolpropane.
Add 207.4 parts of a compound in which two isocyanate groups are blocked with methyl ethyl ketoxime, and
The active isocyanate groups were allowed to react with the acrylic resin by heating for an hour.

Next, the thus obtained acrylic resin solution containing blocked isocyanate groups was added to 47.0% of triethylamine.
The mixture was slowly added to 880 parts of an aqueous solution containing 18 parts of ethylenediamine and 18 parts of ethylenediamine while stirring well.

Thereafter, the aqueous dispersion thus obtained was maintained at 80°C for 2 hours with stirring, and then methyl ethyl ketone and the dissociated blocking agent were distilled off under reduced pressure, resulting in a non-volatile content of 45.3. %, a pH of 7.4 and a viscosity of 840 cpS, a bluish appearance, the desired acrylic-urethane aqueous dispersion was obtained.

This acrylic-urethane aqueous dispersion formed a film with extremely good gloss and transparency, and had excellent chemical resistance, water resistance, and good weather resistance.

Example 3 Add 500 parts of methyl ethyl ketone to the same apparatus as in Example 1, start stirring while flowing nitrogen gas, and stir at 80°.
Heat to C. Furthermore, 20% of n-butyl methacrylate
0 parts, 100 parts of methyl methacrylate, 20 parts of lauryl methacrylate, 180 parts of hydroxyethyl acrylate
a mixture of polymerizable unsaturated bond-containing compounds,
10 parts of tert~butyl hydroperoxide,
The mixture was added dropwise into the flask from separate dropping funnels over a period of 3 hours, and even after the addition was completed, the same temperature was maintained for 6 hours to continue the copolymerization reaction and complete it.

The OH value at this time was 173.4 (per solid content).

583 parts of a compound in which one of the two active isocyanate groups is blocked with epsilon-caprolactam, which is 2 moles of hexamethylene diisocyanate added to 1 mole of dimethylolpropionic acid, are then added, and 8
Warming to 0°C for 2 hours allowed the active isocyanate groups to react with the acrylic resin. 248 parts of an amine compound prepared by reacting 172 parts of anhydrous piperazine with 380 parts of a bisphenol A type epoxy resin having an epoxy equivalent of 190, prepared in advance, was added to the obtained acrylic resin solution containing blocked isocyanate groups. The mixture was stirred and mixed so as to be uniform, and slowly added to 1,480 parts of an aqueous solution in which 101 parts of triethylamine had been dissolved, while stirring well.

Thereafter, the aqueous dispersion thus obtained was maintained at 80°C for 2 hours with stirring, and then methyl ethyl ketone and the dissociated blocking agent were distilled off under reduced pressure, resulting in a nonvolatile content of 45.7. %, a pH of 7.4 and a viscosity of 1,230 cps, an aqueous acrylic-urethane dispersion with a bluish appearance was obtained.

This acrylic-urethane aqueous dispersion formed a film with extremely good gloss and transparency, and had excellent chemical resistance and water resistance, as well as good weather resistance.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 2, except that in preparing an acrylic resin, the same amount of isopropyl methacrylate was used in place of hydro-dipropyl methacrylate. There was no OH value.

Thereafter, in the same manner as in Example 2, 2,074 mol of a compound in which two isocyanate groups of a prepolymer obtained by adding 3 mol of tolylene diisocyanate to 1 mol of trimethylolpropane were blocked with methyl ethyl ketoxime was used.
of the mixture was added and heated at 80°C for 2 hours.

Thereafter, the solution of the acrylic resin containing blocked isocyanate groups obtained in this way was mixed with triethylamine
The dispersion was slowly added to 880 parts of an aqueous solution containing 7.0 parts of ethylenediamine and 18 parts of ethylenediamine while stirring well, but an aqueous dispersion was not obtained and the whole agglomerated.

In addition, a film was formed by dissolving a part of this aggregate in methyl ethyl ketone, but the film became cloudy and a transparent film could not be obtained in the end.

Comparative Example 2 When 35.0 parts of tolylene diisocyanate was reacted with the OH groups in the acrylic resin obtained in the same manner as in Example 1, that is, the acrylic resin containing no blocked isocyanate groups, the solution significantly decreased. It was observed that the viscosity increased and that the entire solution finally turned into a gel.

(Effects of the Invention) As described above, the method of the present invention provides a novel and useful one-component aqueous acrylic-urethane dispersion having good compatibility. The novel acrylic-urethane aqueous dispersion obtained according to the method is extremely practical, having both the weather resistance of an acrylic resin and the flexibility and strength of a polyurethane resin.

Claims (1)

[Scope of Claims] 1. A method for producing an aqueous acrylic-urethane dispersion, which comprises carrying out chain elongation by deblocking in an aqueous dispersion of an acrylic resin containing blocked isocyanate groups. 2. A prepolymer in which the aqueous acrylic-urethane dispersion has at least one active isocyanate group and a blocked isocyanate group in one molecule;
The method for producing an aqueous acrylic-urethane dispersion according to claim 1, which is obtained through a reaction with a hydroxyl group-containing acrylic resin. 3. The acrylic-urethane aqueous dispersion described above is first
A prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule is mixed into an acrylic resin solution having a hydroxyl value in the range of 5 to 200, and the hydroxyl group in the acrylic resin and the above reacting with the isocyanate groups in the prepolymer to form a solution of the blocked isocyanate-containing acrylic resin, and then adding water to form a stable dispersion;
The method for producing an aqueous acrylic-urethane dispersion according to claim 1 or 2, which is obtained by subsequently elongating the chain in the aqueous dispersion using an amino group-containing compound. 4. The prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule has a carboxyl group or a sulfonic acid group that is relatively non-reactive with the isocyanate group,
and a prepolymer capable of forming a salt of a carboxyl group or a sulfonic acid group in an amount sufficient to form a stable aqueous dispersion. Manufacturing method. 5. Claim 2, 3 or 4, wherein the prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule contains a compound to which polyoxyethylene glycol monomethyl ether is added. A method for producing the aqueous acrylic-urethane dispersion described. 6. The acrylic according to any one of claims 2 to 5, wherein the prepolymer having at least one active isocyanate group and a blocked isocyanate group in one molecule is blocked with an oxime. - A method for producing an aqueous urethane dispersion.