JP3453175B2 - Method of forming curable film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a curable film, and more specifically, it cures in a short time even at a low temperature (for example, 0-40 ° C.) to give a solvent resistance, water resistance, mechanical strength, The present invention relates to a method for forming a curable film which has excellent coating workability and is useful for applications such as paints, coating agents, surface treatment agents and adhesives.

[0002]

2. Description of the Related Art The reaction between a 2-oxazoline group and a carboxyl group is known, and an ester amide bond: -CONH-CR (R) -CR is formed by a ring-opening reaction of an oxazoline group.
It is known to produce (R) -OCO-. JP-B-45-31467 discloses that a linear polyesteramide can be obtained by reacting bis-2-oxazoline with a dicarboxylic acid. There is also known a method of applying the reaction to an aqueous resin to form a curable resin film. For example, JP-B-63-48884 discloses an aqueous resin dispersion having a 2-oxazoline group and an aqueous resin having a carboxyl group. A method for obtaining a cured film by mixing the resin dispersion and coating and drying is disclosed.

[0003]

However, if the aqueous resin dispersion having a 2-oxazoline group and the aqueous resin dispersion having a carboxyl group are simply mixed, good solvent resistance is obtained when cured at high temperature. A film having water resistance and mechanical strength can be obtained, but the curing rate is slow under low-temperature (eg, 0-40 ° C., the same below) drying conditions,
There is a problem that the obtained film has insufficient solvent resistance, water resistance, mechanical strength, etc., and when applied to a substrate with poor heat resistance such as paper, plastic, wood, building materials and large structures Satisfactory performance cannot be obtained under conditions where it is difficult to cure at high temperature, such as when applying on site.

Further, depending on the kind of the carboxyl group-containing aqueous resin dispersion, there is a problem that the viscosity of the mixed solution is too high and the coating workability is unsatisfactory.

According to the present invention, the viscosity of the mixed solution is low, the workability is good, and it can be cured in a short time even at a low temperature, and the cured product has excellent solvent resistance, water resistance and mechanical strength. An object is to provide a method for forming a conductive film.

[0006]

In order to solve the above problems BRIEF SUMMARY OF THE INVENTION This invention provides 2-oxazoline group polymer aqueous dispersion of having (A) a polymer aqueous dispersion of a carboxyl group (B ) and mixed dispersion of (C), 5 in a liquid state
After aging by heating at a temperature of 0-100 ° C , coating or coating
And Sting, to provide a method of forming a curable coating, characterized in that to form a film by curing at 0-40 ° C..

The aqueous dispersion (A) of the polymer having a 2-oxazoline group used in the present invention means an addition-polymerizable oxazoline compound (a-) represented by the following general formula.
It is an aqueous dispersion of a polymer having a plurality of oxazolines as side chains, which is obtained by polymerizing a monomer component (a) containing 1), and preferably has a number average molecular weight of 1000 or more. The monomer component (a) is, if necessary, addition-polymerizable with the addition-polymerizable oxazoline compound (a-1), copolymerizable with the compound (a-1), and does not react with the 2-oxazoline group. The compound (a-2) may be contained in one kind or more.

[0008]

[Chemical 1]

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen, halogen, alkyl, aralkyl, phenyl or substituted phenyl, and R ⁵ is an acyclic group having an addition-polymerizable unsaturated bond. Specific examples of the addition-polymerizable oxazoline compound include 2-vinyl-2.
-Oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline,
2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline and the like can be mentioned. One compound selected from these groups can be used alone, or two or more compounds can be mixed. Can be used. Among them, 2-isopropenyl-2-oxazoline is industrially easily available and preferable.

Addition-polymerizable oxazoline compound (a-1)
The amount used of is not particularly limited, but is preferably 1% by weight or more in the polymer in the aqueous dispersion (A). If the amount is less than 1% by weight, the degree of curing will be insufficient, and the solvent resistance and mechanical strength of the film will tend to be impaired.

The addition polymerizable compound (a-2) used in the present invention is not particularly limited as long as it is a monomer that does not react with the oxazoline group and is copolymerizable with the addition polymerizable oxazoline (a-1). None, for example, (meth) acrylic acid esters such as methyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; unsaturated nitriles such as (meth) acrylonitrile;
Unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene. ; Vinyl chloride,
Vinylidene chloride, halogen-containing α, β- such as vinyl fluoride
Unsaturated monomers: α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like, and one kind or a mixture of two or more kinds thereof can be used.

An aqueous dispersion (A) of a polymer having an oxazoline group is prepared by emulsifying a monomer component (a) containing an addition-polymerizable oxazoline compound (a-1) by a conventionally known polymerization method in an aqueous medium. It can be produced by a polymerization method, a dispersion polymerization method, or the like. It can also be produced by post-dispersing a polymer previously produced by a known polymerization method in water.

In the present invention, the aqueous dispersion (B) of the polymer having a carboxyl group is an unsaturated carboxylic acid (b-
It is an aqueous dispersion (B-1) of a polymer obtained by polymerizing a monomer component (b) containing 1) or an aqueous dispersion (B-2) of a condensation polymer having a carboxyl group. The monomer component (b) may optionally contain at least one other monomer (b-2).

Examples of the unsaturated carboxylic acid (b-1) include unsaturated monocarboxylic acids such as (meth) acrylic acid, cinnamic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid and fumaric acid. Or the monoesters etc. can be mentioned. The amount of the unsaturated carboxylic acid used is not particularly limited, but is preferably in the range of 1 to 20% by weight in the polymer in the aqueous dispersion (B).

If the amount used is less than 1% by weight, it cannot be a substantially effective amount in the reaction with the aqueous dispersion (A).
If it exceeds 0% by weight, the water resistance of the cured product decreases, which is not preferable.

Other monomers used in this reaction (b-
As 2), in addition to the above-mentioned monomer (a-2), a monomer having a functional group capable of reacting with an oxazoline group, for example, aminoethyl (meth) acrylate, glycidyl (meth) acrylate, p-vinylphenol. Etc. can be mentioned, and these 1 type (s) or 2 or more types can be used.

The aqueous dispersion (B-1) can be produced by the same method as the aqueous dispersion (A). Aqueous dispersion (B-
As 2), for example, an aqueous dispersion of polyester resin, an aqueous dispersion of polyurethane resin, etc. containing a carboxyl group,
A wide variety of known materials can be used.

In the present invention, the mixing ratio of the aqueous dispersion (A) and the aqueous dispersion (B) is not particularly limited, but for example, 1 mol of the oxazoline group in the aqueous dispersion (A). And the carboxyl group in the aqueous dispersion (B) is 0.1-
It is preferable to mix within the range of 50 mol. If the blending ratio is outside this range, the curing is not sufficiently performed, and the solvent resistance and mechanical physical properties of the cured film are deteriorated, which is not preferable.

The present invention is characterized in that a film is formed after heating and aging the mixed dispersion (C) of the aqueous dispersion (A) and the aqueous dispersion (B) in a liquid state. During the heating and aging, the pH of the mixed dispersion (C) is preferably adjusted to 7 or more, more preferably in the range of 8-10.
Even if the pH is less than 7 and aging with heating, there is a tendency that the whole system gels due to destabilization of the system, or insufficient low temperature curability is obtained. When the pH is 10 or more, it was obtained. The water resistance of the coating may be deteriorated.

The neutralizing agent for adjusting the pH of the mixed dispersion (C) is not particularly limited, and triethylamine,
Organic amines such as monoethanolamine, ammonia,
Generally used basic compounds such as sodium hydroxide and potassium hydroxide can be used.

The heating and aging of the mixed dispersion (C) may be carried out in a usual stirrable reaction tank, and the liquid temperature at the time of aging is preferably in the range of 50 to 100 ° C., but if necessary, from this temperature. Lower or higher temperatures may be used. However, when the treatment is performed at a temperature lower than 50 ° C., the treatment takes a long time, which is often impractical. At 100 ° C. or higher, the stability of the system tends to be impaired. The heating treatment time varies depending on the treatment temperature and may be performed until the effect is substantially obtained. For example, the heating treatment may be performed at 80 ° C. for about 2 to 4 hours.

In the present invention, the mixed dispersion (C) is
If necessary within the range that does not impair the object of the invention, for example,
Plasticizers such as phthalates; fillers such as calcium carbonate, talc, clay, mica; pigments such as titanium white, zinc white, rouge, phthalocyanine; dyes; thickeners such as polyvinyl alcohol, hydroxyethyl cellulose, starch;
A dispersant; a wetting agent; an antifoaming agent such as silicone may be appropriately contained. These additives may be added before the heating and aging, or after the heating and aging.

The mixed dispersion (C) of the present invention has a film forming property and can be used as a paint (or coating agent), a surface treatment agent, an adhesive, a sealing agent, and the like.

As a coating method at this time, a base coater may be applied by a conventional method such as a roll coater, spraying, dipping or brush coating and then cured. As the substrate, for example, wood, plastic, organic or inorganic fibrous material (for example, paper, cloth, etc.), metal, inorganic material and the like can be used. It is also possible to form a film, tape, sheet or the like by the casting method or the like.

[0025]

[Function] A mixture dispersion (C) of an aqueous dispersion (A) of a polymer having a 2-oxazoline group and an aqueous dispersion (B) of a polymer having a carboxyl group is heat-aged in a liquid state. As a result, the coating liquid has excellent coating workability, is cured in a short time even at a low temperature (for example, 0-40 ° C.), and has good solvent resistance,
It forms a curable film that exhibits mechanical strength and is useful for applications such as paints, coating agents, surface treatment agents, and adhesives.

[0026]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, unless otherwise indicated,% means% by weight and part means part by weight.

Reference Example 1 782.4 parts of deionized water and Hitenol N-08 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were placed in a flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer and a dropping funnel. 128 parts of a 15% aqueous solution was charged, the pH was adjusted to 9.0 with an appropriate amount of aqueous ammonia (28%), and the mixture was heated to 70 ° C. while gently flowing nitrogen gas. 64 parts of a 5% aqueous solution of potassium persulfate was added thereto, and then 3 parts of a previously prepared monomer mixture of 288 parts of butyl acrylate, 320 parts of styrene and 32 parts of 2-isopropenyl-2-oxazoline were mixed. Dropped over time. During the reaction, nitrogen gas was continuously blown in to maintain the internal temperature at 70 ± 1 ° C. After the dropping was completed, the internal temperature was raised to 80 ° C. and stirring was continued for 1 hour to complete the reaction. Then, cool to a nonvolatile content of 3
An aqueous resin dispersion (1) having a pH of 8.0 and 9.8% was obtained.

Reference Example 2-5 The same procedure as in Reference Example 1 was repeated except that the composition of the polymerizable monomer mixture was changed as shown in Table 1 in Reference Example 1 to obtain an aqueous resin dispersion liquid. (2)-(5) were obtained. However, in Reference Examples 4 and 5, pH adjustment with aqueous ammonia was performed after the reaction was completed.

(Examples 1-4 and Comparative Examples 1-6) (Viscosity of Aqueous Dispersion) The viscosity of the aqueous dispersion was adjusted by adjusting the composition and heating and aging conditions shown in Table 2.

(Physical properties of film) The above aqueous resin composition was cast on a plate of tetrafluoroethylene resin under the conditions of 23 ± 2 ° C. and 65 ± 3% RH and then left for 2 days to give a film thickness of about A 0.3 mm film was made. Using the obtained film as a test piece, the following tests were conducted. The results are shown in Table 3.

(1) Solvent resistance The test piece was immersed in toluene at room temperature for 24 hours,
The swelling rate was calculated according to the following formula.

Swelling rate (%) = (weight after immersion−weight before immersion) / weight after immersion / drying × 100 (2) Water resistance At room temperature, a test piece was immersed in water for 24 hours to obtain its water absorption rate. Was calculated according to the following formula.

Water absorption rate (%) = (weight after soaking-weight before soaking) / weight after soaking / drying × 100 (3) Film strength The film strength was measured with an Instron tester at a tensile speed of 5 cm / min.

As can be seen from Table 2, the aqueous dispersions of the Examples have low viscosities in spite of the same composition and pH, as compared with the aqueous resin dispersions of Comparative Examples which are not heat-aged. The workability during painting was excellent.

As can be seen from Table 3, the coatings obtained from the aqueous dispersions which had been heat-aged as described in Examples were good in solvent resistance, water resistance, coating strength and coating elongation.

[0036]

According to the present invention, it is possible to form a coating film having a low viscosity, excellent coating workability, solvent resistance, water resistance and mechanical strength. Therefore, the present invention is useful for applications such as paints, coating agents, surface treatment agents, and adhesives.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 101/02 C08L 33/00-33/16 C08L 39/04 C09D 201/02 C09D 133/00-133 / 16 C09D 139/04 WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A 2-oxazoline group polymer aqueous dispersion of having (A) a mixed dispersion of an aqueous dispersion of a polymer having a carboxyl group (B) and (C), in a liquid state 50-1
Apply or cast after aging at a temperature of 00 ° C.
And curing at 0-40 ° C to form a film, which is a method for forming a curable film. 2. The p of the mixed dispersion liquid (C) at the time of aging by heating.
H is adjusted to 7 or more, the method of forming the curable coating of claim 1.