JP3375395B2 - One-part curable aqueous emulsion composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-part curable emulsion composition which is excellent in adhesive strength, water resistance, heat resistance, solvent resistance and the like when cured at room temperature or by heat.

[0002]

2. Description of the Related Art Conventionally, adhesives used in the above fields are formalin condensation resins such as urea resin, melamine resin and phenol resin, one- or two-liquid solvent type synthetic rubber, polyurethane resin and epoxy resin. , Polyester resin, one- or two-component vinyl acetate emulsion,
Aqueous emulsions such as acrylic emulsion, synthetic rubber latex, urethane dispersion, epoxy resin dispersion and the like.

[0003]

Among the above resins, the formalin condensation type resins require equipment such as cold pressure or hot pressure press, and are mainly used for panel adhesives produced in factories. Odor and toxicity are problems. Due to the recent problems of environmental pollution, adverse effects on human bodies, fires, etc., solvent type resins are gradually changing to pollution-free resins. Aqueous emulsion is non-polluting and does not cause problems such as environmental pollution, but one liquid has a limit to obtain high adhesive strength, water resistance, heat resistance, etc., and a curing agent or curing accelerator is used together. However, there are problems such as complexity of the compounding work, restriction on the pot life of the two-component compound, and poor adhesion due to measurement errors during compounding. In order to solve this two-pack type problem, a one-pack aqueous acrylic urethane emulsion having inter-emulsion cross-linking ability by dehydration reaction of carbonyl group and hydrazide group has been introduced, but lacks water resistance, heat resistance, etc. .

[0004]

Means for Solving the Problems The present inventor
Solution of problems such as adverse effects on humans and fire, and adhesion with a one-liquid aqueous emulsion, water resistance, heat resistance, as a result of repeated intensive studies for the purpose of imparting solvent resistance, the epoxy resin and acrylic emulsion, It has been found that so-called hybridized emulsions are effective. That is, after forming an emulsion particle in which an epoxy resin is copolymerized with an aromatic vinyl monomer, an unsaturated carboxylic acid ester monomer and an acrylic monomer having an amide group, the outer side is continuously subjected to an aromatic vinyl monomer and an unsaturated carboxylic acid. Ester monomer, acrylic monomer having hydroxyl group,
A so-called core-shell structure epoxy-modified acrylic emulsion having a glass transition temperature of −30 to + 30 ° C., which is obtained by copolymerizing an acrylic monomer having an amide group and an acrylic monomer having a carboxyl group, has a viscosity change during long-term storage. It has excellent stability, and even if this emulsion is mixed with a curing agent for epoxy resins represented by amine and polyamide, this stability is maintained and the adhesive strength, water resistance, heat resistance, solvent resistance, etc. However, they found that they have physical properties not found in conventional one-liquid aqueous emulsions, and completed the present invention.

That is, the present invention is as follows. 1. The core layer is a copolymer of an aromatic vinyl monomer, an unsaturated carboxylic acid ester monomer, an amide group-containing acrylic monomer and an epoxy resin, and the shell layer has an aromatic vinyl monomer, an unsaturated carboxylic acid ester monomer, and a hydroxyl group. 100 parts by weight of the solid content of the epoxy-modified acrylic emulsion (a) having a core-shell structure, which is a copolymer of an acrylic monomer, an acrylic monomer having an amide group and an acrylic monomer having a carboxyl group, is added to a curing agent (b) for an epoxy resin. 1-3 as the solid content
A one-component curable aqueous emulsion composition containing 0 part by weight. 2. The epoxy-modified acrylic emulsion (a)
The one-part curable aqueous emulsion composition according to claim 1, which is obtained by copolymerizing 1 to 30 parts by weight of an epoxy resin in 100 parts by weight of the solid content of the emulsion.
3. The one-part curable aqueous emulsion composition according to claim 1, wherein the epoxy-modified acrylic emulsion (a) has a glass transition temperature (Tg) in the range of -30 to + 30 ° C. 4. The glass transition temperature (Tg) of the core layer of the epoxy-modified acrylic emulsion (a) is −30 to −30.
+ 80 ° C, glass transition temperature (Tg) of shell layer is -60
The one-part curable aqueous emulsion composition according to claim 1, which is in the range of + 30 ° C.

The epoxy-modified acrylic emulsion (a) having a core-shell structure of the present invention (hereinafter referred to as EPAE) is prepared by dissolving an epoxy resin in various monomers such as an aromatic vinyl monomer and an unsaturated carboxylic acid ester monomer. The mixed monomer was gradually added to distilled water containing a surfactant prepared in advance while stirring at room temperature,
A so-called pre-emulsifying monomer is prepared. Next, a flask equipped with a stirrer and a condenser was charged with distilled water and a surfactant, nitrogen substitution was performed, the temperature was raised to 70 ° C., a polymerization initiator was administered, and the pre-emulsified monomer was added dropwise over a certain period of time.
After the completion of the dropping, the residual monomer is reacted at the same temperature to form emulsion particles as the core of the present invention. Subsequently, various monomers used in advance for the shell layer, which are emulsified monomers in the same manner as in the case of the core layer, are dropped into the flask over a certain period of time to treat and polymerize the residual monomer. After the reaction is completed, the temperature is cooled to 40 ° C. or lower, pH is adjusted to 6 to 9 with aqueous ammonia, and 100
E used in the present invention by filtering with a mesh wire mesh
PAE is obtained.

Aromatic vinyl monomers used for emulsion polymerization of EPAE of the present invention include styrene, α-methylstyrene and divinylbenzene, and unsaturated carboxylic acid esters include methylmethacrylate, ethylmethacrylate, isobutylmethacrylate and tert. Acrylic acid or methacrylic acid ester having an alkyl group having 4 to 12 carbon atoms such as butyl methacrylate, vinyl acetate, acrylonitrile, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, 2 ethylhexyl acrylate, 2 ethylhexyl methacrylate and lauryl methacrylate. Among them, a combination of styrene and n-butyl acrylate is preferable from the viewpoint of economy and ease of emulsion polymerization.

Examples of the monomer having an amide group include acrylamide, methacrylamide, maleimide, N-methylol acrylamide, N-methylol methacrylamide, N-methoxymethyl acrylamide, N-isopropoxymethyl acrylamide, N-butoxymethyl acrylamide and N-iso Examples thereof include butoxymethyl acrylamide, N-octyloxymethyl acrylamide, N-carboxymethylene oxymethyl acrylamide and the like. Among them, methacrylamide or N-methylol methacrylamide is preferable from the viewpoint of adhesive strength, water resistance, warm water resistance and the like. As the monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid,
Fumaric acid and the like can be mentioned, among which stability during emulsion polymerization,
Acrylic acid or methacrylic acid is preferred from the viewpoint of mechanical and chemical stability. Examples of the monomer having a hydroxyl group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and the like, and among them, hydroxyethyl methacrylate is preferable because of stability after compounding with a curing agent for epoxy resin.

The epoxy resin is a bis-epi type consisting of bisphenol A type and epichlorohydrin, a cyclic fatty acid type consisting of a cyclic fatty acid unsaturated compound and peracetic acid, a novolak type consisting of a phenol resin and epichlorohydrin,
Tetraepoxy type consisting of glyoxal and phenol and epichlorohydrin, polybutadiene type consisting of polybutadiene and peracetic acid, halogenated type consisting of halogenated bisphenol A and epichlorohydrin, side chain type consisting of bisphenol A and epichlorohydrin and propylene oxide, and other polyalkylene ether type , Ester type, methyl substitution type and the like. Among these, due to the emulsion copolymerizability with the above-mentioned monomer, bisphenol A-
An epichlorohydrin type resin is suitable, for example, an epoxy resin having an epoxy equivalent of 180 to 270 and a viscosity of 5 to 150 poise is preferable. The copolymerization ratio of the epoxy resin in 100 parts by weight of the solid content of EPAE is in the range of 1 to 30 parts by weight. That is, it means that the above epoxy resin is used for the emulsion core layer. It is preferably in the range of 5 to 20 parts by weight. If the amount is less than 1 part by weight, the adhesive strength, water resistance, warm water resistance, heat resistance, solvent resistance, etc. will be insufficient, and
When the amount is more than the amount by weight, stability cannot be obtained during emulsion polymerization of the core layer, which causes a problem in production.

The glass transition temperature (T
g) (hereinafter abbreviated as Tg) is in the range of -30 to + 30 ° C. More preferably, it is in the range of -20 to + 20 ° C. If the temperature is lower than -30 ° C, the adhesive strength, heat resistance, etc. will be poor.
When the temperature is higher than + 30 ° C., there is no problem under the condition of heating and curing, but the film-forming property at room temperature is lacking, and the adhesive force, water resistance, heat resistance and the like cannot be obtained. The Tg expressed in the present invention means a calculated value from all monomers except the epoxy resin.
The Tg of the core layer of the EPAE of the present invention is -30 to + 80 ° C.
And preferably in the range of -10 to + 60 ° C. When the temperature is lower than -30 ° C, the adhesive strength and heat resistance cannot be obtained, and when the temperature is higher than + 80 ° C, the film-forming property at room temperature is insufficient, and the adhesive strength and the water resistance are deteriorated. Similarly, the Tg of the shell layer is in the range of −60 to + 30 ° C., more preferably −40 to + 20 ° C. When the temperature is lower than -60 ° C, the adhesive strength and heat resistance are insufficient, and when the temperature is higher than + 30 ° C, the film-forming property at room temperature is insufficient and sufficient adhesive strength and water resistance cannot be obtained.

The weight ratio of the monomers used in the core layer and the shell layer of EPAE is not particularly limited,
The preferred core-shell composition ratio is in the range of 7/3 to 3/7. When the amount of the monomer used in the core layer is increased to 7/3 or more, there is a risk that the core is not completely covered, and the stability during storage is impaired. Examples of the curing agent (b) for epoxy resin include aromatic amines, aliphatic amines, heterocyclic modified amines, amines such as polyamides, thiochols such as polysulfides, and acid anhydrides.
Of these, although not particularly limited, those which can be freely diluted with water or those which can be made into an aqueous emulsion are more preferable in view of mixing with an aqueous emulsion.

The compounding ratio of the curing agent for epoxy resin is EP
1 to 100 parts by weight of the solid content of AE as a solid content
30 parts by weight, more preferably 5 to 15 parts by weight. When the amount is less than 1 part by weight, the dry coating of EPAE does not proceed with curing and the adhesive strength, water resistance, heat resistance, solvent resistance and the like are not sufficiently exhibited, and when the amount is more than 30 parts by weight, the odor of the adhesive agent, Yellowing, reduction of solid content, and an excess of epoxy curing agent exhibit a plasticizing effect to reduce adhesive strength, heat resistance and the like.

As described above, in the one-component curable aqueous emulsion comprising the EPAE of the present invention and the curing agent for epoxy resin, a carboxyl group which reacts with a glycidyl group coexists in the emulsion particles, and the aqueous layer is treated like an amine. Despite the fact that the curing agent for epoxy resin is blended, the glycidyl group has a shape protected by the shell layer, so it has excellent long-term storage stability, and has a high adhesive strength when cured at room temperature or by heating. Since it has water resistance, heat resistance, solvent resistance, bending resistance, etc., it is used as a base resin for adhesives, granular, powdered or fibrous inorganic or wood fiber binders, architectural paints, and anticorrosive paints. Moreover, it has high practical value as a binder for paper processing, fiber processing, etc. The present one-component curable aqueous emulsion, in the range that does not hinder the desired effect, thickener, dispersant, antifoaming agent film-forming aid, water, organic solvent, plasticizer,
A colorant, an antifreezing agent, a pH adjusting agent, a silane coupling agent and the like may be used in combination.

[0014]

EXAMPLES The present invention will be described below with reference to production examples, examples and comparative examples. Parts and% unless otherwise specified
Is based on weight.

Examples 1 to 9 A mixture of 100 parts of a mixed monomer for the core and shell layers and a chain transfer agent having the compositional ratios shown in Table 1 was weighed in advance, and 50 parts of distilled water and 0.5 parts of sodium dodecylbenzenesulfonate were used. Under agitation conditions,
A pre-emulsified monomer was used. Separately, add 100 parts of distilled water and 0.2 part of sodium dodecylbenzenesulfonate to a 1 liter flask, and stir at 70 ° C under a nitrogen blanket while stirring.
After the temperature was raised to 0.5 parts, 0.5 parts of potassium persulfate and n-butyl acrylate, methyl methacrylate and hydroxyethyl methacrylate were mixed with each other to obtain an emulsion seed.
0.5 part of a mixed monomer having a ratio of 1: 1 was charged and reacted for 20 minutes to form nuclei of emulsion particles. Next, the pre-emulsified monomer for core was continuously added dropwise over 3 hours, and the residual monomer was reacted for 2 hours after completion of the addition. Subsequently, the emulsified monomer for shell was dropped over the same 3 hours as described above. After the dropping is completed, the temperature is raised to 80 ° C. and the residual monomer reaction is carried out to
After the completion of time, 0.2 parts of potassium persulfate was dissolved in 10 parts of water, an aqueous solution of which the pH was adjusted to 8 to 9 with 25% aqueous ammonia was added, and the remaining monomer was polymerized for another 2 hours at the same temperature. After that, it was cooled to 40 ° C. or lower and adjusted to pH 7 with aqueous ammonia to obtain EPAE having a solid content of 50%. This EPAE1
After mixing the epoxy resin curing agent in the ratio shown in Table 1 with respect to 00 parts, the mixture was filtered through a 100-mesh wire net to obtain a one-component curable aqueous emulsion of the present invention.

The obtained one-pack curable aqueous emulsion was
100 g / m ^{2 was} evenly applied onto a 3 mm-thick silica plate, and 0.5 mm-thick steel plates that had been previously cut into 5 × 5 cm squares were attached to each other. The bonded product was dried with a hot air dryer at 100 ° C. for 10 minutes, and then aged at room temperature for 24 hours.
After the bonding, two kinds of samples which were aged at room temperature for 24 hours were prepared and subjected to the following tests.

1) Storage stability The one-component curable aqueous emulsions obtained in Examples 1 to 9 were stored in a constant temperature bath at 30 ° C., and the number of days required until the viscosity doubled from the initial value or abnormalities such as gelation occurred. Displayed in. 2) Adhesion test 2-1) Normal adhesive strength Using a Kenken type tensile tester, a sample aged for 24 hours was subjected to a plane tensile test, and the adhesive strength was shown in Kg / cm ² , and shown in Table-2. 2-2) Water-resistant adhesive strength The sample after curing was immersed in 20 ° C. city water for 24 hours, and immediately subjected to a test in accordance with the normal-state adhesive strength in a wet state. The results are shown in Table 2. 2-3)
The heat-resistant adhesive strength-cured sample was left in a hot air dryer at 80 ° C. for 168 hours, and immediately after being taken out, subjected to a test in accordance with the normal-state adhesive strength, and the results are shown in Table 2. 2-4) Warm water-resistant adhesive strength The sample after curing was immersed in warm water at 60 ° C. for 24 hours, taken out, and immediately subjected to a test in accordance with the normal adhesive strength in a wet state, and the results are shown in Table 2. .

Comparative Example 1 EPAE was prepared according to the same emulsion polymerization method as in the core layer of Example 1 by mixing the core and shell layer monomers used in Example 1 with the same epoxy resin as in Example 1 below. A curing agent was added, and the same test as in Example 1 was performed and the results are shown in Table 2.

Comparative Example 2 The same test as in Example 1 was carried out except that the curing agent for epoxy resin was removed from Example 1, and the results are shown in Table 2.
It was shown to.

Comparative Example 3 Example 1 was carried out by using only the core layer monomer used in Example 1 and reducing the amount of distilled water initially charged.
An EPAE having a solid content of 50% was prepared according to the same emulsion polymerization method as in the core layer of Example 1, and the same epoxy resin curing agent as in Example 1 was blended, and the mixture was subjected to the same test as in Example 1 and the results are shown in Table-2. It was shown to.

Comparative Example 4 Using the core layer monomer used in Example 1 and the shell layer monomer of Example 8, an EPAE was prepared according to the same emulsion polymerization method as in Example 1 and the same as in Example 1 below. The epoxy resin curing agent was mixed and subjected to the same test as in Example 1, and the results are shown in Table 2.

Comparative Example 5 Using the core layer monomer used in Example 8 and the shell layer monomer used in Example 1, an EPAE was prepared according to the same emulsion polymerization method as in Example 1,
The same epoxy resin curing agent as in Example 1 was blended below,
The same test as in Example 1 was performed and the results are shown in Table 2.

[0023]

[Table 1]

[0024]

[Table 2]

Examples 10 to 18 As shown in Table 3, titanium white was mixed with water and a 5% sodium pyrophosphate aqueous solution, and uniformly dispersed using a three-roll mill to prepare a titanium white slurry.
This slurry was collected in a 500 cc poly cup, and the one-part curable aqueous emulsion used in Examples 1 to 9 was uniformly mixed while stirring with a stirrer, and then 6 parts of ethylene glycol and butyl were used as an antifreezing agent and a film-forming auxiliary. 6 parts of carbitol and 0.1 part of Nopco 8034 as an antifoaming agent were mixed, and the mixture was filtered through a 300-mesh wire net to prepare an aqueous emulsion-type paint. This coating composition was uniformly applied to a steel plate having a thickness of 0.3 mm to a thickness of 50 g / m ² using an applicator. This coated steel sheet was dried with a hot air dryer at 100 ° C for 20 minutes and then cured at room temperature for 24 hours, and two kinds of coated samples with different drying conditions, which were cured at room temperature for 72 hours, were prepared and subjected to the following test. The results are shown in Table-4.

1) Storage stability The aqueous emulsion paints of Examples 10 to 18 were stored in a thermostat at 30 ° C., and the initial viscosity was 2
The number of days until a change in viscosity more than twice or abnormalities such as gelation occurred was checked and displayed in days. 2) Immediately after water proofing, immerse in 20 ° C city water for 24 hours and apply 5
A scratching test was performed with a rotating nail, and the state of the coating film was displayed as follows. ○ The coating film is not scratched, and no abnormalities such as peeling phenomenon are seen. △ The coating film has some scratches but does not peel off. × The coating film was peeled from the steel plate surface after 1 to 2 scratch tests. Dropping 3) Immediately after aging the solvent resistance, it was immersed in toluene for 24 hours, dried in a 100 ° C. dryer for 30 minutes and cooled, and the amount of coating film eluted was determined from the initial sample weight and the weight change after drying the immersed product. Displayed in%.

Comparative Examples 6 to 10 As shown in Table 3, the aqueous emulsions used in Comparative Examples 1 to 5 were used, and Example 1 was used.
A water-based emulsion paint was prepared according to No. 0 and subjected to the same tests as in Example 10, and the results are shown in Table 4.

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

As is clear from Tables 2 and 4, in the one-component curable aqueous emulsion of the present invention, a carboxyl group that reacts with a glycidyl group coexists in the emulsion particles, and the aqueous layer is like an amine. Despite containing a curing agent for epoxy resin, it has excellent storage stability for a long period of time because it has a shape in which the glycidyl group is protected by the shell layer. Since it has adhesive strength, water resistance, heat resistance, solvent resistance, bending resistance, etc., it is used as an adhesive, as well as a granular, powdery or fibrous inorganic or wood fiber binder, architectural paint, rust preventive It has a high practical value as a base resin for paints and as a binder for paper processing, fiber processing, etc.

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Claims (4)

(57) [Claims] 1. A core layer is a copolymer of an aromatic vinyl monomer, an unsaturated carboxylic acid ester monomer, an amide group-containing acrylic monomer and an epoxy resin, and a shell layer is an aromatic vinyl monomer, an unsaturated carboxylic acid ester. For the epoxy resin, 100 parts by weight of the solid content of the epoxy modified acrylic emulsion (a) having a core-shell structure, which is a copolymer of a monomer, an acrylic monomer having a hydroxyl group, an acrylic monomer having an amide group and an acrylic monomer having a carboxyl group, A one-component curable aqueous emulsion composition containing 1 to 30 parts by weight of a curing agent (b) as a solid content. 2. An epoxy modified acrylic emulsion (a).
Is a copolymer of 1 to 30 parts by weight of an epoxy resin in 100 parts by weight of the solid content of the emulsion, and the one-part curable aqueous emulsion composition according to claim 1. 3. An epoxy modified acrylic emulsion (a).
The glass transition temperature (Tg) of the above is in the range of -30 to + 30 ° C, and the one-part curable aqueous emulsion composition according to claim 1. 4. An epoxy modified acrylic emulsion (a).
Glass transition temperature (Tg) of the core layer of -30 to +80
° C, the glass transition temperature (Tg) of the shell layer is -60 to +3
The one-part curable aqueous emulsion composition according to claim 1, which is in the range of 0 ° C.