JPH06329877A - Aqueous dispersion of epoxy resin - Google Patents

Abstract

PURPOSE:To obtain the subject dispersion, composed of an epoxy resin, a surfactant and microcrystalline cellulose without impairing the storage stability of the aqueous dispersion, capable of readily controlling the viscosity and improving the water resistance and adhesion of a cured film and useful as coatings, etc. CONSTITUTION:The objective dispersion is composed of (A) 100 pts.wt. epoxy resin, (B) 0.1-10 pts.wt. surfactant and (C) 0.1-50 pts.wt. microcrystalline cellulose. Furthermore, e.g. a substance, prepared by hydrolyzing cellulose with an acid, etc., having a prescribed polymerization degree and containing <=5wt.% particles, having <=1mum Stokes diameter and present therein is preferably used as the component (C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous dispersion of epoxy resin which provides excellent properties as a basic composition for paints, adhesives, admixtures for cement and the like.
More specifically, the water resistance and adhesiveness of the cured product do not deteriorate,
The present invention relates to an epoxy resin aqueous dispersion that can sufficiently exhibit the performance of an epoxy resin.

[0002]

2. Description of the Related Art Polymer aqueous dispersions of thermoplastic resins obtained by emulsion polymerization of acrylic, acrylic-styrene, vinyl acetate, ethylene-vinyl acetate, etc. in recent years have been mixed with paints, adhesives and cements. It has come to be widely used in industrial applications such as agents. However, since the film formed from these conventional polymer aqueous dispersions has insufficient adhesion to metals, wood, hardened cement, plastics, etc., and also insufficient water resistance and heat resistance, for example, in a wet state. Peeling and blistering often occurred at high temperatures. In order to improve such defects of the polymer aqueous dispersion of the thermoplastic resin, it has been attempted to introduce a functional group into the polymer skeleton to form a crosslinked structure, but it is still not sufficient. Therefore, the use of an aqueous dispersion of a thermosetting resin, for example, an epoxy resin, in the above applications is being promoted.

[0003]

However, the epoxy resin water dispersion is a hard coating because the epoxy resin is added in a large amount in order to prevent the epoxy resin from settling and separating during storage and separation during storage. The water resistance and adhesiveness of the film are poor and practically unusable, as a means to prevent separation during storage, carboxylated methyl cellulose, hydroxyethyl cellulose, etc. are added to increase the viscosity, but in the low viscosity region The problem is that it is difficult to prevent sedimentation. In order to solve these problems, JP-A-57-115418 discloses an epoxy resin-containing water dispersion composition obtained by combining an epoxy resin and an acrylic resin. Although the storage stability of the water dispersion is improved, it has a drawback that the high adhesiveness and water resistance originally possessed by the epoxy resin are impaired by incorporating the acrylic resin. Therefore, there has been a demand for an epoxy resin aqueous dispersion which is free from sedimentation / separation, has good storage stability, and has high adhesiveness and water resistance originally possessed by epoxy resins.

[0004]

Therefore, as a result of repeated studies to solve the above-mentioned problems, the storage stability of the epoxy resin water dispersion is not impaired, the viscosity of the water dispersion can be easily controlled, and a cured coating film thereof can be obtained. The inventors have arrived at the present invention by finding means for improving the water resistance and adhesiveness of the above. That is, the present invention relates to an epoxy resin aqueous dispersion containing 100 parts by weight of an epoxy resin, 0.1 to 10 parts by weight of a surfactant, and 0.1 to 5.0 parts of microcrystalline cellulose.

The present invention will be described in detail below. The epoxy resin used in the present invention has two or more epoxy groups in one molecule and includes, for example, glycidyl ethers, glycidyl esters, glycidyl amines, linear aliphatic epoxides, and alicyclic compounds. Examples include epoxides. Examples of the glycidyl ethers include bisphenol diglycidyl ether, phenol novolac polyglycidyl ether, alkylene glycol or polyalkylene glycol diglycidyl ether. Examples of the diglycidyl ether of bisphenol include diglycidyl ethers of dihydric phenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A and tetrabromobisphenol A, and polyglycidyl ethers of the phenol novolac. Examples of the polyglycidyl ether of novolac resin such as phenol novolac, cresol novolac, and brominated phenol novolac include diglycidyl ether of the alkylene glycol or polyalkylene glycol such as polyethylene glycol, polypropylene glycol and butanediol. Diglycidyl ethers of glycols may be mentioned.

Further, as the glycidyl esters,
For example, the diglycidyl ester of hexahydrophthalic acid,
Examples thereof include diglycidyl ester of dimer acid.
Examples of the glycidyl amines include tetraglycidyl diaminodiphenylmethane, tetraglycidyl metaxylylenediamine, triglycidyl aminophenol, triglycidyl isocyanurate and the like. Furthermore, examples of linear aliphatic epoxides include epoxidized polybutadiene and epoxidized soybean oil,
Examples of the alicyclic epoxides include 3,4-epoxy-6-methylcyclohexylmethylcarboxylate and 3,4-epoxycyclohexylmethylcarboxylate.

Although the epoxy resin is not limited to these, preferred epoxy resins are glycidyl ethers, glycidyl amines and glycidyl esters, more preferably glycidyl ethers.
Of the glycidyl ethers, diglycidyl ethers of bisphenols are preferable, and diglycidyl ethers of bisphenol A and bisphenol F are particularly preferable. The epoxy resins may be used alone or in combination of two or more.

The epoxy resin used has an epoxy equivalent of 100 to 1500, preferably 150 to 750. Microcrystalline cellulose used in the present invention refers to a cellulose crystallite aggregate having a substantially constant degree of polymerization obtained by acid hydrolysis or alkali oxidation decomposition of cellulose.
And Engineering Chemistry, Volume 42,
OA described on pages 502 to 507
It is defined by Mr. Batista's report.
To make the effect of the present invention more remarkable, the Stokes diameter is 1
It is preferable to use microcrystalline cellulose such that the proportion of μm or less is 5% by weight or more. Further, when milling in the presence of water, it is preferable that the average particle size of the microcrystalline cellulose after milling is 5 μm or less in Stokes diameter.
In the present invention, the weight ratio of the epoxy resin and the microcrystalline cellulose is preferably 0.1 to 5.0 parts by weight of microcrystalline cellulose with respect to 100 parts by weight of the epoxy resin. If the amount of microcrystalline cellulose is less than 0.1 parts by weight, the epoxy resin will have poor water dispersibility and will precipitate and separate. On the other hand, if it exceeds 5.0 parts by weight, the water resistance of the cured coating film is lowered and it cannot be put to practical use. More preferably, 0.5 to 3.0 parts by weight of microcrystalline cellulose is preferable with respect to 100 parts by weight of the epoxy resin.

Examples of the surface active agent include anionic surface active agents, cationic surface active agents, amphoteric surface active agents and nonionic surface active agents. Examples of the anion activator include fatty acid salts, sulfuric acid ester salts of higher alcohols, sulfuric acid ester salts of liquid fatty oils, sulfuric acid salts of aliphatic amines and aliphatic amides, phosphoric acid esters of aliphatic alcohols, and dibasic fatty acid esters. Examples thereof include sulfonates, aliphatic amide sulfonates, alkylallyl sulfonates, and formalin condensed naphthalene sulfonates. As the cationic activator, for example, a primary amine salt, a secondary amine salt,
Examples include tertiary amine salts, quaternary ammonium salts, pyridinium salts and the like. Examples of the amphoteric activator include carboxylic acid type (betaine type), sulfuric acid ester type, and sulfonic acid type. Examples of the nonionic activator include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, and oxyethyleneoxypropylene block copolymer.

The surfactant is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin. Surfactant is 0.1
If it is less than the weight part, the water dispersibility becomes poor and the epoxy resin precipitates and separates. On the other hand, if it exceeds 10 parts by weight, the water resistance and the adhesiveness of the cured coating film are deteriorated, and it cannot be put to practical use. Preferably, it is 0.5 to 100 parts by weight of the epoxy resin.
8 parts by weight is preferred.

In addition to the surfactant, a dispersant, a water-soluble polymer, a protective colloid and the like can be added, for example, polyphosphate, polyacrylate, maleic anhydride copolymer, polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, gelatin. , Albumin, gum arabic and the like. The epoxy resin aqueous dispersion of the present invention comprises an epoxy resin, microcrystalline cellulose, and water,
It can be obtained by a dispersing machine to which a surfactant is added and shearing force is applied.

Examples of the shearing disperser include a homomixer, a rotary homogenizer, a piston homogenizer, and a planetary mixer. Regarding the method for producing the epoxy resin aqueous dispersion of the present invention, the order of addition of the epoxy resin, microcrystalline cellulose, water, and the surfactant is not particularly specified, and all substances may be mixed and emulsified all at once, or as appropriate. The order of charging may be determined according to the purpose. However, as the microcrystalline cellulose, it is preferable to use an aqueous dispersion prepared in advance by using a disperser in an amount of 2 to 5% by weight.

The aqueous dispersion of epoxy resin of the present invention can be added with a generally used curing agent for epoxy resin to obtain a cured coating film. Examples of the curing agent include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, polyamidoamines, modified polyamines, polymercaptans, and tertiary polyamines.
Examples include primary amines, imidazoles, amino resins, phenol resins, polyisocyanates, and the like. After adding these curing agents, it is dried and, if necessary, heated to form a cured coating film having a crosslinked network structure.

If desired, a latex of a thermoplastic or thermosetting resin can be added to the aqueous dispersion of the epoxy resin of the present invention. For example, SB latex, acrylic latex, vinylidene chloride latex, ethylene-vinyl acetate latex, urethane latex, melamine latex and the like can be mentioned. If desired, various additives, fillers, reinforcing materials, pigments, etc. may be added.

Since the epoxy resin aqueous dispersion of the present invention has excellent water resistance, heat resistance and adhesiveness, it is used as a paint, an adhesive, an adhesive, a processed paper, a fiber processing agent, a building material, a coating material. It can be used for a wide range of applications such as paper water resistance enhancers. Examples of the paint include concrete paint, wood paint, metal paint, household paint, leather paint, floor polish and the like. Examples of the adhesive include wood adhesive, packaging lamination adhesive, box making adhesive, tile adhesive, flooring adhesive, and the like. Examples of the adhesive include an adhesive tape for packaging, an adhesive label, a frozen food label, a ream bubble label, a POS label, an adhesive wallpaper, an adhesive flooring material and the like. Examples of the processed paper include art paper, coated paper, lightweight coated paper, cast coated paper, coated paperboard, carbonless copy paper, and impregnated paper. Examples of the fiber processing agent include non-woven fabric, carpet, electric flocked cloth, laminated cloth, textile printing cloth, tire cord and the like. Examples of building materials include sealing materials, cement admixtures, and waterproof materials.

[0016]

EXAMPLES The present invention will be specifically described with reference to examples.

[0017]

Examples 1 to 15 (a) Method for Preparing Epoxy Resin Aqueous Dispersion The components shown in Tables 1 to 4 were uniformly dispersed and adjusted using a homomixer. The surfactant was a 25% by weight aqueous solution, and microcrystalline cellulose (Avicel RC591;
Asahi Kasei Kogyo Co., Ltd.) is 5% by weight that has been sufficiently dispersed in advance.
An aqueous dispersion was used. The temperature at which the homomixer was dispersed was the temperature shown in Table 1.

(B) Evaluation of Epoxy Resin Aqueous Dispersion Tables 1 to 4 also show the evaluation results of the epoxy resin aqueous dispersion. The test method of the epoxy resin aqueous dispersion is as follows. Storage stability Leave the epoxy water dispersion in an oven at 50 ° C for 30 days,
The dispersed state was observed.

Evaluation ⊙: No settling / separation of epoxy resin, no problem in practical use ○: Some settling / separation of epoxy resin, but no problem in practical use ×: Settling / separation of epoxy resin, problem in practical use Viscosity Measured using a B-type viscometer at 25 ° C.

(C) Evaluation of Cured Product of Epoxy Resin Aqueous Dispersion Film Preparation An equivalent amount of triethylenetetramine was added to the epoxy resin aqueous dispersion and mixed well, and then applied to a tin plate using a 10 mil applicator. After standing at 20 ° C. for 7 days, an epoxy resin water dispersion cured film was obtained.

Film Water Resistance A film peeled from a tin plate was made into a size of 4 cm × 4 cm and immersed in distilled water for 7 days. The weight of the film before and after immersion was measured and the rate of change was determined.

[0022]

[Equation 1]

Water resistance of coating film A coating film which has been applied and cured on a mild steel plate is soaked in boiling water for 2 hours.
Soak. After that, the appearance of the coating film and the cross-cut adhesion (JISK5400) are measured.

[0024]

[Comparative Examples 1 to 7] Various components shown in Table 5 were uniformly dispersed and adjusted using a homomixer in accordance with Examples.
The evaluation results are also shown in Table 5. The test method is the same as in the example.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

[Table 5]

[0030]

Since the epoxy resin water dispersion obtained in the present invention uses the microcrystalline cellulose having water dispersibility, the particle size of the epoxy resin dispersion is 10 to 3 on average.
Even at 0 μm, neither sedimentation nor separation occurs, and the viscosity of the aqueous dispersion does not significantly increase compared to before addition. In addition, compared with conventional aqueous dispersions of epoxy resin, the added amounts of surfactants, protective colloids, etc. can be greatly reduced, resulting in significantly improved water resistance and adhesiveness. The present invention is characterized by the use of microcrystalline cellulose, commonly used hydroxyethyl cellulose, methyl cellulose,
Since carboxylated cellulose is an amorphous type, it cannot exhibit the effects of the present invention.

Claims (1)

[Claims] 1. An epoxy resin of 100 parts by weight, a surfactant of 0.1 to 10 parts by weight, and microcrystalline cellulose of 0.1 to 10.
5.0 parts by weight of epoxy resin water dispersion.