JPH0753908A - Water-base coating composition - Google Patents

Abstract

PURPOSE:To reduce the amt. of an org. solvent used therein and obtain a water- resistant cross-linked coating film by compounding a specific carboxyalkylcellulose nitrate with a cross-linker in a specified wt. ratio. CONSTITUTION:The compsn. comprises 60.0-99.9wt.% carboxyalkylcellulose nitrate having a degree of nitration per anhydrous glucose unit of 0.2 or greater and a degree of carboxyalkyl-etherification per anhydrous glucose unit of 0.05 or greater and 0.1-40.0wt.% cross-linker (e.g. a carboxyl- or hydroxyl-reactive compd. such as a melamine resin, or an organometallic chelating compd. contg. Zn, Al, etc.). The compsn. is prepd. by adding a specified amt. of water, if necessary together with a specified amt. of a water-sol. solvent (e.g. an alcohol), to the nitrate in a hermetically sealed reactor equipped with a stirrer, stirring them to provide a homogeneous mixture, and dissolving the cross-linker in the mixture. A coating film formed from the compsn. is dried at 20-40 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The aqueous coating composition of the present invention relates to a functional coating material used for paints, printing inks, paper coatings, fiber processing, magnetic paints, conductive pastes and the like.

[0002]

2. Description of the Related Art Conventionally, cellulose esters such as nitrocellulose and cellulose acetate butyrate are functional coatings such as paints, printing inks, paper coatings, fiber processing, magnetic paints and conductive pastes from the viewpoint of drying property and heat resistance. It is used as a material.

[0003]

However, since cellulose esters such as nitrocellulose and cellulose acetate butyrate use a large amount of organic solvent,
There are problems such as air pollution due to volatilized solvent, deterioration of working environment, and risk of fire. In order to improve the problem, aqueous cellulose acetate butyrate has been proposed. However, the coating film using it has a problem that it is inferior in water resistance and further physical properties are unstable such as thickening due to hydrolysis during storage.

[0004]

[Means for Solving the Problems] In order to solve the above-mentioned problems, it is possible to significantly reduce the amount of organic solvent to be used by adopting aqueous carboxyalkyl cellulose nitrate esters, and air pollution by volatile solvents and work environment,
The risk of fire is improved. Further, they have found that a crosslinked film obtained from a crosslinking agent and nitrates of carboxyalkyl cellulose has good water resistance, and completed the present invention.

That is, according to the present invention, the degree of substitution of nitrate ester group per anhydrous glucose residue is 0.2 or more and the degree of substitution of carboxyalkyl ether group is 0.05 or more, and the nitrate ester of carboxyalkyl cellulose is 6
The present invention relates to a water-based coating composition containing 0.0 to 99.9% by weight and 0.1 to 40.0% by weight of a crosslinking agent.

The carboxyalkyl cellulose nitrates used in the present invention are reacted with carboxyalkyl celluloses such as carboxymethyl cellulose and carboxyethyl cellulose by a known mixed acid for nitric acid esterification, for example, a mixed acid of sulfuric acid / nitric acid / water. The degree of substitution of nitrate ester group contained in carboxyalkyl cellulose is 0.2 or more, and the degree of substitution of carboxyalkyl ether group is 0.05 or more.
-39301 and the aqueous cellulose derivatives disclosed in JP-A-5-39302. If the degree of substitution of the nitrate ester group is less than 0.2, the water resistance of the treated film will be insufficient, and if the degree of substitution of the carboxyalkyl ether group is less than 0.05, the solubility in water will decrease. The amount increases.

The carboxyl groups contained in the nitrates of carboxylalkyl cellulose may be partially neutralized. As the neutralizing agent, an alkali metal ion, an ammonium ion or a monobasic organic amine can be used. The term "crosslinking agent" as used in the present invention means an agent that forms a crosslinked film having an intermolecular bond by reacting with a carboxyl group or a hydroxyl group contained in the structure of nitrate ester of carboxylalkyl cellulose.

The cross-linking agent used in the present invention includes a carboxyl group, an amino group capable of reacting with a hydroxyl group, an epoxy group,
A compound having a functional group such as an aziridine group or an oxazoline group, or an organometallic chelate compound such as a zinc, aluminum, titanium or zirconium group can be used. As the compound having an amino group, a melamine resin,
Examples thereof include benzoguanamine resin and urea resin.

Examples of the compound having an epoxy group include diglycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, diethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol. Polyglycidyl ether, sorbitol polyglycidyl ether, allyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether,
Alkylphenol glycidyl ether, polyethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin polyglycidyl ether, diglycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether Examples thereof include ether, cresyl glycidyl ether, aliphatic diglycidyl ether, polyfunctional glycidyl ether, tertiary fatty acid monoglycidyl ether, and spiroglycol diglycidyl ether.

Examples of the compound having an aziridine group include Chemitite PZ-33 manufactured by Nippon Shokubai Co., Ltd. The compound having an oxazoline group is, for example, Epocros K1010E, K1020E, K1 manufactured by Nippon Shokubai Co., Ltd. as a polymer having an oxazoline group.
030E, CX-K2010E, CX-K2020E,
CX-K2030E etc. are mentioned.

Examples of the organometallic chelate compound include zinc ammonium carbonate, di-n-butoxybis (triethanolamine) titanate, tetra-octylene glycol titanate, di-iso-propoxybis (acetylacetone) titanate and di-hydroxybis (lactide). Take acid) titanate, di-iso-propoxybis (ethyl acetoacetate) titanate, titanium chelate compounds such as poly- (hydroxytitanium stearate), di-iso-propoxyaluminum monoethylacetoacetate, di-iso-propoxyaluminum. Monomethyl acetoacetate, aluminum tris (ethylacetoacetate), aluminum monoacetylacetonate bis (ethylacetoacetate), aluminum tris (acetylacetoacetate) Over door), aluminum - di -n-
Examples thereof include aluminum compounds such as butoxide-mono-methylacetoacetate and aluminum-diisobutoxide-mono-methylacetoacetate, and zirconium compounds such as ammonium trilactate zirconate, ammonium triglycolate zirconate and ammonium zirconyl carbonate.

In the present invention, the amount of nitrate ester of carboxyalkyl cellulose is 60.0% by weight or more, 9
9.9% by weight or less, the amount of the crosslinking agent is 0.1% by weight or more, 4
It is 0.0% by weight or less. If the nitrate ester of carboxyalkyl cellulose is less than 60.0% by weight, the drying property and heat resistance, which are the characteristics, cannot be expressed, and the crosslinking agent is 0.1
If it is less than 10% by weight, a crosslinked film of the coating composition can be obtained, but the water resistance is inferior, which is not preferable in practice.

In the aqueous coating composition of the present invention, other water-soluble resins can be included in the composition.
The water-soluble resin is a water-based resin used for water-based paints, inks, water-based binders, etc., and includes maleic acid-styrene copolymer, maleic acid-acrylic acid ester-based copolymer, maleic acid-methacrylic acid ester-based copolymer, and acrylic acid. Acid-styrene copolymer, acrylic acid-acrylic acid ester copolymer, acrylic acid-methacrylic acid ester copolymer, polyurethane resin,
Examples include polyamide resins, shellac, casein, polyvinyl alcohol, and one or a combination of two or more cellulose ethers such as hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose.

The aqueous coating composition of the present invention may contain pigments and / or dyes depending on the purpose of use. As the pigment, titanium oxide, iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, wachchan red, color pigments such as quinacridone yellow, barium sulfate, calcium carbonate, extender pigment such as clay, magnetic iron oxide, barium titanate, One or a combination of two or more kinds of functional pigments such as gold and silver can be used. Known dyes such as methylene blue, malachite green, rhodamine, and alizarin can be used as the dye.

An example of the method of preparing the water-based coating composition of the present invention and forming a coating film will be described. A predetermined amount of nitrate ester of carboxyalkyl cellulose is added to a reaction closed container equipped with a stirrer, and a specified amount of water is added thereto. If necessary, an aqueous solvent such as alcohols is further added in a specified amount. Stir until the mixing system is uniform. Next, a cross-linking agent is added in a specified amount to completely dissolve it, and an aqueous coating composition is diluted to a desired viscosity.
The prepared water-based coating composition of the present invention is applied onto a film by a bar coater, and the crosslinking reaction and the drying of the coating film proceed at a predetermined temperature. The temperature at which the crosslinking reaction and the drying of the coating film proceed is set depending on the type and amount of the crosslinking agent used and the amount of water used. Generally above 20 ° C or 40
Crosslinking reaction and coating film drying proceed at a temperature of ℃ or more. The water resistance of the obtained coating film was evaluated by the following method.

<Water resistance evaluation method> The water-based coating composition prepared by the above-mentioned preparation method was applied to an applicator (10 mi
1) coated on a glass plate to form a dry film according to JIS-K54
According to (00), the film is taken out at 20 ° C. for 18 hours, taken out, and allowed to stand for 2 hours, and the state of the film is visually judged. If there is no change in the film before and after immersion in water, the water resistance was considered good. The water-based coating composition of the present invention is excellent in water resistance, and is also excellent in drying property and heat resistance, so that it is a vehicle for paints, inks, paper coatings, fiber processing, etc. and its additives, or magnetic paints and conductive materials. It can be used as a functional coating material for a coating resin such as a conductive paste and its additives. Since it can be applied to all uses required as an aqueous resin, it is not limited to the uses shown above.

[0017]

The present invention will be described in more detail with reference to the following examples.

[0018]

Example 1 100 g of carboxymethyl cellulose (degree of carboxymethyl group substitution = 0.5) and sulfuric acid / nitric acid / water =
3 liters of a mixed acid consisting of 66.0 / 29.0 / 5.0 wt% was placed in a 5 liter reaction vessel and stirred for 1 hour at 5 ° C., the product was added to 50 liters of 30 liters of water. After being placed in a stainless steel container, it was separated and recovered using a stainless steel filter, and further dried at 100 ° C. for 1 hour to obtain carboxymethyl cellulose nitrate.
The obtained carboxymethyl cellulose nitrate ester is
The degree of carboxyl group substitution was 0.5 and the degree of nitrate ester group substitution was 1.7, as determined from the nitrogen content.

20 g of carboxymethyl cellulose nitrate obtained by the reaction, 24.0 g of ion-exchanged water and 56.0 g of ethylene glycol monobutyl ether were put in an autoclave and stirred. Next, it was completely dissolved while being heated to 60 ° C., returned to room temperature, and 8.0 g of diethylene glycol glycidyl ether as a crosslinking agent was added thereto to prepare an aqueous coating composition.

The prepared composition was coated on a glass plate,
Leave for 1 hour in 0 ° C atmosphere. The water resistance of the obtained film was evaluated. As a result, the film did not change and the water resistance was good.

[0021]

Example 2 10 g of the carboxymethyl cellulose nitrate obtained in Example 1, 18.0 g of ion-exchanged water, 67.5 g of ethylene glycol monobutyl ether and 4.5 g of isopropyl alcohol were placed in an autoclave and stirred. Next, it was completely dissolved while heating at 80 ° C., returned to room temperature, and 0.5 g of aluminum monoacetylacetonate bis (ethylacetoacetate) was added as a cross-linking agent to prepare an aqueous coating composition.

The prepared composition was coated on a glass plate, and 8
Leave for 1 hour in 0 ° C atmosphere. The water resistance of the obtained film was evaluated. As a result, the film did not change and the water resistance was good.

[0023]

Example 3 100 g of carboxymethyl cellulose (carboxymethyl group substitution degree = 0.7) and sulfuric acid / nitric acid / water =
3 liters of a mixed acid consisting of 57.5 / 20.2 / 22.3 wt% was placed in a 5 liter reaction vessel and stirred for 1 hour at 5 ° C. and the product was added to 50 liters of water in 30 liters. After being placed in a stainless steel container, it was separated and recovered using a stainless steel filter, and further dried at 100 ° C. for 1 hour to obtain carboxymethyl cellulose nitrate. The obtained carboxymethyl cellulose nitrate had a carboxyl group substitution degree of 0.7, and the nitrate ester group substitution degree was 1.0 as determined from the nitrogen content.

15 g of the obtained carboxymethyl cellulose nitrate ester, 65.5 g of ion-exchanged water, 12.7 g of ethanol and 4.3 g of pentanol were placed in an autoclave and stirred. Next, 2.5 g of 28% ammonia water was added as a neutralizing agent after the stirring was stopped, and the mixture was completely dissolved while stirring and heating at 70 ° C. The temperature was returned to room temperature, and 6.0 g of diethylene glycol diglycidyl ether was added as a cross-linking agent to prepare an aqueous coating composition.

The prepared composition was coated on a glass plate, and 8
Leave for 1 hour in 0 ° C atmosphere. The water resistance of the obtained film was evaluated. As a result, the film did not change and the water resistance was good.

[0026]

EFFECT OF THE INVENTION The water-based coating composition of the present invention can significantly reduce the amount of organic solvent used, and can improve problems such as air pollution due to volatilization, deterioration of working environment, and risk of fire. By adding the agent, a crosslinked film having good water resistance can be obtained. Therefore, it can be used as a functional coating material such as paint, printing ink, paper coating, fiber processing, magnetic paint and conductive paste.

Claims (1)

[Claims] 1. Nitrate ester of carboxyalkyl cellulose having a degree of substitution of nitrate ester group of 0.2 or more and a degree of substitution of carboxyalkyl ether group of 0.05 or more per anhydrous glucose residue 60.0 to 99. An aqueous coating composition comprising 9% by weight and a crosslinking agent of 0.1 to 40.0% by weight.