JP2001214120A - Water base coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material for protecting images, particularly images to be formed with a water base ink. SOLUTION: A composition with improved water resistance which does not cause crazing when dried and formed into films comprises a colloidal silica- containing acrylic resin emulsion and a compound represented by formula (1): R1O(A-O)nR2 (wherein A is either one of -CH2CH2-, -CH2CH2CH2- or a group represented by formula (2); (n) is an integer of 1-3: R1 and R2 may be the same or different and each a hydrogen atom, a 1-4C alkyl group, a 1-4C acyl group or a glycidyl group, provided that R1 and R2 are not simultaneously hydrogen atoms).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous coating composition, and more particularly to an aqueous coating composition useful as a coating agent for protecting an image formed by an aqueous ink.

[0002]

2. Description of the Related Art With the spread of ink jet printers in recent years, it has become possible to easily obtain high-quality images similar to photographs. Since many of these ink jet printers use water-based ink for image output, various attempts have been made to improve the durability and water resistance of the output image.

For example, by imparting water resistance to paper (media) itself used for ink jet output, the bleeding of ink at the time of output is suppressed, and the water resistance of the obtained image is improved. There has been proposed a coating composition for providing an ink-receiving layer on the surface (for example, JP-A-11-29738). By using these technologies to create media suitable for image output using water-based inks such as inkjets, users can obtain images with improved water resistance simply by performing normal output without any special work. There is a merit that can be.

[0004] In an image output to such a medium, bleeding or elution of the image is scarcely observed even when moisture or the like adheres, and a remarkable improvement in water resistance is recognized. However, when drinking water such as coffee is accidentally spilled on an output image, it is unavoidable that these beverages are absorbed by the medium and become dirty.

In order to protect the image from such moisture-containing stains, a so-called laminating process of covering the image by sandwiching both sides of the medium on which the image is output with a plastic film is widely performed. In the case where this lamination is performed, even if dirt such as a drink or mud splashes adheres, the dirt can be easily removed only by wiping the laminate surface. In addition, by using a plastic film containing an ultraviolet absorber, discoloration of an image due to ultraviolet light can be greatly improved, and water resistance and weather resistance are required for a commercial display. Ink images can be used.

As described above, laminating has a great effect on improving the durability of an image. However, a special device is required for laminating, the image is bent, or the like.
Since it is necessary to get used to laminating the film so that no air bubbles enter between the film and the image, there is a demand for a method for more easily imparting durability to the image.

On the other hand, there have been proposed coating agents which improve the water resistance of an image by applying the image using an aqueous ink onto the image output using a spray or a coater, but most of these agents use a resin. It is an organic solvent type coating agent dissolved in an organic solvent, and has a problem of odor and environmental problems due to volatilization of the organic solvent at the time of application.

Further, as a coating agent having a low odor and environmental load, a coating agent using an aqueous emulsion in which a resin is dispersed in an aqueous solvent without using a volatile organic solvent has been proposed. Most of the emulsion type coating agents could not be used as coating agents for aqueous ink images because they dissolve and destroy the aqueous ink image. However, those using an acrylic resin emulsion containing colloidal silica, while being an aqueous emulsion, do not dissolve the aqueous ink image at the time of coating agent application and do not damage the image, and are used for aqueous ink images. It can be used favorably as a coating agent. Examples of the colloidal silica-containing acrylic resin emulsion include those described in JP-B-59-152972.

[0009]

However, this coating agent, like other aqueous coating agents, has a poor drying property. To completely dry the coated film and form a strong film, For example, 60 ° C,
A long drying time such as 5 to 6 hours is required. If drying is performed under a high temperature condition of, for example, 60 ° C. for one hour in order to shorten the drying time, there is a problem that cracks are apt to be generated when forming a film (hereinafter, referred to as film formation or film formation). If the coating film is severely cracked, the appearance will be significantly impaired.If the cracks are slight, the presence of cracks may not be confirmed by visual inspection. Therefore, there is a problem that the water resistance of the coating film is remarkably reduced because moisture easily penetrates from the surface.

The cause of cracks during the dry film formation is liable to be caused not only by the drying temperature but also by the properties of the medium to be coated. For example, media for ink jet printers are classified into two types called swelling type and porous type according to the difference in the properties of the ink receiving surface coat layer of the medium. It is known that swelling media can print out higher quality images than porous media.However, if an aqueous coating agent is used for the swelling media, coating can be performed even when dry film formation is performed at low temperature. There is a problem that the coating is apt to crack.

A first object of the present invention is to solve these problems and provide an aqueous coating composition capable of obtaining a coating film having excellent water resistance without cracking under any drying conditions and media. It is to provide.

In the conventional laminating process using a plastic film, since the image surface after lamination is covered with the plastic film, light reflection occurs, and the image cannot be viewed depending on the viewing angle. It was easy to be difficult. Also, when the above-mentioned organic solvent type or water solvent type resin emulsion coating agent is used, there is a problem that similar light reflection is apt to occur due to the generation of gloss peculiar to the resin. For this reason, there is often a need for a so-called mattable coating agent that can provide a matting effect while suppressing light reflection while adding water resistance.

As a method of imparting a matting effect to a coating agent, a method of adding a filler is known. However, when a filler is added to the above-mentioned colloidal silica-containing acrylic resin emulsion, the matting effect is certainly enhanced. There is a problem that the occurrence of cracks at the time of dry film formation is significantly increased as compared with the case where no filler is added.

Accordingly, a second object of the present invention is to provide an aqueous coating agent capable of performing a matting process while suppressing the reflection of light on the surface, and particularly, even when a filler is added to enhance the matting effect. Another object of the present invention is to provide an aqueous coating composition which does not easily crack.

The coating agent can be quickly and simply applied by using a device such as a coater. However, the aqueous coating agent which has been known so far can be applied by using a roller coater or the like. In addition, there is a problem that coating unevenness in which a trace of a roller remains in a streak shape easily occurs. Furthermore, since the obtained coating film is liable to be scratched due to friction or the like, when it is used in a restaurant menu, it is immediately full of scratches, and there is a problem that the appearance is impaired.

Accordingly, a third object of the present invention is to solve these problems and to provide no coating unevenness by any coating method, and the obtained coating film is strong and hard to be damaged. An object of the present invention is to provide an aqueous coating composition from which a coating film having high scratch resistance can be easily obtained.

[0017]

The present invention is an aqueous type which does not contain a highly volatile organic solvent by containing a colloidal silica-containing acrylic resin emulsion and a compound represented by the following general formula (1). While not destroying the image produced using the aqueous ink, it is possible to impart water resistance to the image, and regardless of the application method, drying conditions and media, it has excellent water resistance without cracking A coating is an aqueous coating composition from which a coating can be obtained. General formula (1)

Embedded image A in the formula is

Embedded image

Embedded image

Embedded image And n represents an integer of 1 to 3. Also, R ₁
And R ₂ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an acyl group having 1 to 4 carbon atoms, or a glycidyl group. (However,
Except when R ₁ and R ₂ are simultaneously a hydrogen atom. )

Further, even when an acrylic filler is added for the purpose of obtaining a matting effect on the aqueous coating composition, the aqueous coating composition contains an aqueous vinyl acetate polymer emulsion and / or polyethylene glycol to prevent cracking during dry film formation. An aqueous coating composition that can provide a coating film having a high matting effect without being generated, and is less likely to cause uneven coating even when applied using a coater or the like, and a strong coating film having excellent scratch resistance is obtained. is there.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous coating composition of the present invention can be used not only for images output using an ink jet printer, but also for paintings, photographs, characters, etc. prepared using a broadly defined aqueous ink containing paints, ink, etc. It can provide water resistance and matte effect to the image of the same, and can provide the same effect to the aqueous ink image drawn on a substrate such as cloth, glass, and plastic other than paper. .

The colloidal silica-containing acrylic resin emulsion used in the present invention is an aqueous emulsion obtained by further dispersing colloidal silica in an aqueous acrylic resin emulsion in which an acrylic resin is dispersed in water. The acrylic resin used here is acrylic acid,
It is a polymer or a copolymer mainly composed of a compound selected from acrylate, acrylamide, acrylonitrile, methacrylic acid and methacrylate alone or as a mixture. The aqueous acrylic resin emulsion can be obtained by dispersing the acrylic resin obtained by polymerization in water using a device such as a disperser or a mixer, or by synthesizing the acrylic resin by emulsion polymerization in water. be able to.

As the colloidal silica, a colloidal aqueous dispersion of silicon dioxide or a hydrate thereof can be used. A colloidal silica-containing acrylic resin emulsion can be prepared from these aqueous acrylic resin emulsion and colloidal silica by a known method. For example, a type in which colloidal silica is dispersed in an acrylic resin emulsion obtained by copolymerizing vinyl silane,
It can be adjusted using the method described in JP-A-59-152972. A type in which colloidal silica is dispersed in an acrylic resin emulsion and tetramethoxysilane is added is described in JP-A-10-7940. And a type in which a colloidal silica obtained by reacting an organosilicon compound with an acrylic resin emulsion having a hydrolyzable organosiloxane terminal is dispersed is described in JP-A-9-59568. It is possible to adjust using the method.

When these emulsions have an MFT (minimum film forming temperature) adjusted to <O ° C. by adding a plasticizer or the like, an aqueous coating composition having an excellent dry film forming rate can be obtained. ,preferable. (MFT is JIS
Can be measured by the method described in K6828 5.11. It is also possible to obtain a commercially available colloidal silica-containing acrylic resin emulsion which has been prepared. For example, "Movinyl 8020" and "Movinyl 8030" from Clariant Polymer Co., Ltd. (Movinyl is Clariant, Gezenshaft, Mitt). , Peschlenktel, a registered trademark of Hubring) can be preferably used.

The compound represented by the general formula (1) is added to the aqueous coating composition of the present invention as a film-forming aid. This makes it possible to obtain a coating film free from cracks regardless of the conditions for dry film formation and the properties of the medium to be applied. General formula (1)

Embedded image A in the formula is

Embedded image

Embedded image

Embedded image

In the above formula (1), n represents an integer of 1 to 3, and R ₁ and R ₂ may be the same or different from each other, and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,
Represents an acyl group having 1 to 4 carbon atoms or a glycidyl group. (However, this excludes the case where R ₁ and R ₂ are simultaneously hydrogen atoms.)

Specific examples of the compound represented by the general formula (1) include ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-t-butyl ether,
Ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether,
Glycol ethers such as diethylene glycol mono-n-butyl ether, diethylene glycol di-n-butyl ether, triethylene glycol monoethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monobutyl ether; Glycol esters such as ethylene glycol monoacetate, ethylene glycol diacetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol diacetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; Ethylene glycol jig Ethers, diethylene glycol diglycidyl ether, etc. glycol glycidyl ethers such as tetraethylene glycol butyl glycidyl ether.

Of these, diethylene glycol mono-n-butyl ether can be particularly preferably used from the viewpoint of the stability of the coating composition over time. If the amount of diethylene glycol mono-n-butyl ether is too large, the obtained coating film tends to be sticky, and if the amount is small, fine cracks are generated in the coating film at the time of dry film formation, leading to deterioration of water resistance. . Therefore, the addition amount of diethylene glycol mono-n-butyl ether is preferably 1 part to 30 parts, and particularly preferably 5 parts to 15 parts with respect to 100 parts of the colloidal silica-containing acrylic resin emulsion.

The aqueous coating composition of the present invention contains a vinyl acetate polymer emulsion and / or polyethylene glycol for the purpose of obtaining a coating film free from cracks without deteriorating the film-forming properties even when a filler is added. Is done. When aqueous coating compositions are prepared without adding fillers, they act as mild matting agents. The use of a vinyl acetate polymer emulsion has a higher matting effect than the one using polyethylene glycol, but the coating composition using polyethylene glycol is harder to coagulate and can be used stably for a longer period of time. it can.

The aqueous vinyl acetate polymer emulsion used in the present invention is an aqueous emulsion obtained by dispersing a vinyl acetate polymer or a vinyl acetate copolymer in water. The aqueous vinyl acetate polymer emulsion can be obtained by a known method such as dispersing the polymer or copolymer in water using a device such as a disperser or a mixer, or by emulsion polymerization in water. For example, an aqueous emulsion of a vinyl acetate polymer is disclosed in
1-188411 and U.S. Pat. No. 2,398,34.
No. 4,043,916 and US Pat. No. 4,133,7. The aqueous emulsion of vinyl acetate / ethylene copolymer can be prepared by the method described in the specification of US Pat.
It can be adjusted by the method described in the specification of JP-A No. 19.

When the aqueous vinyl acetate polymer emulsion is used whose MFT (minimum film forming temperature) is adjusted to <O ° C. by adding a plasticizer such as dibutyl phthalate, the dry film forming speed is excellent. An aqueous coating composition can be obtained and is preferred. (MFT is JIS K
It can be measured by the method described in 6828 5.11. As the aqueous vinyl acetate polymer emulsion adjusted to MFT <O ° C., a commercially available product can be obtained. For example, a product commercially available as “Movinyl 506” from Clariant Polymer Co., Ltd. is preferably used. can do.

If the amount of the aqueous vinyl acetate polymer emulsion is large, the emulsion is likely to solidify or become highly viscous, resulting in inferior stability of the coating composition over time or the addition of polyvinyl alcohol as an emulsifier to the vinyl acetate polymer emulsion. In such cases, the water resistance of the coating film obtained tends to be reduced due to the influence. For this reason, the addition amount of the aqueous vinyl acetate polymer emulsion is preferably 1 part to 30 parts, and particularly preferably 5 parts to 15 parts based on 100 parts of the colloidal silica-containing acrylic resin emulsion.

As the polyethylene glycol used in the present invention, those having an average molecular weight of 2,000 or more can be used, and those having an average molecular weight of 4,000 or more can be preferably used from the viewpoint of improving water resistance. If the added amount of polyethylene glycol is also large, the prepared aqueous coating composition tends to coagulate or become highly viscous, so that the colloidal silica-containing acrylic resin emulsion 1
The amount of polyethylene glycol added to 00 parts is
The addition of 0.5 to 2.0 parts is preferable, and the addition of 0.8 to 1.2 parts is particularly preferable from the viewpoint of hardly coagulating and showing an appropriate matting effect.

By adding a filler to the aqueous coating composition of the present invention, a coating film having a higher matting effect can be obtained. When only a filler is added to the colloidal silica-containing acrylic resin emulsion, a crack occurs in the coating film at the time of dry film formation, which causes a significant decrease in water resistance.However, the aqueous coating composition of the present invention is an aqueous vinyl acetate polymer emulsion and By containing polyethylene glycol, a coating film excellent in water resistance without cracking can be obtained even when a filler is added. Moreover, due to the synergistic effect of the filler and the aqueous vinyl acetate polymer emulsion and / or polyethylene glycol, it is possible to prevent the coating unevenness that tends to occur when applying using a device such as a roller coater, and at the same time, the obtained coating film has scratch resistance. The effect that the property is improved is also obtained.

As the filler used in the present invention, commercially available acrylic fillers, resin fillers, glass bubble fillers, calcium carbonate fillers, hollow vinylidene chloride fillers, silica fillers and the like can be used. Among these, acrylic fillers can be particularly preferably used because they are uniformly dispersed in the aqueous coating composition, and the resulting coating film has a matte effect and does not have a rough surface. When the particle size of the acrylic filler used is large, irregularities are recognized on the surface of the obtained coating film, so that the surface becomes rough and the appearance is impaired. When the particle size is 0.8 μm or less, the matting effect is hardly observed, and the effect of improving the scratch resistance of the coating film and preventing the occurrence of uneven coating is not recognized. For this reason, the acrylic filler used in the aqueous coating composition of the present invention preferably has a particle size of 1 μm to 50 μm, and particularly preferably 5 μm to 10 μm.
As the acrylic filler having these particle sizes, for example, those commercially available as MR series from Soken Chemical Co., Ltd. can be preferably used.

The aqueous coating composition of the present invention comprises
Further, by adding a normal acrylic resin emulsion containing no colloidal silica, particularly a soap-free acrylic resin emulsion, the water resistance of the obtained coating film can be further improved. The soap-free referred to here refers to an emulsion obtained by emulsion polymerization without the presence of a surfactant, and is commercially available under a name such as a soap-free acrylic resin emulsion or a soapless acrylic resin emulsion. It is possible. As commercially available products, LA-723J1 manufactured by Clariant Polymer Co., Ltd. and HD-1, HD-5, A-104 manufactured by Toagosei Co., Ltd. can be preferably used.

The addition of such a soap-free acrylic resin emulsion not only improves the water resistance in the sense that the time from the attachment of moisture to the coating film until the film is melted is improved, and the coating film is improved. Can also be enhanced in water repellency. For this reason, the coating film itself has the property of repelling water, and in actual use, it is more effective for protecting the image than simply improving the water resistance. The addition of the acrylic resin emulsion is effective in an amount of 10 to 40 parts based on 100 parts of the colloidal silica-containing acrylic resin emulsion. If the amount added is more than this, the water repellency of the coating composition itself becomes too strong, and it tends to cause a problem that the coating composition breaks during application and becomes difficult to apply.

The aqueous coating composition of the present invention can be prepared by adding and dispersing each component in the following order while stirring using a disperser, a homogenizer, a mixer or the like. First, an aqueous vinyl acetate polymer emulsion is added to a colloidal silica-containing acrylic resin emulsion serving as a base while stirring, and the mixture is further stirred and sufficiently dispersed to obtain a liquid A. Separately, an acrylic filler was added to diethylene glycol mono-n-butyl ether and thoroughly stirred and dispersed.
Prepare as a liquid. Then add solution B to solution A and stir,
By sufficiently mixing and dispersing, the aqueous coating composition of the present invention can be prepared. With such a mixing order, coagulation of the emulsion which is generated when the aqueous vinyl acetate polymer emulsion and diethylene glycol mono-n-butyl ether are directly mixed can be prevented.

When preparing an aqueous coating composition containing polyethylene glycol, polyethylene glycol was added to diethylene glycol mono-n-butyl ether, stirred and dissolved, and an acrylic filler was added thereto and sufficiently stirred and dispersed. The solution is prepared separately as a solution B, and the solution B is added to the solution A or the colloidal silica-containing acrylic resin emulsion alone, stirred, and thoroughly mixed and dispersed to prepare an aqueous coating composition. Is easy to dissolve.

The aqueous coating composition containing these acrylic fillers can be used as a mat type having a high matting effect of the resulting coating film. However, a semi-mat type aqueous coating composition having a lower matting effect can be used. If desired, a semi-mat type can be obtained by removing the acrylic filler and making the same adjustment. Although this semi-mat type aqueous coating composition has no effect of completely preventing uneven coating generated by a roller coater or the like, it is useful as a semi-mat type aqueous coating composition used in other application methods.

Another form of the present invention is an aqueous coating composition in which only diethylene glycol mono-n-butyl ether is added to a colloidal silica-containing acrylic resin emulsion and sufficiently stirred and dispersed. This composition does not have a matting effect at all, but it does not dissolve or destroy the aqueous ink image at the time of application, and has an excellent effect of preventing cracking at the time of dry film formation. It is useful as an agent or a coating agent for imparting water resistance.

The aqueous coating composition of the present invention may contain, in addition to the above components, an ultraviolet ray inhibitor (such as a benzotriazole derivative), a viscosity modifier, a preservative, an antioxidant, an antistatic agent, and other commonly used ingredients. An appropriate amount of an additive may be contained as needed. When a low water-soluble one of these additives is added to the aqueous coating composition of the present invention, it is easily adjusted by dissolving it in diethylene glycol mono-n-butyl ether and then adding it to the emulsion. desirable.

As a method of applying the aqueous coating composition on an image, a method of applying using a coater such as a bar coater or a roller coater, a method of spraying using a spray, a hand coating using a brush or the like, and a dipping method A method or the like can be used. For an image formed on a flat medium such as paper or cloth, a method of applying with a coater is preferable because it can be easily and uniformly applied, but in the case of an image formed on a three-dimensional object such as a cup, It is possible to impart water resistance by spraying the aqueous coating composition of the present invention with a spray or the like.

As a method for drying the coating composition added on the image, a general drying method such as blast drying or drying by heat irradiation using an infrared heater or the like may be used in addition to drying by leaving it to stand naturally. it can. In the case of drying by heat irradiation, the coating surface dries in a drying time of several tens of seconds and does not become sticky even when held by hand, so-called handling is possible, but to obtain a coating film excellent in water resistance. It is necessary to dry completely and form a film sufficiently. For this reason, drying at 60 ° C. for about 1 hour is recommended. Further, after the medium is coated with heat irradiation and dried for several tens of seconds to be ready for handling,
It is also possible to take a method of leaving the film naturally for about 24 hours to complete the film formation.

[0043]

Next, an embodiment of the present invention will be described specifically. The aqueous coating compositions of Examples 1 to 9 and Comparative Examples 1 to 7 were prepared by the methods described below. In addition, the part in an example shows a weight part.

Example 1 100 parts of Movinyl 8020 (a colloidal silica-containing acrylic resin emulsion manufactured by Clariant Polymer Co., Ltd., Movinyl is a trademark) was used as solution A, and diethylene glycol mono-n-butyl ether (DEGMBE) was used while stirring solution A. Abbreviated.)
10 parts were added and further stirred until sufficiently dispersed to obtain a coating composition.

Example 2 Movinyl 8020, 100
Part of the solution A, 10 parts of diethylene glycol methyl ether acetate was added while the solution A was stirred, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

[Embodiment 3] Movinyl 8020, 100
To the mixture, add 10 parts of Movinyl 506 and further stir the mixture to obtain a fully dispersed solution A.
EGMBE (10 parts) was added, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Embodiment 4 Movinyl 8020, 100
Part as liquid A, and 10 parts of DEGMBE with an average molecular weight of 400.
A solution prepared by dissolving 1 part of polyethylene glycol (hereinafter abbreviated as PEG # 4000) is designated as solution B. Liquid B was added while stirring liquid A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Example 5 Movinyl 8020, 100
Part as solution A, and 10 parts of DEGMBE with PEG # 400.
0 and 1 part were dissolved, and 4 parts of MR-10G (acrylic filler manufactured by Soken Chemical Co., Ltd., particle size 9 μm) was further added and stirred. Liquid B was added while stirring liquid A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Embodiment 6 Movinyl 8020, 100
Add 10 parts of Movinyl 506 to 10 parts and further stir, and fully disperse it as liquid A. Add 10 parts of MR-10G to 10 parts of DEGMBE, stir and fully disperse it as liquid B. I do. Add solution B while stirring solution A,
The mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Example 7 Movinyl 8020, 100
30 parts of LA-723J1 (acrylic resin emulsion, soap-free type, manufactured by Clariant Polymer Co., Ltd.) was added to the mixture, and the mixture was stirred. The mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Example 8 Movinyl 8020, 100
Add LA-723J1 (30 parts) to the mixture, stir and sufficiently disperse the solution A, and add 10 parts of DEGMBE to MR.
Add -10 G, 4 parts, stir, and sufficiently disperse to obtain Liquid B. Liquid B was added while stirring liquid A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

[Embodiment 9] Movinyl 8020, 100
To 30 parts of LA-723J1, 30 parts of LA-723J was added and stirred to sufficiently disperse. Further, 10 parts of Movinyl 506 were added and stirred, and the mixture was sufficiently dispersed to obtain a liquid A. DEGMBE
To 10 parts, add 4 parts of MR-10G, stir, and sufficiently disperse to obtain Liquid B. Liquid B was added while stirring liquid A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Comparative Example 1 A coating composition was used without any addition to Movinyl 8020.

Comparative Example 2 A coating composition was used as it was without adding anything to Movinyl.

Comparative Example 3 Movinyl 8020, 100
Part of solution A, 10 parts of diethylene glycol was added while stirring solution A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

[Comparative Example 4] Movinyl 8020, 100
Part of solution A, 10 parts of hexylene glycol was added while stirring solution A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

Comparative Example 5 Movinyl 8020, 100
Part is liquid A, and while stirring liquid A, movinyl 506,
10 parts were added and further stirred until sufficiently dispersed to obtain a coating composition.

Comparative Example 6 Movinyl 8020, 100
Part to liquid A, and 10 parts of DEGMBE to MR-10G, 4 parts.
The mixture was added and stirred, and fully dispersed to obtain a liquid B. Liquid B was added while stirring liquid A, and the mixture was further stirred until it was sufficiently dispersed to obtain a coating composition.

[Comparative Example 7] Movinyl 8020, 100
While stirring, add 10 parts of Movinyl 506 and further stir, and fully disperse the mixture into Liquid A.
R-10G (4 parts) was added, and the mixture was further stirred until sufficiently dispersed to obtain a coating composition.

The compositions of Examples 1 to 9 and Comparative Examples 1 to 7 are listed in Table 1. The performance tests shown below were performed using these coating compositions.

[Stability test] Each coating agent was put in a poly bottle, sealed, and allowed to stand at room temperature for 30 days to observe the change of the coating composition and evaluate the stability of the composition. Table 1 shows the test results. Stability test results ：: No change to liquid at all after 30 days. Δ: Coagulated or significantly increased in viscosity within 15 days, and could not be used. ×: Coagulation or extremely high viscosity within one day, making it unusable.

As shown in Table 1, when the compound represented by the general formula (1) of the present invention was added to the colloidal silica-containing acrylic resin emulsion, the coating composition was obtained without impairing the stability. It is understood that the water resistance of the coating film can be improved.

[Preparation of Evaluation Samples] Coating performance tests described below were performed on samples having no problem in the stability test. Using an inkjet printer (MJ-930C manufactured by Epson), yellow, magenta, and cyan are output on an inkjet output paper (HG-101 manufactured by Canon) so that each of the yellow, magenta, and cyan colors has a solid surface of 10 mm × 10 mm. An image material for evaluation was used. Each of the coating compositions was uniformly applied on the output surface of this image material using a kiss coater type roller coater (application roller diameter: 30 mm, rotation speed: 19.5 rpm, conveyance speed: 13.8 m / min). The coating was repeated three times as described above, and dried in a dryer at 60 ° C. for 1 hour to obtain a coating sample. The weight of each of these coating samples before and after application of the coating composition was measured, and only those having a coating amount of 7.0 g / m ² ± 0.2 g were selected as evaluation samples. (At this time, the thickness of the obtained coating film is about 7 μm.)

Using the evaluation sample thus prepared, the following tests were performed to evaluate the performance of the coating film obtained from each coating composition. still,
In each test, each coating composition was tested using 10 evaluation samples, and the average value was taken as the result value. Table 1 shows the test results.

[Evaluation of Film Formability of Coating Film] The surface of the coating film of each evaluation sample was visually inspected for cracks or irregularities, and the surface of the film was touched with the hand to make it sticky. It was evaluated whether or not a film formation defect occurred. Evaluation of film forming properties ○: No cracks or the like can be visually observed. Δ: There are fine cracks on the coating surface. ×: Severe cracks impairing the appearance are found on the coating surface. Alternatively, the coating is sticky.

[Evaluation of coating unevenness] The coating film of each evaluation sample was observed, and the occurrence of coating unevenness was examined. Evaluation of coating unevenness ：: No coating unevenness occurred. Δ: Slight coating unevenness was observed, which was indistinguishable if not carefully observed. ×: Streak-like coating unevenness was observed.

[Water Resistance Test of Coating Film] A drop of water was dropped on the coating film with a dropper, and the time from when the water droplets adhered to when the coating film was destroyed and a portion where the image was melted into a pinhole was formed. The measurement was performed to evaluate the water resistance of the coating film. Evaluation of water resistance A: 10 minutes or more until film destruction and image dissolution. ：: 5 minutes or more until film destruction and image elution. Δ: 5 minutes or less until film destruction and image elution. ×: The film was destroyed and the image was eluted within 30 seconds after the water droplet was dropped.

[Coating film strength test] The strength of each coating film is determined by measuring the pencil scratching value using the pencil scratching value and the handwriting method described in 8.4.2 of JIS K5400 (1990). An evaluation was performed. Evaluation of coating strength ○: The scratch value of the pencil is HB or more. Δ: Pencil scratch value is B or more. X: The scratch value of the pencil is B or less.

[Confirmation of matting effect] The evaluation sample was placed horizontally, and 45 mm was placed on the coating surface from the front of the evaluation sample.
A fluorescent lamp was installed so that the light hit at an angle of degree, and the degree of reflection of light was visually observed at a position 135 degrees from the coating surface behind the evaluation sample to evaluate the matting effect of the coating film. Evaluation of matting effect ：: There is no light reflection, and the shape of the fluorescent lamp cannot be confirmed.
(Excellent matting effect.) Δ: Reflects light, but hardly confirms the shape of the fluorescent lamp. (There is a matting effect.) ×: Strong light reflection, and the shape of the fluorescent lamp can be clearly confirmed. (No matte effect.)

[0070]

[Table 1] Movinyl 8020: Colloidal silica-containing acrylic resin emulsion (manufactured by Clariant Polymer Co., Ltd.) DEGMBE: diethylene glycol mono-n-butyl ether (compound of general formula (1)) EGME acetate: ethylene glycol methyl ether acetate (general formula (1) Compound) Movinyl 506: aqueous vinyl acetate polymer emulsion (manufactured by Clariant Polymer Co., Ltd.) PEG # 4000: polyethylene glycol (average molecular weight: 4000) MR-10G: acrylic filler, particle size 9 μm (manufactured by Soken Chemical Co., Ltd.) LA-723J1: Soap-free acrylic resin emulsion (Clariant Polymer Co., Ltd.)

As shown in Table 1, when the colloidal silica-containing acrylic resin emulsion is used alone as a coating agent as in Comparative Example 1, cracks are liable to occur at the time of dry film formation, not only deteriorating the appearance but also deteriorating the appearance. The water resistance was poor, and it was not practical. Further, when the vinyl acetate polymer emulsion was used alone as in Comparative Example 2,
Although no cracks occurred during the dry film formation, the resulting coating film was tacky and the water resistance of the film was poor.

Further, as in Comparative Examples 3 and 4, glycols generally known as film-forming aids are added to the colloidal silica-containing acrylic resin emulsion.
Since the emulsion solidifies or becomes extremely viscous in a short time, it must be adjusted each time it is used as a coating agent.

On the other hand, as shown in Examples 1 and 2, the aqueous coating composition of the present invention in which the compound of the general formula (1) is added to the colloidal silica-containing acrylic resin emulsion has almost no emulsion stability. It was possible to obtain a coating film having no damage, no cracks during dry film formation, and improved water resistance. In particular, when the compound of the general formula (1) is diethylene glycol mono-n-butyl ether as in Example 1, the stability of the emulsion is not impaired at all.

Further, a semi-mat type of which the reflection of light on the surface of the coating film is reduced by further adding a vinyl acetate polymer emulsion as in Example 3 or by further adding polyethylene glycol as in Example 4. A coating composition having a matting effect can be obtained.
On the other hand, when only the vinyl acetate polymer emulsion is added to the colloidal silica-containing acrylic resin emulsion without containing the compound of the general formula (1) as in Comparative Example 5, although the matting effect is obtained, Water resistance was remarkably poor.

In Comparative Example 6, in which only the acrylic filler was added to the coating composition of Example 1, the unexpected result was that the water resistance and the film strength deteriorated despite the addition of the acrylic filler. . On the other hand, in Examples 5 and 6 in which an acrylic filler was further added to the coating compositions of Examples 3 and 4 containing the compound of the general formula (1), the water resistance and strength of the coating film (scratch resistance) The matting effect was further improved, and a very excellent coating film could be obtained. Example 7
As shown in Nos. 9 to 10, an acrylic resin emulsion containing no colloidal silica, especially a soap-free type acrylic resin emulsion, was added to obtain a water-repellent type coating composition, and a coating film having particularly excellent water resistance was obtained. I was able to.

[0076]

As described above, claims 1 and 2 of the present invention.
According to the method, the aqueous coating composition is an aqueous type that has a low odor and a low load on the environment, but does not destroy the image even when applied on an aqueous ink image, and also causes cracking during dry film formation. As a result, a coating film having excellent water resistance can be obtained.

Further, according to the third and fourth aspects, in addition to the above, it has a matting effect of suppressing the reflection of light on the surface of the coating film, so that it is possible to prevent the coated image from being difficult to see. Have.

According to claim 5, claims 1, 2, 2,
In addition to the effects of 3 and 4, the coating film itself has the property of repelling water, which is more effective for protecting images than improving water resistance.

According to claims 6 and 7, in addition to the above, not only a strong coating film having excellent scratch resistance can be obtained, but also coating unevenness occurs even when applied using a coater or the like. Because there is no, water resistance, matte effect easily,
It is possible to apply a coating having excellent scratch resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C09D 171/02 C09D 171/02 F-term (Reference) 2H086 BA31 BA33 BA35 BA36 4J038 CD022 CF022 CG031 CG141 CG142 CG161 CG171 EA012 HA286 HA446 HA486 JA26 JA27 JA57 KA08 KA20 KA21 MA08 MA10 NA01 NA04 NA11 NA24 PB11 PC10

Claims (7)

[Claims] An aqueous coating composition comprising a colloidal silica-containing acrylic resin emulsion and a compound represented by the following general formula (1). General formula (1) A in the formula is Embedded image Embedded image And n represents an integer of 1 to 3. Also, R ₁
And R ₂ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an acyl group having 1 to 4 carbon atoms, or a glycidyl group. (However,
Except when R ₁ and R ₂ are both hydrogen atoms. ) 2. The aqueous coating composition according to claim 1, wherein the compound represented by the general formula (1) is diethylene glycol mono-n-butyl ether. 3. The aqueous coating composition according to claim 1, which comprises an aqueous vinyl acetate polymer emulsion. 4. The aqueous coating composition according to claim 1, which comprises polyethylene glycol. 5. The aqueous coating composition according to claim 1, further comprising an acrylic resin emulsion. 6. The aqueous coating composition according to claim 3, further comprising a filler. 7. The aqueous coating composition according to claim 6, wherein the filler is an acrylic filler.